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2018-05-29kconfig: reference environment variables directly and remove 'option env='Masahiro Yamada
To get access to environment variables, Kconfig needs to define a symbol using "option env=" syntax. It is tedious to add a symbol entry for each environment variable given that we need to define much more such as 'CC', 'AS', 'srctree' etc. to evaluate the compiler capability in Kconfig. Adding '$' for symbol references is grammatically inconsistent. Looking at the code, the symbols prefixed with 'S' are expanded by: - conf_expand_value() This is used to expand 'arch/$ARCH/defconfig' and 'defconfig_list' - sym_expand_string_value() This is used to expand strings in 'source' and 'mainmenu' All of them are fixed values independent of user configuration. So, they can be changed into the direct expansion instead of symbols. This change makes the code much cleaner. The bounce symbols 'SRCARCH', 'ARCH', 'SUBARCH', 'KERNELVERSION' are gone. sym_init() hard-coding 'UNAME_RELEASE' is also gone. 'UNAME_RELEASE' should be replaced with an environment variable. ARCH_DEFCONFIG is a normal symbol, so it should be simply referenced without '$' prefix. The new syntax is addicted by Make. The variable reference needs parentheses, like $(FOO), but you can omit them for single-letter variables, like $F. Yet, in Makefiles, people tend to use the parenthetical form for consistency / clarification. At this moment, only the environment variable is supported, but I will extend the concept of 'variable' later on. The variables are expanded in the lexer so we can simplify the token handling on the parser side. For example, the following code works. [Example code] config MY_TOOLCHAIN_LIST string default "My tools: CC=$(CC), AS=$(AS), CPP=$(CPP)" [Result] $ make -s alldefconfig && tail -n 1 .config CONFIG_MY_TOOLCHAIN_LIST="My tools: CC=gcc, AS=as, CPP=gcc -E" Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Reviewed-by: Kees Cook <keescook@chromium.org>
2018-04-30Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparcLinus Torvalds
- Fixup license text for oradax driver, from Rob Gardner. - Release device object with put_device() instead of straight kfree(), from Arvind Yadav. * git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc: sparc: vio: use put_device() instead of kfree() sparc64: Fix mistake in oradax license text
2018-04-30sparc: vio: use put_device() instead of kfree()Arvind Yadav
Never directly free @dev after calling device_register(), even if it returned an error. Always use put_device() to give up the reference initialized. Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-04-30sparc64: Fix mistake in oradax license textRob Gardner
The license text in both oradax files mistakenly specifies "version 3" of the GNU General Public License. This is corrected to specify "version 2". Signed-off-by: Rob Gardner <rob.gardner@oracle.com> Signed-off-by: Jonathan Helman <jonathan.helman@oracle.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-04-15Merge tag 'kbuild-v4.17-2' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild Pull more Kbuild updates from Masahiro Yamada: - pass HOSTLDFLAGS when compiling single .c host programs - build genksyms lexer and parser files instead of using shipped versions - rename *-asn1.[ch] to *.asn1.[ch] for suffix consistency - let the top .gitignore globally ignore artifacts generated by flex, bison, and asn1_compiler - let the top Makefile globally clean artifacts generated by flex, bison, and asn1_compiler - use safer .SECONDARY marker instead of .PRECIOUS to prevent intermediate files from being removed - support -fmacro-prefix-map option to make __FILE__ a relative path - fix # escaping to prepare for the future GNU Make release - clean up deb-pkg by using debian tools instead of handrolled source/changes generation - improve rpm-pkg portability by supporting kernel-install as a fallback of new-kernel-pkg - extend Kconfig listnewconfig target to provide more information * tag 'kbuild-v4.17-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: kconfig: extend output of 'listnewconfig' kbuild: rpm-pkg: use kernel-install as a fallback for new-kernel-pkg Kbuild: fix # escaping in .cmd files for future Make kbuild: deb-pkg: split generating packaging and build kbuild: use -fmacro-prefix-map to make __FILE__ a relative path kbuild: mark $(targets) as .SECONDARY and remove .PRECIOUS markers kbuild: rename *-asn1.[ch] to *.asn1.[ch] kbuild: clean up *-asn1.[ch] patterns from top-level Makefile .gitignore: move *-asn1.[ch] patterns to the top-level .gitignore kbuild: add %.dtb.S and %.dtb to 'targets' automatically kbuild: add %.lex.c and %.tab.[ch] to 'targets' automatically genksyms: generate lexer and parser during build instead of shipping kbuild: clean up *.lex.c and *.tab.[ch] patterns from top-level Makefile .gitignore: move *.lex.c *.tab.[ch] patterns to the top-level .gitignore kbuild: use HOSTLDFLAGS for single .c executables
2018-04-13mm/gup.c: document return valueMichael S. Tsirkin
__get_user_pages_fast handles errors differently from get_user_pages_fast: the former always returns the number of pages pinned, the later might return a negative error code. Link: http://lkml.kernel.org/r/1522962072-182137-6-git-send-email-mst@redhat.com Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Thorsten Leemhuis <regressions@leemhuis.info> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11exec: pass stack rlimit into mm layout functionsKees Cook
Patch series "exec: Pin stack limit during exec". Attempts to solve problems with the stack limit changing during exec continue to be frustrated[1][2]. In addition to the specific issues around the Stack Clash family of flaws, Andy Lutomirski pointed out[3] other places during exec where the stack limit is used and is assumed to be unchanging. Given the many places it gets used and the fact that it can be manipulated/raced via setrlimit() and prlimit(), I think the only way to handle this is to move away from the "current" view of the stack limit and instead attach it to the bprm, and plumb this down into the functions that need to know the stack limits. This series implements the approach. [1] 04e35f4495dd ("exec: avoid RLIMIT_STACK races with prlimit()") [2] 779f4e1c6c7c ("Revert "exec: avoid RLIMIT_STACK races with prlimit()"") [3] to security@kernel.org, "Subject: existing rlimit races?" This patch (of 3): Since it is possible that the stack rlimit can change externally during exec (either via another thread calling setrlimit() or another process calling prlimit()), provide a way to pass the rlimit down into the per-architecture mm layout functions so that the rlimit can stay in the bprm structure instead of sitting in the signal structure until exec is finalized. Link: http://lkml.kernel.org/r/1518638796-20819-2-git-send-email-keescook@chromium.org Signed-off-by: Kees Cook <keescook@chromium.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Ben Hutchings <ben@decadent.org.uk> Cc: Willy Tarreau <w@1wt.eu> Cc: Hugh Dickins <hughd@google.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: "Jason A. Donenfeld" <Jason@zx2c4.com> Cc: Rik van Riel <riel@redhat.com> Cc: Laura Abbott <labbott@redhat.com> Cc: Greg KH <greg@kroah.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Ben Hutchings <ben.hutchings@codethink.co.uk> Cc: Brad Spengler <spender@grsecurity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-07Merge branch 'misc.sparc' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull sparc syscall cleanups from Al Viro: "sparc syscall stuff - killing pointless wrappers, conversions to {COMPAT_,}SYSCALL_DEFINE" * 'misc.sparc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: sparc: get rid of asm wrapper for nis_syscall() sparc: switch compat {f,}truncate64() to COMPAT_SYSCALL_DEFINE sparc: switch compat pread64 and pwrite64 to COMPAT_SYSCALL_DEFINE convert compat sync_file_range() to COMPAT_SYSCALL_DEFINE switch sparc_remap_file_pages() to SYSCALL_DEFINE sparc: get rid of memory_ordering(2) wrapper sparc: trivial conversions to {COMPAT_,}SYSCALL_DEFINE() sparc: bury a zombie extern that had been that way for twenty years sparc: get rid of remaining SIGN... wrappers sparc: kill useless SIGN... wrappers sparc: get rid of sys_sparc_pipe() wrappers
2018-04-07kbuild: mark $(targets) as .SECONDARY and remove .PRECIOUS markersMasahiro Yamada
GNU Make automatically deletes intermediate files that are updated in a chain of pattern rules. Example 1) %.dtb.o <- %.dtb.S <- %.dtb <- %.dts Example 2) %.o <- %.c <- %.c_shipped A couple of makefiles mark such targets as .PRECIOUS to prevent Make from deleting them, but the correct way is to use .SECONDARY. .SECONDARY Prerequisites of this special target are treated as intermediate files but are never automatically deleted. .PRECIOUS When make is interrupted during execution, it may delete the target file it is updating if the file was modified since make started. If you mark the file as precious, make will never delete the file if interrupted. Both can avoid deletion of intermediate files, but the difference is the behavior when Make is interrupted; .SECONDARY deletes the target, but .PRECIOUS does not. The use of .PRECIOUS is relatively rare since we do not want to keep partially constructed (possibly corrupted) targets. Another difference is that .PRECIOUS works with pattern rules whereas .SECONDARY does not. .PRECIOUS: $(obj)/%.lex.c works, but .SECONDARY: $(obj)/%.lex.c has no effect. However, for the reason above, I do not want to use .PRECIOUS which could cause obscure build breakage. The targets specified as .SECONDARY must be explicit. $(targets) contains all targets that need to include .*.cmd files. So, the intermediates you want to keep are mostly in there. Therefore, mark $(targets) as .SECONDARY. It means primary targets are also marked as .SECONDARY, but I do not see any drawback for this. I replaced some .SECONDARY / .PRECIOUS markers with 'targets'. This will make Kbuild search for non-existing .*.cmd files, but this is not a noticeable performance issue. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Acked-by: Frank Rowand <frowand.list@gmail.com> Acked-by: Ingo Molnar <mingo@kernel.org>
2018-04-06Merge tag 'pci-v4.17-changes' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci Pull PCI updates from Bjorn Helgaas: - move pci_uevent_ers() out of pci.h (Michael Ellerman) - skip ASPM common clock warning if BIOS already configured it (Sinan Kaya) - fix ASPM Coverity warning about threshold_ns (Gustavo A. R. Silva) - remove last user of pci_get_bus_and_slot() and the function itself (Sinan Kaya) - add decoding for 16 GT/s link speed (Jay Fang) - add interfaces to get max link speed and width (Tal Gilboa) - add pcie_bandwidth_capable() to compute max supported link bandwidth (Tal Gilboa) - add pcie_bandwidth_available() to compute bandwidth available to device (Tal Gilboa) - add pcie_print_link_status() to log link speed and whether it's limited (Tal Gilboa) - use PCI core interfaces to report when device performance may be limited by its slot instead of doing it in each driver (Tal Gilboa) - fix possible cpqphp NULL pointer dereference (Shawn Lin) - rescan more of the hierarchy on ACPI hotplug to fix Thunderbolt/xHCI hotplug (Mika Westerberg) - add support for PCI I/O port space that's neither directly accessible via CPU in/out instructions nor directly mapped into CPU physical memory space. This is fairly intrusive and includes minor changes to interfaces used for I/O space on most platforms (Zhichang Yuan, John Garry) - add support for HiSilicon Hip06/Hip07 LPC I/O space (Zhichang Yuan, John Garry) - use PCI_EXP_DEVCTL2_COMP_TIMEOUT in rapidio/tsi721 (Bjorn Helgaas) - remove possible NULL pointer dereference in of_pci_bus_find_domain_nr() (Shawn Lin) - report quirk timings with dev_info (Bjorn Helgaas) - report quirks that take longer than 10ms (Bjorn Helgaas) - add and use Altera Vendor ID (Johannes Thumshirn) - tidy Makefiles and comments (Bjorn Helgaas) - don't set up INTx if MSI or MSI-X is enabled to align cris, frv, ia64, and mn10300 with x86 (Bjorn Helgaas) - move pcieport_if.h to drivers/pci/pcie/ to encapsulate it (Frederick Lawler) - merge pcieport_if.h into portdrv.h (Bjorn Helgaas) - move workaround for BIOS PME issue from portdrv to PCI core (Bjorn Helgaas) - completely disable portdrv with "pcie_ports=compat" (Bjorn Helgaas) - remove portdrv link order dependency (Bjorn Helgaas) - remove support for unused VC portdrv service (Bjorn Helgaas) - simplify portdrv feature permission checking (Bjorn Helgaas) - remove "pcie_hp=nomsi" parameter (use "pci=nomsi" instead) (Bjorn Helgaas) - remove unnecessary "pcie_ports=auto" parameter (Bjorn Helgaas) - use cached AER capability offset (Frederick Lawler) - don't enable DPC if BIOS hasn't granted AER control (Mika Westerberg) - rename pcie-dpc.c to dpc.c (Bjorn Helgaas) - use generic pci_mmap_resource_range() instead of powerpc and xtensa arch-specific versions (David Woodhouse) - support arbitrary PCI host bridge offsets on sparc (Yinghai Lu) - remove System and Video ROM reservations on sparc (Bjorn Helgaas) - probe for device reset support during enumeration instead of runtime (Bjorn Helgaas) - add ACS quirk for Ampere (née APM) root ports (Feng Kan) - add function 1 DMA alias quirk for Marvell 88SE9220 (Thomas Vincent-Cross) - protect device restore with device lock (Sinan Kaya) - handle failure of FLR gracefully (Sinan Kaya) - handle CRS (config retry status) after device resets (Sinan Kaya) - skip various config reads for SR-IOV VFs as an optimization (KarimAllah Ahmed) - consolidate VPD code in vpd.c (Bjorn Helgaas) - add Tegra dependency on PCI_MSI_IRQ_DOMAIN (Arnd Bergmann) - add DT support for R-Car r8a7743 (Biju Das) - fix a PCI_EJECT vs PCI_BUS_RELATIONS race condition in Hyper-V host bridge driver that causes a general protection fault (Dexuan Cui) - fix Hyper-V host bridge hang in MSI setup on 1-vCPU VMs with SR-IOV (Dexuan Cui) - fix Hyper-V host bridge hang when ejecting a VF before setting up MSI (Dexuan Cui) - make several structures static (Fengguang Wu) - increase number of MSI IRQs supported by Synopsys DesignWare bridges from 32 to 256 (Gustavo Pimentel) - implemented multiplexed IRQ domain API and remove obsolete MSI IRQ API from DesignWare drivers (Gustavo Pimentel) - add Tegra power management support (Manikanta Maddireddy) - add Tegra loadable module support (Manikanta Maddireddy) - handle 64-bit BARs correctly in endpoint support (Niklas Cassel) - support optional regulator for HiSilicon STB (Shawn Guo) - use regulator bulk API for Qualcomm apq8064 (Srinivas Kandagatla) - support power supplies for Qualcomm msm8996 (Srinivas Kandagatla) * tag 'pci-v4.17-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci: (123 commits) MAINTAINERS: Add John Garry as maintainer for HiSilicon LPC driver HISI LPC: Add ACPI support ACPI / scan: Do not enumerate Indirect IO host children ACPI / scan: Rename acpi_is_serial_bus_slave() for more general use HISI LPC: Support the LPC host on Hip06/Hip07 with DT bindings of: Add missing I/O range exception for indirect-IO devices PCI: Apply the new generic I/O management on PCI IO hosts PCI: Add fwnode handler as input param of pci_register_io_range() PCI: Remove __weak tag from pci_register_io_range() MAINTAINERS: Add missing /drivers/pci/cadence directory entry fm10k: Report PCIe link properties with pcie_print_link_status() net/mlx5e: Use pcie_bandwidth_available() to compute bandwidth net/mlx5: Report PCIe link properties with pcie_print_link_status() net/mlx4_core: Report PCIe link properties with pcie_print_link_status() PCI: Add pcie_print_link_status() to log link speed and whether it's limited PCI: Add pcie_bandwidth_available() to compute bandwidth available to device misc: pci_endpoint_test: Handle 64-bit BARs properly PCI: designware-ep: Make dw_pcie_ep_reset_bar() handle 64-bit BARs properly PCI: endpoint: Make sure that BAR_5 does not have 64-bit flag set when clearing PCI: endpoint: Make epc->ops->clear_bar()/pci_epc_clear_bar() take struct *epf_bar ...
2018-04-05headers: untangle kmemleak.h from mm.hRandy Dunlap
Currently <linux/slab.h> #includes <linux/kmemleak.h> for no obvious reason. It looks like it's only a convenience, so remove kmemleak.h from slab.h and add <linux/kmemleak.h> to any users of kmemleak_* that don't already #include it. Also remove <linux/kmemleak.h> from source files that do not use it. This is tested on i386 allmodconfig and x86_64 allmodconfig. It would be good to run it through the 0day bot for other $ARCHes. I have neither the horsepower nor the storage space for the other $ARCHes. Update: This patch has been extensively build-tested by both the 0day bot & kisskb/ozlabs build farms. Both of them reported 2 build failures for which patches are included here (in v2). [ slab.h is the second most used header file after module.h; kernel.h is right there with slab.h. There could be some minor error in the counting due to some #includes having comments after them and I didn't combine all of those. ] [akpm@linux-foundation.org: security/keys/big_key.c needs vmalloc.h, per sfr] Link: http://lkml.kernel.org/r/e4309f98-3749-93e1-4bb7-d9501a39d015@infradead.org Link: http://kisskb.ellerman.id.au/kisskb/head/13396/ Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Reviewed-by: Ingo Molnar <mingo@kernel.org> Reported-by: Michael Ellerman <mpe@ellerman.id.au> [2 build failures] Reported-by: Fengguang Wu <fengguang.wu@intel.com> [2 build failures] Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Wei Yongjun <weiyongjun1@huawei.com> Cc: Luis R. Rodriguez <mcgrof@kernel.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Mimi Zohar <zohar@linux.vnet.ibm.com> Cc: John Johansen <john.johansen@canonical.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-05mm: fix races between swapoff and flush dcacheHuang Ying
Thanks to commit 4b3ef9daa4fc ("mm/swap: split swap cache into 64MB trunks"), after swapoff the address_space associated with the swap device will be freed. So page_mapping() users which may touch the address_space need some kind of mechanism to prevent the address_space from being freed during accessing. The dcache flushing functions (flush_dcache_page(), etc) in architecture specific code may access the address_space of swap device for anonymous pages in swap cache via page_mapping() function. But in some cases there are no mechanisms to prevent the swap device from being swapoff, for example, CPU1 CPU2 __get_user_pages() swapoff() flush_dcache_page() mapping = page_mapping() ... exit_swap_address_space() ... kvfree(spaces) mapping_mapped(mapping) The address space may be accessed after being freed. But from cachetlb.txt and Russell King, flush_dcache_page() only care about file cache pages, for anonymous pages, flush_anon_page() should be used. The implementation of flush_dcache_page() in all architectures follows this too. They will check whether page_mapping() is NULL and whether mapping_mapped() is true to determine whether to flush the dcache immediately. And they will use interval tree (mapping->i_mmap) to find all user space mappings. While mapping_mapped() and mapping->i_mmap isn't used by anonymous pages in swap cache at all. So, to fix the race between swapoff and flush dcache, __page_mapping() is add to return the address_space for file cache pages and NULL otherwise. All page_mapping() invoking in flush dcache functions are replaced with page_mapping_file(). [akpm@linux-foundation.org: simplify page_mapping_file(), per Mike] Link: http://lkml.kernel.org/r/20180305083634.15174-1-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Chen Liqin <liqin.linux@gmail.com> Cc: Russell King <linux@armlinux.org.uk> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: "James E.J. Bottomley" <jejb@parisc-linux.org> Cc: Guan Xuetao <gxt@mprc.pku.edu.cn> Cc: "David S. Miller" <davem@davemloft.net> Cc: Chris Zankel <chris@zankel.net> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Ley Foon Tan <lftan@altera.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Andi Kleen <ak@linux.intel.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-03Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-nextLinus Torvalds
Pull sparc updates from David Miller: 1) Add support for ADI (Application Data Integrity) found in more recent sparc64 cpus. Essentially this is keyed based access to virtual memory, and if the key encoded in the virual address is wrong you get a trap. The mm changes were reviewed by Andrew Morton and others. Work by Khalid Aziz. 2) Validate DAX completion index range properly, from Rob Gardner. 3) Add proper Kconfig deps for DAX driver. From Guenter Roeck. * git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-next: sparc64: Make atomic_xchg() an inline function rather than a macro. sparc64: Properly range check DAX completion index sparc: Make auxiliary vectors for ADI available on 32-bit as well sparc64: Oracle DAX driver depends on SPARC64 sparc64: Update signal delivery to use new helper functions sparc64: Add support for ADI (Application Data Integrity) mm: Allow arch code to override copy_highpage() mm: Clear arch specific VM flags on protection change mm: Add address parameter to arch_validate_prot() sparc64: Add auxiliary vectors to report platform ADI properties sparc64: Add handler for "Memory Corruption Detected" trap sparc64: Add HV fault type handlers for ADI related faults sparc64: Add support for ADI register fields, ASIs and traps mm, swap: Add infrastructure for saving page metadata on swap signals, sparc: Add signal codes for ADI violations
2018-04-03sparc64: Make atomic_xchg() an inline function rather than a macro.David S. Miller
This avoids a lot of -Wunused warnings such as: ==================== kernel/debug/debug_core.c: In function ‘kgdb_cpu_enter’: ./arch/sparc/include/asm/cmpxchg_64.h:55:22: warning: value computed is not used [-Wunused-value] #define xchg(ptr,x) ((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr)))) ./arch/sparc/include/asm/atomic_64.h:86:30: note: in expansion of macro ‘xchg’ #define atomic_xchg(v, new) (xchg(&((v)->counter), new)) ^~~~ kernel/debug/debug_core.c:508:4: note: in expansion of macro ‘atomic_xchg’ atomic_xchg(&kgdb_active, cpu); ^~~~~~~~~~~ ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
2018-04-02Merge branch 'syscalls-next' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/brodo/linux Pull removal of in-kernel calls to syscalls from Dominik Brodowski: "System calls are interaction points between userspace and the kernel. Therefore, system call functions such as sys_xyzzy() or compat_sys_xyzzy() should only be called from userspace via the syscall table, but not from elsewhere in the kernel. At least on 64-bit x86, it will likely be a hard requirement from v4.17 onwards to not call system call functions in the kernel: It is better to use use a different calling convention for system calls there, where struct pt_regs is decoded on-the-fly in a syscall wrapper which then hands processing over to the actual syscall function. This means that only those parameters which are actually needed for a specific syscall are passed on during syscall entry, instead of filling in six CPU registers with random user space content all the time (which may cause serious trouble down the call chain). Those x86-specific patches will be pushed through the x86 tree in the near future. Moreover, rules on how data may be accessed may differ between kernel data and user data. This is another reason why calling sys_xyzzy() is generally a bad idea, and -- at most -- acceptable in arch-specific code. This patchset removes all in-kernel calls to syscall functions in the kernel with the exception of arch/. On top of this, it cleans up the three places where many syscalls are referenced or prototyped, namely kernel/sys_ni.c, include/linux/syscalls.h and include/linux/compat.h" * 'syscalls-next' of git://git.kernel.org/pub/scm/linux/kernel/git/brodo/linux: (109 commits) bpf: whitelist all syscalls for error injection kernel/sys_ni: remove {sys_,sys_compat} from cond_syscall definitions kernel/sys_ni: sort cond_syscall() entries syscalls/x86: auto-create compat_sys_*() prototypes syscalls: sort syscall prototypes in include/linux/compat.h net: remove compat_sys_*() prototypes from net/compat.h syscalls: sort syscall prototypes in include/linux/syscalls.h kexec: move sys_kexec_load() prototype to syscalls.h x86/sigreturn: use SYSCALL_DEFINE0 x86: fix sys_sigreturn() return type to be long, not unsigned long x86/ioport: add ksys_ioperm() helper; remove in-kernel calls to sys_ioperm() mm: add ksys_readahead() helper; remove in-kernel calls to sys_readahead() mm: add ksys_mmap_pgoff() helper; remove in-kernel calls to sys_mmap_pgoff() mm: add ksys_fadvise64_64() helper; remove in-kernel call to sys_fadvise64_64() fs: add ksys_fallocate() wrapper; remove in-kernel calls to sys_fallocate() fs: add ksys_p{read,write}64() helpers; remove in-kernel calls to syscalls fs: add ksys_truncate() wrapper; remove in-kernel calls to sys_truncate() fs: add ksys_sync_file_range helper(); remove in-kernel calls to syscall kernel: add ksys_setsid() helper; remove in-kernel call to sys_setsid() kernel: add ksys_unshare() helper; remove in-kernel calls to sys_unshare() ...
2018-04-02Merge tag 'nds32-for-linus-4.17' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/greentime/linux Pull nds32 architecture support from Greentime Hu: "This contains the core nds32 Linux port (including interrupt controller driver and timer driver), which has been through seven rounds of review on mailing list. It is able to boot to shell and passes most LTP-2017 testsuites in nds32 AE3XX platform: Total Tests: 1901 Total Skipped Tests: 618 Total Failures: 78" Reviewed-by: Arnd Bergmann <arnd@arndb.de> * tag 'nds32-for-linus-4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/greentime/linux: (44 commits) nds32: To use the generic dump_stack() nds32: fix building failed if using elf toolchain. nios2: add ioremap_nocache declaration before include asm-generic/io.h. nds32: fix building failed if using older version gcc. dt-bindings: timer: Add andestech atcpit100 timer binding doc clocksource/drivers/atcpit100: VDSO support clocksource/drivers/atcpit100: Add andestech atcpit100 timer net: faraday add nds32 support. irqchip: Andestech Internal Vector Interrupt Controller driver dt-bindings: interrupt-controller: Andestech Internal Vector Interrupt Controller dt-bindings: nds32 SoC Bindings dt-bindings: nds32 L2 cache controller Bindings dt-bindings: nds32 CPU Bindings MAINTAINERS: Add nds32 nds32: Build infrastructure nds32: defconfig nds32: Miscellaneous header files nds32: Device tree support nds32: Generic timers support nds32: Loadable modules ...
2018-04-02mm: add ksys_readahead() helper; remove in-kernel calls to sys_readahead()Dominik Brodowski
Using this helper allows us to avoid the in-kernel calls to the sys_readahead() syscall. The ksys_ prefix denotes that this function is meant as a drop-in replacement for the syscall. In particular, it uses the same calling convention as sys_readahead(). This patch is part of a series which removes in-kernel calls to syscalls. On this basis, the syscall entry path can be streamlined. For details, see http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net Cc: Andrew Morton <akpm@linux-foundation.org> Cc: linux-mm@kvack.org Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
2018-04-02mm: add ksys_mmap_pgoff() helper; remove in-kernel calls to sys_mmap_pgoff()Dominik Brodowski
Using this helper allows us to avoid the in-kernel calls to the sys_mmap_pgoff() syscall. The ksys_ prefix denotes that this function is meant as a drop-in replacement for the syscall. In particular, it uses the same calling convention as sys_mmap_pgoff(). This patch is part of a series which removes in-kernel calls to syscalls. On this basis, the syscall entry path can be streamlined. For details, see http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net Cc: Andrew Morton <akpm@linux-foundation.org> Cc: linux-mm@kvack.org Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
2018-04-02mm: add ksys_fadvise64_64() helper; remove in-kernel call to sys_fadvise64_64()Dominik Brodowski
Using the ksys_fadvise64_64() helper allows us to avoid the in-kernel calls to the sys_fadvise64_64() syscall. The ksys_ prefix denotes that this function is meant as a drop-in replacement for the syscall. In particular, it uses the same calling convention as ksys_fadvise64_64(). Some compat stubs called sys_fadvise64(), which then just passed through the arguments to sys_fadvise64_64(). Get rid of this indirection, and call ksys_fadvise64_64() directly. This patch is part of a series which removes in-kernel calls to syscalls. On this basis, the syscall entry path can be streamlined. For details, see http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net Cc: Andrew Morton <akpm@linux-foundation.org> Cc: linux-mm@kvack.org Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
2018-04-02fs: add ksys_fallocate() wrapper; remove in-kernel calls to sys_fallocate()Dominik Brodowski
Using the ksys_fallocate() wrapper allows us to get rid of in-kernel calls to the sys_fallocate() syscall. The ksys_ prefix denotes that this function is meant as a drop-in replacement for the syscall. In particular, it uses the same calling convention as sys_fallocate(). This patch is part of a series which removes in-kernel calls to syscalls. On this basis, the syscall entry path can be streamlined. For details, see http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
2018-04-02fs: add ksys_p{read,write}64() helpers; remove in-kernel calls to syscallsDominik Brodowski
Using the ksys_p{read,write}64() wrappers allows us to get rid of in-kernel calls to the sys_pread64() and sys_pwrite64() syscalls. The ksys_ prefix denotes that this function is meant as a drop-in replacement for the syscall. In particular, it uses the same calling convention as sys_p{read,write}64(). This patch is part of a series which removes in-kernel calls to syscalls. On this basis, the syscall entry path can be streamlined. For details, see http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
2018-04-02fs: add ksys_truncate() wrapper; remove in-kernel calls to sys_truncate()Dominik Brodowski
Using the ksys_truncate() wrapper allows us to get rid of in-kernel calls to the sys_truncate() syscall. The ksys_ prefix denotes that this function is meant as a drop-in replacement for the syscall. In particular, it uses the same calling convention as sys_truncate(). This patch is part of a series which removes in-kernel calls to syscalls. On this basis, the syscall entry path can be streamlined. For details, see http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
2018-04-02fs: add ksys_sync_file_range helper(); remove in-kernel calls to syscallDominik Brodowski
Using this helper allows us to avoid the in-kernel calls to the sys_sync_file_range() syscall. The ksys_ prefix denotes that this function is meant as a drop-in replacement for the syscall. In particular, it uses the same calling convention as sys_sync_file_range(). This patch is part of a series which removes in-kernel calls to syscalls. On this basis, the syscall entry path can be streamlined. For details, see http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
2018-04-02fs: add ksys_sync() helper; remove in-kernel calls to sys_sync()Dominik Brodowski
Using this helper allows us to avoid the in-kernel calls to the sys_sync() syscall. The ksys_ prefix denotes that this function is meant as a drop-in replacement for the syscall. In particular, it uses the same calling convention as sys_sync(). This patch is part of a series which removes in-kernel calls to syscalls. On this basis, the syscall entry path can be streamlined. For details, see http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net Cc: Alexander Viro <viro@zeniv.linux.org.uk> Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
2018-04-02fs: add ksys_ftruncate() wrapper; remove in-kernel calls to sys_ftruncate()Dominik Brodowski
Using the ksys_ftruncate() wrapper allows us to get rid of in-kernel calls to the sys_ftruncate() syscall. The ksys_ prefix denotes that this function is meant as a drop-in replacement for the syscall. In particular, it uses the same calling convention as sys_ftruncate(). This patch is part of a series which removes in-kernel calls to syscalls. On this basis, the syscall entry path can be streamlined. For details, see http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
2018-03-20sparc/PCI: Stop reserving System ROM and Video ROM in PCI spaceBjorn Helgaas
Previously, pci_register_legacy_regions() reserved PCI address space under every PCI host bridge for the System ROM and the Video ROM, but these regions are not part of PCI address space. Previously, pci_register_legacy_regions() reserved the following areas of PCI address space under every PCI host bridge: [bus 0xa0000-0xbffff] Video RAM area (VGA frame buffer) [bus 0xc0000-0xc7fff] Video ROM [bus 0xf0000-0xfffff] System ROM It does need to reserve the [bus 0xa0000-0xbffff] region (at least if there's a possibility of a VGA device below the bridge) because VGA devices can respond to that even if they don't describe it with a BAR. But the Video ROM and System ROM areas don't seem necessary because they are not areas that legacy PCI devices respond to. They appear to be copied from x86, where they describe areas of system memory that depend on BIOS conventions. On x86, BIOS copies the option ROM of the primary VGA device to RAM at 0xc0000, and the 0xf0000-0xfffff region is reserved for the motherboard BIOS. Neither of these things applies to sparc. Stop reserving the System ROM and Video ROM regions in PCI space. Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Acked-by: David S. Miller <davem@davemloft.net>
2018-03-20sparc: get rid of asm wrapper for nis_syscall()Al Viro
just use current_pt_regs() Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2018-03-20sparc: switch compat {f,}truncate64() to COMPAT_SYSCALL_DEFINEAl Viro
... and drop the pointless checks - sys_truncate() itself might've lacked the check when that stuff was first written, but it has already grown one by the time that stuff went into mainline. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2018-03-20sparc: switch compat pread64 and pwrite64 to COMPAT_SYSCALL_DEFINEAl Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2018-03-20convert compat sync_file_range() to COMPAT_SYSCALL_DEFINEAl Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2018-03-20switch sparc_remap_file_pages() to SYSCALL_DEFINEAl Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2018-03-20sparc: get rid of memory_ordering(2) wrapperAl Viro
use current_pt_regs() in it instead Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2018-03-20sparc: trivial conversions to {COMPAT_,}SYSCALL_DEFINE()Al Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2018-03-20sparc: bury a zombie extern that had been that way for twenty yearsAl Viro
Back in January 1998, in 2.1.79 check_pending() got taken out and shot. Users in arch/sparc and arch/sparc64 got converted away from it. One of the externs (in arch/sparc) was taken out at the same time. Two other (in arch/sparc64/kernel/sys_sparc{,32}.c) got stuck. The one in sys_sparc32.c was quietly removed 6 years later by an unrelated commit. The last one kept shambling until now. It's time to end that depravity, let's bury the body... Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2018-03-20sparc: get rid of remaining SIGN... wrappersAl Viro
just convert compat_sys_{readahead,fadvise64,fadvise64_64} to COMPAT_SYSCALL_DEFINE Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2018-03-20sparc: kill useless SIGN... wrappersAl Viro
SYSCALL_DEFINE and COMPAT_SYSCALL_DEFINE already give argument normalization. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2018-03-20sparc: Make auxiliary vectors for ADI available on 32-bit as wellKhalid Aziz
Commit c6202ca764ac ("sparc64: Add auxiliary vectors to report platform ADI properties") adds auxiliary vectors to report ADI capabilities on sparc64 platform only. This needs to be uniform across 64-bit and 32-bit. This patch makes the same vectors available on 32-bit as well. Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com> Cc: Khalid Aziz <khalid@gonehiking.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-03-19sparc: get rid of sys_sparc_pipe() wrappersAl Viro
just use current_pt_regs() Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2018-03-19Merge tag 'v4.16-rc6' into perf/core, to pick up fixesIngo Molnar
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-03-18sparc64: Update signal delivery to use new helper functionsKhalid Aziz
Commit f8ec66014ffd ("signal: Add send_sig_fault and force_sig_fault") added new helper functions to streamline signal delivery. This patch updates signal delivery for new/updated handlers for ADI related exceptions to use the helper function. Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com> Cc: Khalid Aziz <khalid@gonehiking.org> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-03-18sparc64: Add support for ADI (Application Data Integrity)Khalid Aziz
ADI is a new feature supported on SPARC M7 and newer processors to allow hardware to catch rogue accesses to memory. ADI is supported for data fetches only and not instruction fetches. An app can enable ADI on its data pages, set version tags on them and use versioned addresses to access the data pages. Upper bits of the address contain the version tag. On M7 processors, upper four bits (bits 63-60) contain the version tag. If a rogue app attempts to access ADI enabled data pages, its access is blocked and processor generates an exception. Please see Documentation/sparc/adi.txt for further details. This patch extends mprotect to enable ADI (TSTATE.mcde), enable/disable MCD (Memory Corruption Detection) on selected memory ranges, enable TTE.mcd in PTEs, return ADI parameters to userspace and save/restore ADI version tags on page swap out/in or migration. ADI is not enabled by default for any task. A task must explicitly enable ADI on a memory range and set version tag for ADI to be effective for the task. Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com> Cc: Khalid Aziz <khalid@gonehiking.org> Reviewed-by: Anthony Yznaga <anthony.yznaga@oracle.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-03-18sparc64: Add auxiliary vectors to report platform ADI propertiesKhalid Aziz
ADI feature on M7 and newer processors has three important properties relevant to userspace apps using ADI capabilities - (1) Size of block of memory an ADI version tag applies to, (2) Number of uppermost bits in virtual address used to encode ADI tag, and (3) The value M7 processor will force the ADI tags to if it detects uncorrectable error in an ADI tagged cacheline. Kernel can retrieve these properties for a platform through machine description provided by the firmware. This patch adds code to retrieve these properties and report them to userspace through auxiliary vectors. Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com> Cc: Khalid Aziz <khalid@gonehiking.org> Reviewed-by: Anthony Yznaga <anthony.yznaga@oracle.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-03-18sparc64: Add handler for "Memory Corruption Detected" trapKhalid Aziz
M7 and newer processors add a "Memory corruption Detected" trap with the addition of ADI feature. This trap is vectored into kernel by HV through resumable error trap with error attribute for the resumable error set to 0x00000800. Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com> Cc: Khalid Aziz <khalid@gonehiking.org> Reviewed-by: Anthony Yznaga <anthony.yznaga@oracle.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-03-18sparc64: Add HV fault type handlers for ADI related faultsKhalid Aziz
ADI (Application Data Integrity) feature on M7 and newer processors adds new fault types for hypervisor - Invalid ASI and MCD disabled. This patch expands data access exception handler to handle these faults. Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com> Cc: Khalid Aziz <khalid@gonehiking.org> Reviewed-by: Anthony Yznaga <anthony.yznaga@oracle.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-03-18sparc64: Add support for ADI register fields, ASIs and trapsKhalid Aziz
SPARC M7 processor adds new control register fields, ASIs and a new trap to support the ADI (Application Data Integrity) feature. This patch adds definitions for these register fields, ASIs and a handler for the new precise memory corruption detected trap. Signed-off-by: Khalid Aziz <khalid.aziz@oracle.com> Cc: Khalid Aziz <khalid@gonehiking.org> Reviewed-by: Anthony Yznaga <anthony.yznaga@oracle.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2018-03-16perf: Fix sibling iterationPeter Zijlstra
Mark noticed that the change to sibling_list changed some iteration semantics; because previously we used group_list as list entry, sibling events would always have an empty sibling_list. But because we now use sibling_list for both list head and list entry, siblings will report as having siblings. Fix this with a custom for_each_sibling_event() iterator. Fixes: 8343aae66167 ("perf/core: Remove perf_event::group_entry") Reported-by: Mark Rutland <mark.rutland@arm.com> Suggested-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: vincent.weaver@maine.edu Cc: alexander.shishkin@linux.intel.com Cc: torvalds@linux-foundation.org Cc: alexey.budankov@linux.intel.com Cc: valery.cherepennikov@intel.com Cc: eranian@google.com Cc: acme@redhat.com Cc: linux-tip-commits@vger.kernel.org Cc: davidcc@google.com Cc: kan.liang@intel.com Cc: Dmitry.Prohorov@intel.com Cc: jolsa@redhat.com Link: https://lkml.kernel.org/r/20180315170129.GX4043@hirez.programming.kicks-ass.net
2018-03-15sparc64: Fix regression in pmdp_invalidate().David S. Miller
pmdp_invalidate() was changed to update the pmd atomically (to not lose dirty/access bits) and return the original pmd value. However, in doing so, we lost a lot of the essential work that set_pmd_at() does, namely to update hugepage mapping counts and queuing up the batched TLB flush entry. Thus we were not flushing entries out of the TLB when making such PMD changes. Fix this by abstracting the accounting work of set_pmd_at() out into a separate function, and call it from pmdp_establish(). Fixes: a8e654f01cb7 ("sparc64: update pmdp_invalidate() to return old pmd value") Signed-off-by: David S. Miller <davem@davemloft.net>
2018-03-12perf/core: Remove perf_event::group_entryPeter Zijlstra
Now that all the grouping is done with RB trees, we no longer need group_entry and can replace the whole thing with sibling_list. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Alexey Budankov <alexey.budankov@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: David Carrillo-Cisneros <davidcc@google.com> Cc: Dmitri Prokhorov <Dmitry.Prohorov@intel.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Kan Liang <kan.liang@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Stephane Eranian <eranian@google.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Valery Cherepennikov <valery.cherepennikov@intel.com> Cc: Vince Weaver <vincent.weaver@maine.edu> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-02-22asm-generic/io.h: move ioremap_nocache/ioremap_uc/ioremap_wc/ioremap_wt out ↵Greentime Hu
of ifndef CONFIG_MMU It allows some architectures to use this generic macro instead of defining theirs. sparc: io: To use the define of ioremap_[nocache|wc|wb] in asm-generic/io.h It will move the ioremap_nocache out of the CONFIG_MMU ifdef. This means that in order to suppress re-definition errors we need to remove the #define in arch/sparc/include/asm/io_32.h. Also, the change adds a prototype for ioremap where size is size_t and offset is phys_addr_t so fix that as well. Signed-off-by: Greentime Hu <greentime@andestech.com>
2018-02-21bug.h: work around GCC PR82365 in BUG()Arnd Bergmann
Looking at functions with large stack frames across all architectures led me discovering that BUG() suffers from the same problem as fortify_panic(), which I've added a workaround for already. In short, variables that go out of scope by calling a noreturn function or __builtin_unreachable() keep using stack space in functions afterwards. A workaround that was identified is to insert an empty assembler statement just before calling the function that doesn't return. I'm adding a macro "barrier_before_unreachable()" to document this, and insert calls to that in all instances of BUG() that currently suffer from this problem. The files that saw the largest change from this had these frame sizes before, and much less with my patch: fs/ext4/inode.c:82:1: warning: the frame size of 1672 bytes is larger than 800 bytes [-Wframe-larger-than=] fs/ext4/namei.c:434:1: warning: the frame size of 904 bytes is larger than 800 bytes [-Wframe-larger-than=] fs/ext4/super.c:2279:1: warning: the frame size of 1160 bytes is larger than 800 bytes [-Wframe-larger-than=] fs/ext4/xattr.c:146:1: warning: the frame size of 1168 bytes is larger than 800 bytes [-Wframe-larger-than=] fs/f2fs/inode.c:152:1: warning: the frame size of 1424 bytes is larger than 800 bytes [-Wframe-larger-than=] net/netfilter/ipvs/ip_vs_core.c:1195:1: warning: the frame size of 1068 bytes is larger than 800 bytes [-Wframe-larger-than=] net/netfilter/ipvs/ip_vs_core.c:395:1: warning: the frame size of 1084 bytes is larger than 800 bytes [-Wframe-larger-than=] net/netfilter/ipvs/ip_vs_ftp.c:298:1: warning: the frame size of 928 bytes is larger than 800 bytes [-Wframe-larger-than=] net/netfilter/ipvs/ip_vs_ftp.c:418:1: warning: the frame size of 908 bytes is larger than 800 bytes [-Wframe-larger-than=] net/netfilter/ipvs/ip_vs_lblcr.c:718:1: warning: the frame size of 960 bytes is larger than 800 bytes [-Wframe-larger-than=] drivers/net/xen-netback/netback.c:1500:1: warning: the frame size of 1088 bytes is larger than 800 bytes [-Wframe-larger-than=] In case of ARC and CRIS, it turns out that the BUG() implementation actually does return (or at least the compiler thinks it does), resulting in lots of warnings about uninitialized variable use and leaving noreturn functions, such as: block/cfq-iosched.c: In function 'cfq_async_queue_prio': block/cfq-iosched.c:3804:1: error: control reaches end of non-void function [-Werror=return-type] include/linux/dmaengine.h: In function 'dma_maxpq': include/linux/dmaengine.h:1123:1: error: control reaches end of non-void function [-Werror=return-type] This makes them call __builtin_trap() instead, which should normally dump the stack and kill the current process, like some of the other architectures already do. I tried adding barrier_before_unreachable() to panic() and fortify_panic() as well, but that had very little effect, so I'm not submitting that patch. Vineet said: : For ARC, it is double win. : : 1. Fixes 3 -Wreturn-type warnings : : | ../net/core/ethtool.c:311:1: warning: control reaches end of non-void function : [-Wreturn-type] : | ../kernel/sched/core.c:3246:1: warning: control reaches end of non-void function : [-Wreturn-type] : | ../include/linux/sunrpc/svc_xprt.h:180:1: warning: control reaches end of : non-void function [-Wreturn-type] : : 2. bloat-o-meter reports code size improvements as gcc elides the : generated code for stack return. Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82365 Link: http://lkml.kernel.org/r/20171219114112.939391-1-arnd@arndb.de Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Vineet Gupta <vgupta@synopsys.com> [arch/arc] Tested-by: Vineet Gupta <vgupta@synopsys.com> [arch/arc] Cc: Mikael Starvik <starvik@axis.com> Cc: Jesper Nilsson <jesper.nilsson@axis.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Christopher Li <sparse@chrisli.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Kees Cook <keescook@chromium.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Will Deacon <will.deacon@arm.com> Cc: "Steven Rostedt (VMware)" <rostedt@goodmis.org> Cc: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>