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2020-06-02powerpc/64s: Don't let DT CPU features set FSCR_DSCRMichael Ellerman
The device tree CPU features binding includes FSCR bit numbers which Linux is instructed to set by firmware. Whether that's a good idea or not, in the case of the DSCR the Linux implementation has a hard requirement that the FSCR_DSCR bit not be set by default. We use it to track when a process reads/writes to DSCR, so it must be clear to begin with. So if firmware tells us to set FSCR_DSCR we must ignore it. Currently this does not cause a bug in our DSCR handling because the value of FSCR that the device tree CPU features code establishes is only used by swapper. All other tasks use the value hard coded in init_task.thread.fscr. However we'd like to fix that in a future commit, at which point this will become necessary. Fixes: 5a61ef74f269 ("powerpc/64s: Support new device tree binding for discovering CPU features") Cc: stable@vger.kernel.org # v4.12+ Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200527145843.2761782-2-mpe@ellerman.id.au
2020-06-02powerpc/64s: Don't init FSCR_DSCR in __init_FSCR()Michael Ellerman
__init_FSCR() was added originally in commit 2468dcf641e4 ("powerpc: Add support for context switching the TAR register") (Feb 2013), and only set FSCR_TAR. At that point FSCR (Facility Status and Control Register) was not context switched, so the setting was permanent after boot. Later we added initialisation of FSCR_DSCR to __init_FSCR(), in commit 54c9b2253d34 ("powerpc: Set DSCR bit in FSCR setup") (Mar 2013), again that was permanent after boot. Then commit 2517617e0de6 ("powerpc: Fix context switch DSCR on POWER8") (Aug 2013) added a limited context switch of FSCR, just the FSCR_DSCR bit was context switched based on thread.dscr_inherit. That commit said "This clears the H/FSCR DSCR bit initially", but it didn't, it left the initialisation of FSCR_DSCR in __init_FSCR(). However the initial context switch from init_task to pid 1 would clear FSCR_DSCR because thread.dscr_inherit was 0. That commit also introduced the requirement that FSCR_DSCR be clear for user processes, so that we can take the facility unavailable interrupt in order to manage dscr_inherit. Then in commit 152d523e6307 ("powerpc: Create context switch helpers save_sprs() and restore_sprs()") (Dec 2015) FSCR was added to thread_struct. However it still wasn't fully context switched, we just took the existing value and set FSCR_DSCR if the new thread had dscr_inherit set. FSCR was still initialised at boot to FSCR_DSCR | FSCR_TAR, but that value was not propagated into the thread_struct, so the initial context switch set FSCR_DSCR back to 0. Finally commit b57bd2de8c6c ("powerpc: Improve FSCR init and context switching") (Jun 2016) added a full context switch of the FSCR, and added an initialisation of init_task.thread.fscr to FSCR_TAR | FSCR_EBB, but omitted FSCR_DSCR. The end result is that swapper runs with FSCR_DSCR set because of the initialisation in __init_FSCR(), but no other processes do, they use the value from init_task.thread.fscr. Having FSCR_DSCR set for swapper allows it to access SPR 3 from userspace, but swapper never runs userspace, so it has no useful effect. It's also confusing to have the value initialised in two places to two different values. So remove FSCR_DSCR from __init_FSCR(), this at least gets us to the point where there's a single value of FSCR, even if it's still set in two places. Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Tested-by: Alistair Popple <alistair@popple.id.au> Link: https://lore.kernel.org/r/20200527145843.2761782-1-mpe@ellerman.id.au
2020-06-02powerpc/32s: Fix another build failure with CONFIG_PPC_KUAP_DEBUGChristophe Leroy
'thread' doesn't exist in kuap_check() macro. Use 'current' instead. Fixes: a68c31fc01ef ("powerpc/32s: Implement Kernel Userspace Access Protection") Cc: stable@vger.kernel.org Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/b459e1600b969047a74e34251a84a3d6fdf1f312.1590858925.git.christophe.leroy@csgroup.eu
2020-06-02powerpc/module_64: Use special stub for _mcount() with -mprofile-kernelNaveen N. Rao
Since commit c55d7b5e64265f ("powerpc: Remove STRICT_KERNEL_RWX incompatibility with RELOCATABLE"), powerpc kernels with -mprofile-kernel can crash in certain scenarios with a trace like below: BUG: Unable to handle kernel instruction fetch (NULL pointer?) Faulting instruction address: 0x00000000 Oops: Kernel access of bad area, sig: 11 [#1] LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=256 DEBUG_PAGEALLOC NUMA PowerNV <snip> NIP [0000000000000000] 0x0 LR [c0080000102c0048] ext4_iomap_end+0x8/0x30 [ext4] Call Trace: iomap_apply+0x20c/0x920 (unreliable) iomap_bmap+0xfc/0x160 ext4_bmap+0xa4/0x180 [ext4] bmap+0x4c/0x80 jbd2_journal_init_inode+0x44/0x1a0 [jbd2] ext4_load_journal+0x440/0x860 [ext4] ext4_fill_super+0x342c/0x3ab0 [ext4] mount_bdev+0x25c/0x290 ext4_mount+0x28/0x50 [ext4] legacy_get_tree+0x4c/0xb0 vfs_get_tree+0x4c/0x130 do_mount+0xa18/0xc50 sys_mount+0x158/0x180 system_call+0x5c/0x68 The NIP points to NULL, or a random location (data even), while the LR always points to the LEP of a function (with an offset of 8), indicating that something went wrong with ftrace. However, ftrace is not necessarily active when such crashes occur. The kernel OOPS sometimes follows a warning from ftrace indicating that some module functions could not be patched with a nop. Other times, if a module is loaded early during boot, instruction patching can fail due to a separate bug, but the error is not reported due to missing error reporting. In all the above cases when instruction patching fails, ftrace will be disabled but certain kernel module functions will be left with default calls to _mcount(). This is not a problem with ELFv1. However, with -mprofile-kernel, the default stub is problematic since it depends on a valid module TOC in r2. If the kernel (or a different module) calls into a function that does not use the TOC, the function won't have a prologue to setup the module TOC. When that function calls into _mcount(), we will end up in the relocation stub that will use the previous TOC, and end up trying to jump into a random location. From the above trace: iomap_apply+0x20c/0x920 [kernel TOC] | V ext4_iomap_end+0x8/0x30 [no GEP == kernel TOC] | V _mcount() stub [uses kernel TOC -> random entry] To address this, let's change over to using the special stub that is used for ftrace_[regs_]caller() for _mcount(). This ensures that we are not dependent on a valid module TOC in r2 for default _mcount() handling. Reported-by: Qian Cai <cai@lca.pw> Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Tested-by: Qian Cai <cai@lca.pw> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/8affd4298d22099bbd82544fab8185700a6222b1.1587488954.git.naveen.n.rao@linux.vnet.ibm.com
2020-06-02powerpc/module_64: Simplify check for -mprofile-kernel ftrace relocationsNaveen N. Rao
For -mprofile-kernel, we need special handling when generating stubs for ftrace calls such as _mcount(). To faciliate this, we check if a R_PPC64_REL24 relocation is for a symbol named "_mcount()" along with also checking the instruction sequence. The latter is not really required since "_mcount()" is an exported symbol and kernel modules cannot use it. As such, drop the additional checking and simplify the code. This helps unify stub creation for ftrace stubs with -mprofile-kernel and aids in code reuse. Also rename is_mprofile_mcount_callsite() to is_mprofile_ftrace_call() to reflect the checking being done. Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/7d9c316adfa1fb787ad268bb4691e7e4059ff2d5.1587488954.git.naveen.n.rao@linux.vnet.ibm.com
2020-06-02powerpc/module_64: Consolidate ftrace codeNaveen N. Rao
module_trampoline_target() is only used by ftrace. Move the prototype within the appropriate #ifdef in the header. Also, move the function body to the end of module_64.c so as to consolidate all ftrace code in one place. No functional changes. Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/2527351f65c53c5866068ae130dc34c5d4ee8ad9.1587488954.git.naveen.n.rao@linux.vnet.ibm.com
2020-06-02powerpc/32: Disable KASAN with pages bigger than 16kChristophe Leroy
Mapping of early shadow area is implemented by using a single static page table having all entries pointing to the same early shadow page. The shadow area must therefore occupy full PGD entries. The shadow area has a size of 128MB starting at 0xf8000000. With 4k pages, a PGD entry is 4MB With 16k pages, a PGD entry is 64MB With 64k pages, a PGD entry is 1GB which is too big. Until we rework the early shadow mapping, disable KASAN when the page size is too big. Fixes: 2edb16efc899 ("powerpc/32: Add KASAN support") Cc: stable@vger.kernel.org # v5.2+ Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/7195fcde7314ccbf7a081b356084a69d421b10d4.1590660977.git.christophe.leroy@csgroup.eu
2020-06-02powerpc/uaccess: Don't set KUEP by default on book3s/32Christophe Leroy
On book3s/32, KUEP is an heavy process as it requires to set/unset the NX bit in each of the 12 user segments everytime the kernel is entered/exited from/to user space. Don't select KUEP by default on book3s/32. Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/1492bb150c1aaa53d99a604b49992e60ea20cd5f.1586962582.git.christophe.leroy@c-s.fr
2020-06-02powerpc/uaccess: Don't set KUAP by default on book3s/32Christophe Leroy
On book3s/32, KUAP is an heavy process as it requires to determine which segments are impacted and unlock/lock each of them. And since the implementation of user_access_begin/end, it is even worth for the time being because unlike __get_user(), user_access_begin doesn't make difference between read and write and unlocks access also for read allthought that's unneeded on book3s/32. As shown by the size of a kernel built with KUAP and one without, the overhead is 64k bytes of code. As a comparison a similar build on an 8xx has an overhead of only 8k bytes of code. text data bss dec hex filename 7230416 1425868 837376 9493660 90dc9c vmlinux.kuap6xx 7165012 1425548 837376 9427936 8fdbe0 vmlinux.nokuap6xx 6519796 1960028 477464 8957288 88ad68 vmlinux.kuap8xx 6511664 1959864 477464 8948992 888d00 vmlinux.nokuap8xx Until a more optimised KUAP is implemented on book3s/32, don't select it by default. Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/154a99399317b096ac1f04827b9f8d7a9179ddc1.1586962586.git.christophe.leroy@c-s.fr
2020-06-02powerpc/8xx: Reduce time spent in allow_user_access() and friendsChristophe Leroy
To enable/disable kernel access to user space, the 8xx has to modify the properties of access group 1. This is done by writing predefined values into SPRN_Mx_AP registers. As of today, a __put_user() gives: 00000d64 <my_test>: d64: 3d 20 4f ff lis r9,20479 d68: 61 29 ff ff ori r9,r9,65535 d6c: 7d 3a c3 a6 mtspr 794,r9 d70: 39 20 00 00 li r9,0 d74: 90 83 00 00 stw r4,0(r3) d78: 3d 20 6f ff lis r9,28671 d7c: 61 29 ff ff ori r9,r9,65535 d80: 7d 3a c3 a6 mtspr 794,r9 d84: 4e 80 00 20 blr Because only groups 0 and 1 are used, the definition of groups 2 to 15 doesn't matter. By setting unused bits to 0 instead on 1, one instruction is removed for each lock and unlock action: 00000d5c <my_test>: d5c: 3d 20 40 00 lis r9,16384 d60: 7d 3a c3 a6 mtspr 794,r9 d64: 39 20 00 00 li r9,0 d68: 90 83 00 00 stw r4,0(r3) d6c: 3d 20 60 00 lis r9,24576 d70: 7d 3a c3 a6 mtspr 794,r9 d74: 4e 80 00 20 blr Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/57425c33dd72f292b1a23570244b81419072a7aa.1586945153.git.christophe.leroy@c-s.fr
2020-06-02powerpc/entry32: Blacklist exception exit points for kprobe.Christophe Leroy
kprobe does not handle events happening in real mode. The very last part of exception exits cannot support a trap. Blacklist them from kprobe. While we are at it, remove exc_exit_start symbol which is not used to avoid having to blacklist it. Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/098b0fd3f6299aa1bd692bd576bd7012c84608de.1585670437.git.christophe.leroy@c-s.fr
2020-06-02powerpc/entry32: Blacklist syscall exit points for kprobe.Christophe Leroy
kprobe does not handle events happening in real mode. The very last part of syscall cannot support a trap. Add a symbol syscall_exit_finish to identify that part and blacklist it from kprobe. Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/23eddf49abb03d1359fa0be4206998eb3800f42c.1585670437.git.christophe.leroy@c-s.fr
2020-06-02powerpc/entry32: Blacklist exception entry points for kprobe.Christophe Leroy
kprobe does not handle events happening in real mode. As exception entry points are running with MMU disabled, blacklist them. The handling of TLF_NAPPING and TLF_SLEEPING is moved before the CONFIG_TRACE_IRQFLAGS which contains 'reenable_mmu' because from there kprobe will be possible as the kernel will run with MMU enabled. Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/f61ac599855e674ebb592464d0ea32a3ba9c6644.1585670437.git.christophe.leroy@c-s.fr
2020-06-02powerpc/32: Blacklist functions running with MMU disabled for kprobeChristophe Leroy
kprobe does not handle events happening in real mode, all functions running with MMU disabled have to be blacklisted. Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/3bf57066d05518644dee0840af69d36ab5086729.1585670437.git.christophe.leroy@c-s.fr
2020-06-02powerpc/rtas: Remove machine_check_in_rtas()Christophe Leroy
machine_check_in_rtas() is just a trap. Do the trap directly in the machine check exception handler. Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/78899f40f89cb3c4f69bdff7f04eb6ec7cb753d5.1585670437.git.christophe.leroy@c-s.fr
2020-06-02powerpc/32s: Blacklist functions running with MMU disabled for kprobeChristophe Leroy
kprobe does not handle events happening in real mode, all functions running with MMU disabled have to be blacklisted. Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/dabed523c1b8955dd425152ce260b390053e727a.1585670437.git.christophe.leroy@c-s.fr
2020-06-02powerpc/32s: Make local symbols non visible in hash_low.Christophe Leroy
In hash_low.S, a lot of named local symbols are used instead of numbers to ease code readability. However, they don't need to be visible. In order to ease blacklisting of functions running with MMU disabled for kprobe, rename the symbols to .Lsymbols in order to hide them as if they were numbered labels. Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/90c430d9e0f7af772a58aaeaf17bcc6321265340.1585670437.git.christophe.leroy@c-s.fr
2020-06-02powerpc/mem: Blacklist flush_dcache_icache_phys() for kprobeChristophe Leroy
kprobe does not handle events happening in real mode, all functions running with MMU disabled have to be blacklisted. Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/eaab3bff961c3bfe149f1d0bd3593291ef939dcc.1585670437.git.christophe.leroy@c-s.fr
2020-06-02powerpc/powermac: Blacklist functions running with MMU disabled for kprobeChristophe Leroy
kprobe does not handle events happening in real mode, all functions running with MMU disabled have to be blacklisted. Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/6316e8883753499073f47301857e4e88b73c3ddd.1585670437.git.christophe.leroy@c-s.fr
2020-06-02powerpc/83xx: Blacklist mpc83xx_deep_resume() for kprobeChristophe Leroy
kprobe does not handle events happening in real mode, all functions running with MMU disabled have to be blacklisted. Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/3ac4ab8dd7008b9706d9228a60645a1756fa84bf.1585670437.git.christophe.leroy@c-s.fr
2020-06-02powerpc/82xx: Blacklist pq2_restart() for kprobeChristophe Leroy
kprobe does not handle events happening in real mode, all functions running with MMU disabled have to be blacklisted. Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/5dca36682383577a3c2b2bca4d577e8654944461.1585670437.git.christophe.leroy@c-s.fr
2020-06-02powerpc/52xx: Blacklist functions running with MMU disabled for kprobeChristophe Leroy
kprobe does not handle events happening in real mode, all functions running with MMU disabled have to be blacklisted. Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/1ae02b6637b87fc5aaa1d5012c3e2cb30e62b4a3.1585670437.git.christophe.leroy@c-s.fr
2020-06-02powerpc/kprobes: Use probe_address() to read instructionsChristophe Leroy
In order to avoid Oopses, use probe_address() to read the instruction at the address where the trap happened. Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/7f24b5961a6839ff01df792816807f74ff236bf6.1582567319.git.christophe.leroy@c-s.fr
2020-06-02powerpc/configs: Add LIBNVDIMM to ppc64_defconfigMichael Neuling
This gives us OF_PMEM which is useful in mambo. This adds 153K to the text of ppc64le_defconfig which 0.8% of the total text. LIBNVDIMM text data bss dec hex Without 18574833 5518150 1539240 25632223 1871ddf With 18727834 5546206 1539368 25813408 189e1a0 Signed-off-by: Michael Neuling <mikey@neuling.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200519043009.3081885-1-mikey@neuling.org
2020-06-02powerpc/rtas: Implement reentrant rtas callLeonardo Bras
Implement rtas_call_reentrant() for reentrant rtas-calls: "ibm,int-on", "ibm,int-off",ibm,get-xive" and "ibm,set-xive". On LoPAPR Version 1.1 (March 24, 2016), from 7.3.10.1 to 7.3.10.4, items 2 and 3 say: 2 - For the PowerPC External Interrupt option: The * call must be reentrant to the number of processors on the platform. 3 - For the PowerPC External Interrupt option: The * argument call buffer for each simultaneous call must be physically unique. So, these rtas-calls can be called in a lockless way, if using a different buffer for each cpu doing such rtas call. For this, it was suggested to add the buffer (struct rtas_args) in the PACA struct, so each cpu can have it's own buffer. The PACA struct received a pointer to rtas buffer, which is allocated in the memory range available to rtas 32-bit. Reentrant rtas calls are useful to avoid deadlocks in crashing, where rtas-calls are needed, but some other thread crashed holding the rtas.lock. This is a backtrace of a deadlock from a kdump testing environment: #0 arch_spin_lock #1 lock_rtas () #2 rtas_call (token=8204, nargs=1, nret=1, outputs=0x0) #3 ics_rtas_mask_real_irq (hw_irq=4100) #4 machine_kexec_mask_interrupts #5 default_machine_crash_shutdown #6 machine_crash_shutdown #7 __crash_kexec #8 crash_kexec #9 oops_end Signed-off-by: Leonardo Bras <leobras.c@gmail.com> [mpe: Move under #ifdef PSERIES to avoid build breakage] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200518234245.200672-3-leobras.c@gmail.com
2020-06-02powerpc/rtas: Move type/struct definitions from rtas.h into rtas-types.hLeonardo Bras
In order to get any rtas* struct into other headers, including rtas.h may cause a lot of errors, regarding include dependency needed for inline functions. Create rtas-types.h and move there all type/struct definitions from rtas.h, then include rtas-types.h into rtas.h. Also, as suggested by checkpath.pl, replace uint8_t for u8. Signed-off-by: Leonardo Bras <leobras.c@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200518234245.200672-2-leobras.c@gmail.com
2020-06-02powerpc/crash: Use NMI context for printk when starting to crashLeonardo Bras
Currently, if printk lock (logbuf_lock) is held by other thread during crash, there is a chance of deadlocking the crash on next printk, and blocking a possibly desired kdump. At the start of default_machine_crash_shutdown, make printk enter NMI context, as it will use per-cpu buffers to store the message, and avoid locking logbuf_lock. Suggested-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Leonardo Bras <leobras.c@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200512214533.93878-1-leobras.c@gmail.com
2020-06-02powerpc/kernel: Enables memory hot-remove after reboot on pseries guestsLeonardo Bras
While providing guests, it's desirable to resize it's memory on demand. By now, it's possible to do so by creating a guest with a small base memory, hot-plugging all the rest, and using 'movable_node' kernel command-line parameter, which puts all hot-plugged memory in ZONE_MOVABLE, allowing it to be removed whenever needed. But there is an issue regarding guest reboot: If memory is hot-plugged, and then the guest is rebooted, all hot-plugged memory goes to ZONE_NORMAL, which offers no guaranteed hot-removal. It usually prevents this memory to be hot-removed from the guest. It's possible to use device-tree information to fix that behavior, as it stores flags for LMB ranges on ibm,dynamic-memory-vN. It involves marking each memblock with the correct flags as hotpluggable memory, which mm/memblock.c puts in ZONE_MOVABLE during boot if 'movable_node' is passed. For carrying such information, the new flag DRCONF_MEM_HOTREMOVABLE was proposed and accepted into Power Architecture documentation. This flag should be: - true (b=1) if the hypervisor may want to hot-remove it later, and - false (b=0) if it does not care. During boot, guest kernel reads the device-tree, early_init_drmem_lmb() is called for every added LMBs. Here, checking for this new flag and marking memblocks as hotplugable memory is enough to get the desirable behavior. This should cause no change if 'movable_node' parameter is not passed in kernel command-line. Signed-off-by: Leonardo Bras <leonardo@linux.ibm.com> Reviewed-by: Bharata B Rao <bharata@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200402195156.626430-1-leonardo@linux.ibm.com
2020-06-02powerpc/xmon: Show task->thread.regs in process displayMichael Ellerman
Show the address of the tasks regs in the process listing in xmon. The regs should always be on the stack page that we also print the address of, but it's still helpful not to have to find them by hand. Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200520111740.953679-1-mpe@ellerman.id.au
2020-06-02powerpc/configs/64s: Enable CONFIG_PRINTK_CALLERMichael Ellerman
This adds the CPU or thread number to printk messages. This helps a lot when deciphering concurrent oopses that have been interleaved. Example output, of PID1 (T1) triggering a warning: [ 1.581678][ T1] WARNING: CPU: 0 PID: 1 at crypto/rsa-pkcs1pad.c:539 pkcs1pad_verify+0x38/0x140 [ 1.581681][ T1] Modules linked in: [ 1.581693][ T1] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.5.0-rc5-gcc-8.2.0-00121-gf84c2e595927-dirty #1515 [ 1.581700][ T1] NIP: c000000000207d64 LR: c000000000207d3c CTR: c000000000207d2c [ 1.581708][ T1] REGS: c0000000fd2e7560 TRAP: 0700 Not tainted (5.5.0-rc5-gcc-8.2.0-00121-gf84c2e595927-dirty) [ 1.581712][ T1] MSR: 9000000000029033 <SF,HV,EE,ME,IR,DR,RI,LE> CR: 44000222 XER: 00040000 Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200520121257.961112-1-mpe@ellerman.id.au
2020-06-02powerpc: Fix misleading small cores printMichael Neuling
Currently when we boot on a big core system, we get this print: [ 0.040500] Using small cores at SMT level This is misleading as we've actually detected big cores. This patch clears up the print to say we've detect big cores but are using small cores for scheduling. Signed-off-by: Michael Neuling <mikey@neuling.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200528230731.1235752-1-mikey@neuling.org
2020-06-02powerpc/fadump: Account for memory_limit while reserving memoryHari Bathini
If the memory chunk found for reserving memory overshoots the memory limit imposed, do not proceed with reserving memory. Default behavior was this until commit 140777a3d8df ("powerpc/fadump: consider reserved ranges while reserving memory") changed it unwittingly. Fixes: 140777a3d8df ("powerpc/fadump: consider reserved ranges while reserving memory") Cc: stable@vger.kernel.org Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Hari Bathini <hbathini@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/159057266320.22331.6571453892066907320.stgit@hbathini.in.ibm.com
2020-06-02powerpc/crashkernel: Take "mem=" option into accountPingfan Liu
'mem=" option is an easy way to put high pressure on memory during some test. Hence after applying the memory limit, instead of total mem, the actual usable memory should be considered when reserving mem for crashkernel. Otherwise the boot up may experience OOM issue. E.g. it would reserve 4G prior to the change and 512M afterward, if passing crashkernel="2G-4G:384M,4G-16G:512M,16G-64G:1G,64G-128G:2G,128G-:4G", and mem=5G on a 256G machine. This issue is powerpc specific because it puts higher priority on fadump and kdump reservation than on "mem=". Referring the following code: if (fadump_reserve_mem() == 0) reserve_crashkernel(); ... /* Ensure that total memory size is page-aligned. */ limit = ALIGN(memory_limit ?: memblock_phys_mem_size(), PAGE_SIZE); memblock_enforce_memory_limit(limit); While on other arches, the effect of "mem=" takes a higher priority and pass through memblock_phys_mem_size() before calling reserve_crashkernel(). Signed-off-by: Pingfan Liu <kernelfans@gmail.com> Reviewed-by: Hari Bathini <hbathini@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/1585749644-4148-1-git-send-email-kernelfans@gmail.com
2020-06-02hw-breakpoints: Fix build warnings with clangRavi Bangoria
kbuild test robot reported some build warnings in the hw_breakpoint code when compiled with clang[1]. Some of them were introduced by the recent powerpc change to add arch_reserve_bp_slot() and arch_release_bp_slot(). Fix them all. kernel/events/hw_breakpoint.c:71:12: warning: no previous prototype for function 'hw_breakpoint_weight' kernel/events/hw_breakpoint.c:216:12: warning: no previous prototype for function 'arch_reserve_bp_slot' kernel/events/hw_breakpoint.c:221:13: warning: no previous prototype for function 'arch_release_bp_slot' kernel/events/hw_breakpoint.c:228:13: warning: no previous prototype for function 'arch_unregister_hw_breakpoint' [1]: https://lore.kernel.org/linuxppc-dev/202005192233.oi9CjRtA%25lkp@intel.com/ Fixes: 29da4f91c0c1 ("powerpc/watchpoint: Don't allow concurrent perf and ptrace events") Reported-by: kbuild test robot <lkp@intel.com> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com> [mpe: Drop extern, flesh out change log, add Fixes tag] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200602041208.128913-1-ravi.bangoria@linux.ibm.com
2020-06-02Merge branches 'arm/msm', 'arm/allwinner', 'arm/smmu', 'x86/vt-d', ↵Joerg Roedel
'hyper-v', 'core' and 'x86/amd' into next
2020-06-01Merge branch 'from-miklos' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull vfs updates from Al Viro: "Assorted patches from Miklos. An interesting part here is /proc/mounts stuff..." The "/proc/mounts stuff" is using a cursor for keeeping the location data while traversing the mount listing. Also probably worth noting is the addition of faccessat2(), which takes an additional set of flags to specify how the lookup is done (AT_EACCESS, AT_SYMLINK_NOFOLLOW, AT_EMPTY_PATH). * 'from-miklos' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: vfs: add faccessat2 syscall vfs: don't parse "silent" option vfs: don't parse "posixacl" option vfs: don't parse forbidden flags statx: add mount_root statx: add mount ID statx: don't clear STATX_ATIME on SB_RDONLY uapi: deprecate STATX_ALL utimensat: AT_EMPTY_PATH support vfs: split out access_override_creds() proc/mounts: add cursor aio: fix async fsync creds vfs: allow unprivileged whiteout creation
2020-06-01Merge branch 'work.set_fs-exec' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull uaccess/coredump updates from Al Viro: "set_fs() removal in coredump-related area - mostly Christoph's stuff..." * 'work.set_fs-exec' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: binfmt_elf_fdpic: remove the set_fs(KERNEL_DS) in elf_fdpic_core_dump binfmt_elf: remove the set_fs(KERNEL_DS) in elf_core_dump binfmt_elf: remove the set_fs in fill_siginfo_note signal: refactor copy_siginfo_to_user32 powerpc/spufs: simplify spufs core dumping powerpc/spufs: stop using access_ok powerpc/spufs: fix copy_to_user while atomic
2020-06-01Merge branch 'uaccess.csum' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull uaccess/csum updates from Al Viro: "Regularize the sitation with uaccess checksum primitives: - fold csum_partial_... into csum_and_copy_..._user() - on x86 collapse several access_ok()/stac()/clac() into user_access_begin()/user_access_end()" * 'uaccess.csum' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: default csum_and_copy_to_user(): don't bother with access_ok() take the dummy csum_and_copy_from_user() into net/checksum.h arm: switch to csum_and_copy_from_user() sh32: convert to csum_and_copy_from_user() m68k: convert to csum_and_copy_from_user() xtensa: switch to providing csum_and_copy_from_user() sparc: switch to providing csum_and_copy_from_user() parisc: turn csum_partial_copy_from_user() into csum_and_copy_from_user() alpha: turn csum_partial_copy_from_user() into csum_and_copy_from_user() ia64: turn csum_partial_copy_from_user() into csum_and_copy_from_user() ia64: csum_partial_copy_nocheck(): don't abuse csum_partial_copy_from_user() x86: switch 32bit csum_and_copy_to_user() to user_access_{begin,end}() x86: switch both 32bit and 64bit to providing csum_and_copy_from_user() x86_64: csum_..._copy_..._user(): switch to unsafe_..._user() get rid of csum_partial_copy_to_user()
2020-06-01Merge tag 'docs-5.8' of git://git.lwn.net/linuxLinus Torvalds
Pull documentation updates from Jonathan Corbet: "A fair amount of stuff this time around, dominated by yet another massive set from Mauro toward the completion of the RST conversion. I *really* hope we are getting close to the end of this. Meanwhile, those patches reach pretty far afield to update document references around the tree; there should be no actual code changes there. There will be, alas, more of the usual trivial merge conflicts. Beyond that we have more translations, improvements to the sphinx scripting, a number of additions to the sysctl documentation, and lots of fixes" * tag 'docs-5.8' of git://git.lwn.net/linux: (130 commits) Documentation: fixes to the maintainer-entry-profile template zswap: docs/vm: Fix typo accept_threshold_percent in zswap.rst tracing: Fix events.rst section numbering docs: acpi: fix old http link and improve document format docs: filesystems: add info about efivars content Documentation: LSM: Correct the basic LSM description mailmap: change email for Ricardo Ribalda docs: sysctl/kernel: document unaligned controls Documentation: admin-guide: update bug-hunting.rst docs: sysctl/kernel: document ngroups_max nvdimm: fixes to maintainter-entry-profile Documentation/features: Correct RISC-V kprobes support entry Documentation/features: Refresh the arch support status files Revert "docs: sysctl/kernel: document ngroups_max" docs: move locking-specific documents to locking/ docs: move digsig docs to the security book docs: move the kref doc into the core-api book docs: add IRQ documentation at the core-api book docs: debugging-via-ohci1394.txt: add it to the core-api book docs: fix references for ipmi.rst file ...
2020-06-01Merge tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-armLinus Torvalds
Pull ARM updates from Russell King: - remove a now unnecessary usage of the KERNEL_DS for sys_oabi_epoll_ctl() - update my email address in a number of drivers - decompressor EFI updates from Ard Biesheuvel - module unwind section handling updates - sparsemem Kconfig cleanups - make act_mm macro respect THREAD_SIZE * tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm: ARM: 8980/1: Allow either FLATMEM or SPARSEMEM on the multiplatform build ARM: 8979/1: Remove redundant ARCH_SPARSEMEM_DEFAULT setting ARM: 8978/1: mm: make act_mm() respect THREAD_SIZE ARM: decompressor: run decompressor in place if loaded via UEFI ARM: decompressor: move GOT into .data for EFI enabled builds ARM: decompressor: defer loading of the contents of the LC0 structure ARM: decompressor: split off _edata and stack base into separate object ARM: decompressor: move headroom variable out of LC0 ARM: 8976/1: module: allow arch overrides for .init section names ARM: 8975/1: module: fix handling of unwind init sections ARM: 8974/1: use SPARSMEM_STATIC when SPARSEMEM is enabled ARM: 8971/1: replace the sole use of a symbol with its definition ARM: 8969/1: decompressor: simplify libfdt builds Update rmk's email address in various drivers ARM: compat: remove KERNEL_DS usage in sys_oabi_epoll_ctl()
2020-06-01Merge tag 'arm64-upstream' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux Pull arm64 updates from Will Deacon: "A sizeable pile of arm64 updates for 5.8. Summary below, but the big two features are support for Branch Target Identification and Clang's Shadow Call stack. The latter is currently arm64-only, but the high-level parts are all in core code so it could easily be adopted by other architectures pending toolchain support Branch Target Identification (BTI): - Support for ARMv8.5-BTI in both user- and kernel-space. This allows branch targets to limit the types of branch from which they can be called and additionally prevents branching to arbitrary code, although kernel support requires a very recent toolchain. - Function annotation via SYM_FUNC_START() so that assembly functions are wrapped with the relevant "landing pad" instructions. - BPF and vDSO updates to use the new instructions. - Addition of a new HWCAP and exposure of BTI capability to userspace via ID register emulation, along with ELF loader support for the BTI feature in .note.gnu.property. - Non-critical fixes to CFI unwind annotations in the sigreturn trampoline. Shadow Call Stack (SCS): - Support for Clang's Shadow Call Stack feature, which reserves platform register x18 to point at a separate stack for each task that holds only return addresses. This protects function return control flow from buffer overruns on the main stack. - Save/restore of x18 across problematic boundaries (user-mode, hypervisor, EFI, suspend, etc). - Core support for SCS, should other architectures want to use it too. - SCS overflow checking on context-switch as part of the existing stack limit check if CONFIG_SCHED_STACK_END_CHECK=y. CPU feature detection: - Removed numerous "SANITY CHECK" errors when running on a system with mismatched AArch32 support at EL1. This is primarily a concern for KVM, which disabled support for 32-bit guests on such a system. - Addition of new ID registers and fields as the architecture has been extended. Perf and PMU drivers: - Minor fixes and cleanups to system PMU drivers. Hardware errata: - Unify KVM workarounds for VHE and nVHE configurations. - Sort vendor errata entries in Kconfig. Secure Monitor Call Calling Convention (SMCCC): - Update to the latest specification from Arm (v1.2). - Allow PSCI code to query the SMCCC version. Software Delegated Exception Interface (SDEI): - Unexport a bunch of unused symbols. - Minor fixes to handling of firmware data. Pointer authentication: - Add support for dumping the kernel PAC mask in vmcoreinfo so that the stack can be unwound by tools such as kdump. - Simplification of key initialisation during CPU bringup. BPF backend: - Improve immediate generation for logical and add/sub instructions. vDSO: - Minor fixes to the linker flags for consistency with other architectures and support for LLVM's unwinder. - Clean up logic to initialise and map the vDSO into userspace. ACPI: - Work around for an ambiguity in the IORT specification relating to the "num_ids" field. - Support _DMA method for all named components rather than only PCIe root complexes. - Minor other IORT-related fixes. Miscellaneous: - Initialise debug traps early for KGDB and fix KDB cacheflushing deadlock. - Minor tweaks to early boot state (documentation update, set TEXT_OFFSET to 0x0, increase alignment of PE/COFF sections). - Refactoring and cleanup" * tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (148 commits) KVM: arm64: Move __load_guest_stage2 to kvm_mmu.h KVM: arm64: Check advertised Stage-2 page size capability arm64/cpufeature: Add get_arm64_ftr_reg_nowarn() ACPI/IORT: Remove the unused __get_pci_rid() arm64/cpuinfo: Add ID_MMFR4_EL1 into the cpuinfo_arm64 context arm64/cpufeature: Add remaining feature bits in ID_AA64PFR1 register arm64/cpufeature: Add remaining feature bits in ID_AA64PFR0 register arm64/cpufeature: Add remaining feature bits in ID_AA64ISAR0 register arm64/cpufeature: Add remaining feature bits in ID_MMFR4 register arm64/cpufeature: Add remaining feature bits in ID_PFR0 register arm64/cpufeature: Introduce ID_MMFR5 CPU register arm64/cpufeature: Introduce ID_DFR1 CPU register arm64/cpufeature: Introduce ID_PFR2 CPU register arm64/cpufeature: Make doublelock a signed feature in ID_AA64DFR0 arm64/cpufeature: Drop TraceFilt feature exposure from ID_DFR0 register arm64/cpufeature: Add explicit ftr_id_isar0[] for ID_ISAR0 register arm64: mm: Add asid_gen_match() helper firmware: smccc: Fix missing prototype warning for arm_smccc_version_init arm64: vdso: Fix CFI directives in sigreturn trampoline arm64: vdso: Don't prefix sigreturn trampoline with a BTI C instruction ...
2020-06-01Merge tag 'm68k-for-v5.8-tag1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/geert/linux-m68k Pull m68k updates from Geert Uytterhoeven: - several Mac fixes - defconfig updates - minor cleanups and fixes * tag 'm68k-for-v5.8-tag1' of git://git.kernel.org/pub/scm/linux/kernel/git/geert/linux-m68k: m68k: tools: Replace zero-length array with flexible-array member m68k: Add missing __user annotation in get_user() m68k: mac: Avoid stuck ISM IOP interrupt on Quadra 900/950 m68k: mac: Remove misleading comment m68k: mac: Don't call via_flush_cache() on Mac IIfx m68k: defconfig: Update defconfigs for v5.7-rc1 m68k: amiga: config: Replace zero-length array with flexible-array member m68k: amiga: config: Mark expected switch fall-through
2020-06-01Merge tag 'x86-vdso-2020-06-01' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 vdso updates from Ingo Molnar: "Clean up various aspects of the vDSO code, no change in functionality intended" * tag 'x86-vdso-2020-06-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/vdso/Makefile: Add vobjs32 x86/vdso/vdso2c: Convert iterators to unsigned x86/vdso/vdso2c: Correct error messages on file open
2020-06-01Merge tag 'x86-platform-2020-06-01' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 platform updates from Ingo Molnar: "This tree cleans up various aspects of the UV platform support code, it removes unnecessary functions and cleans up the rest" * tag 'x86-platform-2020-06-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/apic/uv: Remove code for unused distributed GRU mode x86/platform/uv: Remove the unused _uv_cpu_blade_processor_id() macro x86/platform/uv: Unexport uv_apicid_hibits x86/platform/uv: Remove _uv_hub_info_check() x86/platform/uv: Simplify uv_send_IPI_one() x86/platform/uv: Mark uv_min_hub_revision_id static x86/platform/uv: Mark is_uv_hubless() static x86/platform/uv: Remove the UV*_HUB_IS_SUPPORTED macros x86/platform/uv: Unexport symbols only used by x2apic_uv_x.c x86/platform/uv: Unexport sn_coherency_id x86/platform/uv: Remove the uv_partition_coherence_id() macro x86/platform/uv: Mark uv_bios_call() and uv_bios_call_irqsave() static
2020-06-01Merge tag 'x86-fpu-2020-06-01' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 FPU updates from Ingo Molnar: "Most of the changes here related to 'XSAVES supervisor state' support, which is a feature that allows kernel-only data to be automatically saved/restored by the FPU context switching code. CPU features that can be supported this way are Intel PT, 'PASID' and CET features" * tag 'x86-fpu-2020-06-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/fpu/xstate: Restore supervisor states for signal return x86/fpu/xstate: Preserve supervisor states for the slow path in __fpu__restore_sig() x86/fpu: Introduce copy_supervisor_to_kernel() x86/fpu/xstate: Update copy_kernel_to_xregs_err() for supervisor states x86/fpu/xstate: Update sanitize_restored_xstate() for supervisor xstates x86/fpu/xstate: Define new functions for clearing fpregs and xstates x86/fpu/xstate: Introduce XSAVES supervisor states x86/fpu/xstate: Separate user and supervisor xfeatures mask x86/fpu/xstate: Define new macros for supervisor and user xstates x86/fpu/xstate: Rename validate_xstate_header() to validate_user_xstate_header()
2020-06-01parisc: module: Update references to parisc websiteHelge Deller
The PA-RISC Linux project web page is now hosted at https://parisc.wiki.kernel.org Signed-off-by: Helge Deller <deller@gmx.de>
2020-06-01parisc: hardware: Update references to parisc websiteHelge Deller
The PA-RISC Linux project web page is now hosted at https://parisc.wiki.kernel.org Signed-off-by: Helge Deller <deller@gmx.de>
2020-06-01parisc: firmware: Update references to parisc websiteHelge Deller
The PA-RISC Linux project web page is now hosted at https://parisc.wiki.kernel.org Signed-off-by: Helge Deller <deller@gmx.de>
2020-06-01parisc: Kconfig: Update references to parisc websiteHelge Deller
The PA-RISC Linux project web page is now hosted at https://parisc.wiki.kernel.org Signed-off-by: Helge Deller <deller@gmx.de>
2020-06-01Merge tag 'x86-cpu-2020-06-01' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 cpu updates from Ingo Molnar: "Misc updates: - Extend the x86 family/model macros with a steppings dimension, because x86 life isn't complex enough and Intel uses steppings to differentiate between different CPUs. :-/ - Convert the TSC deadline timer quirks to the steppings macros. - Clean up asm mnemonics. - Fix the handling of an AMD erratum, or in other words, fix a kernel erratum" * tag 'x86-cpu-2020-06-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/cpu: Use RDRAND and RDSEED mnemonics in archrandom.h x86/cpu: Use INVPCID mnemonic in invpcid.h x86/cpu/amd: Make erratum #1054 a legacy erratum x86/apic: Convert the TSC deadline timer matching to steppings macro x86/cpu: Add a X86_MATCH_INTEL_FAM6_MODEL_STEPPINGS() macro x86/cpu: Add a steppings field to struct x86_cpu_id