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This function isn't much needed as NAPI skb queue gets bulk-freed
anyway when there's no more room, and even may reduce the efficiency
of bulk operations.
It will be even less needed after reusing skb cache on allocation path,
so remove it and this way lighten network softirqs a bit.
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Just call __build_skb_around() instead of open-coding it.
Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Use unlikely() annotations for skbuff_head and data similarly to the
two other allocation functions and remove totally redundant goto.
Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Signed-off-by: David S. Miller <davem@davemloft.net>
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__build_skb_around() can never fail and always returns passed skb.
Make it return void to simplify and optimize the code.
Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Eversince the introduction of __kmalloc_reserve(), "ip" argument
hasn't been used. _RET_IP_ is embedded inside
kmalloc_node_track_caller().
Remove the redundant macro and rename the function after it.
Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Signed-off-by: David S. Miller <davem@davemloft.net>
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In preparation before reusing several functions in all three skb
allocation variants, move __alloc_skb() next to the
__netdev_alloc_skb() and __napi_alloc_skb().
No functional changes.
Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Signed-off-by: David S. Miller <davem@davemloft.net>
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git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux
Pull clk fix from Stephen Boyd:
"One small fix for the Allwinner clk driver so that display clks figure
out the correct rate to use.
This fixes displays running 4k@60Hz and some other resolutions that
haven't been exercised and fully understood until now"
* tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux:
clk: sunxi-ng: mp: fix parent rate change flag check
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git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi
Pull SCSI fix from James Bottomley:
"One fix for scsi_debug that fixes a memory leak on module removal"
* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
scsi: scsi_debug: Fix a memory leak
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Writing one of key two values into the configuration key register
is a common operation, so a utility function has been added to
provide consistent behavior and eliminate code duplication.
Signed-off-by: Kevin P. Fleming <kevin+linux@km6g.us>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
To: linux-rtc@vger.kernel.org
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20200615105113.57770-2-kevin+linux@km6g.us
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Fix to return PTR_ERR() error code from the error handling case instead
fo 0 in function alloc_wbufs(), as done elsewhere in this function.
Fixes: 6a98bc4614de ("ubifs: Add authentication nodes to journal")
Signed-off-by: Wang ShaoBo <bobo.shaobowang@huawei.com>
Reviewed-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Richard Weinberger <richard@nod.at>
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Properly set flag WD_CD for rtc chips(pcf2129, pca2129)
Signed-off-by: Biwen Li <biwen.li@nxp.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20201202031840.15582-1-biwen.li@oss.nxp.com
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This patch fixes the following checkpatch.pl check:
CHECK: Alignment should match open parenthesis
Signed-off-by: Mukul Mehar <mukulmehar02@gmail.com>
Link: https://lore.kernel.org/r/20210213120556.73579-1-mukulmehar02@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Fixed the spelling of 'transfered' to 'transferred'.
Signed-off-by: Pritthijit Nath <pritthijit.nath@icloud.com>
Link: https://lore.kernel.org/r/20210212101324.12391-1-pritthijit.nath@icloud.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Fix sparse byte-order warnings in the i2400m_bm_cmd_prepare()
function:
wimax/i2400m/fw.c:194:36: warning: restricted __le32 degrades to integer
wimax/i2400m/fw.c:195:34: warning: invalid assignment: +=
wimax/i2400m/fw.c:195:34: left side has type unsigned int
wimax/i2400m/fw.c:195:34: right side has type restricted __le32
wimax/i2400m/fw.c:196:32: warning: restricted __le32 degrades to integer
wimax/i2400m/fw.c:196:47: warning: restricted __le32 degrades to integer
wimax/i2400m/fw.c:196:66: warning: restricted __le32 degrades to integer
Signed-off-by: Anirudh Rayabharam <mail@anirudhrb.com>
Link: https://lore.kernel.org/r/20210212153843.8554-1-mail@anirudhrb.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Fix some "incorrect type in assignment" warnings reported
by sparse in tx.c
sparse warnings:
wimax/i2400m/tx.c:788:35: warning: cast to restricted __le16
wimax/i2400m/tx.c:788:33: warning: incorrect type in assignment
(different base types)
wimax/i2400m/tx.c:788:33: expected restricted __le16 [usertype] num_pls
wimax/i2400m/tx.c:788:33: got unsigned short [usertype]
wimax/i2400m/tx.c:896:32: warning: cast to restricted __le32
wimax/i2400m/tx.c:896:30: warning: incorrect type in assignment
(different base types)
wimax/i2400m/tx.c:896:30: expected restricted __le32 [usertype] barker
wimax/i2400m/tx.c:896:30: got unsigned int [usertype]
wimax/i2400m/tx.c:897:34: warning: cast to restricted __le32
wimax/i2400m/tx.c:897:32: warning: incorrect type in assignment
(different base types)
wimax/i2400m/tx.c:897:32: expected restricted __le32 [usertype] sequence
wimax/i2400m/tx.c:897:32: got unsigned int [usertype]
wimax/i2400m/tx.c:899:15: warning: cast to restricted __le32
wimax/i2400m/tx.c:899:15: warning: cast from restricted __le16
Signed-off-by: Ayush <ayush@disroot.org>
Link: https://lore.kernel.org/r/20210212213628.801642-1-ayush@disroot.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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checkpatch warning fix for string split across lines
Signed-off-by: Manikantan Ravichandran <ravman1991@gmail.com>
Link: https://lore.kernel.org/r/20210212225035.GA16260@whach
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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memdup_user() is shorter and safer equivalent
of kmalloc/copy_from_user pair.
Signed-off-by: Ivan Safonov <insafonov@gmail.com>
Link: https://lore.kernel.org/r/20210213120527.451531-1-insafonov@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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_TO_DS_, _FROM_DS_, _MORE_FRAG_, _RETRY_, _PWRMGT_, _MORE_DATA_,
_PRIVACY_, _ORDER_ definitions are duplicate IEEE80211_FCTL_*
kernel definitions.
Signed-off-by: Ivan Safonov <insafonov@gmail.com>
Link: https://lore.kernel.org/r/20210213131148.458582-1-insafonov@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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This patch removes some blank lines in order to fix a checkpatch issue.
Signed-off-by: William Durand <will+git@drnd.me>
Link: https://lore.kernel.org/r/20210213034711.14823-1-will+git@drnd.me
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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The NXP PCA8565 is software compatible with the NXP PCF8563,
add DT and ACPI compatible entries.
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Alexandre Belloni <alexandre.belloni@bootlin.com>
To: linux-rtc@vger.kernel.org
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20210210220623.23233-1-marex@denx.de
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git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fixes from Tejun Heo:
"Two cgroup fixes:
- fix a NULL deref when trying to poll PSI in the root cgroup
- fix confusing controller parsing corner case when mounting cgroup
v1 hierarchies
And doc / maintainer file updates"
* 'for-5.11-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: update PSI file description in docs
cgroup: fix psi monitor for root cgroup
MAINTAINERS: Update my email address
MAINTAINERS: Remove stale URLs for cpuset
cgroup-v1: add disabled controller check in cgroup1_parse_param()
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Merge fixes from Andrew Morton:
"6 patches.
Subsystems affected by this patch series: mm/pagemap, scripts,
MAINTAINERS, and h8300"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
h8300: fix PREEMPTION build, TI_PRE_COUNT undefined
MAINTAINERS: add Andrey Konovalov to KASAN reviewers
MAINTAINERS: update Andrey Konovalov's email address
MAINTAINERS: update KASAN file list
scripts/recordmcount.pl: support big endian for ARCH sh
m68k: make __pfn_to_phys() and __phys_to_pfn() available for !MMU
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git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux
Pull i2c fix from Wolfram Sang:
"One more I2C driver bugfix"
* 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
i2c: stm32f7: fix configuration of the digital filter
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git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs fix from David Sterba:
"A regression fix caused by a refactoring in 5.11.
A corrupted superblock wouldn't be detected by checksum verification
due to wrongly placed initialization of the checksum length, thus
making memcmp always work"
* tag 'for-5.11-rc7-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: initialize fs_info::csum_size earlier in open_ctree
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Fix a build error for undefined 'TI_PRE_COUNT' by adding it to
asm-offsets.c.
h8300-linux-ld: arch/h8300/kernel/entry.o: in function `resume_kernel': (.text+0x29a): undefined reference to `TI_PRE_COUNT'
Link: https://lkml.kernel.org/r/20210212021650.22740-1-rdunlap@infradead.org
Fixes: df2078b8daa7 ("h8300: Low level entry")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: kernel test robot <lkp@intel.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Add my personal email address to KASAN reviewers list.
Link: https://lkml.kernel.org/r/c1ce89a7aae0e2d6852249c280b1eb59aeac30c0.1613150186.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Use my personal email address.
Link: https://lkml.kernel.org/r/b0ec98dabbc12336c162788f5ccde97045a0d65e.1613150186.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Account for the following files:
- lib/Kconfig.kasan
- lib/test_kasan_module.c
- arch/arm64/include/asm/mte-kasan.h
Link: https://lkml.kernel.org/r/7f9771d97b34d396bfdc4e288ad93486bb865a06.1613150186.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The kernel test robot reported the following issue:
CC [M] drivers/soc/litex/litex_soc_ctrl.o
sh4-linux-objcopy: Unable to change endianness of input file(s)
sh4-linux-ld: cannot find drivers/soc/litex/.tmp_gl_litex_soc_ctrl.o: No such file or directory
sh4-linux-objcopy: 'drivers/soc/litex/.tmp_mx_litex_soc_ctrl.o': No such file
The problem is that the format of input file is elf32-shbig-linux, but
sh4-linux-objcopy wants to output a file which format is elf32-sh-linux:
$ sh4-linux-objdump -d drivers/soc/litex/litex_soc_ctrl.o | grep format
drivers/soc/litex/litex_soc_ctrl.o: file format elf32-shbig-linux
Link: https://lkml.kernel.org/r/20210210150435.2171567-1-rong.a.chen@intel.com
Link: https://lore.kernel.org/linux-mm/202101261118.GbbYSlHu-lkp@intel.com
Signed-off-by: Rong Chen <rong.a.chen@intel.com>
Reported-by: kernel test robot <lkp@intel.com>
Cc: Yoshinori Sato <ysato@users.osdn.me>
Cc: Rich Felker <dalias@libc.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Recent changes that obsoleted DISCONTIGMEM on m68k switched the MMU
variant to use generic definitions of __pfn_to_phys() and __phys_to_pfn(),
but missed the !MMU variant which caused a build failure:
drivers/media/common/videobuf2/videobuf2-dma-contig.c: In function 'vb2_dc_get_userptr':
drivers/media/common/videobuf2/videobuf2-dma-contig.c:509:5: error: implicit declaration of function '__pfn_to_phys' [-Werror=implicit-function-declaration]
509 | __pfn_to_phys(nums[0]), size, buf->dma_dir, 0);
| ^~~~~~~~~~~~~
cc1: some warnings being treated as errors
Enable __pfn_to_phys() and __phys_to_pfn() on !MMU builds.
Link: https://lkml.kernel.org/r/20210211232202.GS299309@linux.ibm.com
Fixes: 4bfc848e0981 ("m68k/mm: enable use of generic memory_model.h for !DISCONTIGMEM")
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Reported-by: kernel test robot <lkp@intel.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greg Ungerer <gerg@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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For non-QEBSM devices, get_buf_states() merges PENDING and EMPTY buffers
into a single group of finished buffers. To allow the upper-layer driver
to differentiate between the two states, qdio_check_pending() looks at
each buffer's state again and sets the sbal_state flag to
QDIO_OUTBUF_STATE_FLAG_PENDING accordingly.
So effectively we're spending overhead on _every_ Output Queue
inspection, just to avoid some additional TX completion calls in case
a group of buffers has completed with mixed EMPTY / PENDING state.
Given that PENDING buffers should rarely occur, this is a bad trade-off.
In particular so as the additional checks in get_buf_states() affect
_all_ device types (even those that don't use the PENDING state).
Rip it all out, and just report the PENDING completions separately as
we already do for QEBSM devices.
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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For QEBSM devices the 'merge_pending' mechanism in get_buf_states()
doesn't apply, and we can actually get SLSB_P_OUTPUT_PENDING returned.
So for this case propagating the PENDING state to the driver via the
queue's sbal_state doesn't make sense and creates unnecessary overhead.
Instead introduce a new QDIO_ERROR_* flag that gets passed to the
driver, and triggers the same processing as if the buffers were flagged
as QDIO_OUTBUF_STATE_FLAG_PENDING.
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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When inspecting a queue, any error is currently returned back through
the queue's qdio_error field. Turn this into a proper variable that gets
passed through the call chain, so that the lifetime is clear and the
error state can be accessed along the way.
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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We don't kick the handler for Input Queues anymore. Move the remaining
code into its only caller.
Signed-off-by: Julian Wiedmann <jwi@linux.ibm.com>
Reviewed-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Remove get_tod_clock_ext() and the STORE_CLOCK_EXT_SIZE define. This
enforces all users of the existing low level functions to use a union
tod_clock.
This way there is now a compile time check for the correct time and
therefore also if the size of the argument matches what will be
written to by the STORE CLOCK EXTENDED instruction.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Use store_tod_clock_ext() in order to be able to get rid
get_tod_clock_ext().
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Use store_tod_clock_ext() instead of get_tod_clock_ext().
Unfortunately one usage has to be converted to a cast, since
otherwise a uapi header file would have to be changed.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Use union tod_clock and get rid of the kvm specific struct
kvm_s390_tod_clock_ext which apparently was introduced for the same
purpose.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Convert tod_clock_base to union tod_clock. This simplifies quite a bit
of code and also fixes a bug in read_persistent_clock64();
void read_persistent_clock64(struct timespec64 *ts)
{
__u64 delta;
delta = initial_leap_seconds + TOD_UNIX_EPOCH;
get_tod_clock_ext(clk);
*(__u64 *) &clk[1] -= delta;
if (*(__u64 *) &clk[1] > delta)
clk[0]--;
ext_to_timespec64(clk, ts);
}
Assume &clk[1] == 3 and delta == 2; then after the substraction the if
condition becomes true and the epoch part of the clock is decremented
by one because of an assumed overflow, even though there is none.
Fix this by using 128 bit arithmetics and let the compiler do the
right thing:
void read_persistent_clock64(struct timespec64 *ts)
{
union tod_clock clk;
u64 delta;
delta = initial_leap_seconds + TOD_UNIX_EPOCH;
store_tod_clock_ext(&clk);
clk.eitod -= delta;
ext_to_timespec64(&clk, ts);
}
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Introduce new store_tod_clock_ext() function, which is the same like
store_tod_clock_ext_cc() except that it doesn't return a condition
code.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Rename store_tod_clock_ext() to store_tod_clock_ext_cc() to reflect
that it returns a condition code and also use union tod_clock as
parameter.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Introduce union tod_clock which is supposed to be used to decode and
access various fields of the result of STORE CLOCK EXTENDED.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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s390 and alpha are the only 64 bit architectures with a 32-bit ino_t.
Since this is quite unusual this causes bugs from time to time.
See e.g. commit ebce3eb2f7ef ("ceph: fix inode number handling on
arches with 32-bit ino_t") for an example.
This (obviously) also prevents s390 and alpha to use 64-bit ino_t for
tmpfs. See commit b85a7a8bb573 ("tmpfs: disallow CONFIG_TMPFS_INODE64
on s390").
Therefore switch both s390 and alpha to 64-bit ino_t. This should only
have an effect on the ustat system call. To prevent ABI breakage
define struct ustat compatible to the old layout and change
sys_ustat() accordingly.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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The current code uses the address in %r11 to figure out whether
it was called from the machine check handler or from a normal
interrupt handler. Instead of doing this implicit logic (which
is mostly a leftover from the old critical cleanup approach)
just add a second label and use that.
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Instead of thrashing r11 which is normally our pointer to struct
pt_regs on the stack, use r13 as temporary register in the BR_EX
macro. r13 is already used in cleanup_sie, so no need to thrash
another register.
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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If a machine check is coming in during sie, the PU saves the
control registers to the machine check save area. Afterwards
mcck_int_handler is called, which loads __LC_KERNEL_ASCE into
%cr1. Later the code restores %cr1 from the machine check area,
but that is wrong when SIE was interrupted because the machine
check area still contains the gmap asce. Instead it should return
with either __KERNEL_ASCE in %cr1 when interrupted in SIE or
the previous %cr1 content saved in the machine check save area.
Fixes: 87d598634521 ("s390/mm: remove set_fs / rework address space handling")
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Cc: <stable@kernel.org> # v5.8+
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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The previous code used the normal kernel stack for machine checks.
This is problematic when a machine check interrupts a system call
or interrupt handler right at the beginning where registers are set up.
Assume system_call is interrupted at the first instruction and a machine
check is triggered. The machine check handler is called, checks the PSW
to see whether it is coming from user space, notices that it is already
in kernel mode but %r15 still contains the user space stack. This would
lead to a kernel crash.
There are basically two ways of fixing that: Either using the 'critical
cleanup' approach which compares the address in the PSW to see whether
it is already at a point where the stack has been set up, or use an extra
stack for the machine check handler.
For simplicity, we will go with the second approach and allocate an extra
stack. This adds some memory overhead for large systems, but usually large
system have plenty of memory so this isn't really a concern. But it keeps
the mchk stack setup simple and less error prone.
Fixes: 0b0ed657fe00 ("s390: remove critical section cleanup from entry.S")
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Cc: <stable@kernel.org> # v5.8+
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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The code does:
S390_lowcore.async_stack = new + STACK_INIT_OFFSET;
But the compiler is free to first assign one value and
add the other value later. If a IRQ would be coming in
between these two operations, it would run with an invalid
stack. Prevent this by using WRITE_ONCE.
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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