# git rev-parse -q --verify 590ce02bd148cd35721560c140e3759e39a6e56a^{commit}
590ce02bd148cd35721560c140e3759e39a6e56a
already have revision, skipping fetch
# git checkout -q -f -B kisskb 590ce02bd148cd35721560c140e3759e39a6e56a
# git clean -qxdf
# < git log -1
# commit 590ce02bd148cd35721560c140e3759e39a6e56a
# Author: Nicholas Piggin <npiggin@gmail.com>
# Date:   Wed Jul 22 17:34:37 2020 +1000
# 
#     powerpc/64s: Fix irq tracing corruption in interrupt/syscall return caused by perf interrupts
#     
#     Alexey reports lockdep_assert_irqs_enabled() warnings when stress
#     testing perf, e.g.,
#     
#       WARNING: CPU: 0 PID: 1556 at kernel/softirq.c:169 __local_bh_enable_ip+0x258/0x270
#       CPU: 0 PID: 1556 Comm: syz-executor
#       NIP:  c0000000001ec888 LR: c0000000001ec884 CTR: c000000000ef0610
#       REGS: c000000022d4f8a0 TRAP: 0700   Not tainted  (5.8.0-rc3-x)
#       MSR:  8000000000029033 <SF,EE,ME,IR,DR,RI,LE>  CR: 28008844  XER: 20040000
#       CFAR: c0000000001dc1d0 IRQMASK: 0
#     
#     The interesting thing is MSR[EE] and IRQMASK shows interrupts are
#     enabled, suggesting the current->hardirqs_enabled irq tracing state is
#     going out of sync with the actual interrupt enable state.
#     
#     The cause is a window in interrupt/syscall return where irq tracing
#     state is being adjusted for an irqs-enabled return while MSR[EE] is
#     still enabled. A perf interrupt hits and ends up calling
#     trace_hardirqs_off() when restoring interrupt flags to a disable
#     state.
#     
#     Fix this by disabling perf interrupts as well while adjusting irq
#     tracing state.
#     
#     Add a debug check that catches the condition sooner.
#     
#     Fixes: 68b34588e202 ("powerpc/64/sycall: Implement syscall entry/exit logic in C")
#     Cc: stable@vger.kernel.org # v5.7+
#     Reported-by: Alexey Kardashevskiy <aik@ozlabs.ru>
#     Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
#     Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
#     Link: https://lore.kernel.org/r/20200722073437.930521-1-npiggin@gmail.com
# < /opt/cross/kisskb/korg/gcc-4.9.4-nolibc/ia64-linux/bin/ia64-linux-gcc --version
# < /opt/cross/kisskb/korg/gcc-4.9.4-nolibc/ia64-linux/bin/ia64-linux-ld --version
# < git log --format=%s --max-count=1 590ce02bd148cd35721560c140e3759e39a6e56a
# < make -s -j 24 ARCH=ia64 O=/kisskb/build/powerpc-fixes_ia64-defconfig_ia64-gcc4.9 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-4.9.4-nolibc/ia64-linux/bin/ia64-linux-  defconfig
# < make -s -j 24 ARCH=ia64 O=/kisskb/build/powerpc-fixes_ia64-defconfig_ia64-gcc4.9 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-4.9.4-nolibc/ia64-linux/bin/ia64-linux-  help
# make -s -j 24 ARCH=ia64 O=/kisskb/build/powerpc-fixes_ia64-defconfig_ia64-gcc4.9 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-4.9.4-nolibc/ia64-linux/bin/ia64-linux-  olddefconfig
# make -s -j 24 ARCH=ia64 O=/kisskb/build/powerpc-fixes_ia64-defconfig_ia64-gcc4.9 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-4.9.4-nolibc/ia64-linux/bin/ia64-linux-  
<stdin>:1511:2: warning: #warning syscall clone3 not implemented [-Wcpp]
In file included from /kisskb/src/arch/ia64/include/uapi/asm/intrinsics.h:22:0,
                 from /kisskb/src/arch/ia64/include/asm/intrinsics.h:11,
                 from /kisskb/src/arch/ia64/include/asm/bitops.h:19,
                 from /kisskb/src/include/linux/bitops.h:29,
                 from /kisskb/src/include/linux/kernel.h:12,
                 from /kisskb/src/include/linux/list.h:9,
                 from /kisskb/src/include/linux/preempt.h:11,
                 from /kisskb/src/include/linux/spinlock.h:51,
                 from /kisskb/src/include/linux/seqlock.h:36,
                 from /kisskb/src/include/linux/time.h:6,
                 from /kisskb/src/fs/nfs/read.c:11:
/kisskb/src/fs/nfs/read.c: In function 'nfs_read_completion':
/kisskb/src/arch/ia64/include/uapi/asm/cmpxchg.h:57:2: warning: value computed is not used [-Wunused-value]
 ((__typeof__(*(ptr))) __xchg((unsigned long) (x), (ptr), sizeof(*(ptr))))
  ^
/kisskb/src/fs/nfs/read.c:196:5: note: in expansion of macro 'xchg'
     xchg(&nfs_req_openctx(req)->error, error);
     ^
/kisskb/src/fs/nfs/read.c: In function 'nfs_readpage':
/kisskb/src/arch/ia64/include/uapi/asm/cmpxchg.h:57:2: warning: value computed is not used [-Wunused-value]
 ((__typeof__(*(ptr))) __xchg((unsigned long) (x), (ptr), sizeof(*(ptr))))
  ^
/kisskb/src/fs/nfs/read.c:355:2: note: in expansion of macro 'xchg'
  xchg(&ctx->error, 0);
  ^
No errors detected in 22248 functions.
Completed OK
# rm -rf /kisskb/build/powerpc-fixes_ia64-defconfig_ia64-gcc4.9
# Build took: 0:02:54.883667