diff options
| author | Michael Ellerman <mpe@ellerman.id.au> | 2017-08-07 21:25:01 +1000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2017-08-07 21:36:56 +1000 |
| commit | 44a12806d010944a5727f1dc99123121e3e2c8c6 (patch) | |
| tree | 0b87f297d0ae8e975e6bdb8fd0b398bc4fc595df /arch/powerpc/kernel/process.c | |
| parent | 3db40c312c2c1eb2187c5731102fa8ff380e6e40 (diff) | |
Revert "powerpc/64: Avoid restore_math call if possible in syscall exit"
This reverts commit bc4f65e4cf9d6cc43e0e9ba0b8648cf9201cd55f.
As reported by Andreas, this commit is causing unrecoverable SLB misses in the
system call exit path:
Unrecoverable exception 4100 at c00000000000a1ec
Oops: Unrecoverable exception, sig: 6 [#1]
SMP NR_CPUS=2 PowerMac
...
CPU: 0 PID: 18626 Comm: rm Not tainted 4.13.0-rc3 #1
task: c00000018335e080 task.stack: c000000139e50000
NIP: c00000000000a1ec LR: c00000000000a118 CTR: 0000000000000000
REGS: c000000139e53bb0 TRAP: 4100 Not tainted (4.13.0-rc3)
MSR: 9000000000001030 <SF,HV,ME,IR,DR> CR: 24000044 XER: 20000000 SOFTE: 1
GPR00: 0000000000000000 c000000139e53e30 c000000000abb500 fffffffffffffffe
GPR04: c0000001eb866298 0000000000000000 0000000000000000 c00000018335e080
GPR08: 900000000000d032 0000000000000000 0000000000000002 fffffffffffff001
GPR12: c000000139e50000 c00000000ffff000 00003fffa8c0dca0 00003fffa8c0dc88
GPR16: 0000000010000000 0000000000000001 00003fffa8c0eaa0 0000000000000000
GPR20: 00003fffa8c27528 00003fffa8c27b00 0000000000000000 0000000000000000
GPR24: 00003fffa8c0d918 00003ffff1b3efa0 00003fffa8c26d68 0000000000000000
GPR28: 00003fffa8c249e8 00003fffa8c263d0 00003fffa8c27550 00003ffff1b3ef10
NIP [c00000000000a1ec] system_call_exit+0xc0/0x21c
LR [c00000000000a118] system_call+0x58/0x6c
Call Trace:
[c000000139e53e30] [c00000000000a118] system_call+0x58/0x6c (unreliable)
Instruction dump:
64a51000 7c6300d0 f8a101a0 4bffff9c 3c000000 60000006 780007c6 64000000
60000000 7c004039 4082001c e8ed0170 <88070b78> 88c70b79 7c003214 2c200000
This is caused by us trying to load THREAD_LOAD_FP with MSR_RI=0, and taking an
SLB miss on the thread struct.
Reported-by: Andreas Schwab <schwab@linux-m68k.org>
Diagnosed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/kernel/process.c')
| -rw-r--r-- | arch/powerpc/kernel/process.c | 4 |
1 files changed, 0 insertions, 4 deletions
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index 9f3e2c932dcc..ec480966f9bf 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -511,10 +511,6 @@ void restore_math(struct pt_regs *regs) { unsigned long msr; - /* - * Syscall exit makes a similar initial check before branching - * to restore_math. Keep them in synch. - */ if (!msr_tm_active(regs->msr) && !current->thread.load_fp && !loadvec(current->thread)) return; |