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| author |   Tong Bo <bo.tong@intel.com> | 2019-04-19 15:10:55 +0800 |
|---|---|---|
| committer |   Shuah Khan <skhan@linuxfoundation.org> | 2019-05-21 09:24:30 -0600 |
| commit | a20d452a2db7e092a9b214976306a36857b88ade (patch) | |
| tree | a606e24366f9598ee93da9a9a75c88acd7ab3121 /tools/testing/selftests/x86 | |
| parent | Linux 5.2-rc1 (diff) | |
| download | linux-dev-a20d452a2db7e092a9b214976306a36857b88ade.tar.xz linux-dev-a20d452a2db7e092a9b214976306a36857b88ade.zip | |
selftests/x86: Support Atom for syscall_arg_fault test
Atom-based CPUs trigger stack fault when invoke 32-bit SYSENTER instruction
with invalid register values. So we also need SIGBUS handling in this case.
Following is assembly when the fault exception happens.
(gdb) disassemble $eip
Dump of assembler code for function __kernel_vsyscall:
0xf7fd8fe0 <+0>: push %ecx
0xf7fd8fe1 <+1>: push %edx
0xf7fd8fe2 <+2>: push %ebp
0xf7fd8fe3 <+3>: mov %esp,%ebp
0xf7fd8fe5 <+5>: sysenter
0xf7fd8fe7 <+7>: int $0x80
=> 0xf7fd8fe9 <+9>: pop %ebp
0xf7fd8fea <+10>: pop %edx
0xf7fd8feb <+11>: pop %ecx
0xf7fd8fec <+12>: ret
End of assembler dump.
According to Intel SDM, this could also be a Stack Segment Fault(#SS, 12),
except a normal Page Fault(#PF, 14). Especially, in section 6.9 of Vol.3A,
both stack and page faults are within the 10th(lowest priority) class, and
as it said, "exceptions within each class are implementation-dependent and
may vary from processor to processor". It's expected for processors like
Intel Atom to trigger stack fault(SIGBUS), while we get page fault(SIGSEGV)
from common Core processors.
Signed-off-by: Tong Bo <bo.tong@intel.com>
Acked-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Diffstat (limited to 'tools/testing/selftests/x86')
| -rw-r--r-- | tools/testing/selftests/x86/syscall_arg_fault.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/tools/testing/selftests/x86/syscall_arg_fault.c b/tools/testing/selftests/x86/syscall_arg_fault.c index 7db4fc9fa09f..d2548401921f 100644 --- a/tools/testing/selftests/x86/syscall_arg_fault.c +++ b/tools/testing/selftests/x86/syscall_arg_fault.c @@ -43,7 +43,7 @@ static sigjmp_buf jmpbuf; static volatile sig_atomic_t n_errs; -static void sigsegv(int sig, siginfo_t *info, void *ctx_void) +static void sigsegv_or_sigbus(int sig, siginfo_t *info, void *ctx_void) { ucontext_t *ctx = (ucontext_t*)ctx_void; @@ -73,7 +73,13 @@ int main() if (sigaltstack(&stack, NULL) != 0) err(1, "sigaltstack"); - sethandler(SIGSEGV, sigsegv, SA_ONSTACK); + sethandler(SIGSEGV, sigsegv_or_sigbus, SA_ONSTACK); + /* + * The actual exception can vary. On Atom CPUs, we get #SS + * instead of #PF when the vDSO fails to access the stack when + * ESP is too close to 2^32, and #SS causes SIGBUS. + */ + sethandler(SIGBUS, sigsegv_or_sigbus, SA_ONSTACK); sethandler(SIGILL, sigill, SA_ONSTACK); /* |