| Message ID | 1555657855-31855-1-git-send-email-bo.tong@intel.com (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | a20d452a2db7e092a9b214976306a36857b88ade |
| Headers | show |
| Series | [v3] selftests/x86: Support Atom for syscall_arg_fault test | expand |
On 4/19/19 1:10 AM, Tong Bo wrote: > 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> > --- > tools/testing/selftests/x86/syscall_arg_fault.c | 10 ++++++++-- > 1 file 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 7db4fc9..d2548401 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); > > /* > In case there is a dependency on x86 tree, here is my Ack Acked-by: Shuah Khan <skhan@linuxfoundation.org> thanks, -- Shuah
Is this patch going to be merged? Or still any blocking issue there? Thanks, Bo -----Original Message----- From: shuah [mailto:shuah@kernel.org] Sent: Friday, April 19, 2019 10:05 PM To: Tong, Bo <bo.tong@intel.com>; luto@kernel.org; x86@kernel.org Cc: linux-kselftest@vger.kernel.org; linux-kernel@vger.kernel.org; skhan@linuxfoundation.org; shuah@kernel.org Subject: Re: [PATCH v3] selftests/x86: Support Atom for syscall_arg_fault test On 4/19/19 1:10 AM, Tong Bo wrote: > 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> > --- > tools/testing/selftests/x86/syscall_arg_fault.c | 10 ++++++++-- > 1 file 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 7db4fc9..d2548401 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); > > /* > In case there is a dependency on x86 tree, here is my Ack Acked-by: Shuah Khan <skhan@linuxfoundation.org> thanks, -- Shuah
Hi Bo, On 5/17/19 1:02 AM, Tong, Bo wrote: > Is this patch going to be merged? Or still any blocking issue there? > > Thanks, > Bo > > -----Original Message----- > From: shuah [mailto:shuah@kernel.org] > Sent: Friday, April 19, 2019 10:05 PM > To: Tong, Bo <bo.tong@intel.com>; luto@kernel.org; x86@kernel.org > Cc: linux-kselftest@vger.kernel.org; linux-kernel@vger.kernel.org; skhan@linuxfoundation.org; shuah@kernel.org > Subject: Re: [PATCH v3] selftests/x86: Support Atom for syscall_arg_fault test > > On 4/19/19 1:10 AM, Tong Bo wrote: >> 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> >> --- >> tools/testing/selftests/x86/syscall_arg_fault.c | 10 ++++++++-- >> 1 file 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 7db4fc9..d2548401 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); >> >> /* >> > > In case there is a dependency on x86 tree, here is my Ack > > Acked-by: Shuah Khan <skhan@linuxfoundation.org> > Looks like it got left behind in the confusion of which tree. I will apply this to my tree. thanks, -- Shuah
diff --git a/tools/testing/selftests/x86/syscall_arg_fault.c b/tools/testing/selftests/x86/syscall_arg_fault.c index 7db4fc9..d2548401 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); /*