On Tue, Mar 16, 2021 at 06:26:46PM +0000, Bae, Chang Seok wrote:
> I suspect the AVX-512 states not enabled there.
Ok, I found a machine which has AVX-512:
[ 0.000000] x86/fpu: Supporting XSAVE feature 0x001: 'x87 floating point
registers'
[ 0.000000] x86/fpu: Supporting XSAVE feature 0x002: 'SSE registers'
[ 0.000000] x86/fpu: Supporting XSAVE feature 0x004: 'AVX registers'
[ 0.000000] x86/fpu: Supporting XSAVE feature 0x020: 'AVX-512 opmask'
[ 0.000000] x86/fpu: Supporting XSAVE feature 0x040: 'AVX-512 Hi256'
[ 0.000000] x86/fpu: Supporting XSAVE feature 0x080: 'AVX-512 ZMM_Hi256'
[ 0.000000] x86/fpu: Supporting XSAVE feature 0x200: 'Protection Keys User
registers'
[ 0.000000] x86/fpu: xstate_offset[2]: 576, xstate_sizes[2]: 256
[ 0.000000] x86/fpu: xstate_offset[5]: 832, xstate_sizes[5]: 64
[ 0.000000] x86/fpu: xstate_offset[6]: 896, xstate_sizes[6]: 512
[ 0.000000] x86/fpu: xstate_offset[7]: 1408, xstate_sizes[7]: 1024
[ 0.000000] x86/fpu: xstate_offset[9]: 2432, xstate_sizes[9]: 8
[ 0.000000] x86/fpu: Enabled xstate features 0x2e7, context size is 2440
bytes, using 'compacted' format.
and applied your patch and added a debug printk, see end of mail.
Then, I ran the test case:
$ gcc tst-minsigstksz-2.c -DMY_MINSIGSTKSZ=3453 -o tst-minsigstksz-2
$ ./tst-minsigstksz-2
tst-minsigstksz-2: changed byte 50 bytes below configured stack
Whoops.
And the debug print said:
[ 5395.252884] signal: get_sigframe: sp: 0x7f54ec39e7b8, sas_ss_sp:
0x7f54ec39e6ce, sas_ss_size 0xd7d
which tells me that, AFAICT, your check whether we have enough alt stack
doesn't seem to work in this case.
Thx.
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index a06cb107c0e8..a7396f7c3832 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -237,7 +237,7 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
size_t frame_size,
unsigned long math_size = 0;
unsigned long sp = regs->sp;
unsigned long buf_fx = 0;
- int onsigstack = on_sig_stack(sp);
+ bool onsigstack = on_sig_stack(sp);
int ret;
/* redzone */
@@ -246,8 +246,11 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
size_t frame_size,
/* This is the X/Open sanctioned signal stack switching. */
if (ka->sa.sa_flags & SA_ONSTACK) {
- if (sas_ss_flags(sp) == 0)
+ if (sas_ss_flags(sp) == 0) {
sp = current->sas_ss_sp + current->sas_ss_size;
+ /* On the alternate signal stack */
+ onsigstack = true;
+ }
} else if (IS_ENABLED(CONFIG_X86_32) &&
!onsigstack &&
regs->ss != __USER_DS &&
@@ -263,11 +266,16 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs
*regs, size_t frame_size,
sp = align_sigframe(sp - frame_size);
+ if (onsigstack)
+ pr_info("%s: sp: 0x%lx, sas_ss_sp: 0x%lx, sas_ss_size 0x%lx\n",
+ __func__, sp, current->sas_ss_sp, current->sas_ss_size);
+
/*
* If we are on the alternate signal stack and would overflow it, don't.
* Return an always-bogus address instead so we will die with SIGSEGV.
*/
- if (onsigstack && !likely(on_sig_stack(sp)))
+ if (onsigstack && unlikely(sp <= current->sas_ss_sp ||
+ sp - current->sas_ss_sp >
current->sas_ss_size))
return (void __user *)-1L;
/* save i387 and extended state */
--
Regards/Gruss,
Boris.
SUSE Software Solutions Germany GmbH, GF: Felix Imendörffer, HRB 36809, AG
Nürnberg
