Messages in this thread | | | Date | Wed, 2 Jun 2021 14:38:11 +0200 | From | Borislav Petkov <> | Subject | Re: [patch 1/8] selftests/x86: Test signal frame XSTATE header corruption handling |
| |
On Wed, Jun 02, 2021 at 11:55:44AM +0200, Thomas Gleixner wrote: > From: Andy Lutomirski <luto@kernel.org> > > This is very heavily based on some code from Thomas Gleixner. On a system > without XSAVES, it triggers the WARN_ON(): > > Bad FPU state detected at copy_kernel_to_fpregs+0x2f/0x40, reinitializing FPU registers.
That triggers
[ 149.497274] corrupt_xstate_[1627] bad frame in rt_sigreturn frame:00000000dad08ab1 ip:7f031449ffe1 sp:7ffd0c5c59f0 orax:ffffffffffffffff in libpthread-2.31.so[7f0314493000+10000]
on an AMD laptop here.
> +static inline void __cpuid(unsigned int *eax, unsigned int *ebx, > + unsigned int *ecx, unsigned int *edx) > +{ > + asm volatile( > + "cpuid;" > + : "=a" (*eax), > + "=b" (*ebx), > + "=c" (*ecx), > + "=d" (*edx) > + : "0" (*eax), "2" (*ecx)); > +} > + > +static inline int xsave_enabled(void) > +{ > + unsigned int eax, ebx, ecx, edx; > + > + eax = 0x1; > + ecx = 0x0; > + __cpuid(&eax, &ebx, &ecx, &edx); > + > + /* Is CR4.OSXSAVE enabled ? */ > + return ecx & (1U << 27); > +}
One fine day someone should sit down and unify all those auxillary functions used in the selftests into a lib...
> + > +static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *), > + int flags) > +{ > + struct sigaction sa; > + > + memset(&sa, 0, sizeof(sa)); > + sa.sa_sigaction = handler; > + sa.sa_flags = SA_SIGINFO | flags; > + sigemptyset(&sa.sa_mask); > + if (sigaction(sig, &sa, 0)) > + err(1, "sigaction"); > +} > + > +static void sigusr1(int sig, siginfo_t *info, void *uc_void) > +{ > + ucontext_t *uc = uc_void; > + uint8_t *fpstate = (uint8_t *)uc->uc_mcontext.fpregs; > + uint64_t *xfeatures = (uint64_t *)(fpstate + 512); > + > + printf("\tWreckage XSTATE header\n"); > + /* Wreckage the first reserved byte in the header */ > + *(xfeatures + 2) = 0xfffffff; > +} > + > +static void sigsegv(int sig, siginfo_t *info, void *uc_void) > +{ > + printf("\tGot SIGSEGV\n"); > +} > + > +int main()
ERROR: Bad function definition - int main() should probably be int main(void)
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
| |