Messages in this thread | | | Date | Fri, 22 May 2020 11:28:48 +0200 | From | Peter Zijlstra <> | Subject | Re: [RFC PATCH 5/5] selftest/x86: Add CET quick test |
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On Thu, May 21, 2020 at 02:17:20PM -0700, Yu-cheng Yu wrote:
> +#pragma GCC push_options > +#pragma GCC optimize ("O0") > +void ibt_violation(void) > +{ > +#ifdef __i386__ > + asm volatile("lea 1f, %eax"); > + asm volatile("jmp *%eax"); > +#else > + asm volatile("lea 1f, %rax"); > + asm volatile("jmp *%rax"); > +#endif > + asm volatile("1:"); > + result[test_id] = -1; > + test_id++; > + setcontext(&ucp); > +} > + > +void shstk_violation(void) > +{ > +#ifdef __i386__ > + unsigned long x = 0; > + > + ((unsigned long *)&x)[2] = (unsigned long)stack_hacked; > +#else > + unsigned long long x = 0; > + > + ((unsigned long long *)&x)[2] = (unsigned long)stack_hacked; > +#endif > +} > +#pragma GCC pop_options
This is absolutely atrocious.
The #pragma like Kees already said just need to go. Also, there's absolutely no clue what so ever what it attempts to achieve.
The __i386__ ifdeffery is horrible crap. Splitting an asm with #ifdef like that is also horrible crap.
This is not how you write code.
Get asm/asm.h into userspace and then write something like:
void ibt_violation(void) { asm volatile("lea 1f, %" _ASM_AX "\n\t" "jmp *%" _ASM_AX "\n\t" "1:\n\t" ::: "a");
WRITE_ONCE(result[test_id], -1); WRITE_ONCE(test_id, test_id+1);
setcontext(&ucp); }
void shstk_violation(void) { unsigned long x = 0;
WRITE_ONCE(x[2], stack_hacked); }
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