You need to sign in or sign up before continuing.
-
Ammar Faizi authored
The ABI mandates that the %esp register must be a multiple of 16 when executing a 'call' instruction. Commit 2ab44633 ("tools/nolibc: i386: shrink _start with _start_c") simplified the _start function, but it didn't take care of the %esp alignment, causing SIGSEGV on SSE and AVX programs that use aligned move instruction (e.g., movdqa, movaps, and vmovdqa). The 'and $-16, %esp' aligns the %esp at a multiple of 16. Then 'push %eax' will subtract the %esp by 4; thus, it breaks the 16-byte alignment. Make sure the %esp is correctly aligned after the push by subtracting 12 before the push. Extra: Add 'add $12, %esp' before the 'and $-16, %esp' to avoid over-estimating for particular cases as suggested by Willy. A test program to validate the %esp alignment on _start can be found at: https://lore.kernel.org/lkml/ZOoindMFj1UKqo+s@biznet-home.integral.gnuweeb.org [ Thomas: trim Fixes tag commit id ] Cc: Zhangjin Wu <falcon@tinylab.org> Fixes: 2...
d873a364
