On Mon, Oct 09, 2023 at 01:50:50PM +0200, Ahmad Fatoum wrote: > x86 stack is expected to be 16-byte aligned to allow for instructions > like movaps that involve xmm operands to directly use the stack. > > However the 16-byte alignment is what's expected at startup time. > All later functions will have the stack misaligned by a pointer size's > worth because call pushes the return address to the call stack. > > Add the missing (mis)alignment. This fixes a segmentation fault observed > using initjmp on x86_64. > > Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx> > --- > arch/x86/lib/setjmp_32.S | 4 +++- > arch/x86/lib/setjmp_64.S | 2 ++ > 2 files changed, 5 insertions(+), 1 deletion(-) Applied, thanks Sascha > > diff --git a/arch/x86/lib/setjmp_32.S b/arch/x86/lib/setjmp_32.S > index 38dcb68c1b59..30db5f989af6 100644 > --- a/arch/x86/lib/setjmp_32.S > +++ b/arch/x86/lib/setjmp_32.S > @@ -8,6 +8,7 @@ > #define _REGPARM > > #include <linux/linkage.h> > +#include <asm-generic/pointer.h> > > .text > .align 8 > @@ -53,7 +54,8 @@ ENDPROC(longjmp) > ENTRY(initjmp) > > movl %edx, 20(%eax) /* Return address */ > - movl %ecx, 4(%eax) /* Post-return %esp! */ > + sub $ASM_SZPTR, %ecx /* ESP - 4 has to be 16-byte aligned on entry */ > + movl %ecx, 4(%eax) /* Stack top */ > xorl %eax, %eax /* Return value */ > ret > > diff --git a/arch/x86/lib/setjmp_64.S b/arch/x86/lib/setjmp_64.S > index 28ea576cd22e..d5cf99a1557f 100644 > --- a/arch/x86/lib/setjmp_64.S > +++ b/arch/x86/lib/setjmp_64.S > @@ -6,6 +6,7 @@ > */ > > #include <linux/linkage.h> > +#include <asm-generic/pointer.h> > > .text > .align 8 > @@ -53,6 +54,7 @@ ENDPROC(longjmp) > ENTRY(initjmp) > > movq %rsi, (%rdi) /* Return address */ > + sub $ASM_SZPTR, %rdx /* RSP - 8 has to be 16-byte aligned on entry */ > movq %rdx, 8(%rdi) /* Stack top */ > xorq %rax, %rax > ret > -- > 2.39.2 > > > -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
