diff options
Diffstat (limited to 'sysdeps/unix/sysv/linux/x86_64/____longjmp_chk.S')
| -rw-r--r-- | sysdeps/unix/sysv/linux/x86_64/____longjmp_chk.S | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/sysdeps/unix/sysv/linux/x86_64/____longjmp_chk.S b/sysdeps/unix/sysv/linux/x86_64/____longjmp_chk.S index 8a9f2e1a3c..7eb26fafca 100644 --- a/sysdeps/unix/sysv/linux/x86_64/____longjmp_chk.S +++ b/sysdeps/unix/sysv/linux/x86_64/____longjmp_chk.S @@ -20,7 +20,13 @@ #include <asm-syntax.h> #include <stap-probe.h> +/* Don't restore shadow stack register if shadow stack isn't enabled. */ +#if !SHSTK_ENABLED +# undef SHADOW_STACK_POINTER_OFFSET +#endif + #include <sigaltstack-offsets.h> +#include <jmp_buf-ssp.h> .section .rodata.str1.1,"aMS",@progbits,1 .type longjmp_msg,@object @@ -105,6 +111,38 @@ ENTRY(____longjmp_chk) cfi_restore (%rsi) .Lok: +#ifdef SHADOW_STACK_POINTER_OFFSET +# if IS_IN (libc) && defined SHARED && defined FEATURE_1_OFFSET + /* Check if Shadow Stack is enabled. */ + testl $X86_FEATURE_1_SHSTK, %fs:FEATURE_1_OFFSET + jz L(skip_ssp) +# else + xorl %eax, %eax +# endif + /* Check and adjust the Shadow-Stack-Pointer. */ + rdsspq %rax + /* And compare it with the saved ssp value. */ + subq SHADOW_STACK_POINTER_OFFSET(%rdi), %rax + je L(skip_ssp) + /* Count the number of frames to adjust and adjust it + with incssp instruction. The instruction can adjust + the ssp by [0..255] value only thus use a loop if + the number of frames is bigger than 255. */ + negq %rax + shrq $3, %rax + /* NB: We saved Shadow-Stack-Pointer of setjmp. Since we are + restoring Shadow-Stack-Pointer of setjmp's caller, we + need to unwind shadow stack by one more frame. */ + addq $1, %rax + movl $255, %ebx +L(loop): + cmpq %rbx, %rax + cmovb %rax, %rbx + incsspq %rbx + subq %rbx, %rax + ja L(loop) +L(skip_ssp): +#endif LIBC_PROBE (longjmp, 3, LP_SIZE@%RDI_LP, -4@%esi, LP_SIZE@%RDX_LP) /* We add unwind information for the target here. */ cfi_def_cfa(%rdi, 0) |