diff options
Diffstat (limited to 'sysdeps/x86_64/__longjmp.S')
| -rw-r--r-- | sysdeps/x86_64/__longjmp.S | 46 |
1 files changed, 45 insertions, 1 deletions
diff --git a/sysdeps/x86_64/__longjmp.S b/sysdeps/x86_64/__longjmp.S index c164626577..d7d123e4bc 100644 --- a/sysdeps/x86_64/__longjmp.S +++ b/sysdeps/x86_64/__longjmp.S @@ -1,4 +1,4 @@ -/* Copyright (C) 2001-2016 Free Software Foundation, Inc. +/* Copyright (C) 2001-2018 Free Software Foundation, Inc. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or @@ -17,9 +17,18 @@ #include <sysdep.h> #include <jmpbuf-offsets.h> +#include <jmp_buf-ssp.h> #include <asm-syntax.h> #include <stap-probe.h> +/* Don't restore shadow stack register if + 1. Shadow stack isn't enabled. Or + 2. __longjmp is defined for __longjmp_cancel. + */ +#if !SHSTK_ENABLED || defined __longjmp +# undef SHADOW_STACK_POINTER_OFFSET +#endif + /* Jump to the position specified by ENV, causing the setjmp call there to return VAL, or 1 if VAL is 0. void __longjmp (__jmp_buf env, int val). */ @@ -42,6 +51,41 @@ ENTRY(__longjmp) orq %rax, %r9 # endif #endif +#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. */ + /* Get the current ssp. */ + 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) |