Add a checksum to jmp_buf on x86_64.
Bug: http://b/27856501
Bug: http://b/27417786
Change-Id: I541f5a7ce4972ef56b3f69e73927ca7df362609a
diff --git a/libc/arch-x86_64/bionic/setjmp.S b/libc/arch-x86_64/bionic/setjmp.S
index 92bd5a9..34b4365 100644
--- a/libc/arch-x86_64/bionic/setjmp.S
+++ b/libc/arch-x86_64/bionic/setjmp.S
@@ -50,7 +50,7 @@
// 7 pc
// 8 sigflag/cookie setjmp cookie in top 31 bits, signal mask flag in low bit
// 9 sigmask signal mask (includes rt signals as well)
-// 10 reserved
+// 10 checksum checksum of the core registers, to give better error messages.
#define _JB_RBX 0
#define _JB_RBP 1
@@ -62,8 +62,10 @@
#define _JB_PC 7
#define _JB_SIGFLAG 8
#define _JB_SIGMASK 9
+#define _JB_CHECKSUM 10
#define MANGLE_REGISTERS 1
+
.macro m_mangle_registers reg
#if MANGLE_REGISTERS
xorq \reg,%rbx
@@ -81,6 +83,12 @@
m_mangle_registers \reg
.endm
+.macro m_calculate_checksum dst, src
+ movq $0, \dst
+ .irp i,0,1,2,3,4,5,6,7
+ xorq (\i*8)(\src), \dst
+ .endr
+.endm
ENTRY(setjmp)
movl $1,%esi
@@ -131,6 +139,9 @@
movq %r11,(_JB_PC * 8)(%rdi)
m_unmangle_registers %rax
+ m_calculate_checksum %rax, %rdi
+ movq %rax, (_JB_CHECKSUM * 8)(%rdi)
+
xorl %eax,%eax
ret
END(sigsetjmp)
@@ -140,6 +151,10 @@
movq %rdi,%r12
pushq %rsi // Push 'value'.
+ m_calculate_checksum %rax, %rdi
+ xorq (_JB_CHECKSUM * 8)(%rdi), %rax
+ jnz 3f
+
// Do we need to restore the signal mask?
movq (_JB_SIGFLAG * 8)(%rdi), %rdi
pushq %rdi // Push cookie
@@ -185,6 +200,9 @@
1:
movq %r11,0(%rsp)
ret
+
+3:
+ call PIC_PLT(__bionic_setjmp_checksum_mismatch)
END(siglongjmp)
ALIAS_SYMBOL(longjmp, siglongjmp)
