diff options
| author | Chris Wailes <chriswailes@google.com> | 2021-05-03 14:27:12 -0700 |
|---|---|---|
| committer | Chris Wailes <chriswailes@google.com> | 2021-05-07 15:00:55 -0700 |
| commit | 559f27828cbc51851978c5781618fe5b3d34e4ba (patch) | |
| tree | 4b6cb79ec78207cbe3faa1fab72597db1c436b07 /libc | |
| parent | 3e0defac5d546c3a0ed0f5faae1a40502ffac003 (diff) | |
Clear the stack frame pointer in _start and __bionic_clone
This CL adds an instruction to the _start label that clears the frame
pointer. This allows stack walking code to determine when it has
reached the end of the stack.
The __bionic_clone function is similarly modified, for architectures
that weren't already doing both.
Test: bionic-unit-tests
Test: CtsBionicTestCases
Change-Id: Iea3949f52c44f7931f9fff2d60d4d9e5c742c120
Diffstat (limited to 'libc')
| -rw-r--r-- | libc/arch-arm/bionic/__bionic_clone.S | 2 | ||||
| -rw-r--r-- | libc/arch-common/bionic/crtbegin.c | 10 | ||||
| -rw-r--r-- | libc/arch-x86/bionic/__bionic_clone.S | 1 |
3 files changed, 9 insertions, 4 deletions
diff --git a/libc/arch-arm/bionic/__bionic_clone.S b/libc/arch-arm/bionic/__bionic_clone.S index 6669b93a2..3fe212b47 100644 --- a/libc/arch-arm/bionic/__bionic_clone.S +++ b/libc/arch-arm/bionic/__bionic_clone.S @@ -61,6 +61,8 @@ ENTRY_PRIVATE(__bionic_clone) b __set_errno_internal .L_bc_child: + # We're in the child now. Set the end of the frame record chain. + mov fp, #0 # Setting lr to 0 will make the unwinder stop at __start_thread. mov lr, #0 # Call __start_thread with the 'fn' and 'arg' we stored on the child stack. diff --git a/libc/arch-common/bionic/crtbegin.c b/libc/arch-common/bionic/crtbegin.c index 628783789..5f681c53c 100644 --- a/libc/arch-common/bionic/crtbegin.c +++ b/libc/arch-common/bionic/crtbegin.c @@ -49,13 +49,15 @@ __used static void _start_main(void* raw_args) { #define POST "; .size _start, .-_start" #if defined(__aarch64__) -__asm__(PRE "bti j; mov x0,sp; b _start_main" POST); +__asm__(PRE "bti j; mov x29,#0; mov x30,#0; mov x0,sp; b _start_main" POST); #elif defined(__arm__) -__asm__(PRE "mov r0,sp; b _start_main" POST); +__asm__(PRE "mov fp,#0; mov lr,#0; mov r0,sp; b _start_main" POST); #elif defined(__i386__) -__asm__(PRE "movl %esp,%eax; andl $~0xf,%esp; subl $12,%esp; pushl %eax; calll _start_main" POST); +__asm__(PRE + "xorl %ebp,%ebp; movl %esp,%eax; andl $~0xf,%esp; subl $12,%esp; pushl %eax;" + "calll _start_main" POST); #elif defined(__x86_64__) -__asm__(PRE "movq %rsp,%rdi; andq $~0xf,%rsp; callq _start_main" POST); +__asm__(PRE "xorl %ebp, %ebp; movq %rsp,%rdi; andq $~0xf,%rsp; callq _start_main" POST); #else #error unsupported architecture #endif diff --git a/libc/arch-x86/bionic/__bionic_clone.S b/libc/arch-x86/bionic/__bionic_clone.S index b682b4863..f0c58a00d 100644 --- a/libc/arch-x86/bionic/__bionic_clone.S +++ b/libc/arch-x86/bionic/__bionic_clone.S @@ -45,6 +45,7 @@ ENTRY_PRIVATE(__bionic_clone) .L_bc_child: # We don't want anyone to unwind past this point. .cfi_undefined %eip + .cfi_undefined %ebp call __start_thread hlt |