diff options
Diffstat (limited to 'libcxxabi')
| -rw-r--r-- | libcxxabi/src/cxa_exception.cpp | 21 |
1 files changed, 13 insertions, 8 deletions
diff --git a/libcxxabi/src/cxa_exception.cpp b/libcxxabi/src/cxa_exception.cpp index 36388d50dad2..059d75ca2ab4 100644 --- a/libcxxabi/src/cxa_exception.cpp +++ b/libcxxabi/src/cxa_exception.cpp @@ -341,10 +341,11 @@ unwinding with _Unwind_Resume. According to ARM EHABI 8.4.1, __cxa_end_cleanup() should not clobber any register, thus we have to write this function in assembly so that we can save {r1, r2, r3}. We don't have to save r0 because it is the return value and the -first argument to _Unwind_Resume(). In addition, we are saving lr in order to -align the stack to 16 bytes and lr will be used to identify the caller and its -frame information. _Unwind_Resume never return and we need to keep the original -lr so just branch to it. +first argument to _Unwind_Resume(). The function also saves/restores r4 to +keep the stack aligned and to provide a temp register. _Unwind_Resume never +returns and we need to keep the original lr so just branch to it. When +targeting bare metal, the function also clobbers ip/r12 to hold the address of +_Unwind_Resume, which may be too far away for an ordinary branch. */ __attribute__((used)) static _Unwind_Exception * __cxa_end_cleanup_impl() @@ -381,15 +382,19 @@ asm(" .pushsection .text.__cxa_end_cleanup,\"ax\",%progbits\n" #if defined(__ARM_FEATURE_BTI_DEFAULT) " bti\n" #endif - " push {r1, r2, r3, lr}\n" + " push {r1, r2, r3, r4}\n" + " mov r4, lr\n" " bl __cxa_end_cleanup_impl\n" - " pop {r1, r2, r3, r4}\n" " mov lr, r4\n" #if defined(LIBCXXABI_BAREMETAL) " ldr r4, =_Unwind_Resume\n" - " bx r4\n" + " mov ip, r4\n" +#endif + " pop {r1, r2, r3, r4}\n" +#if defined(LIBCXXABI_BAREMETAL) + " bx ip\n" #else - " b _Unwind_Resume\n" + " b _Unwind_Resume\n" #endif " .popsection"); #endif // defined(_LIBCXXABI_ARM_EHABI) |