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author | Ryan Prichard <rprichard@google.com> | 2022-03-15 23:57:40 +0000 |
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committer | Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com> | 2022-03-15 23:57:40 +0000 |
commit | d681551325fe219ef90ae260a72b8281af800010 (patch) | |
tree | 16dc2f66b45ceecd98af6af3af3117168c020c3d | |
parent | 6900ac6f36e8548f626ffe601d0780bf3138d741 (diff) | |
parent | 9b8c5479211a1a1dc5d35d399f88344fd1f18610 (diff) | |
download | libcxxabi-d681551325fe219ef90ae260a72b8281af800010.tar.gz |
[ARM] __cxa_end_cleanup: avoid clobbering r4 am: c0a6edcf3b am: 00928ed8ee am: 4b96903904 am: 9b8c547921aml_tz4_332714070aml_tz4_332714050aml_tz4_332714010aml_tz4_331910000aml_tz4_331314030aml_tz4_331314020aml_tz4_331314010aml_tz4_331012050aml_tz4_331012040aml_tz4_331012000aml_ase_331311020aml_ase_331112000aml_ase_331011020android13-mainline-tzdata4-releaseandroid13-mainline-appsearch-releaseaml_tz4_332714010
Original change: https://android-review.googlesource.com/c/platform/external/libcxxabi/+/2024827
Change-Id: I68e4af77b1d5ed6a8d303d4531670d896dbb6181
-rw-r--r-- | src/cxa_exception.cpp | 33 |
1 files changed, 23 insertions, 10 deletions
diff --git a/src/cxa_exception.cpp b/src/cxa_exception.cpp index 8d30e5c..9e650b5 100644 --- a/src/cxa_exception.cpp +++ b/src/cxa_exception.cpp @@ -343,8 +343,11 @@ 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 r4 in order to -align the stack to 16 bytes, even though it is a callee-save register. +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() @@ -374,20 +377,30 @@ __cxa_end_cleanup_impl() return &exception_header->unwindHeader; } -asm ( - " .pushsection .text.__cxa_end_cleanup,\"ax\",%progbits\n" +asm(" .pushsection .text.__cxa_end_cleanup,\"ax\",%progbits\n" " .globl __cxa_end_cleanup\n" " .type __cxa_end_cleanup,%function\n" "__cxa_end_cleanup:\n" +#if defined(__ARM_FEATURE_BTI_DEFAULT) + " bti\n" +#endif " push {r1, r2, r3, r4}\n" + " mov r4, lr\n" " bl __cxa_end_cleanup_impl\n" + " mov lr, r4\n" +#if defined(LIBCXXABI_BAREMETAL) + " ldr r4, =_Unwind_Resume\n" + " mov ip, r4\n" +#endif " pop {r1, r2, r3, r4}\n" - " bl _Unwind_Resume\n" - " bl abort\n" - " .popsection" -); -#endif // defined(_LIBCXXABI_ARM_EHABI) - +#if defined(LIBCXXABI_BAREMETAL) + " bx ip\n" +#else + " b _Unwind_Resume\n" +#endif + " .popsection"); +#endif // defined(_LIBCXXABI_ARM_EHABI) + /* This routine can catch foreign or native exceptions. If native, the exception can be a primary or dependent variety. This routine may remain blissfully |