diff options
Diffstat (limited to 'lib/hwasan/hwasan_tag_mismatch_aarch64.S')
| -rw-r--r-- | lib/hwasan/hwasan_tag_mismatch_aarch64.S | 106 |
1 files changed, 106 insertions, 0 deletions
diff --git a/lib/hwasan/hwasan_tag_mismatch_aarch64.S b/lib/hwasan/hwasan_tag_mismatch_aarch64.S new file mode 100644 index 000000000..92f627480 --- /dev/null +++ b/lib/hwasan/hwasan_tag_mismatch_aarch64.S @@ -0,0 +1,106 @@ +#include "sanitizer_common/sanitizer_asm.h" + +// The content of this file is AArch64-only: +#if defined(__aarch64__) + +// The responsibility of the HWASan entry point in compiler-rt is to primarily +// readjust the stack from the callee and save the current register values to +// the stack. +// This entry point function should be called from a __hwasan_check_* symbol. +// These are generated during a lowering pass in the backend, and are found in +// AArch64AsmPrinter::EmitHwasanMemaccessSymbols(). Please look there for +// further information. +// The __hwasan_check_* caller of this function should have expanded the stack +// and saved the previous values of x0, x1, x29, and x30. This function will +// "consume" these saved values and treats it as part of its own stack frame. +// In this sense, the __hwasan_check_* callee and this function "share" a stack +// frame. This allows us to omit having unwinding information (.cfi_*) present +// in every __hwasan_check_* function, therefore reducing binary size. This is +// particularly important as hwasan_check_* instances are duplicated in every +// translation unit where HWASan is enabled. +// This function calls HwasanTagMismatch to step back into the C++ code that +// completes the stack unwinding and error printing. This function is is not +// permitted to return. + + +// Frame from __hwasan_check_: +// | ... | +// | ... | +// | Previous stack frames... | +// +=================================+ +// | Unused 8-bytes for maintaining | +// | 16-byte SP alignment. | +// +---------------------------------+ +// | Return address (x30) for caller | +// | of __hwasan_check_*. | +// +---------------------------------+ +// | Frame address (x29) for caller | +// | of __hwasan_check_* | +// +---------------------------------+ <-- [SP + 232] +// | ... | +// | | +// | Stack frame space for x2 - x28. | +// | | +// | ... | +// +---------------------------------+ <-- [SP + 16] +// | | +// | Saved x1, as __hwasan_check_* | +// | clobbers it. | +// +---------------------------------+ +// | Saved x0, likewise above. | +// +---------------------------------+ <-- [x30 / SP] + +// This function takes two arguments: +// * x0: The address of read/write instruction that caused HWASan check fail. +// * x1: The tag size. + +.section .text +.file "hwasan_tag_mismatch_aarch64.S" +.global __hwasan_tag_mismatch +.type __hwasan_tag_mismatch, %function +__hwasan_tag_mismatch: + CFI_STARTPROC + + // Set the CFA to be the return address for caller of __hwasan_check_*. Note + // that we do not emit CFI predicates to describe the contents of this stack + // frame, as this proxy entry point should never be debugged. The contents + // are static and are handled by the unwinder after calling + // __hwasan_tag_mismatch. The frame pointer is already correctly setup + // by __hwasan_check_*. + add x29, sp, #232 + CFI_DEF_CFA(w29, 24) + CFI_OFFSET(w30, -16) + CFI_OFFSET(w29, -24) + + // Save the rest of the registers into the preallocated space left by + // __hwasan_check. + str x28, [sp, #224] + stp x26, x27, [sp, #208] + stp x24, x25, [sp, #192] + stp x22, x23, [sp, #176] + stp x20, x21, [sp, #160] + stp x18, x19, [sp, #144] + stp x16, x17, [sp, #128] + stp x14, x15, [sp, #112] + stp x12, x13, [sp, #96] + stp x10, x11, [sp, #80] + stp x8, x9, [sp, #64] + stp x6, x7, [sp, #48] + stp x4, x5, [sp, #32] + stp x2, x3, [sp, #16] + + // Pass the address of the frame to __hwasan_tag_mismatch_stub, so that it can + // extract the saved registers from this frame without having to worry about + // finding this frame. + mov x2, sp + + bl __hwasan_tag_mismatch_stub + CFI_ENDPROC + +.Lfunc_end0: + .size __hwasan_tag_mismatch, .Lfunc_end0-__hwasan_tag_mismatch + +#endif // defined(__aarch64__) + +// We do not need executable stack. +NO_EXEC_STACK_DIRECTIVE |