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runtime: fix inline assembly trampoline for arm64

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Use the program counter to compute the address of the first instruction
of the ret sled. The ret sled is located after 5 instructions from the
MOVD instruction saving the value of the program counter
This commit is contained in:
Khaled Yakdan 2022-05-23 23:11:33 +02:00
parent 2138124143
commit 2719208c6a
1 changed files with 4 additions and 3 deletions
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7
src/runtime/libfuzzer_arm64.s
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@ -43,8 +43,8 @@ TEXT runtime·libfuzzerCallTraceIntCmp(SB), NOSPLIT, $8-32
MOVD R12, RSP
call:
// Load address of the ret sled into the default register for the return
// address (offset of four instructions, which means 16 bytes).
ADR $16, R30
// address.
ADR ret_sled, R30
// Clear the lowest 2 bits of fakePC. All ARM64 instructions are four
// bytes long, so we cannot get better return address granularity than
// multiples of 4.
@ -60,8 +60,9 @@ call:
// has the same byte length of 4 * 128 = 512 as the x86_64 sled, but
// coarser granularity.
#define RET_SLED \
JMP end_of_function;
JMP end_of_function;
ret_sled:
REPEAT_128(RET_SLED);
end_of_function: