From a45f8cb49db6dd6c594c5692c47b148cd93c8201 Mon Sep 17 00:00:00 2001 From: Sergey Fedorov Date: Fri, 23 Feb 2018 20:41:02 -0500 Subject: [PATCH] tcg/aarch64: Make direct jump patching thread-safe Ensure direct jump patching in AArch64 is atomic by using atomic_read()/atomic_set() for code patching. Backports commit 9e269112953be4d670cb0d25042bd6546fcf3e45 from qemu --- qemu/tcg/aarch64/tcg-target.inc.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/qemu/tcg/aarch64/tcg-target.inc.c b/qemu/tcg/aarch64/tcg-target.inc.c index 184c38e9..21ef7b8f 100644 --- a/qemu/tcg/aarch64/tcg-target.inc.c +++ b/qemu/tcg/aarch64/tcg-target.inc.c @@ -77,6 +77,18 @@ static inline void reloc_pc26(tcg_insn_unit *code_ptr, tcg_insn_unit *target) *code_ptr = deposit32(*code_ptr, 0, 26, offset); } +static inline void reloc_pc26_atomic(tcg_insn_unit *code_ptr, + tcg_insn_unit *target) +{ + ptrdiff_t offset = target - code_ptr; + tcg_insn_unit insn; + tcg_debug_assert(offset == sextract64(offset, 0, 26)); + /* read instruction, mask away previous PC_REL26 parameter contents, + set the proper offset, then write back the instruction. */ + insn = atomic_read(code_ptr); + atomic_set(code_ptr, deposit32(insn, 0, 26, offset)); +} + static inline void reloc_pc19(tcg_insn_unit *code_ptr, tcg_insn_unit *target) { ptrdiff_t offset = target - code_ptr; @@ -839,7 +851,7 @@ void aarch64_tb_set_jmp_target(uintptr_t jmp_addr, uintptr_t addr) tcg_insn_unit *code_ptr = (tcg_insn_unit *)jmp_addr; tcg_insn_unit *target = (tcg_insn_unit *)addr; - reloc_pc26(code_ptr, target); + reloc_pc26_atomic(code_ptr, target); flush_icache_range(jmp_addr, jmp_addr + 4); }