Pages can't be both write and executable at the same time on Apple Silicon. macOS provides public API to switch write protection [1] for JIT applications, like TCG.
1. https://developer.apple.com/documentation/apple_silicon/porting_just-in-time_compilers_to_apple_silicon Signed-off-by: Roman Bolshakov <r.bolsha...@yadro.com> --- Happy holidays, everyone. This is somewhat similar to https://patchwork.kernel.org/project/qemu-devel/patch/20201108232425.1705-...@getutm.app/ but I couldn't apply the series so I started from scratch. The primary difference from the patch above is that public API is used. Other differences: * TB pages are mostly kept write-locked except around tcg_qemu_tb_exec() * x86_64 macOS doesn't use MAP_JIT and W^X switches Regards, Roman accel/tcg/cpu-exec.c | 10 ++++++++++ accel/tcg/translate-all.c | 26 ++++++++++++++++++++++++++ include/exec/exec-all.h | 2 ++ tcg/tcg.c | 1 + 4 files changed, 39 insertions(+) diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c index 8689c54499..0042fc9f2b 100644 --- a/accel/tcg/cpu-exec.c +++ b/accel/tcg/cpu-exec.c @@ -175,7 +175,9 @@ static inline tcg_target_ulong cpu_tb_exec(CPUState *cpu, TranslationBlock *itb) } #endif /* DEBUG_DISAS */ + tb_write_lock(); ret = tcg_qemu_tb_exec(env, tb_ptr); + tb_write_unlock(); cpu->can_do_io = 1; last_tb = (TranslationBlock *)(ret & ~TB_EXIT_MASK); tb_exit = ret & TB_EXIT_MASK; @@ -220,9 +222,11 @@ static void cpu_exec_nocache(CPUState *cpu, int max_cycles, cflags |= MIN(max_cycles, CF_COUNT_MASK); mmap_lock(); + tb_write_unlock(); tb = tb_gen_code(cpu, orig_tb->pc, orig_tb->cs_base, orig_tb->flags, cflags); tb->orig_tb = orig_tb; + tb_write_lock(); mmap_unlock(); /* execute the generated code */ @@ -268,7 +272,9 @@ void cpu_exec_step_atomic(CPUState *cpu) tb = tb_lookup__cpu_state(cpu, &pc, &cs_base, &flags, cf_mask); if (tb == NULL) { mmap_lock(); + tb_write_unlock(); tb = tb_gen_code(cpu, pc, cs_base, flags, cflags); + tb_write_lock(); mmap_unlock(); } @@ -428,7 +434,9 @@ static inline TranslationBlock *tb_find(CPUState *cpu, tb = tb_lookup__cpu_state(cpu, &pc, &cs_base, &flags, cf_mask); if (tb == NULL) { mmap_lock(); + tb_write_unlock(); tb = tb_gen_code(cpu, pc, cs_base, flags, cf_mask); + tb_write_lock(); mmap_unlock(); /* We add the TB in the virtual pc hash table for the fast lookup */ qatomic_set(&cpu->tb_jmp_cache[tb_jmp_cache_hash_func(pc)], tb); @@ -444,7 +452,9 @@ static inline TranslationBlock *tb_find(CPUState *cpu, #endif /* See if we can patch the calling TB. */ if (last_tb) { + tb_write_unlock(); tb_add_jump(last_tb, tb_exit, tb); + tb_write_lock(); } return tb; } diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c index b7d50a73d4..1562076ffb 100644 --- a/accel/tcg/translate-all.c +++ b/accel/tcg/translate-all.c @@ -1072,6 +1072,9 @@ static inline void *alloc_code_gen_buffer(void) size_t size = tcg_ctx->code_gen_buffer_size; void *buf; +#if defined(__APPLE__) && defined(__aarch64__) + flags |= MAP_JIT; +#endif buf = mmap(NULL, size, prot, flags, -1, 0); if (buf == MAP_FAILED) { return NULL; @@ -1485,7 +1488,9 @@ static void do_tb_phys_invalidate(TranslationBlock *tb, bool rm_from_page_list) static void tb_phys_invalidate__locked(TranslationBlock *tb) { + tb_write_unlock(); do_tb_phys_invalidate(tb, true); + tb_write_lock(); } /* invalidate one TB @@ -2722,3 +2727,24 @@ void tcg_flush_softmmu_tlb(CPUState *cs) tlb_flush(cs); #endif } + +#if defined(__APPLE__) && defined(__aarch64__) +static void tb_write_protect(bool locked) +{ + if (pthread_jit_write_protect_supported_np()){ + pthread_jit_write_protect_np(locked); + } +} +#else +static void tb_write_protect(bool locked) {} +#endif + +void tb_write_lock(void) +{ + tb_write_protect(true); +} + +void tb_write_unlock(void) +{ + tb_write_protect(false); +} diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h index fab573da06..962dca0975 100644 --- a/include/exec/exec-all.h +++ b/include/exec/exec-all.h @@ -549,6 +549,8 @@ TranslationBlock *tb_htable_lookup(CPUState *cpu, target_ulong pc, target_ulong cs_base, uint32_t flags, uint32_t cf_mask); void tb_set_jmp_target(TranslationBlock *tb, int n, uintptr_t addr); +void tb_write_lock(void); +void tb_write_unlock(void); /* GETPC is the true target of the return instruction that we'll execute. */ #if defined(CONFIG_TCG_INTERPRETER) diff --git a/tcg/tcg.c b/tcg/tcg.c index 43c6cf8f52..303bb436bd 100644 --- a/tcg/tcg.c +++ b/tcg/tcg.c @@ -1065,6 +1065,7 @@ void tcg_prologue_init(TCGContext *s) s->pool_labels = NULL; #endif + tb_write_unlock(); /* Generate the prologue. */ tcg_target_qemu_prologue(s); -- 2.29.2
