MAC_OS_VERSION_11_0 is always defined. You can see in usr/include/AvailabilityVersions.h
... #define MAC_OS_X_VERSION_10_15 101500 #define MAC_OS_X_VERSION_10_15_1 101501 #define MAC_OS_X_VERSION_10_16 101600 #define MAC_OS_VERSION_11_0 110000 The proper way is to do an __builtin_available check but that assumes you have the symbol for pthread_jit_write_protect_np which you won't if building on 10.15, so you need a configure time check as well. I have a newer version of my patch that I haven't submitted yet because I was waiting for some other patches to go in first, but I can decouple it from the iOS stuff and submit it as a separate patchset. -j On Sun, Jan 3, 2021 at 6:54 AM Roman Bolshakov <r.bolsha...@yadro.com> wrote: > > 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> > --- > v1: https://lists.gnu.org/archive/html/qemu-devel/2021-01/msg00073.html > Changes since v1: > > - Pruned not needed fiddling with W^X and dropped symmetry from write > lock/unlock and renamed related functions. > Similar approach is used in JavaScriptCore [1]. > > - Moved jit helper functions to util/osdep > > As > outlined in osdep.h, this matches to (2): > > > * In an ideal world this > header would contain only: > * (1) things which everybody needs > > * (2) things without which code would work on > most platforms but > * fail to compile or misbehave on a minority of host > OSes > > - Fixed a checkpatch error > > - Limit new behaviour only to macOS 11.0 and above, because of the > following declarations: > > __API_AVAILABLE(macos(11.0)) > __API_UNAVAILABLE(ios, tvos, watchos) > void pthread_jit_write_protect_np(int enabled); > > __API_AVAILABLE(macos(11.0)) > __API_UNAVAILABLE(ios, tvos, watchos) > int pthread_jit_write_protect_supported_np(void); > > 1. https://bugs.webkit.org/attachment.cgi?id=402515&action=prettypatch > > accel/tcg/cpu-exec.c | 2 ++ > accel/tcg/translate-all.c | 6 ++++++ > include/qemu/osdep.h | 3 +++ > tcg/tcg.c | 1 + > util/osdep.c | 22 ++++++++++++++++++++++ > 5 files changed, 34 insertions(+) > > diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c > index 8689c54499..374060eb45 100644 > --- a/accel/tcg/cpu-exec.c > +++ b/accel/tcg/cpu-exec.c > @@ -175,6 +175,7 @@ static inline tcg_target_ulong cpu_tb_exec(CPUState *cpu, > TranslationBlock *itb) > } > #endif /* DEBUG_DISAS */ > > + qemu_thread_jit_execute(); > ret = tcg_qemu_tb_exec(env, tb_ptr); > cpu->can_do_io = 1; > last_tb = (TranslationBlock *)(ret & ~TB_EXIT_MASK); > @@ -382,6 +383,7 @@ static inline void tb_add_jump(TranslationBlock *tb, int > n, > { > uintptr_t old; > > + qemu_thread_jit_write(); > assert(n < ARRAY_SIZE(tb->jmp_list_next)); > qemu_spin_lock(&tb_next->jmp_lock); > > diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c > index b7d50a73d4..88ae5d35ef 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(MAC_OS_VERSION_11_0) > + 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) > { > + qemu_thread_jit_write(); > do_tb_phys_invalidate(tb, true); > + qemu_thread_jit_execute(); > } > > /* invalidate one TB > @@ -1687,6 +1692,7 @@ TranslationBlock *tb_gen_code(CPUState *cpu, > #endif > > assert_memory_lock(); > + qemu_thread_jit_write(); > > phys_pc = get_page_addr_code(env, pc); > > diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h > index f9ec8c84e9..89abebcf5d 100644 > --- a/include/qemu/osdep.h > +++ b/include/qemu/osdep.h > @@ -686,4 +686,7 @@ char *qemu_get_host_name(Error **errp); > */ > size_t qemu_get_host_physmem(void); > > +void qemu_thread_jit_write(void); > +void qemu_thread_jit_execute(void); > + > #endif > diff --git a/tcg/tcg.c b/tcg/tcg.c > index 43c6cf8f52..ab8488f5d5 100644 > --- a/tcg/tcg.c > +++ b/tcg/tcg.c > @@ -1065,6 +1065,7 @@ void tcg_prologue_init(TCGContext *s) > s->pool_labels = NULL; > #endif > > + qemu_thread_jit_write(); > /* Generate the prologue. */ > tcg_target_qemu_prologue(s); > > diff --git a/util/osdep.c b/util/osdep.c > index 66d01b9160..80ec7185da 100644 > --- a/util/osdep.c > +++ b/util/osdep.c > @@ -606,3 +606,25 @@ writev(int fd, const struct iovec *iov, int iov_cnt) > return readv_writev(fd, iov, iov_cnt, true); > } > #endif > + > +#if defined(__APPLE__) && defined(MAC_OS_VERSION_11_0) > +static inline void qemu_thread_jit_write_protect(bool enabled) > +{ > + if (pthread_jit_write_protect_supported_np()) { > + pthread_jit_write_protect_np(enabled); > + } > +} > + > +void qemu_thread_jit_execute(void) > +{ > + qemu_thread_jit_write_protect(true); > +} > + > +void qemu_thread_jit_write(void) > +{ > + qemu_thread_jit_write_protect(false); > +} > +#else > +void qemu_thread_jit_write(void) {} > +void qemu_thread_jit_execute(void) {} > +#endif > -- > 2.29.2 >
