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Re: [PATCH v2] tcg: Fix execution on Apple Silicon
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From: |
Roman Bolshakov |
|
Subject: |
Re: [PATCH v2] tcg: Fix execution on Apple Silicon |
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Date: |
Wed, 6 Jan 2021 00:50:13 +0300 |
On Mon, Jan 04, 2021 at 06:02:50PM -0800, Joelle van Dyne wrote:
> Tested-by: Joelle van Dyne <j@getutm.app>
>
> It works for me. But one thing is that if you build it with the macOS
> 11.x SDK it won't run on < 11.x. This is why apple recommends
> something like:
>
> if (__builtin_available(macOS 11, *)) {
> pthread_jit_write_protect_np();
> }
>
> You still need a compile time check like MAC_OS_VERSION_11_0 to
> support linking with older SDKs.
>
I'll address the issue in v3. Thanks for catching it.
Regards,
Roman
> On Sun, Jan 3, 2021 at 6:54 AM Roman Bolshakov <r.bolshakov@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.bolshakov@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
> >