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| author | Sergey Bugaev <bugaevc@gmail.com> | 2023-05-17 22:14:33 +0300 |
|---|---|---|
| committer | Samuel Thibault <samuel.thibault@ens-lyon.org> | 2023-05-17 23:00:59 +0200 |
| commit | 2f8ecb58a59eb82c43214d000842d99644a662d1 (patch) | |
| tree | 72e11c22d8ce150bb4a58583b9e46f57c4036789 | |
| parent | c7fcce38c83a2bb665ef5dc4981bf20c7e586123 (diff) | |
| download | glibc-2f8ecb58a59eb82c43214d000842d99644a662d1.tar.gz | |
hurd: Fix x86_64 _hurd_tls_fork
It is illegal to call thread_get_state () on mach_thread_self (), so
this codepath cannot be used as-is to fork the calling thread's TLS.
Fortunately we can use THREAD_SELF (aka %fs:0x0) to find out the value
of our fs_base without calling into the kernel.
Fixes: f6cf701efc61c9ad910372bda14b9a235db310a8
"hurd: Implement TLS for x86_64"
Checked on x86_64-gnu: fork () now works!
Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
Message-Id: <20230517191436.73636-8-bugaevc@gmail.com>
| -rw-r--r-- | sysdeps/mach/hurd/x86_64/tls.h | 25 |
1 files changed, 19 insertions, 6 deletions
diff --git a/sysdeps/mach/hurd/x86_64/tls.h b/sysdeps/mach/hurd/x86_64/tls.h index 35dcef447e..6487ed3580 100644 --- a/sysdeps/mach/hurd/x86_64/tls.h +++ b/sysdeps/mach/hurd/x86_64/tls.h @@ -140,12 +140,25 @@ _hurd_tls_fork (thread_t child, thread_t orig, error_t err; struct i386_fsgs_base_state state; mach_msg_type_number_t state_count = i386_FSGS_BASE_STATE_COUNT; - err = __thread_get_state (orig, i386_FSGS_BASE_STATE, - (thread_state_t) &state, - &state_count); - if (err) - return err; - assert (state_count == i386_FSGS_BASE_STATE_COUNT); + + extern thread_t hurd_thread_self (void); + if (orig != hurd_thread_self ()) + { + err = __thread_get_state (orig, i386_FSGS_BASE_STATE, + (thread_state_t) &state, + &state_count); + if (err) + return err; + assert (state_count == i386_FSGS_BASE_STATE_COUNT); + } + else + { + /* It is illegal to call thread_get_state () on mach_thread_self (). + But we're only interested in the value of fs_base, and since we're + this thread, we know it points to our TCB. */ + state.fs_base = (unsigned long) THREAD_SELF; + state.gs_base = 0; + } return __thread_set_state (child, i386_FSGS_BASE_STATE, (thread_state_t) &state, |