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| author | Sergey Bugaev <bugaevc@gmail.com> | 2023-05-15 11:33:22 +0300 |
|---|---|---|
| committer | Samuel Thibault <samuel.thibault@ens-lyon.org> | 2023-05-16 16:09:00 +0200 |
| commit | e333759f7752593a69a8f9920a247ed3878fafef (patch) | |
| tree | 0c307ea5d660fea298c4069b301863a38c84284f | |
| parent | ce96593c882b393461084048533120e9c1e9d328 (diff) | |
| download | glibc-e333759f7752593a69a8f9920a247ed3878fafef.tar.gz | |
hurd: Fix sc_i386_thread_state layout
The real i386_thread_state Mach structure has an alignment of 8 on
x86_64. However, in struct sigcontext, the compiler was packing sc_gs
(which is the first member of sc_i386_thread_state) into the same 8-byte
slot as sc_error; this resulted in the rest of sc_i386_thread_state
members having wrong offsets relative to each other, and the overall
sc_i386_thread_state layout mismatching that of i386_thread_state.
Fix this by explicitly adding the required padding members, and
statically asserting that this results in the desired alignment.
The same goes for sc_i386_float_state.
Checked on x86_64-gnu.
Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
Message-Id: <20230515083323.1358039-4-bugaevc@gmail.com>
| -rw-r--r-- | sysdeps/mach/hurd/x86/trampoline.c | 6 | ||||
| -rw-r--r-- | sysdeps/mach/hurd/x86_64/bits/sigcontext.h | 8 |
2 files changed, 14 insertions, 0 deletions
diff --git a/sysdeps/mach/hurd/x86/trampoline.c b/sysdeps/mach/hurd/x86/trampoline.c index 1f92064ebf..6318c9528a 100644 --- a/sysdeps/mach/hurd/x86/trampoline.c +++ b/sysdeps/mach/hurd/x86/trampoline.c @@ -242,11 +242,17 @@ _hurd_setup_sighandler (struct hurd_sigstate *ss, const struct sigaction *action /* struct sigcontext is laid out so that starting at sc_gs mimics a struct i386_thread_state. */ + _Static_assert (offsetof (struct sigcontext, sc_i386_thread_state) + % __alignof__ (struct i386_thread_state) == 0, + "sc_i386_thread_state layout mismatch"); memcpy (&scp->sc_i386_thread_state, &state->basic, sizeof (state->basic)); /* struct sigcontext is laid out so that starting at sc_fpkind mimics a struct i386_float_state. */ + _Static_assert (offsetof (struct sigcontext, sc_i386_float_state) + % __alignof__ (struct i386_float_state) == 0, + "sc_i386_float_state layout mismatch"); ok = machine_get_state (ss->thread, state, i386_FLOAT_STATE, &state->fpu, &scp->sc_i386_float_state, sizeof (state->fpu)); diff --git a/sysdeps/mach/hurd/x86_64/bits/sigcontext.h b/sysdeps/mach/hurd/x86_64/bits/sigcontext.h index 3a3b34bc0a..6396054463 100644 --- a/sysdeps/mach/hurd/x86_64/bits/sigcontext.h +++ b/sysdeps/mach/hurd/x86_64/bits/sigcontext.h @@ -46,6 +46,11 @@ struct sigcontext /* Error code associated with this signal (interpreted as `error_t'). */ int sc_error; + /* Make sure the below members are properly aligned, and not packed + together with sc_error -- otherwise the layout won't match that of + i386_thread_state. */ + int sc_pad1; + /* All following members are machine-dependent. The rest of this structure is written to be laid out identically to: { @@ -86,6 +91,9 @@ struct sigcontext long sc_ursp; /* This stack pointer is used. */ int sc_ss; /* Stack segment register. */ + /* Make sure the below has the same layout as i386_float_state. */ + int sc_pad2; + /* Following mimics struct i386_float_state. Structures and symbolic values can be found in <mach/i386/fp_reg.h>. */ #define sc_i386_float_state sc_fpkind |