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([194.190.106.50]) by smtp.gmail.com with ESMTPSA id p3-20020a05651238c300b004f251e73fc5sm2510677lft.30.2023.05.15.01.33.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 15 May 2023 01:33:27 -0700 (PDT) To: libc-alpha@sourceware.org, bug-hurd@gnu.org Subject: [PATCH 3/4] hurd: Fix sc_i386_thread_state layout Date: Mon, 15 May 2023 11:33:22 +0300 Message-Id: <20230515083323.1358039-4-bugaevc@gmail.com> X-Mailer: git-send-email 2.40.1 In-Reply-To: <20230515083323.1358039-1-bugaevc@gmail.com> References: <20230515083323.1358039-1-bugaevc@gmail.com> MIME-Version: 1.0 X-Spam-Status: No, score=-11.1 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, GIT_PATCH_0, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Sergey Bugaev via Libc-alpha From: Sergey Bugaev Reply-To: Sergey Bugaev Errors-To: libc-alpha-bounces+patchwork=sourceware.org@sourceware.org Sender: "Libc-alpha" 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 --- sysdeps/mach/hurd/x86/trampoline.c | 6 ++++++ sysdeps/mach/hurd/x86_64/bits/sigcontext.h | 8 ++++++++ 2 files changed, 14 insertions(+) diff --git a/sysdeps/mach/hurd/x86/trampoline.c b/sysdeps/mach/hurd/x86/trampoline.c index 1f92064e..6318c952 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 3a3b34bc..63960544 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 . */ #define sc_i386_float_state sc_fpkind