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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id x192sm4807719pfc.142.2020.09.12.04.08.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 12 Sep 2020 04:08:27 -0700 (PDT) From: Kees Cook To: linux-kernel@vger.kernel.org Cc: Kees Cook , Thadeu Lima de Souza Cascardo , Max Filippov , Michael Ellerman , Christian Brauner , Andy Lutomirski , Will Drewry , linux-kselftest@vger.kernel.org, linux-mips@vger.kernel.org, linux-xtensa@linux-xtensa.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org Subject: [PATCH 10/15] selftests/seccomp: Avoid redundant register flushes Date: Sat, 12 Sep 2020 04:08:15 -0700 Message-Id: <20200912110820.597135-11-keescook@chromium.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200912110820.597135-1-keescook@chromium.org> References: <20200912110820.597135-1-keescook@chromium.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When none of the registers have changed, don't flush them back. This can happen if the architecture uses a non-register way to change the syscall (e.g. arm64) , and a return value hasn't been written. Signed-off-by: Kees Cook --- tools/testing/selftests/seccomp/seccomp_bpf.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c index d9346121b89b..2790d9cd50f4 100644 --- a/tools/testing/selftests/seccomp/seccomp_bpf.c +++ b/tools/testing/selftests/seccomp/seccomp_bpf.c @@ -1859,11 +1859,12 @@ int get_syscall(struct __test_metadata *_metadata, pid_t tracee) void change_syscall(struct __test_metadata *_metadata, pid_t tracee, int syscall, int result) { - ARCH_REGS regs; + ARCH_REGS orig, regs; EXPECT_EQ(0, ARCH_GETREGS(regs)) { return; } + orig = regs; SYSCALL_NUM_SET(regs, syscall); @@ -1876,7 +1877,8 @@ void change_syscall(struct __test_metadata *_metadata, #endif /* Flush any register changes made. */ - EXPECT_EQ(0, ARCH_SETREGS(regs)); + if (memcmp(&orig, ®s, sizeof(orig)) != 0) + EXPECT_EQ(0, ARCH_SETREGS(regs)); } void tracer_seccomp(struct __test_metadata *_metadata, pid_t tracee, -- 2.25.1