On Tue, Sep 15, 2020 at 05:55:46PM +0200, Christian Brauner wrote:

On Sat, Sep 12, 2020 at 04:08:08AM -0700, Kees Cook wrote:

quoted

Remove the mips special-case in change_syscall().

Signed-off-by: Kees Cook <redacted>
---
 tools/testing/selftests/seccomp/seccomp_bpf.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c
index 1c83e743bfb1..02a9a6599746 100644
--- a/tools/testing/selftests/seccomp/seccomp_bpf.c
+++ b/tools/testing/selftests/seccomp/seccomp_bpf.c

@@ -1742,6 +1742,13 @@ TEST_F(TRACE_poke, getpid_runs_normally)
 # define ARCH_REGS		struct pt_regs
 # define SYSCALL_NUM(_regs)	(_regs).regs[2]
 # define SYSCALL_SYSCALL_NUM	regs[4]
+# define SYSCALL_NUM_SET(_regs, _nr)			\
+	do {						\
+		if ((_regs).regs[2] == __NR_O32_Linux)	\
+			(_regs).regs[4] = _nr;		\
+		else					\
+			(_regs).regs[2] = _nr;		\
+	} while (0)

I think that

# define SYSCALL_NUM_SET(_regs, _nr)				\
	do {							\
		if (SYSCALL_NUM(_regs) == __NR_O32_Linux)	\
			(_regs).regs[4] = _nr;			\
		else						\
			(_regs).regs[2] = _nr;			\
	} while (0)

would read better but that's just a matter of taste. :)

That's how I started originally, but when I realized that I'd have to
reorganize SYSCALL_NUM() too, it seem best to have minimal churn, so I
left it open coded here, since that's how it needs to be in the end.

Looks good!
Acked-by: Christian Brauner <redacted>

Thanks for the reviews!

-- 
Kees Cook