| From: Aurelien Jarno <aurelien@aurel32.net> |
| Date: Tue, 9 Apr 2019 16:53:55 +0200 |
| Subject: MIPS: scall64-o32: Fix indirect syscall number load |
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| |
| commit 79b4a9cf0e2ea8203ce777c8d5cfa86c71eae86e upstream. |
| |
| Commit 4c21b8fd8f14 (MIPS: seccomp: Handle indirect system calls (o32)) |
| added indirect syscall detection for O32 processes running on MIPS64, |
| but it did not work correctly for big endian kernel/processes. The |
| reason is that the syscall number is loaded from ARG1 using the lw |
| instruction while this is a 64-bit value, so zero is loaded instead of |
| the syscall number. |
| |
| Fix the code by using the ld instruction instead. When running a 32-bit |
| processes on a 64 bit CPU, the values are properly sign-extended, so it |
| ensures the value passed to syscall_trace_enter is correct. |
| |
| Recent systemd versions with seccomp enabled whitelist the getpid |
| syscall for their internal processes (e.g. systemd-journald), but call |
| it through syscall(SYS_getpid). This fix therefore allows O32 big endian |
| systems with a 64-bit kernel to run recent systemd versions. |
| |
| Signed-off-by: Aurelien Jarno <aurelien@aurel32.net> |
| Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> |
| Signed-off-by: Paul Burton <paul.burton@mips.com> |
| Cc: Ralf Baechle <ralf@linux-mips.org> |
| Cc: James Hogan <jhogan@kernel.org> |
| Cc: linux-mips@vger.kernel.org |
| Cc: linux-kernel@vger.kernel.org |
| Signed-off-by: Ben Hutchings <ben@decadent.org.uk> |
| --- |
| arch/mips/kernel/scall64-o32.S | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| --- a/arch/mips/kernel/scall64-o32.S |
| +++ b/arch/mips/kernel/scall64-o32.S |
| @@ -124,7 +124,7 @@ trace_a_syscall: |
| subu t1, v0, __NR_O32_Linux |
| move a1, v0 |
| bnez t1, 1f /* __NR_syscall at offset 0 */ |
| - lw a1, PT_R4(sp) /* Arg1 for __NR_syscall case */ |
| + ld a1, PT_R4(sp) /* Arg1 for __NR_syscall case */ |
| .set pop |
| |
| 1: jal syscall_trace_enter |
