commit 4c21b8fd8f146a22e1eaf92833a32e51f560e82a "MIPS: seccomp: Handle indirect system calls (o32)" added indirect syscall detection for O32 processes running on MIPS64 but it did not work as expected. The reason is the the scall64-o32 implementation differs compared to scall32-o32. In the former, the v0 (syscall number) register contains the absolute syscall number (4000 + X) whereas in the latter it contains the relative syscall number (X). Fix the code to avoid doing an extra addition, and load the v0 register directly to the first argument for syscall_trace_enter. Moreover, set the .reorder assembler option in order to have better control on this part of the assembly code. Signed-off-by: Markos Chandras <markos.chandras@xxxxxxxxxx> --- arch/mips/kernel/scall64-o32.S | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/arch/mips/kernel/scall64-o32.S b/arch/mips/kernel/scall64-o32.S index f1343ccd7ed7..7f5feb25ae04 100644 --- a/arch/mips/kernel/scall64-o32.S +++ b/arch/mips/kernel/scall64-o32.S @@ -113,15 +113,19 @@ trace_a_syscall: move s0, t2 # Save syscall pointer move a0, sp /* - * syscall number is in v0 unless we called syscall(__NR_###) + * absolute syscall number is in v0 unless we called syscall(__NR_###) * where the real syscall number is in a0 * note: NR_syscall is the first O32 syscall but the macro is * only defined when compiling with -mabi=32 (CONFIG_32BIT) * therefore __NR_O32_Linux is used (4000) */ - addiu a1, v0, __NR_O32_Linux - bnez v0, 1f /* __NR_syscall at offset 0 */ - lw a1, PT_R4(sp) + .set push + .set reorder + 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 */ + .set pop 1: jal syscall_trace_enter -- 2.0.2
