| Message ID | 1352587485-18348-4-git-send-email-keescook@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S index 8355d4b..0bef977 100644 --- a/arch/arm/kernel/entry-common.S +++ b/arch/arm/kernel/entry-common.S @@ -448,7 +448,10 @@ __sys_trace: ldmccia r1, {r0 - r6} @ have to reload r0 - r6 stmccia sp, {r4, r5} @ and update the stack args ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine - b 2b + cmp scno, #-1 @ skip the syscall? + bne 2b + add sp, sp, #S_OFF @ restore stack + b ret_slow_syscall __sys_trace_return: str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
On tracehook-friendly platforms, a system call number of -1 falls through without running much code or taking much action. ARM is different. This adds a short-circuit check in the trace path to avoid any additional work, as suggested by Russell King, to make sure that ARM behaves the same way as other platforms. Signed-off-by: Kees Cook <keescook@chromium.org> --- arch/arm/kernel/entry-common.S | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)