arm64: entry32: remove pointless register assignment

We currently set x27 in compat_sys_sigreturn_wrapper and
compat_sys_rt_sigreturn_wrapper, similarly to what we do with r8/why on
32-bit ARM, in an attempt to prevent sigreturns from being restarted.

However, on arm64 we have always used pt_regs::syscallno for syscall
restarting (for both native and compat tasks), and x27 is never
inspected again before being overwritten in kernel_exit.

This patch removes the pointless register assignments.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/kernel/entry32.S b/arch/arm64/kernel/entry32.S
index bd9bfaa..f332d5d 100644 (file)
--- a/arch/arm64/kernel/entry32.S
+++ b/arch/arm64/kernel/entry32.S
@@ -32,13 +32,11 @@
 
 ENTRY(compat_sys_sigreturn_wrapper)
        mov     x0, sp
-       mov     x27, #0         // prevent syscall restart handling (why)
        b       compat_sys_sigreturn
 ENDPROC(compat_sys_sigreturn_wrapper)
 
 ENTRY(compat_sys_rt_sigreturn_wrapper)
        mov     x0, sp
-       mov     x27, #0         // prevent syscall restart handling (why)
        b       compat_sys_rt_sigreturn
 ENDPROC(compat_sys_rt_sigreturn_wrapper)