linux-kernel - [PATCH] riscv: Remove unnecessary path for syscall

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Date:   Mon, 25 May 2020 14:18:26 +0000
From:   guoren@...nel.org
To:     tycho@...ho.ws, keescook@...omium.org, palmerdabbelt@...gle.com,
        paul.walmsley@...ive.com, anup@...infault.org
Cc:     linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Guo Ren <guoren@...ux.alibaba.com>
Subject: [PATCH] riscv: Remove unnecessary path for syscall_trace

From: Guo Ren <guoren@...ux.alibaba.com>

Obviously, there is no need to recover a0-a7 in reject path.

Previous modification is from commit af33d243 by Tycho, to
fixup seccomp reject syscall code path.

Signed-off-by: Guo Ren <guoren@...ux.alibaba.com>
Cc: Tycho Andersen <tycho@...ho.ws>
Cc: Kees Cook <keescook@...omium.org>
Cc: Palmer Dabbelt <palmerdabbelt@...gle.com>
---
 arch/riscv/kernel/entry.S | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S
index 56d071b..ea3444d 100644
--- a/arch/riscv/kernel/entry.S
+++ b/arch/riscv/kernel/entry.S
@@ -306,7 +306,7 @@ work_resched:
 handle_syscall_trace_enter:
 	move a0, sp
 	call do_syscall_trace_enter
-	move t0, a0
+	bnez a0, ret_from_syscall_rejected
 	REG_L a0, PT_A0(sp)
 	REG_L a1, PT_A1(sp)
 	REG_L a2, PT_A2(sp)
@@ -315,7 +315,6 @@ handle_syscall_trace_enter:
 	REG_L a5, PT_A5(sp)
 	REG_L a6, PT_A6(sp)
 	REG_L a7, PT_A7(sp)
-	bnez t0, ret_from_syscall_rejected
 	j check_syscall_nr
 handle_syscall_trace_exit:
 	move a0, sp
-- 
2.7.4