linux-kernel - [PATCH 5.10 026/152] riscv: return -ENOSYS for syscall -1

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Message-Id: <20210118113354.034638065@linuxfoundation.org>
Date:   Mon, 18 Jan 2021 12:33:21 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Andreas Schwab <schwab@...e.de>,
        Tycho Andersen <tycho@...ho.pizza>,
        Palmer Dabbelt <palmerdabbelt@...gle.com>
Subject: [PATCH 5.10 026/152] riscv: return -ENOSYS for syscall -1

From: Andreas Schwab <schwab@...e.de>

commit cf7b2ae4d70432fa94ebba3fbaab825481ae7189 upstream.

Properly return -ENOSYS for syscall -1 instead of leaving the return value
uninitialized.  This fixes the strace teststuite.

Fixes: 5340627e3fe0 ("riscv: add support for SECCOMP and SECCOMP_FILTER")
Cc: stable@...r.kernel.org
Signed-off-by: Andreas Schwab <schwab@...e.de>
Reviewed-by: Tycho Andersen <tycho@...ho.pizza>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@...gle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/riscv/kernel/entry.S |    9 +--------
 1 file changed, 1 insertion(+), 8 deletions(-)

--- a/arch/riscv/kernel/entry.S
+++ b/arch/riscv/kernel/entry.S
@@ -186,14 +186,7 @@ check_syscall_nr:
 	 * Syscall number held in a7.
 	 * If syscall number is above allowed value, redirect to ni_syscall.
 	 */
-	bge a7, t0, 1f
-	/*
-	 * Check if syscall is rejected by tracer, i.e., a7 == -1.
-	 * If yes, we pretend it was executed.
-	 */
-	li t1, -1
-	beq a7, t1, ret_from_syscall_rejected
-	blt a7, t1, 1f
+	bgeu a7, t0, 1f
 	/* Call syscall */
 	la s0, sys_call_table
 	slli t0, a7, RISCV_LGPTR