linux-kernel - [PATCH v2 09/10] xtensa: get rid of stack frame in coprocessor

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 21 Apr 2022 03:10:32 -0700
From:   Max Filippov <jcmvbkbc@...il.com>
To:     linux-xtensa@...ux-xtensa.org
Cc:     Chris Zankel <chris@...kel.net>, linux-kernel@...r.kernel.org,
        Max Filippov <jcmvbkbc@...il.com>
Subject: [PATCH v2 09/10] xtensa: get rid of stack frame in coprocessor_flush

coprocessor_flush is an ordinary function, it can use all registers.
Don't reserve stack frame for it and use a7 to preserve a0 around the
context saving call.

Signed-off-by: Max Filippov <jcmvbkbc@...il.com>
---
Changes v1->v2:

- new patch

 arch/xtensa/kernel/coprocessor.S | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/arch/xtensa/kernel/coprocessor.S b/arch/xtensa/kernel/coprocessor.S
index af11ddaa8c5f..95412409c49e 100644
--- a/arch/xtensa/kernel/coprocessor.S
+++ b/arch/xtensa/kernel/coprocessor.S
@@ -216,10 +216,8 @@ ENDPROC(fast_coprocessor)
 
 ENTRY(coprocessor_flush)
 
-	/* reserve 4 bytes on stack to save a0 */
-	abi_entry(4)
+	abi_entry_default
 
-	s32i	a0, a1, 0
 	movi	a4, .Lcp_regs_jump_table
 	addx8	a4, a3, a4
 	addx4	a3, a3, a4
@@ -227,10 +225,11 @@ ENTRY(coprocessor_flush)
 	beqz	a4, 1f
 	l32i	a3, a3, CP_REGS_TAB_OFFSET
 	add	a2, a2, a3
+	mov	a7, a0
 	callx0	a4
-1:	l32i	a0, a1, 0
-
-	abi_ret(4)
+	mov	a0, a7
+1:
+	abi_ret_default
 
 ENDPROC(coprocessor_flush)
 
-- 
2.30.2