linux-kernel - [PATCH] powerpc/code-patching: Perform hwsync in __patch

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-next>] [day] [month] [year] [list]

Date:   Sat,  7 Oct 2023 12:46:19 +0200
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>
Cc:     Christophe Leroy <christophe.leroy@...roup.eu>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        Hari Bathini <hbathini@...ux.ibm.com>,
        "Christopher M . Riedl" <cmr@...escreens.de>
Subject: [PATCH] powerpc/code-patching: Perform hwsync in __patch_instruction() in case of failure

Commit c28c15b6d28a ("powerpc/code-patching: Use temporary mm for
Radix MMU") added a hwsync for when __patch_instruction() fails,
we results in a quite odd unbalanced logic.

Instead of calling mb() when __patch_instruction() returns an error,
call mb() in the __patch_instruction()'s error path directly.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
Cc: Hari Bathini <hbathini@...ux.ibm.com>
Cc: Christopher M. Riedl <cmr@...escreens.de>
---
 arch/powerpc/lib/code-patching.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
index b00112d7ad46..7a47a871e6b8 100644
--- a/arch/powerpc/lib/code-patching.c
+++ b/arch/powerpc/lib/code-patching.c
@@ -38,6 +38,7 @@ static int __patch_instruction(u32 *exec_addr, ppc_inst_t instr, u32 *patch_addr
 	return 0;
 
 failed:
+	mb();  /* sync */
 	return -EPERM;
 }
 
@@ -309,10 +310,6 @@ static int __do_patch_instruction_mm(u32 *addr, ppc_inst_t instr)
 
 	err = __patch_instruction(addr, instr, patch_addr);
 
-	/* hwsync performed by __patch_instruction (sync) if successful */
-	if (err)
-		mb();  /* sync */
-
 	/* context synchronisation performed by __patch_instruction (isync or exception) */
 	stop_using_temp_mm(patching_mm, orig_mm);
 
-- 
2.41.0