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From: Benjamin Gray <bgray@linux.ibm.com>
To: linuxppc-dev@lists.ozlabs.org, mpe@ellerman.id.au
Cc: Benjamin Gray <bgray@linux.ibm.com>
Subject: [PATCH v1 3/3] powerpc/code-patching: Optimise patch_memcpy() to 4 byte chunks
Date: Fri, 15 Mar 2024 13:57:36 +1100	[thread overview]
Message-ID: <20240315025736.404867-3-bgray@linux.ibm.com> (raw)
In-Reply-To: <20240315025736.404867-1-bgray@linux.ibm.com>

As we are patching instructions, we can assume the length is a multiple
of 4 and the destination address is aligned.

Atomicity of patching a prefixed instruction is not a concern, as the
original implementation doesn't provide it anyway.

Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
---
 arch/powerpc/lib/code-patching.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
index c6633759b509..ed450a32918c 100644
--- a/arch/powerpc/lib/code-patching.c
+++ b/arch/powerpc/lib/code-patching.c
@@ -394,10 +394,10 @@ static int patch_memset32(u32 *addr, u32 val, size_t count)
 	return -EPERM;
 }
 
-static int patch_memcpy(void *dst, void *src, size_t len)
+static int patch_memcpy32(u32 *dst, u32 *src, size_t count)
 {
-	for (void *end = src + len; src < end; dst++, src++)
-		__put_kernel_nofault(dst, src, u8, failed);
+	for (u32 *end = src + count; src < end; dst++, src++)
+		__put_kernel_nofault(dst, src, u32, failed);
 
 	return 0;
 
@@ -424,7 +424,7 @@ static int __patch_instructions(u32 *patch_addr, u32 *code, size_t len, bool rep
 			err = patch_memset32(patch_addr, val, len / 4);
 		}
 	} else {
-		err = patch_memcpy(patch_addr, code, len);
+		err = patch_memcpy32(patch_addr, code, len / 4);
 	}
 
 	smp_wmb();	/* smp write barrier */
-- 
2.44.0


  parent reply	other threads:[~2024-03-15  3:00 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-03-15  2:57 [PATCH v1 1/3] powerpc/code-patching: Test patch_instructions() during boot Benjamin Gray
2024-03-15  2:57 ` [PATCH v1 2/3] powerpc/code-patching: Use dedicated memory routines for patching Benjamin Gray
2024-03-15  3:17   ` Benjamin Gray
2024-03-15  6:36   ` Christophe Leroy
2024-03-17 21:42     ` Benjamin Gray
2024-03-15  2:57 ` Benjamin Gray [this message]
2024-03-15  6:39   ` [PATCH v1 3/3] powerpc/code-patching: Optimise patch_memcpy() to 4 byte chunks Christophe Leroy
2024-03-17 21:44     ` Benjamin Gray
2024-03-15  7:14 ` [PATCH v1 1/3] powerpc/code-patching: Test patch_instructions() during boot Christophe Leroy
2024-03-17 21:38   ` Benjamin Gray
2024-03-17 22:23     ` Benjamin Gray
2024-03-18  2:25       ` Michael Ellerman
2024-03-17 22:24     ` Benjamin Gray

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