From: Borislav Petkov <bp@alien8.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
mhiramat@kernel.org, kirill.shutemov@linux.intel.com,
Andrew.Cooper3@citrix.com, jpoimboe@redhat.com
Subject: Re: [PATCH v3 2/4] x86/alternative: Support relocations in alternatives
Date: Fri, 17 Feb 2023 23:21:21 +0100 [thread overview]
Message-ID: <Y+/94eo4xq9TofOs@zn.tnic> (raw)
In-Reply-To: <20230208171431.313857925@infradead.org>
On Wed, Feb 08, 2023 at 06:10:52PM +0100, Peter Zijlstra wrote:
> + if (insn.opcode.bytes[0] == JMP32_INSN_OPCODE) {
> + s32 imm = insn.immediate.value;
> + imm += src - dest;
> + imm += JMP32_INSN_SIZE - JMP8_INSN_SIZE;
> + if ((imm >> 31) == (imm >> 7)) {
> + buf[i+0] = JMP8_INSN_OPCODE;
> + buf[i+1] = (s8)imm;
> + for (int j = 2; j < insn.length; j++)
> + buf[i+j] = INT3_INSN_OPCODE;
Let's get rid of that third nested loop:
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index e14bc15bf646..28eb1d0bc4a0 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -308,8 +308,8 @@ apply_relocation(u8 *buf, size_t len, u8 *dest, u8 *src, size_t src_len)
if ((imm >> 31) == (imm >> 7)) {
buf[i+0] = JMP8_INSN_OPCODE;
buf[i+1] = (s8)imm;
- for (int j = 2; j < insn.length; j++)
- buf[i+j] = INT3_INSN_OPCODE;
+
+ memset(&buf[i+2], INT3_INSN_OPCODE, insn.length - 2);
}
}
break;
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2023-02-17 22:21 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-08 17:10 [PATCH v3 0/4] x86: Fully relocatable alternatives and some NOPs Peter Zijlstra
2023-02-08 17:10 ` [PATCH v3 1/4] x86/alternative: Make debug-alternative selective Peter Zijlstra
2023-02-14 11:48 ` Borislav Petkov
2023-05-13 13:03 ` [tip: x86/alternatives] " tip-bot2 for Peter Zijlstra
2023-02-08 17:10 ` [PATCH v3 2/4] x86/alternative: Support relocations in alternatives Peter Zijlstra
2023-02-17 20:28 ` Borislav Petkov
2023-02-17 22:21 ` Borislav Petkov [this message]
2023-05-13 13:03 ` [tip: x86/alternatives] " tip-bot2 for Peter Zijlstra
2023-02-08 17:10 ` [PATCH v3 3/4] x86/alternative: Rewrite optimize_nops() some Peter Zijlstra
2023-02-08 19:52 ` Andrew.Cooper3
2023-02-08 20:29 ` Peter Zijlstra
2023-02-08 20:36 ` Peter Zijlstra
2023-02-08 20:44 ` Peter Zijlstra
2023-02-08 20:45 ` Peter Zijlstra
2023-02-08 21:01 ` Peter Zijlstra
2023-02-08 21:08 ` Peter Zijlstra
2023-02-08 21:21 ` Peter Zijlstra
2023-02-09 1:11 ` Andrew.Cooper3
2023-02-09 22:27 ` David Laight
2023-02-09 1:33 ` Andrew.Cooper3
2023-02-08 23:04 ` David Laight
2023-05-13 13:03 ` [tip: x86/alternatives] " tip-bot2 for Peter Zijlstra
2023-02-27 10:49 ` [PATCH] x86/lib/memmove: Decouple ERMS from FSRM Borislav Petkov
2023-04-27 9:22 ` [PATCH TEST] " Yahu Gao
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