linux-kernel - [RFC][PATCH v5 41/51] objtool: mcount: Convert nop writes to elf_write

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Message-ID: <b5ee19c9cadd4e786cf64dea893b47b181d80089.1592510545.git.mhelsley@vmware.com>
Date:   Thu, 18 Jun 2020 13:38:27 -0700
From:   Matt Helsley <mhelsley@...are.com>
To:     <linux-kernel@...r.kernel.org>
CC:     Josh Poimboeuf <jpoimboe@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Julien Thierry <jthierry@...hat.com>,
        Kamalesh Babulal <kamalesh@...ux.vnet.ibm.com>,
        Matt Helsley <mhelsley@...are.com>
Subject: [RFC][PATCH v5 41/51] objtool: mcount: Convert nop writes to elf_write_insn()

objtool's elf_write_insn() does extra checking when writing to
an instruction so use that rather than a plain memcpy().

Signed-off-by: Matt Helsley <mhelsley@...are.com>
---
 tools/objtool/mcount.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/tools/objtool/mcount.c b/tools/objtool/mcount.c
index 629eb7222ef3..029e6e72c972 100644
--- a/tools/objtool/mcount.c
+++ b/tools/objtool/mcount.c
@@ -66,9 +66,7 @@ static int make_nop_x86(struct section *txts, size_t const offset)
 	if (memcmp(op, ip_relative_call_x86, 5) != 0)
 		return -1;
 
-	/* convert to nop */
-	memcpy(op, ideal_nop, 5);
-	return 0;
+	return elf_write_insn(lf, txts, offset, 5, ideal_nop);
 }
 
 static const char ideal_nop4_arm_le[4] = { 0x00, 0x00, 0xa0, 0xe1 }; /* mov r0, r0 */
@@ -117,7 +115,8 @@ static int make_nop_arm(struct section *txts, size_t const offset)
 
 	/* Convert to nop */
 	do {
-		memcpy(map + off, ideal_nop, nop_size);
+		if (elf_write_insn(lf, txts, off, nop_size, ideal_nop))
+			return -1;
 		off += nop_size;
 	} while (--cnt > 0);
 
@@ -136,8 +135,7 @@ static int make_nop_arm64(struct section *txts, size_t const offset)
 		return -1;
 
 	/* Convert to nop */
-	memcpy(map + offset, ideal_nop, 4);
-	return 0;
+	return elf_write_insn(lf, txts, offset, 4, ideal_nop);
 }
 
 /* Names of the sections that could contain calls to mcount. */
-- 
2.20.1