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From:   Matt Helsley <mhelsley@vmware.com>
To:     <linux-kernel@vger.kernel.org>
CC:     Josh Poimboeuf <jpoimboe@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Julien Thierry <jthierry@redhat.com>,
        Ingo Molnar <mingo@redhat.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Miroslav Benes <mbenes@suse.cz>,
        Matt Helsley <mhelsley@vmware.com>
Subject: [RFC][PATCH 35/36] objtool: mcount: Remove wrapper double-include trick
Date:   Fri, 10 Apr 2020 12:35:58 -0700
Message-ID: <d983f169b4da814ff2018965a6945bf7ce7940f1.1586468801.git.mhelsley@vmware.com>
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We no longer need to double-include the recordmcount.h wrapper
All of the types and functions that rely on them have been converted
to using objtool's ELF code. This moves the remaining function to
recordmcount.c and changes the function name to something slightly
more descriptive while dropping the wrapped naming.

Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
 tools/objtool/recordmcount.c | 122 ++++++++++++++++++++++++++++--
 tools/objtool/recordmcount.h | 141 -----------------------------------
 2 files changed, 116 insertions(+), 147 deletions(-)
 delete mode 100644 tools/objtool/recordmcount.h

diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index e6aa1feb234d..50834b065e16 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -441,10 +441,120 @@ static void sift_rel_mcount(GElf_Addr **mlocpp,
 	*mrelpp = is_rela ? (void *)mrelap : (void *)mrelp;
 }
 
-/* 32 bit and 64 bit are very similar */
-#include "recordmcount.h"
-#define RECORD_MCOUNT_64
-#include "recordmcount.h"
+/* Overall supervision for Elf32 ET_REL file. */
+static int do_mcount(unsigned const reltype, size_t rela_size)
+{
+	/* Upper bound on space: assume all relevant relocs are for mcount. */
+	unsigned       totrelsz;
+
+	void *mrel0;
+	void *mrelp;
+
+	GElf_Addr *mloc0;
+	GElf_Addr *mlocp;
+	GElf_Sxword r_offset; /* Used in the added relocations */
+
+	unsigned int rel_entsize = 0;
+
+	struct section *sec, *mlocs, *mrels;
+	unsigned int const old_shnum = lf->ehdr.e_shnum;
+
+	int result = -1;
+	char const *mc_name;
+	bool is_rela;
+
+	if (find_section_by_name(lf, "__mcount_loc") != NULL)
+		return 0;
+
+	totrelsz = tot_relsize(&rel_entsize);
+	if (totrelsz == 0)
+		return 0;
+
+	mrel0 = malloc(totrelsz);
+	mrelp = mrel0;
+	if (!mrel0)
+		return -1;
+
+	/* 2*sizeof(address) <= sizeof(Elf_Rel) */
+	mloc0 = malloc(totrelsz>>1);
+	mlocp = mloc0;
+	if (!mloc0) {
+		free(mrel0);
+		return -1;
+	}
+
+	is_rela = (rela_size == rel_entsize);
+	mc_name = is_rela
+			? ".rela__mcount_loc"
+			:  ".rel__mcount_loc";
+
+	/* add section: __mcount_loc */
+	mlocs = elf_create_section(lf, mc_name + (is_rela ? 1 : 0) + strlen(".rel"), sizeof(*mloc0), 0);
+	if (!mlocs)
+		goto out;
+
+	mlocs->sh.sh_link = 0;
+	mlocs->sh.sh_info = 0;
+	mlocs->sh.sh_addralign = 8;
+	mlocs->data->d_buf = mloc0;
+	mlocs->data->d_type = ELF_T_ADDR; /* elf_xlatetof() conversion */
+
+	/* add section .rel[a]__mcount_loc */
+	mrels = elf_create_section(lf, mc_name, rel_entsize, 0);
+	if (!mrels)
+		goto out;
+	/* Like elf_create_rela_section() without the name bits */
+	mrels->sh.sh_type = is_rela ? SHT_RELA : SHT_REL;
+	mrels->sh.sh_flags = 0;
+	mrels->sh.sh_link = find_section_by_name(lf, ".symtab")->idx;
+	mrels->sh.sh_info = old_shnum;
+	mrels->sh.sh_addralign = 8;
+	mrels->data->d_buf = mrel0;
+	mrels->data->d_type = is_rela ? ELF_T_RELA : ELF_T_REL; /* elf_xlatetof() conversion */
+
+	list_for_each_entry(sec, &lf->sections, list) {
+		char const *txtname;
+
+		txtname = has_rel_mcount(sec);
+		if (txtname && is_mcounted_section_name(txtname)) {
+			unsigned long recval = 0;
+			unsigned int recsym;
+
+			if (find_section_sym_index(sec->sh.sh_info,
+						txtname, &recval, &recsym))
+				goto out;
+
+			sift_rel_mcount(&mlocp, &r_offset, &mrelp, sec,
+				recsym, recval, reltype, is_rela);
+		} else if (txtname && (warn_on_notrace_sect || make_nop)) {
+			/*
+			 * This section is ignored by ftrace, but still
+			 * has mcount calls. Convert them to nops now.
+			 */
+			if (nop_mcount(sec, txtname) < 0)
+				goto out;
+		}
+	}
+
+	if (mloc0 != mlocp) {
+		/* Update the section size and Elf_Data size */
+		mlocs->sh.sh_size = (void *)mlocp - (void *)mloc0;
+		mlocs->len = mlocs->sh.sh_size;
+		mlocs->data->d_size = mlocs->len;
+
+		mrels->sh.sh_size = mrelp - mrel0;
+		mrels->len = mrels->sh.sh_size;
+		mrels->data->d_size = mrels->len;
+
+		/* overwrite the ELF file */
+		result = elf_write(lf);
+	} else
+		result = 0;
+out:
+	free(mrel0);
+	free(mloc0);
+	return result;
+}
 
 static int arm_is_fake_mcount(struct rela const *rp)
 {
@@ -574,7 +684,7 @@ static int do_file(char const *const fname)
 			is_fake_mcount = MIPS_is_fake_mcount;
 		}
 		loc_size = 4;
-		rc = do32(reltype, sizeof(Elf32_Rela));
+		rc = do_mcount(reltype, sizeof(Elf32_Rela));
 		break;
 	case ELFCLASS64: {
 		if (lf->ehdr.e_ehsize != sizeof(Elf64_Ehdr)
@@ -592,7 +702,7 @@ static int do_file(char const *const fname)
 			is_fake_mcount = MIPS_is_fake_mcount;
 		}
 		loc_size = 8;
-		rc = do64(reltype, sizeof(Elf64_Rela));
+		rc = do_mcount(reltype, sizeof(Elf64_Rela));
 		break;
 	}
 	}  /* end switch */
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
deleted file mode 100644
index d116032522e1..000000000000
--- a/tools/objtool/recordmcount.h
+++ /dev/null
@@ -1,141 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-only */
-/*
- * recordmcount.h
- *
- * This code was taken out of recordmcount.c written by
- * Copyright 2009 John F. Reiser <jreiser@BitWagon.com>.  All rights reserved.
- *
- * The original code had the same algorithms for both 32bit
- * and 64bit ELF files, but the code was duplicated to support
- * the difference in structures that were used. This
- * file creates a macro of everything that is different between
- * the 64 and 32 bit code, such that by including this header
- * twice we can create both sets of functions by including this
- * header once with RECORD_MCOUNT_64 undefined, and again with
- * it defined.
- *
- * This conversion to macros was done by:
- * Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
- */
-#undef do_func
-
-#ifdef RECORD_MCOUNT_64
-# define do_func		do64
-#else
-# define do_func		do32
-#endif
-
-/* Overall supervision for Elf32 ET_REL file. */
-static int do_func(unsigned const reltype, size_t rela_size)
-{
-	/* Upper bound on space: assume all relevant relocs are for mcount. */
-	unsigned       totrelsz;
-
-	void *mrel0;
-	void *mrelp;
-
-	GElf_Addr *mloc0;
-	GElf_Addr *mlocp;
-	GElf_Sxword r_offset = 0;
-
-	unsigned int rel_entsize = 0;
-
-	struct section *sec, *mlocs, *mrels;
-	unsigned int const old_shnum = lf->ehdr.e_shnum;
-
-	int result = -1;
-	char const *mc_name;
-	bool is_rela;
-
-	if (find_section_by_name(lf, "__mcount_loc") != NULL)
-		return 0;
-
-	totrelsz = tot_relsize(&rel_entsize);
-	if (totrelsz == 0)
-		return 0;
-
-	mrel0 = malloc(totrelsz);
-	mrelp = mrel0;
-	if (!mrel0)
-		return -1;
-
-	/* 2*sizeof(address) <= sizeof(Elf_Rel) */
-	mloc0 = malloc(totrelsz>>1);
-	mlocp = mloc0;
-	if (!mloc0) {
-		free(mrel0);
-		return -1;
-	}
-
-	is_rela = (rela_size == rel_entsize);
-	mc_name = is_rela
-			? ".rela__mcount_loc"
-			:  ".rel__mcount_loc";
-
-	/* add section: __mcount_loc */
-	mlocs = elf_create_section(lf, mc_name + (is_rela ? 1 : 0) + strlen(".rel"), sizeof(*mloc0), 0);
-	if (!mlocs)
-		goto out;
-
-	mlocs->sh.sh_link = 0;
-	mlocs->sh.sh_info = 0;
-	mlocs->sh.sh_addralign = 8;
-	mlocs->data->d_buf = mloc0;
-	mlocs->data->d_type = ELF_T_ADDR; /* elf_xlatetof() conversion */
-
-	/* add section .rel[a]__mcount_loc */
-	mrels = elf_create_section(lf, mc_name, rel_entsize, 0);
-	if (!mrels)
-		goto out;
-	/* Like elf_create_rela_section() without the name bits */
-	mrels->sh.sh_type = is_rela ? SHT_RELA : SHT_REL;
-	mrels->sh.sh_flags = 0;
-	mrels->sh.sh_link = find_section_by_name(lf, ".symtab")->idx;
-	mrels->sh.sh_info = old_shnum;
-	mrels->sh.sh_addralign = 8;
-	mrels->data->d_buf = mrel0;
-	mrels->data->d_type = is_rela ? ELF_T_RELA : ELF_T_REL; /* elf_xlatetof() conversion */
-
-	list_for_each_entry(sec, &lf->sections, list) {
-		char const *txtname;
-
-		txtname = has_rel_mcount(sec);
-		if (txtname && is_mcounted_section_name(txtname)) {
-			unsigned long recval = 0;
-			unsigned int recsym;
-
-			if (find_section_sym_index(sec->sh.sh_info,
-						txtname, &recval, &recsym))
-				goto out;
-
-			sift_rel_mcount(&mlocp, &r_offset, &mrelp, sec,
-				recsym, recval, reltype, is_rela);
-		} else if (txtname && (warn_on_notrace_sect || make_nop)) {
-			/*
-			 * This section is ignored by ftrace, but still
-			 * has mcount calls. Convert them to nops now.
-			 */
-			if (nop_mcount(sec, txtname) < 0)
-				goto out;
-		}
-	}
-
-	if (mloc0 != mlocp) {
-		/* Update the section size and Elf_Data size */
-		mlocs->sh.sh_size = (void *)mlocp - (void *)mloc0;
-		mlocs->len = mlocs->sh.sh_size;
-		mlocs->data->d_size = mlocs->len;
-
-		mrels->sh.sh_size = mrelp - mrel0;
-		mrels->len = mrels->sh.sh_size;
-		mrels->data->d_size = mrels->len;
-
-		/* overwrite the ELF file */
-		result = elf_write(lf);
-	} else
-		result = 0;
-out:
-	free(mrel0);
-	free(mloc0);
-	return result;
-}
-- 
2.20.1