[RFC][PATCH 00/13] Cleanup recordmcount and begin objtool conversion

[RFC][PATCH 00/13] Cleanup recordmcount and begin objtool conversion

[Matt Helsley]

This series cleans up recordmcount and then makes it into
an objtool subcommand.

The series starts with 8 cleanup patches which make recordmcount
easier to review and integrate with objtool. The final 5 patches
show the beginning steps of converting recordmcount to use objtool's
ELF code rather than its own open-coded methods of accessing ELF
files.

Matt Helsley (13):
  recordmcount: Remove redundant strcmp
  recordmcount: Remove uread()
  recordmcount: Remove unused fd from uwrite() and ulseek()
  recordmcount: Rewrite error/success handling
  recordmcount: Kernel style function signature formatting
  recordmcount: Kernel style formatting
  recordmcount: Remove redundant cleanup() calls
  recordmcount: Clarify what cleanup() does
  objtool: Prepare to merge recordmcount
  objtool: Make recordmcount into an objtool subcmd
  objtool: recordmcount: Start using objtool's elf wrapper
  objtool: recordmcount: Search for __mcount_loc before walking the
    sections
  objtool: recordmcount: Convert do_func() relhdrs

 scripts/.gitignore                         |   1 -
 scripts/Makefile                           |   1 -
 scripts/Makefile.build                     |  22 +-
 tools/objtool/.gitignore                   |   1 +
 tools/objtool/Build                        |   1 +
 tools/objtool/Makefile                     |   7 +-
 tools/objtool/builtin-mcount.c             |  72 +++++
 tools/objtool/builtin-mcount.h             |  23 ++
 tools/objtool/builtin.h                    |   6 +
 tools/objtool/objtool.c                    |   6 +
 {scripts => tools/objtool}/recordmcount.c  | 350 ++++++++++-----------
 {scripts => tools/objtool}/recordmcount.h  | 197 +++++++-----
 {scripts => tools/objtool}/recordmcount.pl |   0
 13 files changed, 420 insertions(+), 267 deletions(-)
 create mode 100644 tools/objtool/builtin-mcount.c
 create mode 100644 tools/objtool/builtin-mcount.h
 rename {scripts => tools/objtool}/recordmcount.c (78%)
 rename {scripts => tools/objtool}/recordmcount.h (78%)
 rename {scripts => tools/objtool}/recordmcount.pl (100%)

-- 
2.20.1

[RFC][PATCH 01/13] recordmcount: Remove redundant strcmp

[Matt Helsley]

The strcmp is unnecessary since .text is already accepted as a
prefix in the strncmp().

Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
 scripts/recordmcount.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c
index a50a2aa963ad..7f835059e7c2 100644
--- a/scripts/recordmcount.c
+++ b/scripts/recordmcount.c
@@ -405,8 +405,7 @@ is_mcounted_section_name(char const *const txtname)
 		strcmp(".irqentry.text", txtname) == 0 ||
 		strcmp(".softirqentry.text", txtname) == 0 ||
 		strcmp(".kprobes.text", txtname) == 0 ||
-		strcmp(".cpuidle.text", txtname) == 0 ||
-		strcmp(".text.unlikely", txtname) == 0;
+		strcmp(".cpuidle.text", txtname) == 0;
 }
 
 /* 32 bit and 64 bit are very similar */
-- 
2.20.1

[RFC][PATCH 02/13] recordmcount: Remove uread()

[Matt Helsley]

uread() is only used to initialize the ELF file's pseudo
private-memory mapping while uwrite() and ulseek() work within
the pseudo-mapping and extend it as necessary.  Thus it is not
a complementary function to uwrite() and ulseek(). It also makes
no sense to do cleanups inside uread() when its only caller,
mmap_file(), is doing the relevant allocations and associated
initializations.

Therefore it's clearer to use a plain read() call to initialize the
data in mmap_file() and remove uread().

Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
 scripts/recordmcount.c | 18 +++++-------------
 1 file changed, 5 insertions(+), 13 deletions(-)

diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c
index 7f835059e7c2..30ef6da68e12 100644
--- a/scripts/recordmcount.c
+++ b/scripts/recordmcount.c
@@ -89,7 +89,7 @@ succeed_file(void)
 	longjmp(jmpenv, SJ_SUCCEED);
 }
 
-/* ulseek, uread, ...:  Check return value for errors. */
+/* ulseek, uwrite, ...:  Check return value for errors. */
 
 static off_t
 ulseek(int const fd, off_t const offset, int const whence)
@@ -112,17 +112,6 @@ ulseek(int const fd, off_t const offset, int const whence)
 	return file_ptr - file_map;
 }
 
-static size_t
-uread(int const fd, void *const buf, size_t const count)
-{
-	size_t const n = read(fd, buf, count);
-	if (n != count) {
-		perror("read");
-		fail_file();
-	}
-	return n;
-}
-
 static size_t
 uwrite(int const fd, void const *const buf, size_t const count)
 {
@@ -298,7 +287,10 @@ static void *mmap_file(char const *fname)
 	if (file_map == MAP_FAILED) {
 		mmap_failed = 1;
 		file_map = umalloc(sb.st_size);
-		uread(fd_map, file_map, sb.st_size);
+		if (read(fd_map, file_map, sb.st_size) != sb.st_size) {
+			perror(fname);
+			fail_file();
+		}
 	}
 	close(fd_map);
 
-- 
2.20.1

[RFC][PATCH 03/13] recordmcount: Remove unused fd from uwrite() and ulseek()

[Matt Helsley]

uwrite() works within the pseudo-mapping and extends it as necessary
without needing the file descriptor (fd) parameter passed to it.
Similarly, ulseek() doesn't need its fd parameter. These parameters
were only added because the functions bear a conceptual resemblance
to write() and lseek(). Worse, they obscure the fact that at the time
uwrite() and ulseek() are called fd_map is not a valid file descriptor.

Remove the unused file descriptor parameters that make it look like
fd_map is still valid.

Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
 scripts/recordmcount.c | 16 ++++++++--------
 scripts/recordmcount.h | 26 +++++++++++++-------------
 2 files changed, 21 insertions(+), 21 deletions(-)

diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c
index 30ef6da68e12..9101b67921cb 100644
--- a/scripts/recordmcount.c
+++ b/scripts/recordmcount.c
@@ -92,7 +92,7 @@ succeed_file(void)
 /* ulseek, uwrite, ...:  Check return value for errors. */
 
 static off_t
-ulseek(int const fd, off_t const offset, int const whence)
+ulseek(off_t const offset, int const whence)
 {
 	switch (whence) {
 	case SEEK_SET:
@@ -113,7 +113,7 @@ ulseek(int const fd, off_t const offset, int const whence)
 }
 
 static size_t
-uwrite(int const fd, void const *const buf, size_t const count)
+uwrite(void const *const buf, size_t const count)
 {
 	size_t cnt = count;
 	off_t idx = 0;
@@ -183,8 +183,8 @@ static int make_nop_x86(void *map, size_t const offset)
 		return -1;
 
 	/* convert to nop */
-	ulseek(fd_map, offset - 1, SEEK_SET);
-	uwrite(fd_map, ideal_nop, 5);
+	ulseek(offset - 1, SEEK_SET);
+	uwrite(ideal_nop, 5);
 	return 0;
 }
 
@@ -232,10 +232,10 @@ static int make_nop_arm(void *map, size_t const offset)
 		return -1;
 
 	/* Convert to nop */
-	ulseek(fd_map, off, SEEK_SET);
+	ulseek(off, SEEK_SET);
 
 	do {
-		uwrite(fd_map, ideal_nop, nop_size);
+		uwrite(ideal_nop, nop_size);
 	} while (--cnt > 0);
 
 	return 0;
@@ -252,8 +252,8 @@ static int make_nop_arm64(void *map, size_t const offset)
 		return -1;
 
 	/* Convert to nop */
-	ulseek(fd_map, offset, SEEK_SET);
-	uwrite(fd_map, ideal_nop, 4);
+	ulseek(offset, SEEK_SET);
+	uwrite(ideal_nop, 4);
 	return 0;
 }
 
diff --git a/scripts/recordmcount.h b/scripts/recordmcount.h
index 2e7793735e14..d9736f41009e 100644
--- a/scripts/recordmcount.h
+++ b/scripts/recordmcount.h
@@ -203,14 +203,14 @@ static void append_func(Elf_Ehdr *const ehdr,
 	new_e_shoff = t;
 
 	/* body for new shstrtab */
-	ulseek(fd_map, sb.st_size, SEEK_SET);
-	uwrite(fd_map, old_shstr_sh_offset + (void *)ehdr, old_shstr_sh_size);
-	uwrite(fd_map, mc_name, 1 + strlen(mc_name));
+	ulseek(sb.st_size, SEEK_SET);
+	uwrite(old_shstr_sh_offset + (void *)ehdr, old_shstr_sh_size);
+	uwrite(mc_name, 1 + strlen(mc_name));
 
 	/* old(modified) Elf_Shdr table, word-byte aligned */
-	ulseek(fd_map, t, SEEK_SET);
+	ulseek(t, SEEK_SET);
 	t += sizeof(Elf_Shdr) * old_shnum;
-	uwrite(fd_map, old_shoff + (void *)ehdr,
+	uwrite(old_shoff + (void *)ehdr,
 	       sizeof(Elf_Shdr) * old_shnum);
 
 	/* new sections __mcount_loc and .rel__mcount_loc */
@@ -226,7 +226,7 @@ static void append_func(Elf_Ehdr *const ehdr,
 	mcsec.sh_info = 0;
 	mcsec.sh_addralign = _w(_size);
 	mcsec.sh_entsize = _w(_size);
-	uwrite(fd_map, &mcsec, sizeof(mcsec));
+	uwrite(&mcsec, sizeof(mcsec));
 
 	mcsec.sh_name = w(old_shstr_sh_size);
 	mcsec.sh_type = (sizeof(Elf_Rela) == rel_entsize)
@@ -240,15 +240,15 @@ static void append_func(Elf_Ehdr *const ehdr,
 	mcsec.sh_info = w(old_shnum);
 	mcsec.sh_addralign = _w(_size);
 	mcsec.sh_entsize = _w(rel_entsize);
-	uwrite(fd_map, &mcsec, sizeof(mcsec));
+	uwrite(&mcsec, sizeof(mcsec));
 
-	uwrite(fd_map, mloc0, (void *)mlocp - (void *)mloc0);
-	uwrite(fd_map, mrel0, (void *)mrelp - (void *)mrel0);
+	uwrite(mloc0, (void *)mlocp - (void *)mloc0);
+	uwrite(mrel0, (void *)mrelp - (void *)mrel0);
 
 	ehdr->e_shoff = _w(new_e_shoff);
 	ehdr->e_shnum = w2(2 + w2(ehdr->e_shnum));  /* {.rel,}__mcount_loc */
-	ulseek(fd_map, 0, SEEK_SET);
-	uwrite(fd_map, ehdr, sizeof(*ehdr));
+	ulseek(0, SEEK_SET);
+	uwrite(ehdr, sizeof(*ehdr));
 }
 
 static unsigned get_mcountsym(Elf_Sym const *const sym0,
@@ -396,8 +396,8 @@ static void nop_mcount(Elf_Shdr const *const relhdr,
 			Elf_Rel rel;
 			rel = *(Elf_Rel *)relp;
 			Elf_r_info(&rel, Elf_r_sym(relp), rel_type_nop);
-			ulseek(fd_map, (void *)relp - (void *)ehdr, SEEK_SET);
-			uwrite(fd_map, &rel, sizeof(rel));
+			ulseek((void *)relp - (void *)ehdr, SEEK_SET);
+			uwrite(&rel, sizeof(rel));
 		}
 		relp = (Elf_Rel const *)(rel_entsize + (void *)relp);
 	}
-- 
2.20.1

[RFC][PATCH 04/13] recordmcount: Rewrite error/success handling

[Matt Helsley]

Recordmcount uses setjmp/longjmp to manage control flow as
it reads and then writes the ELF file. This unusual control
flow is hard to follow and check in addition to being unlike
kernel coding style.

So we rewrite these paths to use regular return values to
indicate error/success. When an error or previously-completed object
file is found we return an error code following kernel
coding conventions -- negative error values and 0 for success when
we're not returning a pointer. We return NULL for those that fail
and return non-NULL pointers otherwise.

One oddity is already_has_rel_mcount -- there we use pointer comparison
rather than string comparison to differentiate between
previously-processed object files and returning the name of a text
section.

Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
 scripts/recordmcount.c | 160 +++++++++++++++++++++--------------------
 scripts/recordmcount.h | 134 +++++++++++++++++++++++++---------
 2 files changed, 182 insertions(+), 112 deletions(-)

diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c
index 9101b67921cb..21dda8a19c4f 100644
--- a/scripts/recordmcount.c
+++ b/scripts/recordmcount.c
@@ -27,7 +27,6 @@
 #include <getopt.h>
 #include <elf.h>
 #include <fcntl.h>
-#include <setjmp.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -43,7 +42,6 @@ static int fd_map;	/* File descriptor for file being modified. */
 static int mmap_failed; /* Boolean flag. */
 static char gpfx;	/* prefix for global symbol name (sometimes '_') */
 static struct stat sb;	/* Remember .st_size, etc. */
-static jmp_buf jmpenv;	/* setjmp/longjmp per-file error escape */
 static const char *altmcount;	/* alternate mcount symbol name */
 static int warn_on_notrace_sect; /* warn when section has mcount not being recorded */
 static void *file_map;	/* pointer of the mapped file */
@@ -53,13 +51,6 @@ static void *file_ptr;	/* current file pointer location */
 static void *file_append; /* added to the end of the file */
 static size_t file_append_size; /* how much is added to end of file */
 
-/* setjmp() return values */
-enum {
-	SJ_SETJMP = 0,  /* hardwired first return */
-	SJ_FAIL,
-	SJ_SUCCEED
-};
-
 /* Per-file resource cleanup when multiple files. */
 static void
 cleanup(void)
@@ -75,20 +66,6 @@ cleanup(void)
 	file_updated = 0;
 }
 
-static void __attribute__((noreturn))
-fail_file(void)
-{
-	cleanup();
-	longjmp(jmpenv, SJ_FAIL);
-}
-
-static void __attribute__((noreturn))
-succeed_file(void)
-{
-	cleanup();
-	longjmp(jmpenv, SJ_SUCCEED);
-}
-
 /* ulseek, uwrite, ...:  Check return value for errors. */
 
 static off_t
@@ -107,12 +84,12 @@ ulseek(off_t const offset, int const whence)
 	}
 	if (file_ptr < file_map) {
 		fprintf(stderr, "lseek: seek before file\n");
-		fail_file();
+		return -1;
 	}
 	return file_ptr - file_map;
 }
 
-static size_t
+static ssize_t
 uwrite(void const *const buf, size_t const count)
 {
 	size_t cnt = count;
@@ -129,7 +106,8 @@ uwrite(void const *const buf, size_t const count)
 		}
 		if (!file_append) {
 			perror("write");
-			fail_file();
+			cleanup();
+			return -1;
 		}
 		if (file_ptr < file_end) {
 			cnt = file_end - file_ptr;
@@ -155,7 +133,8 @@ umalloc(size_t size)
 	void *const addr = malloc(size);
 	if (addr == 0) {
 		fprintf(stderr, "malloc failed: %zu bytes\n", size);
-		fail_file();
+		cleanup();
+		return NULL;
 	}
 	return addr;
 }
@@ -183,8 +162,10 @@ static int make_nop_x86(void *map, size_t const offset)
 		return -1;
 
 	/* convert to nop */
-	ulseek(offset - 1, SEEK_SET);
-	uwrite(ideal_nop, 5);
+	if (ulseek(offset - 1, SEEK_SET) < 0)
+		return -1;
+	if (uwrite(ideal_nop, 5) < 0)
+		return -1;
 	return 0;
 }
 
@@ -232,10 +213,12 @@ static int make_nop_arm(void *map, size_t const offset)
 		return -1;
 
 	/* Convert to nop */
-	ulseek(off, SEEK_SET);
+	if (ulseek(off, SEEK_SET) < 0)
+		return -1;
 
 	do {
-		uwrite(ideal_nop, nop_size);
+		if (uwrite(ideal_nop, nop_size) < 0)
+			return -1;
 	} while (--cnt > 0);
 
 	return 0;
@@ -252,8 +235,10 @@ static int make_nop_arm64(void *map, size_t const offset)
 		return -1;
 
 	/* Convert to nop */
-	ulseek(offset, SEEK_SET);
-	uwrite(ideal_nop, 4);
+	if (ulseek(offset, SEEK_SET) < 0)
+		return -1;
+	if (uwrite(ideal_nop, 4) < 0)
+		return -1;
 	return 0;
 }
 
@@ -272,14 +257,23 @@ static int make_nop_arm64(void *map, size_t const offset)
  */
 static void *mmap_file(char const *fname)
 {
+	file_map = NULL;
+	sb.st_size = 0;
 	fd_map = open(fname, O_RDONLY);
-	if (fd_map < 0 || fstat(fd_map, &sb) < 0) {
+	if (fd_map < 0) {
 		perror(fname);
-		fail_file();
+		cleanup();
+		return NULL;
+	}
+	if (fstat(fd_map, &sb) < 0) {
+		perror(fname);
+		cleanup();
+		goto out;
 	}
 	if (!S_ISREG(sb.st_mode)) {
 		fprintf(stderr, "not a regular file: %s\n", fname);
-		fail_file();
+		cleanup();
+		goto out;
 	}
 	file_map = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_PRIVATE,
 			fd_map, 0);
@@ -287,11 +281,18 @@ static void *mmap_file(char const *fname)
 	if (file_map == MAP_FAILED) {
 		mmap_failed = 1;
 		file_map = umalloc(sb.st_size);
+		if (!file_map) {
+			perror(fname);
+			goto out;
+		}
 		if (read(fd_map, file_map, sb.st_size) != sb.st_size) {
 			perror(fname);
-			fail_file();
+			free(file_map);
+			file_map = NULL;
+			goto out;
 		}
 	}
+out:
 	close(fd_map);
 
 	file_end = file_map + sb.st_size;
@@ -299,13 +300,13 @@ static void *mmap_file(char const *fname)
 	return file_map;
 }
 
-static void write_file(const char *fname)
+static int write_file(const char *fname)
 {
 	char tmp_file[strlen(fname) + 4];
 	size_t n;
 
 	if (!file_updated)
-		return;
+		return 0;
 
 	sprintf(tmp_file, "%s.rc", fname);
 
@@ -317,25 +318,32 @@ static void write_file(const char *fname)
 	fd_map = open(tmp_file, O_WRONLY | O_TRUNC | O_CREAT, sb.st_mode);
 	if (fd_map < 0) {
 		perror(fname);
-		fail_file();
+		cleanup();
+		return -1;
 	}
 	n = write(fd_map, file_map, sb.st_size);
 	if (n != sb.st_size) {
 		perror("write");
-		fail_file();
+		cleanup();
+		close(fd_map);
+		return -1;
 	}
 	if (file_append_size) {
 		n = write(fd_map, file_append, file_append_size);
 		if (n != file_append_size) {
 			perror("write");
-			fail_file();
+			cleanup();
+			close(fd_map);
+			return -1;
 		}
 	}
 	close(fd_map);
 	if (rename(tmp_file, fname) < 0) {
 		perror(fname);
-		fail_file();
+		cleanup();
+		return -1;
 	}
+	return 0;
 }
 
 /* w8rev, w8nat, ...: Handle endianness. */
@@ -438,11 +446,15 @@ static void MIPS64_r_info(Elf64_Rel *const rp, unsigned sym, unsigned type)
 	}).r_info;
 }
 
-static void
+static int
 do_file(char const *const fname)
 {
 	Elf32_Ehdr *const ehdr = mmap_file(fname);
 	unsigned int reltype = 0;
+	int rc = -1;
+
+	if (!ehdr)
+		goto out;
 
 	w = w4nat;
 	w2 = w2nat;
@@ -452,8 +464,8 @@ do_file(char const *const fname)
 	default:
 		fprintf(stderr, "unrecognized ELF data encoding %d: %s\n",
 			ehdr->e_ident[EI_DATA], fname);
-		fail_file();
-		break;
+		cleanup();
+		goto out;
 	case ELFDATA2LSB:
 		if (*(unsigned char const *)&endian != 1) {
 			/* main() is big endian, file.o is little endian. */
@@ -485,7 +497,8 @@ do_file(char const *const fname)
 	||  w2(ehdr->e_type) != ET_REL
 	||  ehdr->e_ident[EI_VERSION] != EV_CURRENT) {
 		fprintf(stderr, "unrecognized ET_REL file %s\n", fname);
-		fail_file();
+		cleanup();
+		goto out;
 	}
 
 	gpfx = 0;
@@ -493,8 +506,8 @@ do_file(char const *const fname)
 	default:
 		fprintf(stderr, "unrecognized e_machine %u %s\n",
 			w2(ehdr->e_machine), fname);
-		fail_file();
-		break;
+		cleanup();
+		goto out;
 	case EM_386:
 		reltype = R_386_32;
 		rel_type_nop = R_386_NONE;
@@ -534,20 +547,22 @@ do_file(char const *const fname)
 	default:
 		fprintf(stderr, "unrecognized ELF class %d %s\n",
 			ehdr->e_ident[EI_CLASS], fname);
-		fail_file();
-		break;
+		cleanup();
+		goto out;
 	case ELFCLASS32:
 		if (w2(ehdr->e_ehsize) != sizeof(Elf32_Ehdr)
 		||  w2(ehdr->e_shentsize) != sizeof(Elf32_Shdr)) {
 			fprintf(stderr,
 				"unrecognized ET_REL file: %s\n", fname);
-			fail_file();
+			cleanup();
+			goto out;
 		}
 		if (w2(ehdr->e_machine) == EM_MIPS) {
 			reltype = R_MIPS_32;
 			is_fake_mcount32 = MIPS32_is_fake_mcount;
 		}
-		do32(ehdr, fname, reltype);
+		if (do32(ehdr, fname, reltype) < 0)
+			goto out;
 		break;
 	case ELFCLASS64: {
 		Elf64_Ehdr *const ghdr = (Elf64_Ehdr *)ehdr;
@@ -555,7 +570,8 @@ do_file(char const *const fname)
 		||  w2(ghdr->e_shentsize) != sizeof(Elf64_Shdr)) {
 			fprintf(stderr,
 				"unrecognized ET_REL file: %s\n", fname);
-			fail_file();
+			cleanup();
+			goto out;
 		}
 		if (w2(ghdr->e_machine) == EM_S390) {
 			reltype = R_390_64;
@@ -567,13 +583,16 @@ do_file(char const *const fname)
 			Elf64_r_info = MIPS64_r_info;
 			is_fake_mcount64 = MIPS64_is_fake_mcount;
 		}
-		do64(ghdr, fname, reltype);
+		if (do64(ghdr, fname, reltype) < 0)
+			goto out;
 		break;
 	}
 	}  /* end switch */
 
-	write_file(fname);
+	rc = write_file(fname);
+out:
 	cleanup();
+	return rc;
 }
 
 int
@@ -604,7 +623,6 @@ main(int argc, char *argv[])
 	/* Process each file in turn, allowing deep failure. */
 	for (i = optind; i < argc; i++) {
 		char *file = argv[i];
-		int const sjval = setjmp(jmpenv);
 		int len;
 
 		/*
@@ -617,28 +635,16 @@ main(int argc, char *argv[])
 		    strcmp(file + (len - ftrace_size), ftrace) == 0)
 			continue;
 
-		switch (sjval) {
-		default:
-			fprintf(stderr, "internal error: %s\n", file);
-			exit(1);
-			break;
-		case SJ_SETJMP:    /* normal sequence */
-			/* Avoid problems if early cleanup() */
-			fd_map = -1;
-			mmap_failed = 1;
-			file_map = NULL;
-			file_ptr = NULL;
-			file_updated = 0;
-			do_file(file);
-			break;
-		case SJ_FAIL:    /* error in do_file or below */
+		/* Avoid problems if early cleanup() */
+		fd_map = -1;
+		mmap_failed = 1;
+		file_map = NULL;
+		file_ptr = NULL;
+		file_updated = 0;
+		if (do_file(file)) {
 			fprintf(stderr, "%s: failed\n", file);
 			++n_error;
-			break;
-		case SJ_SUCCEED:    /* premature success */
-			/* do nothing */
-			break;
-		}  /* end switch */
+		}
 	}
 	return !!n_error;
 }
diff --git a/scripts/recordmcount.h b/scripts/recordmcount.h
index d9736f41009e..8423c51aa8e8 100644
--- a/scripts/recordmcount.h
+++ b/scripts/recordmcount.h
@@ -25,7 +25,9 @@
 #undef mcount_adjust
 #undef sift_rel_mcount
 #undef nop_mcount
+#undef missing_sym
 #undef find_secsym_ndx
+#undef already_has_rel_mcount
 #undef __has_rel_mcount
 #undef has_rel_mcount
 #undef tot_relsize
@@ -55,7 +57,9 @@
 # define append_func		append64
 # define sift_rel_mcount	sift64_rel_mcount
 # define nop_mcount		nop_mcount_64
+# define missing_sym		missing_sym_64
 # define find_secsym_ndx	find64_secsym_ndx
+# define already_has_rel_mcount	already_has_rel_mcount_64
 # define __has_rel_mcount	__has64_rel_mcount
 # define has_rel_mcount		has64_rel_mcount
 # define tot_relsize		tot64_relsize
@@ -88,7 +92,9 @@
 # define append_func		append32
 # define sift_rel_mcount	sift32_rel_mcount
 # define nop_mcount		nop_mcount_32
+# define missing_sym		missing_sym_32
 # define find_secsym_ndx	find32_secsym_ndx
+# define already_has_rel_mcount	already_has_rel_mcount_32
 # define __has_rel_mcount	__has32_rel_mcount
 # define has_rel_mcount		has32_rel_mcount
 # define tot_relsize		tot32_relsize
@@ -175,7 +181,7 @@ static int MIPS_is_fake_mcount(Elf_Rel const *rp)
 }
 
 /* Append the new shstrtab, Elf_Shdr[], __mcount_loc and its relocations. */
-static void append_func(Elf_Ehdr *const ehdr,
+static int append_func(Elf_Ehdr *const ehdr,
 			Elf_Shdr *const shstr,
 			uint_t const *const mloc0,
 			uint_t const *const mlocp,
@@ -203,15 +209,20 @@ static void append_func(Elf_Ehdr *const ehdr,
 	new_e_shoff = t;
 
 	/* body for new shstrtab */
-	ulseek(sb.st_size, SEEK_SET);
-	uwrite(old_shstr_sh_offset + (void *)ehdr, old_shstr_sh_size);
-	uwrite(mc_name, 1 + strlen(mc_name));
+	if (ulseek(sb.st_size, SEEK_SET) < 0)
+		return -1;
+	if (uwrite(old_shstr_sh_offset + (void *)ehdr, old_shstr_sh_size) < 0)
+		return -1;
+	if (uwrite(mc_name, 1 + strlen(mc_name)) < 0)
+		return -1;
 
 	/* old(modified) Elf_Shdr table, word-byte aligned */
-	ulseek(t, SEEK_SET);
+	if (ulseek(t, SEEK_SET) < 0)
+		return -1;
 	t += sizeof(Elf_Shdr) * old_shnum;
-	uwrite(old_shoff + (void *)ehdr,
-	       sizeof(Elf_Shdr) * old_shnum);
+	if (uwrite(old_shoff + (void *)ehdr,
+	       sizeof(Elf_Shdr) * old_shnum) < 0)
+		return -1;
 
 	/* new sections __mcount_loc and .rel__mcount_loc */
 	t += 2*sizeof(mcsec);
@@ -226,7 +237,8 @@ static void append_func(Elf_Ehdr *const ehdr,
 	mcsec.sh_info = 0;
 	mcsec.sh_addralign = _w(_size);
 	mcsec.sh_entsize = _w(_size);
-	uwrite(&mcsec, sizeof(mcsec));
+	if (uwrite(&mcsec, sizeof(mcsec)) < 0)
+		return -1;
 
 	mcsec.sh_name = w(old_shstr_sh_size);
 	mcsec.sh_type = (sizeof(Elf_Rela) == rel_entsize)
@@ -240,15 +252,22 @@ static void append_func(Elf_Ehdr *const ehdr,
 	mcsec.sh_info = w(old_shnum);
 	mcsec.sh_addralign = _w(_size);
 	mcsec.sh_entsize = _w(rel_entsize);
-	uwrite(&mcsec, sizeof(mcsec));
 
-	uwrite(mloc0, (void *)mlocp - (void *)mloc0);
-	uwrite(mrel0, (void *)mrelp - (void *)mrel0);
+	if (uwrite(&mcsec, sizeof(mcsec)) < 0)
+		return -1;
+
+	if (uwrite(mloc0, (void *)mlocp - (void *)mloc0) < 0)
+		return -1;
+	if (uwrite(mrel0, (void *)mrelp - (void *)mrel0) < 0)
+		return -1;
 
 	ehdr->e_shoff = _w(new_e_shoff);
 	ehdr->e_shnum = w2(2 + w2(ehdr->e_shnum));  /* {.rel,}__mcount_loc */
-	ulseek(0, SEEK_SET);
-	uwrite(ehdr, sizeof(*ehdr));
+	if (ulseek(0, SEEK_SET) < 0)
+		return -1;
+	if (uwrite(ehdr, sizeof(*ehdr)) < 0)
+		return -1;
+	return 0;
 }
 
 static unsigned get_mcountsym(Elf_Sym const *const sym0,
@@ -351,9 +370,9 @@ static uint_t *sift_rel_mcount(uint_t *mlocp,
  * that are not going to be traced. The mcount calls here will be converted
  * into nops.
  */
-static void nop_mcount(Elf_Shdr const *const relhdr,
-		       Elf_Ehdr const *const ehdr,
-		       const char *const txtname)
+static int nop_mcount(Elf_Shdr const *const relhdr,
+		      Elf_Ehdr const *const ehdr,
+		      const char *const txtname)
 {
 	Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
 		+ (void *)ehdr);
@@ -376,15 +395,18 @@ static void nop_mcount(Elf_Shdr const *const relhdr,
 			mcountsym = get_mcountsym(sym0, relp, str0);
 
 		if (mcountsym == Elf_r_sym(relp) && !is_fake_mcount(relp)) {
-			if (make_nop)
+			if (make_nop) {
 				ret = make_nop((void *)ehdr, _w(shdr->sh_offset) + _w(relp->r_offset));
+				if (ret < 0)
+					return -1;
+			}
 			if (warn_on_notrace_sect && !once) {
 				printf("Section %s has mcount callers being ignored\n",
 				       txtname);
 				once = 1;
 				/* just warn? */
 				if (!make_nop)
-					return;
+					return 0;
 			}
 		}
 
@@ -396,13 +418,17 @@ static void nop_mcount(Elf_Shdr const *const relhdr,
 			Elf_Rel rel;
 			rel = *(Elf_Rel *)relp;
 			Elf_r_info(&rel, Elf_r_sym(relp), rel_type_nop);
-			ulseek((void *)relp - (void *)ehdr, SEEK_SET);
-			uwrite(&rel, sizeof(rel));
+			if (ulseek((void *)relp - (void *)ehdr, SEEK_SET) < 0)
+				return -1;
+			if (uwrite(&rel, sizeof(rel)) < 0)
+				return -1;
 		}
 		relp = (Elf_Rel const *)(rel_entsize + (void *)relp);
 	}
+	return 0;
 }
 
+static const unsigned int missing_sym = (unsigned int)-1;
 
 /*
  * Find a symbol in the given section, to be used as the base for relocating
@@ -443,9 +469,11 @@ static unsigned find_secsym_ndx(unsigned const txtndx,
 	}
 	fprintf(stderr, "Cannot find symbol for section %u: %s.\n",
 		txtndx, txtname);
-	fail_file();
+	cleanup();
+	return missing_sym;
 }
 
+char const *already_has_rel_mcount = "success"; /* our work here is done! */
 
 /* Evade ISO C restriction: no declaration after statement in has_rel_mcount. */
 static char const *
@@ -461,7 +489,8 @@ __has_rel_mcount(Elf_Shdr const *const relhdr,  /* is SHT_REL or SHT_RELA */
 	if (strcmp("__mcount_loc", txtname) == 0) {
 		fprintf(stderr, "warning: __mcount_loc already exists: %s\n",
 			fname);
-		succeed_file();
+		cleanup();
+		return already_has_rel_mcount;
 	}
 	if (w(txthdr->sh_type) != SHT_PROGBITS ||
 	    !(_w(txthdr->sh_flags) & SHF_EXECINSTR))
@@ -491,6 +520,10 @@ static unsigned tot_relsize(Elf_Shdr const *const shdr0,
 
 	for (; nhdr; --nhdr, ++shdrp) {
 		txtname = has_rel_mcount(shdrp, shdr0, shstrtab, fname);
+		if (txtname == already_has_rel_mcount) {
+			totrelsz = 0;
+			break;
+		}
 		if (txtname && is_mcounted_section_name(txtname))
 			totrelsz += _w(shdrp->sh_size);
 	}
@@ -499,7 +532,7 @@ static unsigned tot_relsize(Elf_Shdr const *const shdr0,
 
 
 /* Overall supervision for Elf32 ET_REL file. */
-static void
+static int
 do_func(Elf_Ehdr *const ehdr, char const *const fname, unsigned const reltype)
 {
 	Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
@@ -513,26 +546,53 @@ do_func(Elf_Ehdr *const ehdr, char const *const fname, unsigned const reltype)
 	unsigned k;
 
 	/* Upper bound on space: assume all relevant relocs are for mcount. */
-	unsigned const totrelsz = tot_relsize(shdr0, nhdr, shstrtab, fname);
-	Elf_Rel *const mrel0 = umalloc(totrelsz);
-	Elf_Rel *      mrelp = mrel0;
+	unsigned       totrelsz;
 
-	/* 2*sizeof(address) <= sizeof(Elf_Rel) */
-	uint_t *const mloc0 = umalloc(totrelsz>>1);
-	uint_t *      mlocp = mloc0;
+	Elf_Rel *      mrel0;
+	Elf_Rel *      mrelp;
+
+	uint_t *      mloc0;
+	uint_t *      mlocp;
 
 	unsigned rel_entsize = 0;
 	unsigned symsec_sh_link = 0;
 
+	int result = 0;
+
+	totrelsz = tot_relsize(shdr0, nhdr, shstrtab, fname);
+	if (totrelsz == 0)
+		return 0;
+	mrel0 = umalloc(totrelsz);
+	mrelp = mrel0;
+	if (!mrel0)
+		return -1;
+
+	/* 2*sizeof(address) <= sizeof(Elf_Rel) */
+	mloc0 = umalloc(totrelsz>>1);
+	mlocp = mloc0;
+	if (!mloc0) {
+		free(mrel0);
+		return -1;
+	}
+
 	for (relhdr = shdr0, k = nhdr; k; --k, ++relhdr) {
 		char const *const txtname = has_rel_mcount(relhdr, shdr0,
 			shstrtab, fname);
+		if (txtname == already_has_rel_mcount) {
+			result = 0;
+			file_updated = 0;
+			goto out; /* Nothing to be done; don't append! */
+		}
 		if (txtname && is_mcounted_section_name(txtname)) {
 			uint_t recval = 0;
-			unsigned const recsym = find_secsym_ndx(
+			unsigned const int recsym = find_secsym_ndx(
 				w(relhdr->sh_info), txtname, &recval,
 				&shdr0[symsec_sh_link = w(relhdr->sh_link)],
 				ehdr);
+			if (recsym == missing_sym) {
+				result = -1;
+				goto out;
+			}
 
 			rel_entsize = _w(relhdr->sh_entsize);
 			mlocp = sift_rel_mcount(mlocp,
@@ -543,13 +603,17 @@ do_func(Elf_Ehdr *const ehdr, char const *const fname, unsigned const reltype)
 			 * This section is ignored by ftrace, but still
 			 * has mcount calls. Convert them to nops now.
 			 */
-			nop_mcount(relhdr, ehdr, txtname);
+			if (nop_mcount(relhdr, ehdr, txtname) < 0) {
+				result = -1;
+				goto out;
+			}
 		}
 	}
-	if (mloc0 != mlocp) {
-		append_func(ehdr, shstr, mloc0, mlocp, mrel0, mrelp,
-			    rel_entsize, symsec_sh_link);
-	}
+	if (!result && mloc0 != mlocp)
+		result = append_func(ehdr, shstr, mloc0, mlocp, mrel0, mrelp,
+				     rel_entsize, symsec_sh_link);
+out:
 	free(mrel0);
 	free(mloc0);
+	return result;
 }
-- 
2.20.1

[RFC][PATCH 05/13] recordmcount: Kernel style function signature formatting

[Matt Helsley]

The uwrite() and ulseek() functions are formatted inconsistently
with the rest of the file and the kernel overall. While we're
making other changes here let's fix this.

Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
 scripts/recordmcount.c | 21 +++++++--------------
 scripts/recordmcount.h | 13 ++++++-------
 2 files changed, 13 insertions(+), 21 deletions(-)

diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c
index 21dda8a19c4f..f32a81251d5d 100644
--- a/scripts/recordmcount.c
+++ b/scripts/recordmcount.c
@@ -52,8 +52,7 @@ static void *file_append; /* added to the end of the file */
 static size_t file_append_size; /* how much is added to end of file */
 
 /* Per-file resource cleanup when multiple files. */
-static void
-cleanup(void)
+static void cleanup(void)
 {
 	if (!mmap_failed)
 		munmap(file_map, sb.st_size);
@@ -68,8 +67,7 @@ cleanup(void)
 
 /* ulseek, uwrite, ...:  Check return value for errors. */
 
-static off_t
-ulseek(off_t const offset, int const whence)
+static off_t ulseek(off_t const offset, int const whence)
 {
 	switch (whence) {
 	case SEEK_SET:
@@ -89,8 +87,7 @@ ulseek(off_t const offset, int const whence)
 	return file_ptr - file_map;
 }
 
-static ssize_t
-uwrite(void const *const buf, size_t const count)
+static ssize_t uwrite(void const *const buf, size_t const count)
 {
 	size_t cnt = count;
 	off_t idx = 0;
@@ -127,8 +124,7 @@ uwrite(void const *const buf, size_t const count)
 	return count;
 }
 
-static void *
-umalloc(size_t size)
+static void * umalloc(size_t size)
 {
 	void *const addr = malloc(size);
 	if (addr == 0) {
@@ -394,8 +390,7 @@ static uint32_t (*w)(uint32_t);
 static uint32_t (*w2)(uint16_t);
 
 /* Names of the sections that could contain calls to mcount. */
-static int
-is_mcounted_section_name(char const *const txtname)
+static int is_mcounted_section_name(char const *const txtname)
 {
 	return strncmp(".text",          txtname, 5) == 0 ||
 		strcmp(".init.text",     txtname) == 0 ||
@@ -446,8 +441,7 @@ static void MIPS64_r_info(Elf64_Rel *const rp, unsigned sym, unsigned type)
 	}).r_info;
 }
 
-static int
-do_file(char const *const fname)
+static int do_file(char const *const fname)
 {
 	Elf32_Ehdr *const ehdr = mmap_file(fname);
 	unsigned int reltype = 0;
@@ -595,8 +589,7 @@ do_file(char const *const fname)
 	return rc;
 }
 
-int
-main(int argc, char *argv[])
+int main(int argc, char *argv[])
 {
 	const char ftrace[] = "/ftrace.o";
 	int ftrace_size = sizeof(ftrace) - 1;
diff --git a/scripts/recordmcount.h b/scripts/recordmcount.h
index 8423c51aa8e8..0ce8e0aaa5ec 100644
--- a/scripts/recordmcount.h
+++ b/scripts/recordmcount.h
@@ -476,11 +476,10 @@ static unsigned find_secsym_ndx(unsigned const txtndx,
 char const *already_has_rel_mcount = "success"; /* our work here is done! */
 
 /* Evade ISO C restriction: no declaration after statement in has_rel_mcount. */
-static char const *
-__has_rel_mcount(Elf_Shdr const *const relhdr,  /* is SHT_REL or SHT_RELA */
-		 Elf_Shdr const *const shdr0,
-		 char const *const shstrtab,
-		 char const *const fname)
+static char const * __has_rel_mcount(Elf_Shdr const *const relhdr, /* reltype */
+				     Elf_Shdr const *const shdr0,
+				     char const *const shstrtab,
+				     char const *const fname)
 {
 	/* .sh_info depends on .sh_type == SHT_REL[,A] */
 	Elf_Shdr const *const txthdr = &shdr0[w(relhdr->sh_info)];
@@ -532,8 +531,8 @@ static unsigned tot_relsize(Elf_Shdr const *const shdr0,
 
 
 /* Overall supervision for Elf32 ET_REL file. */
-static int
-do_func(Elf_Ehdr *const ehdr, char const *const fname, unsigned const reltype)
+static int do_func(Elf_Ehdr *const ehdr, char const *const fname,
+		   unsigned const reltype)
 {
 	Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
 		+ (void *)ehdr);
-- 
2.20.1

[RFC][PATCH 06/13] recordmcount: Kernel style formatting

[Matt Helsley]

Fix up the whitespace irregularity in the ELF switch
blocks.

Swapping the initial value of gpfx allows us to
simplify all but one of the one-line switch cases even
further.

Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
 scripts/recordmcount.c | 47 ++++++++++++++++++++++--------------------
 1 file changed, 25 insertions(+), 22 deletions(-)

diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c
index f32a81251d5d..3301769254ec 100644
--- a/scripts/recordmcount.c
+++ b/scripts/recordmcount.c
@@ -487,15 +487,15 @@ static int do_file(char const *const fname)
 		push_bl_mcount_thumb = push_bl_mcount_thumb_be;
 		break;
 	}  /* end switch */
-	if (memcmp(ELFMAG, ehdr->e_ident, SELFMAG) != 0
-	||  w2(ehdr->e_type) != ET_REL
-	||  ehdr->e_ident[EI_VERSION] != EV_CURRENT) {
+	if (memcmp(ELFMAG, ehdr->e_ident, SELFMAG) != 0 ||
+	    w2(ehdr->e_type) != ET_REL ||
+	    ehdr->e_ident[EI_VERSION] != EV_CURRENT) {
 		fprintf(stderr, "unrecognized ET_REL file %s\n", fname);
 		cleanup();
 		goto out;
 	}
 
-	gpfx = 0;
+	gpfx = '_';
 	switch (w2(ehdr->e_machine)) {
 	default:
 		fprintf(stderr, "unrecognized e_machine %u %s\n",
@@ -508,32 +508,35 @@ static int do_file(char const *const fname)
 		make_nop = make_nop_x86;
 		ideal_nop = ideal_nop5_x86_32;
 		mcount_adjust_32 = -1;
+		gpfx = 0;
+		break;
+	case EM_ARM:
+		reltype = R_ARM_ABS32;
+		altmcount = "__gnu_mcount_nc";
+		make_nop = make_nop_arm;
+		rel_type_nop = R_ARM_NONE;
+		gpfx = 0;
 		break;
-	case EM_ARM:	 reltype = R_ARM_ABS32;
-			 altmcount = "__gnu_mcount_nc";
-			 make_nop = make_nop_arm;
-			 rel_type_nop = R_ARM_NONE;
-			 break;
 	case EM_AARCH64:
-			reltype = R_AARCH64_ABS64;
-			make_nop = make_nop_arm64;
-			rel_type_nop = R_AARCH64_NONE;
-			ideal_nop = ideal_nop4_arm64;
-			gpfx = '_';
-			break;
-	case EM_IA_64:	 reltype = R_IA64_IMM64;   gpfx = '_'; break;
-	case EM_MIPS:	 /* reltype: e_class    */ gpfx = '_'; break;
-	case EM_PPC:	 reltype = R_PPC_ADDR32;   gpfx = '_'; break;
-	case EM_PPC64:	 reltype = R_PPC64_ADDR64; gpfx = '_'; break;
-	case EM_S390:    /* reltype: e_class    */ gpfx = '_'; break;
-	case EM_SH:	 reltype = R_SH_DIR32;                 break;
-	case EM_SPARCV9: reltype = R_SPARC_64;     gpfx = '_'; break;
+		reltype = R_AARCH64_ABS64;
+		make_nop = make_nop_arm64;
+		rel_type_nop = R_AARCH64_NONE;
+		ideal_nop = ideal_nop4_arm64;
+		break;
+	case EM_IA_64:	reltype = R_IA64_IMM64; break;
+	case EM_MIPS:	/* reltype: e_class    */ break;
+	case EM_PPC:	reltype = R_PPC_ADDR32; break;
+	case EM_PPC64:	reltype = R_PPC64_ADDR64; break;
+	case EM_S390:	/* reltype: e_class    */ break;
+	case EM_SH:	reltype = R_SH_DIR32; gpfx = 0; break;
+	case EM_SPARCV9: reltype = R_SPARC_64; break;
 	case EM_X86_64:
 		make_nop = make_nop_x86;
 		ideal_nop = ideal_nop5_x86_64;
 		reltype = R_X86_64_64;
 		rel_type_nop = R_X86_64_NONE;
 		mcount_adjust_64 = -1;
+		gpfx = 0;
 		break;
 	}  /* end switch */
 
-- 
2.20.1

[RFC][PATCH 07/13] recordmcount: Remove redundant cleanup() calls

[Matt Helsley]

Redundant cleanup calls were introduced when transitioning from
the old error/success handling via setjmp/longjmp -- the longjmp
ensured the cleanup() call only happened once but replacing
the success_file()/fail_file() calls with cleanup() meant that
multiple cleanup() calls can happen as we return from function
calls.

In do_file(), looking just before and after the "goto out" jumps we
can see that multiple cleanups() are being performed. We remove
cleanup() calls from the nested functions because it makes the code
easier to review -- the resources being cleaned up are generally
allocated and initialized in the callers so freeing them there
makes more sense.

Other redundant cleanup() calls:

mmap_file() is only called from do_file() and, if mmap_file() fails,
then we goto out and do cleanup() there too.

write_file() is only called from do_file() and do_file()
calls cleanup() unconditionally after returning from write_file()
therefore the cleanup() calls in write_file() are not necessary.

find_secsym_ndx(), called from do_func()'s for-loop, when we are
cleaning up here it's obvious that we break out of the loop and
do another cleanup().

__has_rel_mcount() is called from two parts of do_func()
and calls cleanup(). In theory we move them into do_func(), however
these in turn prove redundant so another simplification step
removes them as well.

Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
 scripts/recordmcount.c | 13 -------------
 scripts/recordmcount.h |  2 --
 2 files changed, 15 deletions(-)

diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c
index 3301769254ec..1c8b38c0d7fe 100644
--- a/scripts/recordmcount.c
+++ b/scripts/recordmcount.c
@@ -258,17 +258,14 @@ static void *mmap_file(char const *fname)
 	fd_map = open(fname, O_RDONLY);
 	if (fd_map < 0) {
 		perror(fname);
-		cleanup();
 		return NULL;
 	}
 	if (fstat(fd_map, &sb) < 0) {
 		perror(fname);
-		cleanup();
 		goto out;
 	}
 	if (!S_ISREG(sb.st_mode)) {
 		fprintf(stderr, "not a regular file: %s\n", fname);
-		cleanup();
 		goto out;
 	}
 	file_map = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_PRIVATE,
@@ -314,13 +311,11 @@ static int write_file(const char *fname)
 	fd_map = open(tmp_file, O_WRONLY | O_TRUNC | O_CREAT, sb.st_mode);
 	if (fd_map < 0) {
 		perror(fname);
-		cleanup();
 		return -1;
 	}
 	n = write(fd_map, file_map, sb.st_size);
 	if (n != sb.st_size) {
 		perror("write");
-		cleanup();
 		close(fd_map);
 		return -1;
 	}
@@ -328,7 +323,6 @@ static int write_file(const char *fname)
 		n = write(fd_map, file_append, file_append_size);
 		if (n != file_append_size) {
 			perror("write");
-			cleanup();
 			close(fd_map);
 			return -1;
 		}
@@ -336,7 +330,6 @@ static int write_file(const char *fname)
 	close(fd_map);
 	if (rename(tmp_file, fname) < 0) {
 		perror(fname);
-		cleanup();
 		return -1;
 	}
 	return 0;
@@ -458,7 +451,6 @@ static int do_file(char const *const fname)
 	default:
 		fprintf(stderr, "unrecognized ELF data encoding %d: %s\n",
 			ehdr->e_ident[EI_DATA], fname);
-		cleanup();
 		goto out;
 	case ELFDATA2LSB:
 		if (*(unsigned char const *)&endian != 1) {
@@ -491,7 +483,6 @@ static int do_file(char const *const fname)
 	    w2(ehdr->e_type) != ET_REL ||
 	    ehdr->e_ident[EI_VERSION] != EV_CURRENT) {
 		fprintf(stderr, "unrecognized ET_REL file %s\n", fname);
-		cleanup();
 		goto out;
 	}
 
@@ -500,7 +491,6 @@ static int do_file(char const *const fname)
 	default:
 		fprintf(stderr, "unrecognized e_machine %u %s\n",
 			w2(ehdr->e_machine), fname);
-		cleanup();
 		goto out;
 	case EM_386:
 		reltype = R_386_32;
@@ -544,14 +534,12 @@ static int do_file(char const *const fname)
 	default:
 		fprintf(stderr, "unrecognized ELF class %d %s\n",
 			ehdr->e_ident[EI_CLASS], fname);
-		cleanup();
 		goto out;
 	case ELFCLASS32:
 		if (w2(ehdr->e_ehsize) != sizeof(Elf32_Ehdr)
 		||  w2(ehdr->e_shentsize) != sizeof(Elf32_Shdr)) {
 			fprintf(stderr,
 				"unrecognized ET_REL file: %s\n", fname);
-			cleanup();
 			goto out;
 		}
 		if (w2(ehdr->e_machine) == EM_MIPS) {
@@ -567,7 +555,6 @@ static int do_file(char const *const fname)
 		||  w2(ghdr->e_shentsize) != sizeof(Elf64_Shdr)) {
 			fprintf(stderr,
 				"unrecognized ET_REL file: %s\n", fname);
-			cleanup();
 			goto out;
 		}
 		if (w2(ghdr->e_machine) == EM_S390) {
diff --git a/scripts/recordmcount.h b/scripts/recordmcount.h
index 0ce8e0aaa5ec..ffab6bb96852 100644
--- a/scripts/recordmcount.h
+++ b/scripts/recordmcount.h
@@ -469,7 +469,6 @@ static unsigned find_secsym_ndx(unsigned const txtndx,
 	}
 	fprintf(stderr, "Cannot find symbol for section %u: %s.\n",
 		txtndx, txtname);
-	cleanup();
 	return missing_sym;
 }
 
@@ -488,7 +487,6 @@ static char const * __has_rel_mcount(Elf_Shdr const *const relhdr, /* reltype */
 	if (strcmp("__mcount_loc", txtname) == 0) {
 		fprintf(stderr, "warning: __mcount_loc already exists: %s\n",
 			fname);
-		cleanup();
 		return already_has_rel_mcount;
 	}
 	if (w(txthdr->sh_type) != SHT_PROGBITS ||
-- 
2.20.1

[RFC][PATCH 08/13] recordmcount: Clarify what cleanup() does

[Matt Helsley]

cleanup() mostly frees/unmaps the malloc'd/privately-mapped
copy of the ELF file recordmcount is working on, which is
set up in mmap_file(). It also deals with positioning within
the pseduo prive-mapping of the file and appending to the ELF
file.

Split into two steps:
	mmap_cleanup() for the mapping itself
	file_append_cleanup() for allocations storing the
		appended ELF data.

Also, move the global variable initializations out of the main,
per-object-file loop and nearer to the alloc/init (mmap_file())
and two cleanup functions so we can more clearly see how they're
related.

Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
 scripts/recordmcount.c | 151 ++++++++++++++++++++++-------------------
 1 file changed, 81 insertions(+), 70 deletions(-)

diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c
index 1c8b38c0d7fe..697c567c2517 100644
--- a/scripts/recordmcount.c
+++ b/scripts/recordmcount.c
@@ -48,21 +48,26 @@ static void *file_map;	/* pointer of the mapped file */
 static void *file_end;	/* pointer to the end of the mapped file */
 static int file_updated; /* flag to state file was changed */
 static void *file_ptr;	/* current file pointer location */
+
 static void *file_append; /* added to the end of the file */
 static size_t file_append_size; /* how much is added to end of file */
 
 /* Per-file resource cleanup when multiple files. */
-static void cleanup(void)
+static void file_append_cleanup(void)
+{
+	free(file_append);
+	file_append = NULL;
+	file_append_size = 0;
+	file_updated = 0;
+}
+
+static void mmap_cleanup(void)
 {
 	if (!mmap_failed)
 		munmap(file_map, sb.st_size);
 	else
 		free(file_map);
 	file_map = NULL;
-	free(file_append);
-	file_append = NULL;
-	file_append_size = 0;
-	file_updated = 0;
 }
 
 /* ulseek, uwrite, ...:  Check return value for errors. */
@@ -103,7 +108,8 @@ static ssize_t uwrite(void const *const buf, size_t const count)
 		}
 		if (!file_append) {
 			perror("write");
-			cleanup();
+			file_append_cleanup();
+			mmap_cleanup();
 			return -1;
 		}
 		if (file_ptr < file_end) {
@@ -129,12 +135,76 @@ static void * umalloc(size_t size)
 	void *const addr = malloc(size);
 	if (addr == 0) {
 		fprintf(stderr, "malloc failed: %zu bytes\n", size);
-		cleanup();
+		file_append_cleanup();
+		mmap_cleanup();
 		return NULL;
 	}
 	return addr;
 }
 
+/*
+ * Get the whole file as a programming convenience in order to avoid
+ * malloc+lseek+read+free of many pieces.  If successful, then mmap
+ * avoids copying unused pieces; else just read the whole file.
+ * Open for both read and write; new info will be appended to the file.
+ * Use MAP_PRIVATE so that a few changes to the in-memory ElfXX_Ehdr
+ * do not propagate to the file until an explicit overwrite at the last.
+ * This preserves most aspects of consistency (all except .st_size)
+ * for simultaneous readers of the file while we are appending to it.
+ * However, multiple writers still are bad.  We choose not to use
+ * locking because it is expensive and the use case of kernel build
+ * makes multiple writers unlikely.
+ */
+static void *mmap_file(char const *fname)
+{
+	/* Avoid problems if early cleanup() */
+	fd_map = -1;
+	mmap_failed = 1;
+	file_map = NULL;
+	file_ptr = NULL;
+	file_updated = 0;
+	sb.st_size = 0;
+
+	fd_map = open(fname, O_RDONLY);
+	if (fd_map < 0) {
+		perror(fname);
+		return NULL;
+	}
+	if (fstat(fd_map, &sb) < 0) {
+		perror(fname);
+		goto out;
+	}
+	if (!S_ISREG(sb.st_mode)) {
+		fprintf(stderr, "not a regular file: %s\n", fname);
+		goto out;
+	}
+	file_map = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_PRIVATE,
+			fd_map, 0);
+	if (file_map == MAP_FAILED) {
+		mmap_failed = 1;
+		file_map = umalloc(sb.st_size);
+		if (!file_map) {
+			perror(fname);
+			goto out;
+		}
+		if (read(fd_map, file_map, sb.st_size) != sb.st_size) {
+			perror(fname);
+			free(file_map);
+			file_map = NULL;
+			goto out;
+		}
+	} else
+		mmap_failed = 0;
+out:
+	close(fd_map);
+	fd_map = -1;
+
+	file_end = file_map + sb.st_size;
+
+	return file_map;
+}
+
+
 static unsigned char ideal_nop5_x86_64[5] = { 0x0f, 0x1f, 0x44, 0x00, 0x00 };
 static unsigned char ideal_nop5_x86_32[5] = { 0x3e, 0x8d, 0x74, 0x26, 0x00 };
 static unsigned char *ideal_nop;
@@ -238,61 +308,6 @@ static int make_nop_arm64(void *map, size_t const offset)
 	return 0;
 }
 
-/*
- * Get the whole file as a programming convenience in order to avoid
- * malloc+lseek+read+free of many pieces.  If successful, then mmap
- * avoids copying unused pieces; else just read the whole file.
- * Open for both read and write; new info will be appended to the file.
- * Use MAP_PRIVATE so that a few changes to the in-memory ElfXX_Ehdr
- * do not propagate to the file until an explicit overwrite at the last.
- * This preserves most aspects of consistency (all except .st_size)
- * for simultaneous readers of the file while we are appending to it.
- * However, multiple writers still are bad.  We choose not to use
- * locking because it is expensive and the use case of kernel build
- * makes multiple writers unlikely.
- */
-static void *mmap_file(char const *fname)
-{
-	file_map = NULL;
-	sb.st_size = 0;
-	fd_map = open(fname, O_RDONLY);
-	if (fd_map < 0) {
-		perror(fname);
-		return NULL;
-	}
-	if (fstat(fd_map, &sb) < 0) {
-		perror(fname);
-		goto out;
-	}
-	if (!S_ISREG(sb.st_mode)) {
-		fprintf(stderr, "not a regular file: %s\n", fname);
-		goto out;
-	}
-	file_map = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_PRIVATE,
-			fd_map, 0);
-	mmap_failed = 0;
-	if (file_map == MAP_FAILED) {
-		mmap_failed = 1;
-		file_map = umalloc(sb.st_size);
-		if (!file_map) {
-			perror(fname);
-			goto out;
-		}
-		if (read(fd_map, file_map, sb.st_size) != sb.st_size) {
-			perror(fname);
-			free(file_map);
-			file_map = NULL;
-			goto out;
-		}
-	}
-out:
-	close(fd_map);
-
-	file_end = file_map + sb.st_size;
-
-	return file_map;
-}
-
 static int write_file(const char *fname)
 {
 	char tmp_file[strlen(fname) + 4];
@@ -436,10 +451,11 @@ static void MIPS64_r_info(Elf64_Rel *const rp, unsigned sym, unsigned type)
 
 static int do_file(char const *const fname)
 {
-	Elf32_Ehdr *const ehdr = mmap_file(fname);
+	Elf32_Ehdr *ehdr;
 	unsigned int reltype = 0;
 	int rc = -1;
 
+	ehdr = mmap_file(fname);
 	if (!ehdr)
 		goto out;
 
@@ -575,7 +591,8 @@ static int do_file(char const *const fname)
 
 	rc = write_file(fname);
 out:
-	cleanup();
+	file_append_cleanup();
+	mmap_cleanup();
 	return rc;
 }
 
@@ -618,12 +635,6 @@ int main(int argc, char *argv[])
 		    strcmp(file + (len - ftrace_size), ftrace) == 0)
 			continue;
 
-		/* Avoid problems if early cleanup() */
-		fd_map = -1;
-		mmap_failed = 1;
-		file_map = NULL;
-		file_ptr = NULL;
-		file_updated = 0;
 		if (do_file(file)) {
 			fprintf(stderr, "%s: failed\n", file);
 			++n_error;
-- 
2.20.1

[RFC][PATCH 09/13] objtool: Prepare to merge recordmcount

[Matt Helsley]

Move recordmcount into the objtool directory. We keep this step separate
so changes which turn recordmcount into a subcommand of objtool don't
get obscured.

Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
 scripts/.gitignore                         |  1 -
 scripts/Makefile                           |  1 -
 scripts/Makefile.build                     | 11 ++++++-----
 tools/objtool/.gitignore                   |  1 +
 tools/objtool/Build                        |  2 ++
 tools/objtool/Makefile                     | 13 ++++++++++++-
 {scripts => tools/objtool}/recordmcount.c  |  0
 {scripts => tools/objtool}/recordmcount.h  |  0
 {scripts => tools/objtool}/recordmcount.pl |  0
 9 files changed, 21 insertions(+), 8 deletions(-)
 rename {scripts => tools/objtool}/recordmcount.c (100%)
 rename {scripts => tools/objtool}/recordmcount.h (100%)
 rename {scripts => tools/objtool}/recordmcount.pl (100%)

diff --git a/scripts/.gitignore b/scripts/.gitignore
index 17f8cef88fa8..1b5b5d595d80 100644
--- a/scripts/.gitignore
+++ b/scripts/.gitignore
@@ -6,7 +6,6 @@ conmakehash
 kallsyms
 pnmtologo
 unifdef
-recordmcount
 sortextable
 asn1_compiler
 extract-cert
diff --git a/scripts/Makefile b/scripts/Makefile
index 9d442ee050bd..5fca50fee42b 100644
--- a/scripts/Makefile
+++ b/scripts/Makefile
@@ -14,7 +14,6 @@ hostprogs-$(CONFIG_BUILD_BIN2C)  += bin2c
 hostprogs-$(CONFIG_KALLSYMS)     += kallsyms
 hostprogs-$(CONFIG_LOGO)         += pnmtologo
 hostprogs-$(CONFIG_VT)           += conmakehash
-hostprogs-$(BUILD_C_RECORDMCOUNT) += recordmcount
 hostprogs-$(CONFIG_BUILDTIME_EXTABLE_SORT) += sortextable
 hostprogs-$(CONFIG_ASN1)	 += asn1_compiler
 hostprogs-$(CONFIG_MODULE_SIG)	 += sign-file
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index ae9cf740633e..f32cfe63bb0e 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -186,18 +186,19 @@ endif
 # files, including recordmcount.
 sub_cmd_record_mcount =					\
 	if [ $(@) != "scripts/mod/empty.o" ]; then	\
-		$(objtree)/scripts/recordmcount $(RECORDMCOUNT_FLAGS) "$(@)";	\
+		$(objtree)/tools/objtool/recordmcount $(RECORDMCOUNT_FLAGS) "$(@)";	\
 	fi;
-recordmcount_source := $(srctree)/scripts/recordmcount.c \
-		    $(srctree)/scripts/recordmcount.h
+
+recordmcount_source := $(srctree)/tools/objtool/recordmcount.c \
+		    $(srctree)/tools/objtool/recordmcount.h
 else
-sub_cmd_record_mcount = perl $(srctree)/scripts/recordmcount.pl "$(ARCH)" \
+sub_cmd_record_mcount = perl $(srctree)/tools/objtool/recordmcount.pl "$(ARCH)" \
 	"$(if $(CONFIG_CPU_BIG_ENDIAN),big,little)" \
 	"$(if $(CONFIG_64BIT),64,32)" \
 	"$(OBJDUMP)" "$(OBJCOPY)" "$(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS)" \
 	"$(LD) $(KBUILD_LDFLAGS)" "$(NM)" "$(RM)" "$(MV)" \
 	"$(if $(part-of-module),1,0)" "$(@)";
-recordmcount_source := $(srctree)/scripts/recordmcount.pl
+recordmcount_source := $(srctree)/tools/objtool/recordmcount.pl
 endif # BUILD_C_RECORDMCOUNT
 cmd_record_mcount = $(if $(findstring $(strip $(CC_FLAGS_FTRACE)),$(_c_flags)),	\
 	$(sub_cmd_record_mcount))
diff --git a/tools/objtool/.gitignore b/tools/objtool/.gitignore
index 914cff12899b..ee471f353caa 100644
--- a/tools/objtool/.gitignore
+++ b/tools/objtool/.gitignore
@@ -1,3 +1,4 @@
 arch/x86/lib/inat-tables.c
 objtool
+recordmcount
 fixdep
diff --git a/tools/objtool/Build b/tools/objtool/Build
index 749becdf5b90..78c4a8a2f9e7 100644
--- a/tools/objtool/Build
+++ b/tools/objtool/Build
@@ -20,3 +20,5 @@ $(OUTPUT)libstring.o: ../lib/string.c FORCE
 $(OUTPUT)str_error_r.o: ../lib/str_error_r.c FORCE
 	$(call rule_mkdir)
 	$(call if_changed_dep,cc_o_c)
+
+recordmcount-y += recordmcount.o
diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
index 88158239622b..bd9d0b6534cf 100644
--- a/tools/objtool/Makefile
+++ b/tools/objtool/Makefile
@@ -29,6 +29,12 @@ OBJTOOL_IN := $(OBJTOOL)-in.o
 LIBELF_FLAGS := $(shell pkg-config libelf --cflags 2>/dev/null)
 LIBELF_LIBS  := $(shell pkg-config libelf --libs 2>/dev/null || echo -lelf)
 
+RECORDMCOUNT := $(OUTPUT)recordmcount
+RECORDMCOUNT_IN := $(RECORDMCOUNT)-in.o
+ifeq ($(BUILD_C_RECORDMCOUNT),y)
+all:  $(RECORDMCOUNT)
+endif
+
 all: $(OBJTOOL)
 
 INCLUDES := -I$(srctree)/tools/include \
@@ -49,16 +55,21 @@ include $(srctree)/tools/build/Makefile.include
 $(OBJTOOL_IN): fixdep FORCE
 	@$(MAKE) $(build)=objtool
 
+$(RECORDMCOUNT_IN): fixdep FORCE
+	@$(MAKE) $(build)=recordmcount
+
 $(OBJTOOL): $(LIBSUBCMD) $(OBJTOOL_IN)
 	@$(CONFIG_SHELL) ./sync-check.sh
 	$(QUIET_LINK)$(CC) $(OBJTOOL_IN) $(LDFLAGS) -o $@
 
+$(RECORDMCOUNT): $(RECORDMCOUNT_IN)
+	$(QUIET_LINK)$(CC) $(RECORDMCOUNT_IN) $(KBUILD_HOSTLDFLAGS) -o $@
 
 $(LIBSUBCMD): fixdep FORCE
 	$(Q)$(MAKE) -C $(SUBCMD_SRCDIR) OUTPUT=$(LIBSUBCMD_OUTPUT)
 
 clean:
-	$(call QUIET_CLEAN, objtool) $(RM) $(OBJTOOL)
+	$(call QUIET_CLEAN, objtool) $(RM) $(OBJTOOL) $(RECORDMCOUNT)
 	$(Q)find $(OUTPUT) -name '*.o' -delete -o -name '\.*.cmd' -delete -o -name '\.*.d' -delete
 	$(Q)$(RM) $(OUTPUT)arch/x86/lib/inat-tables.c $(OUTPUT)fixdep
 
diff --git a/scripts/recordmcount.c b/tools/objtool/recordmcount.c
similarity index 100%
rename from scripts/recordmcount.c
rename to tools/objtool/recordmcount.c
diff --git a/scripts/recordmcount.h b/tools/objtool/recordmcount.h
similarity index 100%
rename from scripts/recordmcount.h
rename to tools/objtool/recordmcount.h
diff --git a/scripts/recordmcount.pl b/tools/objtool/recordmcount.pl
similarity index 100%
rename from scripts/recordmcount.pl
rename to tools/objtool/recordmcount.pl
-- 
2.20.1

[RFC][PATCH 10/13] objtool: Make recordmcount into an objtool subcmd

[Matt Helsley]

Rather than a standalone executable merge recordmcount as a sub
command of objtool. This is a small step towards cleaning up
recordmcount and eventually saving ELF code with objtool.

For the initial step all that's required is a bit of Makefile
changes and invoking the former main() function from recordmcount.c
because the subcommand code uses similar function arguments as
main when dispatching.

Subsequent patches will gradually convert recordmcount to use
more and more of libelf/objtool's ELF accessor code. This will both
clean up recordmcount to be more easily readable and remove
recordmcount's crude accessor wrapping code.

Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
 scripts/Makefile.build         | 15 +++++--
 tools/objtool/Build            |  3 +-
 tools/objtool/Makefile         | 18 +++------
 tools/objtool/builtin-mcount.c | 72 ++++++++++++++++++++++++++++++++++
 tools/objtool/builtin-mcount.h | 23 +++++++++++
 tools/objtool/builtin.h        |  6 +++
 tools/objtool/objtool.c        |  6 +++
 tools/objtool/recordmcount.c   | 29 +++++---------
 8 files changed, 134 insertions(+), 38 deletions(-)
 create mode 100644 tools/objtool/builtin-mcount.c
 create mode 100644 tools/objtool/builtin-mcount.h

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index f32cfe63bb0e..6a3a5a477cbd 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -173,10 +173,13 @@ cmd_modversions_c =								\
 	fi
 endif
 
+objtool_dep =
+
 ifdef CONFIG_FTRACE_MCOUNT_RECORD
 ifndef CC_USING_RECORD_MCOUNT
-# compiler will not generate __mcount_loc use recordmcount or recordmcount.pl
+# compiler will not generate __mcount_loc use objtool mcount record or recordmcount.pl
 ifdef BUILD_C_RECORDMCOUNT
+objtool_dep += $(objtree)/tools/objtool/objtool
 ifeq ("$(origin RECORDMCOUNT_WARN)", "command line")
   RECORDMCOUNT_FLAGS = -w
 endif
@@ -186,10 +189,12 @@ endif
 # files, including recordmcount.
 sub_cmd_record_mcount =					\
 	if [ $(@) != "scripts/mod/empty.o" ]; then	\
-		$(objtree)/tools/objtool/recordmcount $(RECORDMCOUNT_FLAGS) "$(@)";	\
+		$(objtree)/tools/objtool/objtool mcount record $(RECORDMCOUNT_FLAGS) "$(@)";	\
 	fi;
 
-recordmcount_source := $(srctree)/tools/objtool/recordmcount.c \
+recordmcount_source := $(srctree)/tools/objtool/builtin-mcount.c \
+		    $(srctree)/tools/objtool/builtin-mcount.h \
+		    $(srctree)/tools/objtool/recordmcount.c \
 		    $(srctree)/tools/objtool/recordmcount.h
 else
 sub_cmd_record_mcount = perl $(srctree)/tools/objtool/recordmcount.pl "$(ARCH)" \
@@ -203,6 +208,8 @@ endif # BUILD_C_RECORDMCOUNT
 cmd_record_mcount = $(if $(findstring $(strip $(CC_FLAGS_FTRACE)),$(_c_flags)),	\
 	$(sub_cmd_record_mcount))
 endif # CC_USING_RECORD_MCOUNT
+
+objtool_dep += $(recordmcount_source)
 endif # CONFIG_FTRACE_MCOUNT_RECORD
 
 ifdef CONFIG_STACK_VALIDATION
@@ -241,7 +248,7 @@ endif # SKIP_STACK_VALIDATION
 endif # CONFIG_STACK_VALIDATION
 
 # Rebuild all objects when objtool changes, or is enabled/disabled.
-objtool_dep = $(objtool_obj)					\
+objtool_dep += $(objtool_obj)		\
 	      $(wildcard include/config/orc/unwinder.h		\
 			 include/config/stack/validation.h)
 
diff --git a/tools/objtool/Build b/tools/objtool/Build
index 78c4a8a2f9e7..7b71534767bd 100644
--- a/tools/objtool/Build
+++ b/tools/objtool/Build
@@ -1,6 +1,7 @@
 objtool-y += arch/$(SRCARCH)/
 objtool-y += builtin-check.o
 objtool-y += builtin-orc.o
+objtool-$(BUILD_C_RECORDMCOUNT) += builtin-mcount.o recordmcount.o
 objtool-y += check.o
 objtool-y += orc_gen.o
 objtool-y += orc_dump.o
@@ -20,5 +21,3 @@ $(OUTPUT)libstring.o: ../lib/string.c FORCE
 $(OUTPUT)str_error_r.o: ../lib/str_error_r.c FORCE
 	$(call rule_mkdir)
 	$(call if_changed_dep,cc_o_c)
-
-recordmcount-y += recordmcount.o
diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
index bd9d0b6534cf..2b018f2109aa 100644
--- a/tools/objtool/Makefile
+++ b/tools/objtool/Makefile
@@ -29,12 +29,6 @@ OBJTOOL_IN := $(OBJTOOL)-in.o
 LIBELF_FLAGS := $(shell pkg-config libelf --cflags 2>/dev/null)
 LIBELF_LIBS  := $(shell pkg-config libelf --libs 2>/dev/null || echo -lelf)
 
-RECORDMCOUNT := $(OUTPUT)recordmcount
-RECORDMCOUNT_IN := $(RECORDMCOUNT)-in.o
-ifeq ($(BUILD_C_RECORDMCOUNT),y)
-all:  $(RECORDMCOUNT)
-endif
-
 all: $(OBJTOOL)
 
 INCLUDES := -I$(srctree)/tools/include \
@@ -48,28 +42,28 @@ LDFLAGS  += $(LIBELF_LIBS) $(LIBSUBCMD) $(KBUILD_HOSTLDFLAGS)
 elfshdr := $(shell echo '$(pound)include <libelf.h>' | $(CC) $(CFLAGS) -x c -E - | grep elf_getshdr)
 CFLAGS += $(if $(elfshdr),,-DLIBELF_USE_DEPRECATED)
 
+ifeq ($(BUILD_C_RECORDMCOUNT),y)
+CFLAGS += -DCMD_MCOUNT
+endif
+
 AWK = awk
-export srctree OUTPUT CFLAGS SRCARCH AWK
+export srctree OUTPUT CFLAGS SRCARCH AWK BUILD_C_RECORDMCOUNT
 include $(srctree)/tools/build/Makefile.include
 
 $(OBJTOOL_IN): fixdep FORCE
 	@$(MAKE) $(build)=objtool
 
-$(RECORDMCOUNT_IN): fixdep FORCE
-	@$(MAKE) $(build)=recordmcount
 
 $(OBJTOOL): $(LIBSUBCMD) $(OBJTOOL_IN)
 	@$(CONFIG_SHELL) ./sync-check.sh
 	$(QUIET_LINK)$(CC) $(OBJTOOL_IN) $(LDFLAGS) -o $@
 
-$(RECORDMCOUNT): $(RECORDMCOUNT_IN)
-	$(QUIET_LINK)$(CC) $(RECORDMCOUNT_IN) $(KBUILD_HOSTLDFLAGS) -o $@
 
 $(LIBSUBCMD): fixdep FORCE
 	$(Q)$(MAKE) -C $(SUBCMD_SRCDIR) OUTPUT=$(LIBSUBCMD_OUTPUT)
 
 clean:
-	$(call QUIET_CLEAN, objtool) $(RM) $(OBJTOOL) $(RECORDMCOUNT)
+	$(call QUIET_CLEAN, objtool) $(RM) $(OBJTOOL)
 	$(Q)find $(OUTPUT) -name '*.o' -delete -o -name '\.*.cmd' -delete -o -name '\.*.d' -delete
 	$(Q)$(RM) $(OUTPUT)arch/x86/lib/inat-tables.c $(OUTPUT)fixdep
 
diff --git a/tools/objtool/builtin-mcount.c b/tools/objtool/builtin-mcount.c
new file mode 100644
index 000000000000..0ed014b82b9d
--- /dev/null
+++ b/tools/objtool/builtin-mcount.c
@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2019 Matt Helsley <mhelsley@vmware.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*
+ * objtool mcount:
+ *
+ * This command analyzes a .o file and constructs a table of the locations of
+ * calls to 'mcount' useful to ftrace. We can optionally append this table to
+ * the object file ("objtool mcount record foo.o") or output it separately
+ * ("objtool mcount show"). The latter can be used to compare the expected
+ * callers of mcount to those actually found.
+ */
+
+#include <string.h>
+#include <subcmd/parse-options.h>
+#include "builtin.h"
+
+#ifndef cmd_mcount
+#include "builtin-mcount.h"
+
+static const char * const mcount_usage[] = {
+	"objtool mcount record [<options>] file.o [file2.o ...]",
+	NULL,
+};
+
+bool warn_on_notrace_sect;
+
+const static struct option mcount_options[] = {
+	OPT_BOOLEAN('w', "warn-on-notrace-section", &warn_on_notrace_sect,
+			"Emit a warning when a section omitting mcount "
+			"(possibly due to \"notrace\" marking) is encountered"),
+	OPT_END(),
+};
+
+int cmd_mcount(int argc, const char **argv)
+{
+	argc--; argv++;
+	if (argc <= 0)
+		usage_with_options(mcount_usage, mcount_options);
+
+	if (!strncmp(argv[0], "rec", 3)) {
+		if (argc != 2)
+			usage_with_options(mcount_usage, mcount_options);
+
+		argc = parse_options(argc, argv,
+				     mcount_options, mcount_usage, 0);
+		if (argc < 1)
+			usage_with_options(mcount_usage, mcount_options);
+
+		return record_mcount(argc, argv);
+	}
+
+	usage_with_options(mcount_usage, mcount_options);
+
+	return 0;
+}
+#endif /* !def cmd_mcount */
diff --git a/tools/objtool/builtin-mcount.h b/tools/objtool/builtin-mcount.h
new file mode 100644
index 000000000000..b7b508781127
--- /dev/null
+++ b/tools/objtool/builtin-mcount.h
@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2019 Matt Helsley <mhelsley@vmware.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef BUILTIN_SUBCMD_MCOUNT
+#define BUILTIN_SUBCMD_MCOUNT 1
+
+extern int record_mcount(int argc, const char **argv);
+
+#endif /* BUILTIN_SUBCMD_MCOUNT */
diff --git a/tools/objtool/builtin.h b/tools/objtool/builtin.h
index a32736f8d2a4..29ac9be56f7b 100644
--- a/tools/objtool/builtin.h
+++ b/tools/objtool/builtin.h
@@ -13,4 +13,10 @@ extern bool no_fp, no_unreachable, retpoline, module, backtrace, uaccess;
 extern int cmd_check(int argc, const char **argv);
 extern int cmd_orc(int argc, const char **argv);
 
+#ifdef CMD_MCOUNT
+extern int cmd_mcount(int argc, const char **argv);
+#else
+#define cmd_mcount cmd_nop
+#endif
+
 #endif /* _BUILTIN_H */
diff --git a/tools/objtool/objtool.c b/tools/objtool/objtool.c
index 0b3528f05053..002a6322f4a1 100644
--- a/tools/objtool/objtool.c
+++ b/tools/objtool/objtool.c
@@ -29,12 +29,18 @@ struct cmd_struct {
 	const char *help;
 };
 
+static int __attribute__((used)) cmd_nop(int argc, const char **argv)
+{
+	return EXIT_FAILURE;
+}
+
 static const char objtool_usage_string[] =
 	"objtool COMMAND [ARGS]";
 
 static struct cmd_struct objtool_cmds[] = {
 	{"check",	cmd_check,	"Perform stack metadata validation on an object file" },
 	{"orc",		cmd_orc,	"Generate in-place ORC unwind tables for an object file" },
+	{"mcount",	cmd_mcount,	"Construct a table of locations of calls to mcount. Useful for ftrace."},
 };
 
 bool help;
diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index 697c567c2517..8345eb5b681b 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -24,7 +24,6 @@
 #include <sys/types.h>
 #include <sys/mman.h>
 #include <sys/stat.h>
-#include <getopt.h>
 #include <elf.h>
 #include <fcntl.h>
 #include <stdio.h>
@@ -32,6 +31,8 @@
 #include <string.h>
 #include <unistd.h>
 
+#include "builtin-mcount.h"
+
 #ifndef EM_AARCH64
 #define EM_AARCH64	183
 #define R_AARCH64_NONE		0
@@ -470,7 +471,7 @@ static int do_file(char const *const fname)
 		goto out;
 	case ELFDATA2LSB:
 		if (*(unsigned char const *)&endian != 1) {
-			/* main() is big endian, file.o is little endian. */
+			/* objtool is big endian, file.o is little endian. */
 			w = w4rev;
 			w2 = w2rev;
 			w8 = w8rev;
@@ -483,7 +484,7 @@ static int do_file(char const *const fname)
 		break;
 	case ELFDATA2MSB:
 		if (*(unsigned char const *)&endian != 0) {
-			/* main() is little endian, file.o is big endian. */
+			/*  objtool is little endian, file.o is big endian. */
 			w = w4rev;
 			w2 = w2rev;
 			w8 = w8rev;
@@ -596,33 +597,21 @@ static int do_file(char const *const fname)
 	return rc;
 }
 
-int main(int argc, char *argv[])
+int record_mcount(int argc, const char **argv)
 {
 	const char ftrace[] = "/ftrace.o";
 	int ftrace_size = sizeof(ftrace) - 1;
 	int n_error = 0;  /* gcc-4.3.0 false positive complaint */
-	int c;
 	int i;
 
-	while ((c = getopt(argc, argv, "w")) >= 0) {
-		switch (c) {
-		case 'w':
-			warn_on_notrace_sect = 1;
-			break;
-		default:
-			fprintf(stderr, "usage: recordmcount [-w] file.o...\n");
-			return 0;
-		}
-	}
-
-	if ((argc - optind) < 1) {
-		fprintf(stderr, "usage: recordmcount [-w] file.o...\n");
+	if (argc < 1) {
+		fprintf(stderr, "usage: objtool mcount record [-w] file.o...\n");
 		return 0;
 	}
 
 	/* Process each file in turn, allowing deep failure. */
-	for (i = optind; i < argc; i++) {
-		char *file = argv[i];
+	for (i = 0; i < argc; i++) {
+		const char *file = argv[i];
 		int len;
 
 		/*
-- 
2.20.1

[RFC][PATCH 11/13] objtool: recordmcount: Start using objtool's elf wrapper

[Matt Helsley]

Use struct elf to grab the file descriptor. We will later
move these calls into other functions as we expand the
lifetime of the struct elf so that it can be passed to
objtool elf.[ch] functions.

This creates the libelf/objcount data structures and gives
us two separte ways to walk the ELF file -- the libelf/objtool
way and the old recordmcount wrapper way which avoids these
extra data structures by using indices, offsets, and pointers
into the mmapped ELF file.

Subsequent patches will convert from the old recordmcount
accessors to the libelf/objtool accessors.

Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
 tools/objtool/recordmcount.c | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index 8345eb5b681b..71dae95deddc 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -33,6 +33,8 @@
 
 #include "builtin-mcount.h"
 
+#include "elf.h"
+
 #ifndef EM_AARCH64
 #define EM_AARCH64	183
 #define R_AARCH64_NONE		0
@@ -53,6 +55,8 @@ static void *file_ptr;	/* current file pointer location */
 static void *file_append; /* added to the end of the file */
 static size_t file_append_size; /* how much is added to end of file */
 
+static struct elf *lf;
+
 /* Per-file resource cleanup when multiple files. */
 static void file_append_cleanup(void)
 {
@@ -69,6 +73,9 @@ static void mmap_cleanup(void)
 	else
 		free(file_map);
 	file_map = NULL;
+	if (lf)
+		elf_close(lf);
+	lf = NULL;
 }
 
 /* ulseek, uwrite, ...:  Check return value for errors. */
@@ -166,11 +173,12 @@ static void *mmap_file(char const *fname)
 	file_updated = 0;
 	sb.st_size = 0;
 
-	fd_map = open(fname, O_RDONLY);
-	if (fd_map < 0) {
+	lf = elf_open(fname, O_RDONLY);
+	if (!lf) {
 		perror(fname);
 		return NULL;
 	}
+	fd_map = lf->fd;
 	if (fstat(fd_map, &sb) < 0) {
 		perror(fname);
 		goto out;
@@ -190,14 +198,14 @@ static void *mmap_file(char const *fname)
 		}
 		if (read(fd_map, file_map, sb.st_size) != sb.st_size) {
 			perror(fname);
-			free(file_map);
-			file_map = NULL;
+			mmap_cleanup();
 			goto out;
 		}
 	} else
 		mmap_failed = 0;
 out:
-	close(fd_map);
+	elf_close(lf);
+	lf = NULL;
 	fd_map = -1;
 
 	file_end = file_map + sb.st_size;
-- 
2.20.1

[RFC][PATCH 12/13] objtool: recordmcount: Search for __mcount_loc before walking the sections

[Matt Helsley]

recordmcount iterates over the sections in the order they're
listed in the ELF file and checks whether the section name
indicates it's of interest. Objtool's elf code works differently
 -- it scans the elf file and builds up data structures
representing the headers, sections, etc. and then supplies
functions to search these structures. Both walk the elf file
in order, however objtool uses more memory to enable faster
searches it needs for other tools such as the reliable backtrace
support offered by the ORC unwinder.

Rather than walk the section table a second time in the recordmcount
code, we use objtool's elf code to search for the section
recordmcount is interested in. This also simplifies flow and means
we can easily check for already-processed object files before we
do any of the more complex things recordmcount does.

This also allows us to remove the already_has_rel_mcount string
pointer trick.

Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
 tools/objtool/recordmcount.c |  2 --
 tools/objtool/recordmcount.h | 22 +++-------------------
 2 files changed, 3 insertions(+), 21 deletions(-)

diff --git a/tools/objtool/recordmcount.c b/tools/objtool/recordmcount.c
index 71dae95deddc..17d106b88464 100644
--- a/tools/objtool/recordmcount.c
+++ b/tools/objtool/recordmcount.c
@@ -204,8 +204,6 @@ static void *mmap_file(char const *fname)
 	} else
 		mmap_failed = 0;
 out:
-	elf_close(lf);
-	lf = NULL;
 	fd_map = -1;
 
 	file_end = file_map + sb.st_size;
diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index ffab6bb96852..ff14d45041f1 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -27,7 +27,6 @@
 #undef nop_mcount
 #undef missing_sym
 #undef find_secsym_ndx
-#undef already_has_rel_mcount
 #undef __has_rel_mcount
 #undef has_rel_mcount
 #undef tot_relsize
@@ -59,7 +58,6 @@
 # define nop_mcount		nop_mcount_64
 # define missing_sym		missing_sym_64
 # define find_secsym_ndx	find64_secsym_ndx
-# define already_has_rel_mcount	already_has_rel_mcount_64
 # define __has_rel_mcount	__has64_rel_mcount
 # define has_rel_mcount		has64_rel_mcount
 # define tot_relsize		tot64_relsize
@@ -94,7 +92,6 @@
 # define nop_mcount		nop_mcount_32
 # define missing_sym		missing_sym_32
 # define find_secsym_ndx	find32_secsym_ndx
-# define already_has_rel_mcount	already_has_rel_mcount_32
 # define __has_rel_mcount	__has32_rel_mcount
 # define has_rel_mcount		has32_rel_mcount
 # define tot_relsize		tot32_relsize
@@ -472,8 +469,6 @@ static unsigned find_secsym_ndx(unsigned const txtndx,
 	return missing_sym;
 }
 
-char const *already_has_rel_mcount = "success"; /* our work here is done! */
-
 /* Evade ISO C restriction: no declaration after statement in has_rel_mcount. */
 static char const * __has_rel_mcount(Elf_Shdr const *const relhdr, /* reltype */
 				     Elf_Shdr const *const shdr0,
@@ -484,11 +479,6 @@ static char const * __has_rel_mcount(Elf_Shdr const *const relhdr, /* reltype */
 	Elf_Shdr const *const txthdr = &shdr0[w(relhdr->sh_info)];
 	char const *const txtname = &shstrtab[w(txthdr->sh_name)];
 
-	if (strcmp("__mcount_loc", txtname) == 0) {
-		fprintf(stderr, "warning: __mcount_loc already exists: %s\n",
-			fname);
-		return already_has_rel_mcount;
-	}
 	if (w(txthdr->sh_type) != SHT_PROGBITS ||
 	    !(_w(txthdr->sh_flags) & SHF_EXECINSTR))
 		return NULL;
@@ -517,10 +507,6 @@ static unsigned tot_relsize(Elf_Shdr const *const shdr0,
 
 	for (; nhdr; --nhdr, ++shdrp) {
 		txtname = has_rel_mcount(shdrp, shdr0, shstrtab, fname);
-		if (txtname == already_has_rel_mcount) {
-			totrelsz = 0;
-			break;
-		}
 		if (txtname && is_mcounted_section_name(txtname))
 			totrelsz += _w(shdrp->sh_size);
 	}
@@ -556,6 +542,9 @@ static int do_func(Elf_Ehdr *const ehdr, char const *const fname,
 
 	int result = 0;
 
+	if (find_section_by_name(lf, "__mcount_loc") != NULL)
+		return 0;
+
 	totrelsz = tot_relsize(shdr0, nhdr, shstrtab, fname);
 	if (totrelsz == 0)
 		return 0;
@@ -575,11 +564,6 @@ static int do_func(Elf_Ehdr *const ehdr, char const *const fname,
 	for (relhdr = shdr0, k = nhdr; k; --k, ++relhdr) {
 		char const *const txtname = has_rel_mcount(relhdr, shdr0,
 			shstrtab, fname);
-		if (txtname == already_has_rel_mcount) {
-			result = 0;
-			file_updated = 0;
-			goto out; /* Nothing to be done; don't append! */
-		}
 		if (txtname && is_mcounted_section_name(txtname)) {
 			uint_t recval = 0;
 			unsigned const int recsym = find_secsym_ndx(
-- 
2.20.1

[RFC][PATCH 13/13] objtool: recordmcount: Convert do_func() relhdrs

[Matt Helsley]

Use objtool's ELF data structures to visit the relocation
sections in the top-level ELF file walking function, do_func().
This means we can pass pointers to the relocation header structures
into nested functions and avoid the indexing patterns for them.

These conversions don't use libelf/objtool to change the ELF
file -- it only changes the way we walk the ELF sections and
touch pages for memory mapping made by the old recordmcount code.

Signed-off-by: Matt Helsley <mhelsley@vmware.com>
---
 tools/objtool/recordmcount.h | 70 ++++++++++++++++++------------------
 1 file changed, 36 insertions(+), 34 deletions(-)

diff --git a/tools/objtool/recordmcount.h b/tools/objtool/recordmcount.h
index ff14d45041f1..0db5cbabbc12 100644
--- a/tools/objtool/recordmcount.h
+++ b/tools/objtool/recordmcount.h
@@ -289,7 +289,7 @@ static unsigned get_mcountsym(Elf_Sym const *const sym0,
 	return mcountsym;
 }
 
-static void get_sym_str_and_relp(Elf_Shdr const *const relhdr,
+static void get_sym_str_and_relp(GElf_Shdr const *const relhdr,
 				 Elf_Ehdr const *const ehdr,
 				 Elf_Sym const **sym0,
 				 char const **str0,
@@ -297,10 +297,10 @@ static void get_sym_str_and_relp(Elf_Shdr const *const relhdr,
 {
 	Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
 		+ (void *)ehdr);
-	unsigned const symsec_sh_link = w(relhdr->sh_link);
+	unsigned const symsec_sh_link = relhdr->sh_link;
 	Elf_Shdr const *const symsec = &shdr0[symsec_sh_link];
-	Elf_Shdr const *const strsec = &shdr0[w(symsec->sh_link)];
-	Elf_Rel const *const rel0 = (Elf_Rel const *)(_w(relhdr->sh_offset)
+	Elf_Shdr const *const strsec = &shdr0[symsec->sh_link];
+	Elf_Rel const *const rel0 = (Elf_Rel const *)(relhdr->sh_offset
 		+ (void *)ehdr);
 
 	*sym0 = (Elf_Sym const *)(_w(symsec->sh_offset)
@@ -320,9 +320,9 @@ static void get_sym_str_and_relp(Elf_Shdr const *const relhdr,
 static uint_t *sift_rel_mcount(uint_t *mlocp,
 			       unsigned const offbase,
 			       Elf_Rel **const mrelpp,
-			       Elf_Shdr const *const relhdr,
+			       GElf_Shdr const *const relhdr,
 			       Elf_Ehdr const *const ehdr,
-			       unsigned const recsym,
+			       unsigned const recsym_index,
 			       uint_t const recval,
 			       unsigned const reltype)
 {
@@ -331,8 +331,8 @@ static uint_t *sift_rel_mcount(uint_t *mlocp,
 	Elf_Sym const *sym0;
 	char const *str0;
 	Elf_Rel const *relp;
-	unsigned rel_entsize = _w(relhdr->sh_entsize);
-	unsigned const nrel = _w(relhdr->sh_size) / rel_entsize;
+	unsigned int rel_entsize = relhdr->sh_entsize;
+	unsigned const nrel = relhdr->sh_size / rel_entsize;
 	unsigned mcountsym = 0;
 	unsigned t;
 
@@ -347,7 +347,7 @@ static uint_t *sift_rel_mcount(uint_t *mlocp,
 				_w(_w(relp->r_offset) - recval + mcount_adjust);
 			mrelp->r_offset = _w(offbase
 				+ ((void *)mlocp - (void *)mloc0));
-			Elf_r_info(mrelp, recsym, reltype);
+			Elf_r_info(mrelp, recsym_index, reltype);
 			if (rel_entsize == sizeof(Elf_Rela)) {
 				((Elf_Rela *)mrelp)->r_addend = addend;
 				*mlocp++ = 0;
@@ -367,7 +367,7 @@ static uint_t *sift_rel_mcount(uint_t *mlocp,
  * that are not going to be traced. The mcount calls here will be converted
  * into nops.
  */
-static int nop_mcount(Elf_Shdr const *const relhdr,
+static int nop_mcount(GElf_Shdr const *const relhdr,
 		      Elf_Ehdr const *const ehdr,
 		      const char *const txtname)
 {
@@ -376,9 +376,9 @@ static int nop_mcount(Elf_Shdr const *const relhdr,
 	Elf_Sym const *sym0;
 	char const *str0;
 	Elf_Rel const *relp;
-	Elf_Shdr const *const shdr = &shdr0[w(relhdr->sh_info)];
-	unsigned rel_entsize = _w(relhdr->sh_entsize);
-	unsigned const nrel = _w(relhdr->sh_size) / rel_entsize;
+	Elf_Shdr const *const shdr = &shdr0[relhdr->sh_info];
+	unsigned int rel_entsize = relhdr->sh_entsize;
+	unsigned const nrel = relhdr->sh_size / rel_entsize;
 	unsigned mcountsym = 0;
 	unsigned t;
 	int once = 0;
@@ -470,13 +470,13 @@ static unsigned find_secsym_ndx(unsigned const txtndx,
 }
 
 /* Evade ISO C restriction: no declaration after statement in has_rel_mcount. */
-static char const * __has_rel_mcount(Elf_Shdr const *const relhdr, /* reltype */
+static char const * __has_rel_mcount(GElf_Shdr const *const relhdr, /* reltype */
 				     Elf_Shdr const *const shdr0,
 				     char const *const shstrtab,
 				     char const *const fname)
 {
 	/* .sh_info depends on .sh_type == SHT_REL[,A] */
-	Elf_Shdr const *const txthdr = &shdr0[w(relhdr->sh_info)];
+	Elf_Shdr const *const txthdr = &shdr0[relhdr->sh_info];
 	char const *const txtname = &shstrtab[w(txthdr->sh_name)];
 
 	if (w(txthdr->sh_type) != SHT_PROGBITS ||
@@ -485,30 +485,29 @@ static char const * __has_rel_mcount(Elf_Shdr const *const relhdr, /* reltype */
 	return txtname;
 }
 
-static char const *has_rel_mcount(Elf_Shdr const *const relhdr,
+static char const *has_rel_mcount(GElf_Shdr const *const relhdr,
 				  Elf_Shdr const *const shdr0,
 				  char const *const shstrtab,
 				  char const *const fname)
 {
-	if (w(relhdr->sh_type) != SHT_REL && w(relhdr->sh_type) != SHT_RELA)
+	if (relhdr->sh_type != SHT_REL && relhdr->sh_type != SHT_RELA)
 		return NULL;
 	return __has_rel_mcount(relhdr, shdr0, shstrtab, fname);
 }
 
 
 static unsigned tot_relsize(Elf_Shdr const *const shdr0,
-			    unsigned nhdr,
 			    const char *const shstrtab,
 			    const char *const fname)
 {
+	struct section *sec;
 	unsigned totrelsz = 0;
-	Elf_Shdr const *shdrp = shdr0;
 	char const *txtname;
 
-	for (; nhdr; --nhdr, ++shdrp) {
-		txtname = has_rel_mcount(shdrp, shdr0, shstrtab, fname);
+	list_for_each_entry(sec, &lf->sections, list) {
+		txtname = has_rel_mcount(&sec->sh, shdr0, shstrtab, fname);
 		if (txtname && is_mcounted_section_name(txtname))
-			totrelsz += _w(shdrp->sh_size);
+			totrelsz += sec->sh.sh_size;
 	}
 	return totrelsz;
 }
@@ -520,13 +519,11 @@ static int do_func(Elf_Ehdr *const ehdr, char const *const fname,
 {
 	Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
 		+ (void *)ehdr);
-	unsigned const nhdr = w2(ehdr->e_shnum);
 	Elf_Shdr *const shstr = &shdr0[w2(ehdr->e_shstrndx)];
 	char const *const shstrtab = (char const *)(_w(shstr->sh_offset)
 		+ (void *)ehdr);
 
-	Elf_Shdr const *relhdr;
-	unsigned k;
+	GElf_Shdr const *relhdr;
 
 	/* Upper bound on space: assume all relevant relocs are for mcount. */
 	unsigned       totrelsz;
@@ -540,12 +537,14 @@ static int do_func(Elf_Ehdr *const ehdr, char const *const fname,
 	unsigned rel_entsize = 0;
 	unsigned symsec_sh_link = 0;
 
+	struct section *sec;
+
 	int result = 0;
 
 	if (find_section_by_name(lf, "__mcount_loc") != NULL)
 		return 0;
 
-	totrelsz = tot_relsize(shdr0, nhdr, shstrtab, fname);
+	totrelsz = tot_relsize(shdr0, shstrtab, fname);
 	if (totrelsz == 0)
 		return 0;
 	mrel0 = umalloc(totrelsz);
@@ -561,24 +560,27 @@ static int do_func(Elf_Ehdr *const ehdr, char const *const fname,
 		return -1;
 	}
 
-	for (relhdr = shdr0, k = nhdr; k; --k, ++relhdr) {
-		char const *const txtname = has_rel_mcount(relhdr, shdr0,
+	list_for_each_entry(sec, &lf->sections, list) {
+		char const *txtname;
+
+		relhdr = &sec->sh;
+		txtname = has_rel_mcount(relhdr, shdr0,
 			shstrtab, fname);
 		if (txtname && is_mcounted_section_name(txtname)) {
 			uint_t recval = 0;
-			unsigned const int recsym = find_secsym_ndx(
-				w(relhdr->sh_info), txtname, &recval,
-				&shdr0[symsec_sh_link = w(relhdr->sh_link)],
+			unsigned const int recsym_index = find_secsym_ndx(
+				relhdr->sh_info, txtname, &recval,
+				&shdr0[symsec_sh_link = relhdr->sh_link],
 				ehdr);
-			if (recsym == missing_sym) {
+			if (recsym_index == missing_sym) {
 				result = -1;
 				goto out;
 			}
 
-			rel_entsize = _w(relhdr->sh_entsize);
+			rel_entsize = relhdr->sh_entsize;
 			mlocp = sift_rel_mcount(mlocp,
 				(void *)mlocp - (void *)mloc0, &mrelp,
-				relhdr, ehdr, recsym, recval, reltype);
+				relhdr, ehdr, recsym_index, recval, reltype);
 		} else if (txtname && (warn_on_notrace_sect || make_nop)) {
 			/*
 			 * This section is ignored by ftrace, but still
-- 
2.20.1

Re: [RFC][PATCH 00/13] Cleanup recordmcount and begin objtool conversion

[Josh Poimboeuf]

On Wed, May 22, 2019 at 05:03:23PM -0700, Matt Helsley wrote:
> This series cleans up recordmcount and then makes it into
> an objtool subcommand.
> 
> The series starts with 8 cleanup patches which make recordmcount
> easier to review and integrate with objtool. The final 5 patches
> show the beginning steps of converting recordmcount to use objtool's
> ELF code rather than its own open-coded methods of accessing ELF
> files.

Hi Matt,

Thanks for the patches.  This looks like a good step in the right
direction.

What's the performance difference between the old recordmcount and the
new version which relies on elf_open()?  It would be useful to compare
kernel build times, before and after.

Would it be feasible to eventually combine subcommands so that objtool
could do both ORC and mcount generation in a single invocation?  I
wonder what what the interface would look like.

> Matt Helsley (13):
>   recordmcount: Remove redundant strcmp
>   recordmcount: Remove uread()
>   recordmcount: Remove unused fd from uwrite() and ulseek()
>   recordmcount: Rewrite error/success handling
>   recordmcount: Kernel style function signature formatting
>   recordmcount: Kernel style formatting
>   recordmcount: Remove redundant cleanup() calls
>   recordmcount: Clarify what cleanup() does
>   objtool: Prepare to merge recordmcount
>   objtool: Make recordmcount into an objtool subcmd
>   objtool: recordmcount: Start using objtool's elf wrapper
>   objtool: recordmcount: Search for __mcount_loc before walking the
>     sections
>   objtool: recordmcount: Convert do_func() relhdrs
> 
>  scripts/.gitignore                         |   1 -
>  scripts/Makefile                           |   1 -
>  scripts/Makefile.build                     |  22 +-
>  tools/objtool/.gitignore                   |   1 +
>  tools/objtool/Build                        |   1 +
>  tools/objtool/Makefile                     |   7 +-
>  tools/objtool/builtin-mcount.c             |  72 +++++
>  tools/objtool/builtin-mcount.h             |  23 ++
>  tools/objtool/builtin.h                    |   6 +
>  tools/objtool/objtool.c                    |   6 +
>  {scripts => tools/objtool}/recordmcount.c  | 350 ++++++++++-----------
>  {scripts => tools/objtool}/recordmcount.h  | 197 +++++++-----
>  {scripts => tools/objtool}/recordmcount.pl |   0
>  13 files changed, 420 insertions(+), 267 deletions(-)
>  create mode 100644 tools/objtool/builtin-mcount.c
>  create mode 100644 tools/objtool/builtin-mcount.h
>  rename {scripts => tools/objtool}/recordmcount.c (78%)
>  rename {scripts => tools/objtool}/recordmcount.h (78%)
>  rename {scripts => tools/objtool}/recordmcount.pl (100%)
> 
> -- 
> 2.20.1
> 

-- 
Josh

Re: [RFC][PATCH 00/13] Cleanup recordmcount and begin objtool conversion

[Steven Rostedt]

On Tue, 28 May 2019 09:43:28 -0500
Josh Poimboeuf <jpoimboe@redhat.com> wrote:

> Thanks for the patches.  This looks like a good step in the right
> direction.

Good to hear.

> 
> What's the performance difference between the old recordmcount and the
> new version which relies on elf_open()?  It would be useful to compare
> kernel build times, before and after.

I'll let Matt answer these.

> 
> Would it be feasible to eventually combine subcommands so that objtool
> could do both ORC and mcount generation in a single invocation?  I
> wonder what what the interface would look like.

That is actually the goal of this work. To eventually be able to do
single passes to accomplish multiple tasks.

-- Steve

Re: [RFC][PATCH 10/13] objtool: Make recordmcount into an objtool subcmd

[Josh Poimboeuf]

On Wed, May 22, 2019 at 05:03:33PM -0700, Matt Helsley wrote:
> Rather than a standalone executable merge recordmcount as a sub
> command of objtool. This is a small step towards cleaning up
> recordmcount and eventually saving ELF code with objtool.
> 
> For the initial step all that's required is a bit of Makefile
> changes and invoking the former main() function from recordmcount.c
> because the subcommand code uses similar function arguments as
> main when dispatching.
> 
> Subsequent patches will gradually convert recordmcount to use
> more and more of libelf/objtool's ELF accessor code. This will both
> clean up recordmcount to be more easily readable and remove
> recordmcount's crude accessor wrapping code.
> 
> Signed-off-by: Matt Helsley <mhelsley@vmware.com>
> ---
>  scripts/Makefile.build         | 15 +++++--
>  tools/objtool/Build            |  3 +-
>  tools/objtool/Makefile         | 18 +++------
>  tools/objtool/builtin-mcount.c | 72 ++++++++++++++++++++++++++++++++++
>  tools/objtool/builtin-mcount.h | 23 +++++++++++
>  tools/objtool/builtin.h        |  6 +++
>  tools/objtool/objtool.c        |  6 +++
>  tools/objtool/recordmcount.c   | 29 +++++---------
>  8 files changed, 134 insertions(+), 38 deletions(-)
>  create mode 100644 tools/objtool/builtin-mcount.c
>  create mode 100644 tools/objtool/builtin-mcount.h
> 
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index f32cfe63bb0e..6a3a5a477cbd 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -173,10 +173,13 @@ cmd_modversions_c =								\
>  	fi
>  endif
>  
> +objtool_dep =
> +
>  ifdef CONFIG_FTRACE_MCOUNT_RECORD
>  ifndef CC_USING_RECORD_MCOUNT
> -# compiler will not generate __mcount_loc use recordmcount or recordmcount.pl
> +# compiler will not generate __mcount_loc use objtool mcount record or recordmcount.pl
>  ifdef BUILD_C_RECORDMCOUNT
> +objtool_dep += $(objtree)/tools/objtool/objtool
>  ifeq ("$(origin RECORDMCOUNT_WARN)", "command line")
>    RECORDMCOUNT_FLAGS = -w
>  endif
> @@ -186,10 +189,12 @@ endif
>  # files, including recordmcount.
>  sub_cmd_record_mcount =					\
>  	if [ $(@) != "scripts/mod/empty.o" ]; then	\
> -		$(objtree)/tools/objtool/recordmcount $(RECORDMCOUNT_FLAGS) "$(@)";	\
> +		$(objtree)/tools/objtool/objtool mcount record $(RECORDMCOUNT_FLAGS) "$(@)";	\
>  	fi;
>  
> -recordmcount_source := $(srctree)/tools/objtool/recordmcount.c \
> +recordmcount_source := $(srctree)/tools/objtool/builtin-mcount.c \
> +		    $(srctree)/tools/objtool/builtin-mcount.h \
> +		    $(srctree)/tools/objtool/recordmcount.c \
>  		    $(srctree)/tools/objtool/recordmcount.h

Is this needed? if any of these files change, then objtool will change,
and which is already covered by the objtool_dep assignment above.

>  else
>  sub_cmd_record_mcount = perl $(srctree)/tools/objtool/recordmcount.pl "$(ARCH)" \
> @@ -203,6 +208,8 @@ endif # BUILD_C_RECORDMCOUNT
>  cmd_record_mcount = $(if $(findstring $(strip $(CC_FLAGS_FTRACE)),$(_c_flags)),	\
>  	$(sub_cmd_record_mcount))
>  endif # CC_USING_RECORD_MCOUNT
> +
> +objtool_dep += $(recordmcount_source)

I don't think this is needed because recordmcount_source is already
listed as a dependency for .o files.

>  endif # CONFIG_FTRACE_MCOUNT_RECORD
>  
>  ifdef CONFIG_STACK_VALIDATION
> @@ -241,7 +248,7 @@ endif # SKIP_STACK_VALIDATION
>  endif # CONFIG_STACK_VALIDATION
>  
>  # Rebuild all objects when objtool changes, or is enabled/disabled.
> -objtool_dep = $(objtool_obj)					\
> +objtool_dep += $(objtool_obj)		\

The backslash should be aligned with the following ones.

>  	      $(wildcard include/config/orc/unwinder.h		\
>  			 include/config/stack/validation.h)

Should we also add an ftrace config dependency here?
Like include/config/ftrace/mcount/record.h?

>  
> diff --git a/tools/objtool/Build b/tools/objtool/Build
> index 78c4a8a2f9e7..7b71534767bd 100644
> --- a/tools/objtool/Build
> +++ b/tools/objtool/Build
> @@ -1,6 +1,7 @@
>  objtool-y += arch/$(SRCARCH)/
>  objtool-y += builtin-check.o
>  objtool-y += builtin-orc.o
> +objtool-$(BUILD_C_RECORDMCOUNT) += builtin-mcount.o recordmcount.o

Can we just build these files unconditionally, even if they're not used?
Thus far, objtool doesn't have any kernel config dependencies like this.
It helps keep things simple and keeps objtool more separate from the
kernel.

So if you build record mcount unconditionally then I think you can also
get rid of the BUILD_C_RECORDMCOUNT export, the CMD_MCOUNT define, and
cmd_nop().

-- 
Josh

Re: [RFC][PATCH 00/13] Cleanup recordmcount and begin objtool conversion

[Peter Zijlstra]

On Tue, May 28, 2019 at 09:43:28AM -0500, Josh Poimboeuf wrote:
> Would it be feasible to eventually combine subcommands so that objtool
> could do both ORC and mcount generation in a single invocation?  I
> wonder what what the interface would look like.

objtool orc+mcount ?

That is, have '+' be a separator for cmd thingies. That would of course
require all other arguments to be shared between all commands, which is
currently already so, but I've not checked the mcount patches.

Alternatively, we ditch the command thing entirely and live off of pure
flags:

 'o', "orc", "Generate ORC data"
 'c', "mcount', "Generate mcount() location data"

Re: [RFC][PATCH 00/13] Cleanup recordmcount and begin objtool conversion

[Josh Poimboeuf]

On Wed, May 29, 2019 at 03:41:52PM +0200, Peter Zijlstra wrote:
> On Tue, May 28, 2019 at 09:43:28AM -0500, Josh Poimboeuf wrote:
> > Would it be feasible to eventually combine subcommands so that objtool
> > could do both ORC and mcount generation in a single invocation?  I
> > wonder what what the interface would look like.
> 
> objtool orc+mcount ?
> 
> That is, have '+' be a separator for cmd thingies. That would of course
> require all other arguments to be shared between all commands, which is
> currently already so, but I've not checked the mcount patches.

The problem is that you have to combine "orc generate" with "mcount
record".  Because even the subcommands have subcommands ;-)

And also sharing arguments between all subcommands isn't ideal.

Maybe could do:

  objtool orc generate [orc options] + mcount record [mcount options]

> Alternatively, we ditch the command thing entirely and live off of pure
> flags:
> 
>  'o', "orc", "Generate ORC data"
>  'c', "mcount', "Generate mcount() location data"

-- 
Josh

Re: [RFC][PATCH 00/13] Cleanup recordmcount and begin objtool conversion

[Matt Helsley]

On Wed, May 29, 2019 at 09:11:45AM -0500, Josh Poimboeuf wrote:
> On Wed, May 29, 2019 at 03:41:52PM +0200, Peter Zijlstra wrote:
> > On Tue, May 28, 2019 at 09:43:28AM -0500, Josh Poimboeuf wrote:
> > > Would it be feasible to eventually combine subcommands so that objtool
> > > could do both ORC and mcount generation in a single invocation?  I
> > > wonder what what the interface would look like.

I think it'll be feasible. I've done a bit of investigation but don't
have patches for it yet.

> > 
> > objtool orc+mcount ?
> > 
> > That is, have '+' be a separator for cmd thingies. That would of course
> > require all other arguments to be shared between all commands, which is
> > currently already so, but I've not checked the mcount patches.
> 
> The problem is that you have to combine "orc generate" with "mcount
> record".  Because even the subcommands have subcommands ;-)
> 
> And also sharing arguments between all subcommands isn't ideal.
> 
> Maybe could do:
> 
>   objtool orc generate [orc options] + mcount record [mcount options]

I think that makes more sense; it'll be easier to construct
Make recipes this way. I was thinking '+' would be something like the
getopt handling of the '--' argument where it stops argument parsing so
someting else can consume the remainder.

The really interesting part is deciding which file to operate on is
specified by the arguments to the first subcommand and subsequent subcmds
would then operate on the same object file. For example:

objtool orc generate [orc opts] foo.o + mcount record [mcount opts]

Would it be clearer what's going on if the object file(s) were specified
first and then the passes to run and their arguments came afterwards?
I'm thinking it'd go somewhat like this:

objtool foo.o [bar.o] -- check [check opts] + \
			 orc generate [orc opts] + \
			 mcount record [mcount opts]

Then objtool would iterate over the object file(s) to open,
hand off the ELF data structures into each successive pass, and
finally write any accumulated changes back.

Cheers,
    -Matt

Re: [RFC][PATCH 00/13] Cleanup recordmcount and begin objtool conversion

[Josh Poimboeuf]

On Thu, May 30, 2019 at 04:52:19PM -0700, Matt Helsley wrote:
> > > objtool orc+mcount ?
> > > 
> > > That is, have '+' be a separator for cmd thingies. That would of course
> > > require all other arguments to be shared between all commands, which is
> > > currently already so, but I've not checked the mcount patches.
> > 
> > The problem is that you have to combine "orc generate" with "mcount
> > record".  Because even the subcommands have subcommands ;-)
> > 
> > And also sharing arguments between all subcommands isn't ideal.
> > 
> > Maybe could do:
> > 
> >   objtool orc generate [orc options] + mcount record [mcount options]
> 
> I think that makes more sense; it'll be easier to construct
> Make recipes this way. I was thinking '+' would be something like the
> getopt handling of the '--' argument where it stops argument parsing so
> someting else can consume the remainder.
> 
> The really interesting part is deciding which file to operate on is
> specified by the arguments to the first subcommand and subsequent subcmds
> would then operate on the same object file. For example:
> 
> objtool orc generate [orc opts] foo.o + mcount record [mcount opts]
> 
> Would it be clearer what's going on if the object file(s) were specified
> first and then the passes to run and their arguments came afterwards?
> I'm thinking it'd go somewhat like this:
> 
> objtool foo.o [bar.o] -- check [check opts] + \
> 			 orc generate [orc opts] + \
> 			 mcount record [mcount opts]
> 
> Then objtool would iterate over the object file(s) to open,
> hand off the ELF data structures into each successive pass, and
> finally write any accumulated changes back.

Yeah, I forgot about the .o file.  Something like that would probably
work.  The ordering seems a bit funny to me.  Another possibly more
readable variation would be:

  objtool check [check opts] + orc generate [orc opts] + mcount record [mcount opts] -- foo.o [bar.o]

or, just use '--' as a generic separator which can be used to separate
subcommands or file names.

  objtool check [check opts] -- orc generate [orc opts] -- mcount record [mcount opts] -- foo.o [bar.o]

I kind of like that.  But I think any of these variations would probably
work.

-- 
Josh