ftrace/recordmcount: Fix hardlink issue with ccache

index 698768bdc581..91705ef30402 100644
@@ -211,6 +211,20 @@ static void *mmap_file(char const *fname)
 		addr = umalloc(sb.st_size);
 		uread(fd_map, addr, sb.st_size);
 	}
+	if (sb.st_nlink != 1) {
+		/* file is hard-linked, break the hard link */
+		close(fd_map);
+		if (unlink(fname) < 0) {
+			perror(fname);
+			fail_file();
+		}
+		fd_map = open(fname, O_RDWR | O_CREAT, sb.st_mode);
+		if (fd_map < 0) {
+			perror(fname);
+			fail_file();
+		}
+		uwrite(fd_map, addr, sb.st_size);
+	}
 	return addr;
 }
 

index 91705ef30402..301d70b0174f 100644
@@ -48,12 +48,17 @@
 
 static int fd_map;	/* File descriptor for file being modified. */
 static int mmap_failed; /* Boolean flag. */
-static void *ehdr_curr; /* current ElfXX_Ehdr *  for resource cleanup */
 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 */
+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 */
 
 /* setjmp() return values */
 enum {

@@ -67,10 +72,14 @@ static void
 cleanup(void)
 {
 	if (!mmap_failed)
-		munmap(ehdr_curr, sb.st_size);
+		munmap(file_map, sb.st_size);
 	else
-		free(ehdr_curr);
-	close(fd_map);
+		free(file_map);
+	file_map = NULL;
+	free(file_append);
+	file_append = NULL;
+	file_append_size = 0;
+	file_updated = 0;
 }
 
 static void __attribute__((noreturn))

@@ -92,12 +101,22 @@ succeed_file(void)
 static off_t
 ulseek(int const fd, off_t const offset, int const whence)
 {
-	off_t const w = lseek(fd, offset, whence);
-	if (w == (off_t)-1) {
-		perror("lseek");
+	switch (whence) {
+	case SEEK_SET:
+		file_ptr = file_map + offset;
+		break;
+	case SEEK_CUR:
+		file_ptr += offset;
+		break;
+	case SEEK_END:
+		file_ptr = file_map + (sb.st_size - offset);
+		break;
+	}
+	if (file_ptr < file_map) {
+		fprintf(stderr, "lseek: seek before file\n");
 		fail_file();
 	}
-	return w;
+	return file_ptr - file_map;
 }
 
 static size_t

@@ -114,12 +133,38 @@ uread(int const fd, void *const buf, size_t const count)
 static size_t
 uwrite(int const fd, void const *const buf, size_t const count)
 {
-	size_t const n = write(fd, buf, count);
-	if (n != count) {
-		perror("write");
-		fail_file();
+	size_t cnt = count;
+	off_t idx = 0;
+
+	file_updated = 1;
+
+	if (file_ptr + count >= file_end) {
+		off_t aoffset = (file_ptr + count) - file_end;
+
+		if (aoffset > file_append_size) {
+			file_append = realloc(file_append, aoffset);
+			file_append_size = aoffset;
+		}
+		if (!file_append) {
+			perror("write");
+			fail_file();
+		}
+		if (file_ptr < file_end) {
+			cnt = file_end - file_ptr;
+		} else {
+			cnt = 0;
+			idx = aoffset - count;
+		}
 	}
-	return n;
+
+	if (cnt)
+		memcpy(file_ptr, buf, cnt);
+
+	if (cnt < count)
+		memcpy(file_append + idx, buf + cnt, count - cnt);
+
+	file_ptr += count;
+	return count;
 }
 
 static void *

@@ -192,9 +237,7 @@ static int make_nop_arm64(void *map, size_t const offset)
  */
 static void *mmap_file(char const *fname)
 {
-	void *addr;
-
-	fd_map = open(fname, O_RDWR);
+	fd_map = open(fname, O_RDONLY);
 	if (fd_map < 0 || fstat(fd_map, &sb) < 0) {
 		perror(fname);
 		fail_file();

@@ -203,29 +246,58 @@ static void *mmap_file(char const *fname)
 		fprintf(stderr, "not a regular file: %s\n", fname);
 		fail_file();
 	}
-	addr = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_PRIVATE,
-		    fd_map, 0);
+	file_map = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_PRIVATE,
+			fd_map, 0);
 	mmap_failed = 0;
-	if (addr == MAP_FAILED) {
+	if (file_map == MAP_FAILED) {
 		mmap_failed = 1;
-		addr = umalloc(sb.st_size);
-		uread(fd_map, addr, sb.st_size);
+		file_map = umalloc(sb.st_size);
+		uread(fd_map, file_map, sb.st_size);
 	}
-	if (sb.st_nlink != 1) {
-		/* file is hard-linked, break the hard link */
-		close(fd_map);
-		if (unlink(fname) < 0) {
-			perror(fname);
-			fail_file();
-		}
-		fd_map = open(fname, O_RDWR | O_CREAT, sb.st_mode);
-		if (fd_map < 0) {
-			perror(fname);
+	close(fd_map);
+
+	file_end = file_map + sb.st_size;
+
+	return file_map;
+}
+
+static void write_file(const char *fname)
+{
+	char tmp_file[strlen(fname) + 4];
+	size_t n;
+
+	if (!file_updated)
+		return;
+
+	sprintf(tmp_file, "%s.rc", fname);
+
+	/*
+	 * After reading the entire file into memory, delete it
+	 * and write it back, to prevent weird side effects of modifying
+	 * an object file in place.
+	 */
+	fd_map = open(tmp_file, O_WRONLY | O_TRUNC | O_CREAT, sb.st_mode);
+	if (fd_map < 0) {
+		perror(fname);
+		fail_file();
+	}
+	n = write(fd_map, file_map, sb.st_size);
+	if (n != sb.st_size) {
+		perror("write");
+		fail_file();
+	}
+	if (file_append_size) {
+		n = write(fd_map, file_append, file_append_size);
+		if (n != file_append_size) {
+			perror("write");
 			fail_file();
 		}
-		uwrite(fd_map, addr, sb.st_size);
 	}
-	return addr;
+	close(fd_map);
+	if (rename(tmp_file, fname) < 0) {
+		perror(fname);
+		fail_file();
+	}
 }
 
 /* w8rev, w8nat, ...: Handle endianness. */

@@ -332,7 +404,6 @@ do_file(char const *const fname)
 	Elf32_Ehdr *const ehdr = mmap_file(fname);
 	unsigned int reltype = 0;
 
-	ehdr_curr = ehdr;
 	w = w4nat;
 	w2 = w2nat;
 	w8 = w8nat;

@@ -455,6 +526,7 @@ do_file(char const *const fname)
 	}
 	}  /* end switch */
 
+	write_file(fname);
 	cleanup();
 }
 

@@ -507,11 +579,14 @@ main(int argc, char *argv[])
 		case SJ_SETJMP:    /* normal sequence */
 			/* Avoid problems if early cleanup() */
 			fd_map = -1;
-			ehdr_curr = NULL;
 			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 */
+			sprintf("%s: failed\n", file);
 			++n_error;
 			break;
 		case SJ_SUCCEED:    /* premature success */