Merge tag 'trace-v5.10-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

ef6900ac · Linus Torvalds <[email protected]> · 2020-12-01 15:30:18 -08:00

Pull tracing fixes from Steven Rostedt:

 - Use correct timestamp variable for ring buffer write stamp update

 - Fix up before stamp and write stamp when crossing ring buffer sub
   buffers

 - Keep a zero delta in ring buffer in slow path if cmpxchg fails

 - Fix trace_printk static buffer for archs that care

 - Fix ftrace record accounting for ftrace ops with trampolines

 - Fix DYNAMIC_FTRACE_WITH_DIRECT_CALLS dependency

 - Remove WARN_ON in hwlat tracer that triggers on something that is OK

 - Make "my_tramp" trampoline in ftrace direct sample code global

 - Fixes in the bootconfig tool for better alignment management

* tag 'trace-v5.10-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  ring-buffer: Always check to put back before stamp when crossing pages
  ftrace: Fix DYNAMIC_FTRACE_WITH_DIRECT_CALLS dependency
  ftrace: Fix updating FTRACE_FL_TRAMP
  tracing: Fix alignment of static buffer
  tracing: Remove WARN_ON in start_thread()
  samples/ftrace: Mark my_tramp[12]? global
  ring-buffer: Set the right timestamp in the slow path of __rb_reserve_next()
  ring-buffer: Update write stamp with the correct ts
  docs: bootconfig: Update file format on initrd image
  tools/bootconfig: Align the bootconfig applied initrd image size to 4
  tools/bootconfig: Fix to check the write failure correctly
  tools/bootconfig: Fix errno reference after printf()

Commit: ef6900acc89ecfc78ceb0eb1605c954dd6f2ca05
Parents: f43691b5 · 68e10d5f

Merge commit. Changes below are compared with the first parent: f43691b5.

Changes

12 files changed · +138 −62

File	Status	Add	Del	Content
Documentation/admin-guide/bootconfig.rst	modified	+13	−5	View file
include/linux/bootconfig.h	modified	+3	−0	View file
kernel/trace/Kconfig	modified	+1	−1	View file
kernel/trace/ftrace.c	modified	+21	−1	View file
kernel/trace/ring_buffer.c	modified	+9	−11	View file
kernel/trace/trace.c	modified	+1	−1	View file
kernel/trace/trace_hwlat.c	modified	+1	−1	View file
samples/ftrace/ftrace-direct-modify.c	modified	+2	−0	View file
samples/ftrace/ftrace-direct-too.c	modified	+1	−0	View file
samples/ftrace/ftrace-direct.c	modified	+1	−0	View file
tools/bootconfig/main.c	modified	+80	−41	View file
tools/bootconfig/test-bootconfig.sh	modified	+5	−1	View file

Documentation/admin-guide/bootconfig.rst

View file

diff --git a/Documentation/admin-guide/bootconfig.rst b/Documentation/admin-guide/bootconfig.rst
index a22024f..3635996 100644
--- a/Documentation/admin-guide/bootconfig.rst
+++ b/Documentation/admin-guide/bootconfig.rst
@@ -137,15 +137,22 @@ Boot Kernel With a Boot Config
 ==============================
 
 Since the boot configuration file is loaded with initrd, it will be added
-to the end of the initrd (initramfs) image file with size, checksum and
-12-byte magic word as below.
+to the end of the initrd (initramfs) image file with padding, size,
+checksum and 12-byte magic word as below.
 
-[initrd][bootconfig][size(u32)][checksum(u32)][#BOOTCONFIG\n]
+[initrd][bootconfig][padding][size(u32)][checksum(u32)][#BOOTCONFIG\n]
+
+When the boot configuration is added to the initrd image, the total
+file size is aligned to 4 bytes. To fill the gap, null characters
+(``\0``) will be added. Thus the ``size`` is the length of the bootconfig
+file + padding bytes.
 
 The Linux kernel decodes the last part of the initrd image in memory to
 get the boot configuration data.
 Because of this "piggyback" method, there is no need to change or
-update the boot loader and the kernel image itself.
+update the boot loader and the kernel image itself as long as the boot
+loader passes the correct initrd file size. If by any chance, the boot
+loader passes a longer size, the kernel feils to find the bootconfig data.
 
 To do this operation, Linux kernel provides "bootconfig" command under
 tools/bootconfig, which allows admin to apply or delete the config file
@@ -176,7 +183,8 @@ up to 512 key-value pairs. If keys contains 3 words in average, it can
 contain 256 key-value pairs. In most cases, the number of config items
 will be under 100 entries and smaller than 8KB, so it would be enough.
 If the node number exceeds 1024, parser returns an error even if the file
-size is smaller than 32KB.
+size is smaller than 32KB. (Note that this maximum size is not including
+the padding null characters.)
 Anyway, since bootconfig command verifies it when appending a boot config
 to initrd image, user can notice it before boot.
 

include/linux/bootconfig.h

View file

diff --git a/include/linux/bootconfig.h b/include/linux/bootconfig.h
index 9903088..2696eb0 100644
--- a/include/linux/bootconfig.h
+++ b/include/linux/bootconfig.h
@@ -12,6 +12,9 @@
 
 #define BOOTCONFIG_MAGIC	"#BOOTCONFIG\n"
 #define BOOTCONFIG_MAGIC_LEN	12
+#define BOOTCONFIG_ALIGN_SHIFT	2
+#define BOOTCONFIG_ALIGN	(1 << BOOTCONFIG_ALIGN_SHIFT)
+#define BOOTCONFIG_ALIGN_MASK	(BOOTCONFIG_ALIGN - 1)
 
 /* XBC tree node */
 struct xbc_node {

kernel/trace/Kconfig

View file

diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index a4020c0..e1bf522 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -202,7 +202,7 @@ config DYNAMIC_FTRACE_WITH_REGS
 
 config DYNAMIC_FTRACE_WITH_DIRECT_CALLS
 	def_bool y
-	depends on DYNAMIC_FTRACE
+	depends on DYNAMIC_FTRACE_WITH_REGS
 	depends on HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS
 
 config FUNCTION_PROFILER

kernel/trace/ftrace.c

View file

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 8185f72..9c1bba8 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1629,6 +1629,8 @@ static bool test_rec_ops_needs_regs(struct dyn_ftrace *rec)
 static struct ftrace_ops *
 ftrace_find_tramp_ops_any(struct dyn_ftrace *rec);
 static struct ftrace_ops *
+ftrace_find_tramp_ops_any_other(struct dyn_ftrace *rec, struct ftrace_ops *op_exclude);
+static struct ftrace_ops *
 ftrace_find_tramp_ops_next(struct dyn_ftrace *rec, struct ftrace_ops *ops);
 
 static bool __ftrace_hash_rec_update(struct ftrace_ops *ops,
@@ -1778,7 +1780,7 @@ static bool __ftrace_hash_rec_update(struct ftrace_ops *ops,
 			 * to it.
 			 */
 			if (ftrace_rec_count(rec) == 1 &&
-			    ftrace_find_tramp_ops_any(rec))
+			    ftrace_find_tramp_ops_any_other(rec, ops))
 				rec->flags |= FTRACE_FL_TRAMP;
 			else
 				rec->flags &= ~FTRACE_FL_TRAMP;
@@ -2245,6 +2247,24 @@ ftrace_find_tramp_ops_any(struct dyn_ftrace *rec)
 }
 
 static struct ftrace_ops *
+ftrace_find_tramp_ops_any_other(struct dyn_ftrace *rec, struct ftrace_ops *op_exclude)
+{
+	struct ftrace_ops *op;
+	unsigned long ip = rec->ip;
+
+	do_for_each_ftrace_op(op, ftrace_ops_list) {
+
+		if (op == op_exclude || !op->trampoline)
+			continue;
+
+		if (hash_contains_ip(ip, op->func_hash))
+			return op;
+	} while_for_each_ftrace_op(op);
+
+	return NULL;
+}
+
+static struct ftrace_ops *
 ftrace_find_tramp_ops_next(struct dyn_ftrace *rec,
 			   struct ftrace_ops *op)
 {

kernel/trace/ring_buffer.c

View file

diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index dc83b3f..a6268e0 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -3234,14 +3234,12 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
 
 	/* See if we shot pass the end of this buffer page */
 	if (unlikely(write > BUF_PAGE_SIZE)) {
-		if (tail != w) {
-			/* before and after may now different, fix it up*/
-			b_ok = rb_time_read(&cpu_buffer->before_stamp, &info->before);
-			a_ok = rb_time_read(&cpu_buffer->write_stamp, &info->after);
-			if (a_ok && b_ok && info->before != info->after)
-				(void)rb_time_cmpxchg(&cpu_buffer->before_stamp,
-						      info->before, info->after);
-		}
+		/* before and after may now different, fix it up*/
+		b_ok = rb_time_read(&cpu_buffer->before_stamp, &info->before);
+		a_ok = rb_time_read(&cpu_buffer->write_stamp, &info->after);
+		if (a_ok && b_ok && info->before != info->after)
+			(void)rb_time_cmpxchg(&cpu_buffer->before_stamp,
+					      info->before, info->after);
 		return rb_move_tail(cpu_buffer, tail, info);
 	}
 
@@ -3287,11 +3285,11 @@ __rb_reserve_next(struct ring_buffer_per_cpu *cpu_buffer,
 		ts = rb_time_stamp(cpu_buffer->buffer);
 		barrier();
  /*E*/		if (write == (local_read(&tail_page->write) & RB_WRITE_MASK) &&
-		    info->after < ts) {
+		    info->after < ts &&
+		    rb_time_cmpxchg(&cpu_buffer->write_stamp,
+				    info->after, ts)) {
 			/* Nothing came after this event between C and E */
 			info->delta = ts - info->after;
-			(void)rb_time_cmpxchg(&cpu_buffer->write_stamp,
-					      info->after, info->ts);
 			info->ts = ts;
 		} else {
 			/*

kernel/trace/trace.c

View file

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 410cfeb..7d53c5b 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3534,7 +3534,7 @@ __find_next_entry(struct trace_iterator *iter, int *ent_cpu,
 }
 
 #define STATIC_TEMP_BUF_SIZE	128
-static char static_temp_buf[STATIC_TEMP_BUF_SIZE];
+static char static_temp_buf[STATIC_TEMP_BUF_SIZE] __aligned(4);
 
 /* Find the next real entry, without updating the iterator itself */
 struct trace_entry *trace_find_next_entry(struct trace_iterator *iter,

kernel/trace/trace_hwlat.c

View file

diff --git a/kernel/trace/trace_hwlat.c b/kernel/trace/trace_hwlat.c
index c9ad5c6..d071fc2 100644
--- a/kernel/trace/trace_hwlat.c
+++ b/kernel/trace/trace_hwlat.c
@@ -368,7 +368,7 @@ static int start_kthread(struct trace_array *tr)
 	struct task_struct *kthread;
 	int next_cpu;
 
-	if (WARN_ON(hwlat_kthread))
+	if (hwlat_kthread)
 		return 0;
 
 	/* Just pick the first CPU on first iteration */

samples/ftrace/ftrace-direct-modify.c

View file

diff --git a/samples/ftrace/ftrace-direct-modify.c b/samples/ftrace/ftrace-direct-modify.c
index c13a5bc..5b9a099 100644
--- a/samples/ftrace/ftrace-direct-modify.c
+++ b/samples/ftrace/ftrace-direct-modify.c
@@ -21,6 +21,7 @@ static unsigned long my_ip = (unsigned long)schedule;
 asm (
 "	.pushsection    .text, \"ax\", @progbits\n"
 "	.type		my_tramp1, @function\n"
+"	.globl		my_tramp1\n"
 "   my_tramp1:"
 "	pushq %rbp\n"
 "	movq %rsp, %rbp\n"
@@ -29,6 +30,7 @@ asm (
 "	.size		my_tramp1, .-my_tramp1\n"
 "	ret\n"
 "	.type		my_tramp2, @function\n"
+"	.globl		my_tramp2\n"
 "   my_tramp2:"
 "	pushq %rbp\n"
 "	movq %rsp, %rbp\n"

samples/ftrace/ftrace-direct-too.c

View file

diff --git a/samples/ftrace/ftrace-direct-too.c b/samples/ftrace/ftrace-direct-too.c
index d5c5022..3f0079c 100644
--- a/samples/ftrace/ftrace-direct-too.c
+++ b/samples/ftrace/ftrace-direct-too.c
@@ -16,6 +16,7 @@ extern void my_tramp(void *);
 asm (
 "	.pushsection    .text, \"ax\", @progbits\n"
 "	.type		my_tramp, @function\n"
+"	.globl		my_tramp\n"
 "   my_tramp:"
 "	pushq %rbp\n"
 "	movq %rsp, %rbp\n"

samples/ftrace/ftrace-direct.c

View file

diff --git a/samples/ftrace/ftrace-direct.c b/samples/ftrace/ftrace-direct.c
index 63ca06d..a2729d1 100644
--- a/samples/ftrace/ftrace-direct.c
+++ b/samples/ftrace/ftrace-direct.c
@@ -14,6 +14,7 @@ extern void my_tramp(void *);
 asm (
 "	.pushsection    .text, \"ax\", @progbits\n"
 "	.type		my_tramp, @function\n"
+"	.globl		my_tramp\n"
 "   my_tramp:"
 "	pushq %rbp\n"
 "	movq %rsp, %rbp\n"

tools/bootconfig/main.c

View file

diff --git a/tools/bootconfig/main.c b/tools/bootconfig/main.c
index eb92027..4a445b6 100644
--- a/tools/bootconfig/main.c
+++ b/tools/bootconfig/main.c
@@ -147,6 +147,12 @@ static int load_xbc_file(const char *path, char **buf)
 	return ret;
 }
 
+static int pr_errno(const char *msg, int err)
+{
+	pr_err("%s: %d\n", msg, err);
+	return err;
+}
+
 static int load_xbc_from_initrd(int fd, char **buf)
 {
 	struct stat stat;
@@ -162,26 +168,24 @@ static int load_xbc_from_initrd(int fd, char **buf)
 	if (stat.st_size < 8 + BOOTCONFIG_MAGIC_LEN)
 		return 0;
 
-	if (lseek(fd, -BOOTCONFIG_MAGIC_LEN, SEEK_END) < 0) {
-		pr_err("Failed to lseek: %d\n", -errno);
-		return -errno;
-	}
+	if (lseek(fd, -BOOTCONFIG_MAGIC_LEN, SEEK_END) < 0)
+		return pr_errno("Failed to lseek for magic", -errno);
+
 	if (read(fd, magic, BOOTCONFIG_MAGIC_LEN) < 0)
-		return -errno;
+		return pr_errno("Failed to read", -errno);
+
 	/* Check the bootconfig magic bytes */
 	if (memcmp(magic, BOOTCONFIG_MAGIC, BOOTCONFIG_MAGIC_LEN) != 0)
 		return 0;
 
-	if (lseek(fd, -(8 + BOOTCONFIG_MAGIC_LEN), SEEK_END) < 0) {
-		pr_err("Failed to lseek: %d\n", -errno);
-		return -errno;
-	}
+	if (lseek(fd, -(8 + BOOTCONFIG_MAGIC_LEN), SEEK_END) < 0)
+		return pr_errno("Failed to lseek for size", -errno);
 
 	if (read(fd, &size, sizeof(u32)) < 0)
-		return -errno;
+		return pr_errno("Failed to read size", -errno);
 
 	if (read(fd, &csum, sizeof(u32)) < 0)
-		return -errno;
+		return pr_errno("Failed to read checksum", -errno);
 
 	/* Wrong size error  */
 	if (stat.st_size < size + 8 + BOOTCONFIG_MAGIC_LEN) {
@@ -190,10 +194,8 @@ static int load_xbc_from_initrd(int fd, char **buf)
 	}
 
 	if (lseek(fd, stat.st_size - (size + 8 + BOOTCONFIG_MAGIC_LEN),
-		  SEEK_SET) < 0) {
-		pr_err("Failed to lseek: %d\n", -errno);
-		return -errno;
-	}
+		  SEEK_SET) < 0)
+		return pr_errno("Failed to lseek", -errno);
 
 	ret = load_xbc_fd(fd, buf, size);
 	if (ret < 0)
@@ -262,14 +264,16 @@ static int show_xbc(const char *path, bool list)
 
 	ret = stat(path, &st);
 	if (ret < 0) {
-		pr_err("Failed to stat %s: %d\n", path, -errno);
-		return -errno;
+		ret = -errno;
+		pr_err("Failed to stat %s: %d\n", path, ret);
+		return ret;
 	}
 
 	fd = open(path, O_RDONLY);
 	if (fd < 0) {
-		pr_err("Failed to open initrd %s: %d\n", path, fd);
-		return -errno;
+		ret = -errno;
+		pr_err("Failed to open initrd %s: %d\n", path, ret);
+		return ret;
 	}
 
 	ret = load_xbc_from_initrd(fd, &buf);
@@ -307,8 +311,9 @@ static int delete_xbc(const char *path)
 
 	fd = open(path, O_RDWR);
 	if (fd < 0) {
-		pr_err("Failed to open initrd %s: %d\n", path, fd);
-		return -errno;
+		ret = -errno;
+		pr_err("Failed to open initrd %s: %d\n", path, ret);
+		return ret;
 	}
 
 	size = load_xbc_from_initrd(fd, &buf);
@@ -332,11 +337,13 @@ static int delete_xbc(const char *path)
 
 static int apply_xbc(const char *path, const char *xbc_path)
 {
+	char *buf, *data, *p;
+	size_t total_size;
+	struct stat stat;
+	const char *msg;
 	u32 size, csum;
-	char *buf, *data;
+	int pos, pad;
 	int ret, fd;
-	const char *msg;
-	int pos;
 
 	ret = load_xbc_file(xbc_path, &buf);
 	if (ret < 0) {
@@ -346,13 +353,12 @@ static int apply_xbc(const char *path, const char *xbc_path)
 	size = strlen(buf) + 1;
 	csum = checksum((unsigned char *)buf, size);
 
-	/* Prepare xbc_path data */
-	data = malloc(size + 8);
+	/* Backup the bootconfig data */
+	data = calloc(size + BOOTCONFIG_ALIGN +
+		      sizeof(u32) + sizeof(u32) + BOOTCONFIG_MAGIC_LEN, 1);
 	if (!data)
 		return -ENOMEM;
-	strcpy(data, buf);
-	*(u32 *)(data + size) = size;
-	*(u32 *)(data + size + 4) = csum;
+	memcpy(data, buf, size);
 
 	/* Check the data format */
 	ret = xbc_init(buf, &msg, &pos);
@@ -383,28 +389,61 @@ static int apply_xbc(const char *path, const char *xbc_path)
 	/* Apply new one */
 	fd = open(path, O_RDWR | O_APPEND);
 	if (fd < 0) {
-		pr_err("Failed to open %s: %d\n", path, fd);
+		ret = -errno;
+		pr_err("Failed to open %s: %d\n", path, ret);
 		free(data);
-		return fd;
+		return ret;
 	}
 	/* TODO: Ensure the @path is initramfs/initrd image */
-	ret = write(fd, data, size + 8);
-	if (ret < 0) {
-		pr_err("Failed to apply a boot config: %d\n", ret);
+	if (fstat(fd, &stat) < 0) {
+		pr_err("Failed to get the size of %s\n", path);
 		goto out;
 	}
-	/* Write a magic word of the bootconfig */
-	ret = write(fd, BOOTCONFIG_MAGIC, BOOTCONFIG_MAGIC_LEN);
-	if (ret < 0) {
-		pr_err("Failed to apply a boot config magic: %d\n", ret);
-		goto out;
-	}
-	ret = 0;
+
+	/* To align up the total size to BOOTCONFIG_ALIGN, get padding size */
+	total_size = stat.st_size + size + sizeof(u32) * 2 + BOOTCONFIG_MAGIC_LEN;
+	pad = ((total_size + BOOTCONFIG_ALIGN - 1) & (~BOOTCONFIG_ALIGN_MASK)) - total_size;
+	size += pad;
+
+	/* Add a footer */
+	p = data + size;
+	*(u32 *)p = size;
+	p += sizeof(u32);
+
+	*(u32 *)p = csum;
+	p += sizeof(u32);
+
+	memcpy(p, BOOTCONFIG_MAGIC, BOOTCONFIG_MAGIC_LEN);
+	p += BOOTCONFIG_MAGIC_LEN;
+
+	total_size = p - data;
+
+	ret = write(fd, data, total_size);
+	if (ret < total_size) {
+		if (ret < 0)
+			ret = -errno;
+		pr_err("Failed to apply a boot config: %d\n", ret);
+		if (ret >= 0)
+			goto out_rollback;
+	} else
+		ret = 0;
+
 out:
 	close(fd);
 	free(data);
 
 	return ret;
+
+out_rollback:
+	/* Map the partial write to -ENOSPC */
+	if (ret >= 0)
+		ret = -ENOSPC;
+	if (ftruncate(fd, stat.st_size) < 0) {
+		ret = -errno;
+		pr_err("Failed to rollback the write error: %d\n", ret);
+		pr_err("The initrd %s may be corrupted. Recommend to rebuild.\n", path);
+	}
+	goto out;
 }
 
 static int usage(void)

tools/bootconfig/test-bootconfig.sh

View file

diff --git a/tools/bootconfig/test-bootconfig.sh b/tools/bootconfig/test-bootconfig.sh
index d295e40..baed891 100755
--- a/tools/bootconfig/test-bootconfig.sh
+++ b/tools/bootconfig/test-bootconfig.sh
@@ -9,6 +9,7 @@ else
   TESTDIR=.
 fi
 BOOTCONF=${TESTDIR}/bootconfig
+ALIGN=4
 
 INITRD=`mktemp ${TESTDIR}/initrd-XXXX`
 TEMPCONF=`mktemp ${TESTDIR}/temp-XXXX.bconf`
@@ -59,7 +60,10 @@ echo "Show command test"
 xpass $BOOTCONF $INITRD
 
 echo "File size check"
-xpass test $new_size -eq $(expr $bconf_size + $initrd_size + 9 + 12)
+total_size=$(expr $bconf_size + $initrd_size + 9 + 12 + $ALIGN - 1 )
+total_size=$(expr $total_size / $ALIGN)
+total_size=$(expr $total_size \* $ALIGN)
+xpass test $new_size -eq $total_size
 
 echo "Apply command repeat test"
 xpass $BOOTCONF -a $TEMPCONF $INITRD