Commit ef6900ac authored by Linus Torvalds's avatar Linus Torvalds
Browse files

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

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()
parents f43691b5 68e10d5f

Documentation/admin-guide/bootconfig.rst

+13 −5
Original line number Diff line number Diff line
@@ -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

+3 −0
Original line number Diff line number Diff line
@@ -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

+1 −1
Original line number Diff line number Diff line
@@ -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

+21 −1
Original line number Diff line number Diff line
@@ -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;
@@ -2244,6 +2246,24 @@ ftrace_find_tramp_ops_any(struct dyn_ftrace *rec) 
	return NULL;

}



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

+9 −11
Original line number Diff line number Diff line
@@ -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);

		}

		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 {

			/*

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