* [for-next][PATCH 00/15] tracing/seq-buf/printk: New seq-buf utility from trace_seq for printk in NMI
@ 2014-11-20 15:21 Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 01/15] tracing: Create seq_buf layer in trace_seq Steven Rostedt
` (14 more replies)
0 siblings, 15 replies; 16+ messages in thread
From: Steven Rostedt @ 2014-11-20 15:21 UTC (permalink / raw)
To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek
I created a separate branch for this change (although it's still going into
my for-next branch which ends up in linux-next. But that branch is made
up of multiple branches).
I'm hoping that it makes it into 3.19, but I'll give that choice to Linus.
This is based off of a point of my ftrace/core branch which is my normal
branch. But this one is separate because it may not be accepted. I'll just
have to wait and see. New work for tracing will not be based on this branch.
Although Linus may not accept it, I still want it in linux-next for further
testing.
-- Steve
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
for-next
Head SHA1: a9edc88093287183ac934be44f295f183b2c62dd
Steven Rostedt (Red Hat) (15):
tracing: Create seq_buf layer in trace_seq
tracing: Convert seq_buf_path() to be like seq_path()
tracing: Convert seq_buf fields to be like seq_file fields
tracing: Add a seq_buf_clear() helper and clear len and readpos in init
seq_buf: Create seq_buf_used() to find out how much was written
tracing: Clean up tracing_fill_pipe_page()
tracing: Use trace_seq_used() and seq_buf_used() instead of len
tracing: Add paranoid size check in trace_printk_seq()
seq_buf: Add seq_buf_can_fit() helper function
tracing: Have seq_buf use full buffer
tracing: Add seq_buf_get_buf() and seq_buf_commit() helper functions
seq-buf: Make seq_buf_bprintf() conditional on CONFIG_BINARY_PRINTF
seq_buf: Move the seq_buf code to lib/
printk: Add per_cpu printk func to allow printk to be diverted
x86/nmi: Perform a safe NMI stack trace on all CPUs
----
arch/x86/kernel/apic/hw_nmi.c | 91 ++++++++-
include/linux/percpu.h | 3 +
include/linux/printk.h | 2 +
include/linux/seq_buf.h | 136 +++++++++++++
include/linux/trace_seq.h | 30 ++-
kernel/printk/printk.c | 38 +++-
kernel/trace/trace.c | 65 +++++--
kernel/trace/trace_events.c | 9 +-
kernel/trace/trace_functions_graph.c | 11 +-
kernel/trace/trace_seq.c | 177 ++++++++---------
lib/Makefile | 2 +-
lib/seq_buf.c | 359 +++++++++++++++++++++++++++++++++++
12 files changed, 779 insertions(+), 144 deletions(-)
^ permalink raw reply [flat|nested] 16+ messages in thread
* [for-next][PATCH 01/15] tracing: Create seq_buf layer in trace_seq
2014-11-20 15:21 [for-next][PATCH 00/15] tracing/seq-buf/printk: New seq-buf utility from trace_seq for printk in NMI Steven Rostedt
@ 2014-11-20 15:21 ` Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 02/15] tracing: Convert seq_buf_path() to be like seq_path() Steven Rostedt
` (13 subsequent siblings)
14 siblings, 0 replies; 16+ messages in thread
From: Steven Rostedt @ 2014-11-20 15:21 UTC (permalink / raw)
To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek
[-- Attachment #1: 0001-tracing-Create-seq_buf-layer-in-trace_seq.patch --]
[-- Type: text/plain, Size: 26597 bytes --]
From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
Create a seq_buf layer that trace_seq sits on. The seq_buf will not
be limited to page size. This will allow other usages of seq_buf
instead of a hard set PAGE_SIZE one that trace_seq has.
Link: http://lkml.kernel.org/r/20141104160221.864997179@goodmis.org
Link: http://lkml.kernel.org/r/20141114011412.170377300@goodmis.org
Tested-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
include/linux/seq_buf.h | 81 +++++++++
include/linux/trace_seq.h | 12 +-
kernel/trace/Makefile | 1 +
kernel/trace/seq_buf.c | 341 +++++++++++++++++++++++++++++++++++
kernel/trace/trace.c | 39 ++--
kernel/trace/trace_events.c | 6 +-
kernel/trace/trace_functions_graph.c | 6 +-
kernel/trace/trace_seq.c | 178 +++++++++---------
8 files changed, 538 insertions(+), 126 deletions(-)
create mode 100644 include/linux/seq_buf.h
create mode 100644 kernel/trace/seq_buf.c
diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h
new file mode 100644
index 000000000000..4f7a96a9d71a
--- /dev/null
+++ b/include/linux/seq_buf.h
@@ -0,0 +1,81 @@
+#ifndef _LINUX_SEQ_BUF_H
+#define _LINUX_SEQ_BUF_H
+
+#include <linux/fs.h>
+
+/*
+ * Trace sequences are used to allow a function to call several other functions
+ * to create a string of data to use.
+ */
+
+/**
+ * seq_buf - seq buffer structure
+ * @buffer: pointer to the buffer
+ * @size: size of the buffer
+ * @len: the amount of data inside the buffer
+ * @readpos: The next position to read in the buffer.
+ */
+struct seq_buf {
+ unsigned char *buffer;
+ unsigned int size;
+ unsigned int len;
+ unsigned int readpos;
+};
+
+static inline void
+seq_buf_init(struct seq_buf *s, unsigned char *buf, unsigned int size)
+{
+ s->buffer = buf;
+ s->size = size;
+ s->len = 0;
+ s->readpos = 0;
+}
+
+/*
+ * seq_buf have a buffer that might overflow. When this happens
+ * the len and size are set to be equal.
+ */
+static inline bool
+seq_buf_has_overflowed(struct seq_buf *s)
+{
+ return s->len == s->size;
+}
+
+static inline void
+seq_buf_set_overflow(struct seq_buf *s)
+{
+ s->len = s->size;
+}
+
+/*
+ * How much buffer is left on the seq_buf?
+ */
+static inline unsigned int
+seq_buf_buffer_left(struct seq_buf *s)
+{
+ if (seq_buf_has_overflowed(s))
+ return 0;
+
+ return (s->size - 1) - s->len;
+}
+
+extern __printf(2, 3)
+int seq_buf_printf(struct seq_buf *s, const char *fmt, ...);
+extern __printf(2, 0)
+int seq_buf_vprintf(struct seq_buf *s, const char *fmt, va_list args);
+extern int
+seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary);
+extern int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s);
+extern int seq_buf_to_user(struct seq_buf *s, char __user *ubuf,
+ int cnt);
+extern int seq_buf_puts(struct seq_buf *s, const char *str);
+extern int seq_buf_putc(struct seq_buf *s, unsigned char c);
+extern int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len);
+extern int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
+ unsigned int len);
+extern int seq_buf_path(struct seq_buf *s, const struct path *path);
+
+extern int seq_buf_bitmask(struct seq_buf *s, const unsigned long *maskp,
+ int nmaskbits);
+
+#endif /* _LINUX_SEQ_BUF_H */
diff --git a/include/linux/trace_seq.h b/include/linux/trace_seq.h
index db8a73224f1a..85d37106be3d 100644
--- a/include/linux/trace_seq.h
+++ b/include/linux/trace_seq.h
@@ -1,7 +1,7 @@
#ifndef _LINUX_TRACE_SEQ_H
#define _LINUX_TRACE_SEQ_H
-#include <linux/fs.h>
+#include <linux/seq_buf.h>
#include <asm/page.h>
@@ -12,16 +12,14 @@
struct trace_seq {
unsigned char buffer[PAGE_SIZE];
- unsigned int len;
- unsigned int readpos;
+ struct seq_buf seq;
int full;
};
static inline void
trace_seq_init(struct trace_seq *s)
{
- s->len = 0;
- s->readpos = 0;
+ seq_buf_init(&s->seq, s->buffer, PAGE_SIZE);
s->full = 0;
}
@@ -37,7 +35,7 @@ trace_seq_init(struct trace_seq *s)
static inline unsigned char *
trace_seq_buffer_ptr(struct trace_seq *s)
{
- return s->buffer + s->len;
+ return s->buffer + s->seq.len;
}
/**
@@ -49,7 +47,7 @@ trace_seq_buffer_ptr(struct trace_seq *s)
*/
static inline bool trace_seq_has_overflowed(struct trace_seq *s)
{
- return s->full || s->len > PAGE_SIZE - 1;
+ return s->full || seq_buf_has_overflowed(&s->seq);
}
/*
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index 67d6369ddf83..edc98c72a634 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -29,6 +29,7 @@ obj-$(CONFIG_RING_BUFFER_BENCHMARK) += ring_buffer_benchmark.o
obj-$(CONFIG_TRACING) += trace.o
obj-$(CONFIG_TRACING) += trace_output.o
obj-$(CONFIG_TRACING) += trace_seq.o
+obj-$(CONFIG_TRACING) += seq_buf.o
obj-$(CONFIG_TRACING) += trace_stat.o
obj-$(CONFIG_TRACING) += trace_printk.o
obj-$(CONFIG_CONTEXT_SWITCH_TRACER) += trace_sched_switch.o
diff --git a/kernel/trace/seq_buf.c b/kernel/trace/seq_buf.c
new file mode 100644
index 000000000000..e9a7861595d2
--- /dev/null
+++ b/kernel/trace/seq_buf.c
@@ -0,0 +1,341 @@
+/*
+ * seq_buf.c
+ *
+ * Copyright (C) 2014 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
+ *
+ * The seq_buf is a handy tool that allows you to pass a descriptor around
+ * to a buffer that other functions can write to. It is similar to the
+ * seq_file functionality but has some differences.
+ *
+ * To use it, the seq_buf must be initialized with seq_buf_init().
+ * This will set up the counters within the descriptor. You can call
+ * seq_buf_init() more than once to reset the seq_buf to start
+ * from scratch.
+ */
+#include <linux/uaccess.h>
+#include <linux/seq_file.h>
+#include <linux/seq_buf.h>
+
+/* How much buffer is written? */
+#define SEQ_BUF_USED(s) min((s)->len, (s)->size - 1)
+
+/**
+ * seq_buf_print_seq - move the contents of seq_buf into a seq_file
+ * @m: the seq_file descriptor that is the destination
+ * @s: the seq_buf descriptor that is the source.
+ *
+ * Returns zero on success, non zero otherwise
+ */
+int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s)
+{
+ unsigned int len = SEQ_BUF_USED(s);
+
+ return seq_write(m, s->buffer, len);
+}
+
+/**
+ * seq_buf_vprintf - sequence printing of information.
+ * @s: seq_buf descriptor
+ * @fmt: printf format string
+ * @args: va_list of arguments from a printf() type function
+ *
+ * Writes a vnprintf() format into the sequencce buffer.
+ *
+ * Returns zero on success, -1 on overflow.
+ */
+int seq_buf_vprintf(struct seq_buf *s, const char *fmt, va_list args)
+{
+ int len;
+
+ WARN_ON(s->size == 0);
+
+ if (s->len < s->size) {
+ len = vsnprintf(s->buffer + s->len, s->size - s->len, fmt, args);
+ if (s->len + len < s->size) {
+ s->len += len;
+ return 0;
+ }
+ }
+ seq_buf_set_overflow(s);
+ return -1;
+}
+
+/**
+ * seq_buf_printf - sequence printing of information
+ * @s: seq_buf descriptor
+ * @fmt: printf format string
+ *
+ * Writes a printf() format into the sequence buffer.
+ *
+ * Returns zero on success, -1 on overflow.
+ */
+int seq_buf_printf(struct seq_buf *s, const char *fmt, ...)
+{
+ va_list ap;
+ int ret;
+
+ va_start(ap, fmt);
+ ret = seq_buf_vprintf(s, fmt, ap);
+ va_end(ap);
+
+ return ret;
+}
+
+/**
+ * seq_buf_bitmask - write a bitmask array in its ASCII representation
+ * @s: seq_buf descriptor
+ * @maskp: points to an array of unsigned longs that represent a bitmask
+ * @nmaskbits: The number of bits that are valid in @maskp
+ *
+ * Writes a ASCII representation of a bitmask string into @s.
+ *
+ * Returns zero on success, -1 on overflow.
+ */
+int seq_buf_bitmask(struct seq_buf *s, const unsigned long *maskp,
+ int nmaskbits)
+{
+ unsigned int len = seq_buf_buffer_left(s);
+ int ret;
+
+ WARN_ON(s->size == 0);
+
+ /*
+ * The last byte of the buffer is used to determine if we
+ * overflowed or not.
+ */
+ if (len > 1) {
+ ret = bitmap_scnprintf(s->buffer + s->len, len, maskp, nmaskbits);
+ if (ret < len) {
+ s->len += ret;
+ return 0;
+ }
+ }
+ seq_buf_set_overflow(s);
+ return -1;
+}
+
+/**
+ * seq_buf_bprintf - Write the printf string from binary arguments
+ * @s: seq_buf descriptor
+ * @fmt: The format string for the @binary arguments
+ * @binary: The binary arguments for @fmt.
+ *
+ * When recording in a fast path, a printf may be recorded with just
+ * saving the format and the arguments as they were passed to the
+ * function, instead of wasting cycles converting the arguments into
+ * ASCII characters. Instead, the arguments are saved in a 32 bit
+ * word array that is defined by the format string constraints.
+ *
+ * This function will take the format and the binary array and finish
+ * the conversion into the ASCII string within the buffer.
+ *
+ * Returns zero on success, -1 on overflow.
+ */
+int seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary)
+{
+ unsigned int len = seq_buf_buffer_left(s);
+ int ret;
+
+ WARN_ON(s->size == 0);
+
+ if (s->len < s->size) {
+ ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
+ if (s->len + ret < s->size) {
+ s->len += ret;
+ return 0;
+ }
+ }
+ seq_buf_set_overflow(s);
+ return -1;
+}
+
+/**
+ * seq_buf_puts - sequence printing of simple string
+ * @s: seq_buf descriptor
+ * @str: simple string to record
+ *
+ * Copy a simple string into the sequence buffer.
+ *
+ * Returns zero on success, -1 on overflow
+ */
+int seq_buf_puts(struct seq_buf *s, const char *str)
+{
+ unsigned int len = strlen(str);
+
+ WARN_ON(s->size == 0);
+
+ if (s->len + len < s->size) {
+ memcpy(s->buffer + s->len, str, len);
+ s->len += len;
+ return 0;
+ }
+ seq_buf_set_overflow(s);
+ return -1;
+}
+
+/**
+ * seq_buf_putc - sequence printing of simple character
+ * @s: seq_buf descriptor
+ * @c: simple character to record
+ *
+ * Copy a single character into the sequence buffer.
+ *
+ * Returns zero on success, -1 on overflow
+ */
+int seq_buf_putc(struct seq_buf *s, unsigned char c)
+{
+ WARN_ON(s->size == 0);
+
+ if (s->len + 1 < s->size) {
+ s->buffer[s->len++] = c;
+ return 0;
+ }
+ seq_buf_set_overflow(s);
+ return -1;
+}
+
+/**
+ * seq_buf_putmem - write raw data into the sequenc buffer
+ * @s: seq_buf descriptor
+ * @mem: The raw memory to copy into the buffer
+ * @len: The length of the raw memory to copy (in bytes)
+ *
+ * There may be cases where raw memory needs to be written into the
+ * buffer and a strcpy() would not work. Using this function allows
+ * for such cases.
+ *
+ * Returns zero on success, -1 on overflow
+ */
+int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len)
+{
+ WARN_ON(s->size == 0);
+
+ if (s->len + len < s->size) {
+ memcpy(s->buffer + s->len, mem, len);
+ s->len += len;
+ return 0;
+ }
+ seq_buf_set_overflow(s);
+ return -1;
+}
+
+#define MAX_MEMHEX_BYTES 8U
+#define HEX_CHARS (MAX_MEMHEX_BYTES*2 + 1)
+
+/**
+ * seq_buf_putmem_hex - write raw memory into the buffer in ASCII hex
+ * @s: seq_buf descriptor
+ * @mem: The raw memory to write its hex ASCII representation of
+ * @len: The length of the raw memory to copy (in bytes)
+ *
+ * This is similar to seq_buf_putmem() except instead of just copying the
+ * raw memory into the buffer it writes its ASCII representation of it
+ * in hex characters.
+ *
+ * Returns zero on success, -1 on overflow
+ */
+int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
+ unsigned int len)
+{
+ unsigned char hex[HEX_CHARS];
+ const unsigned char *data = mem;
+ unsigned int start_len;
+ int i, j;
+
+ WARN_ON(s->size == 0);
+
+ while (len) {
+ start_len = min(len, HEX_CHARS - 1);
+#ifdef __BIG_ENDIAN
+ for (i = 0, j = 0; i < start_len; i++) {
+#else
+ for (i = start_len-1, j = 0; i >= 0; i--) {
+#endif
+ hex[j++] = hex_asc_hi(data[i]);
+ hex[j++] = hex_asc_lo(data[i]);
+ }
+ if (WARN_ON_ONCE(j == 0 || j/2 > len))
+ break;
+
+ /* j increments twice per loop */
+ len -= j / 2;
+ hex[j++] = ' ';
+
+ seq_buf_putmem(s, hex, j);
+ if (seq_buf_has_overflowed(s))
+ return -1;
+ }
+ return 0;
+}
+
+/**
+ * seq_buf_path - copy a path into the sequence buffer
+ * @s: seq_buf descriptor
+ * @path: path to write into the sequence buffer.
+ *
+ * Write a path name into the sequence buffer.
+ *
+ * Returns zero on success, -1 on overflow
+ */
+int seq_buf_path(struct seq_buf *s, const struct path *path)
+{
+ unsigned int len = seq_buf_buffer_left(s);
+ unsigned char *p;
+
+ WARN_ON(s->size == 0);
+
+ p = d_path(path, s->buffer + s->len, len);
+ if (!IS_ERR(p)) {
+ p = mangle_path(s->buffer + s->len, p, "\n");
+ if (p) {
+ s->len = p - s->buffer;
+ return 0;
+ }
+ }
+ seq_buf_set_overflow(s);
+ return -1;
+}
+
+/**
+ * seq_buf_to_user - copy the squence buffer to user space
+ * @s: seq_buf descriptor
+ * @ubuf: The userspace memory location to copy to
+ * @cnt: The amount to copy
+ *
+ * Copies the sequence buffer into the userspace memory pointed to
+ * by @ubuf. It starts from the last read position (@s->readpos)
+ * and writes up to @cnt characters or till it reaches the end of
+ * the content in the buffer (@s->len), which ever comes first.
+ *
+ * On success, it returns a positive number of the number of bytes
+ * it copied.
+ *
+ * On failure it returns -EBUSY if all of the content in the
+ * sequence has been already read, which includes nothing in the
+ * sequence (@s->len == @s->readpos).
+ *
+ * Returns -EFAULT if the copy to userspace fails.
+ */
+int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, int cnt)
+{
+ int len;
+ int ret;
+
+ if (!cnt)
+ return 0;
+
+ if (s->len <= s->readpos)
+ return -EBUSY;
+
+ len = s->len - s->readpos;
+ if (cnt > len)
+ cnt = len;
+ ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
+ if (ret == cnt)
+ return -EFAULT;
+
+ cnt -= ret;
+
+ s->readpos += cnt;
+ return cnt;
+}
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 3ce3c4ccfc94..7d7a07e9b9e9 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -939,19 +939,20 @@ out:
return ret;
}
+/* TODO add a seq_buf_to_buffer() */
static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
{
int len;
- if (s->len <= s->readpos)
+ if (s->seq.len <= s->seq.readpos)
return -EBUSY;
- len = s->len - s->readpos;
+ len = s->seq.len - s->seq.readpos;
if (cnt > len)
cnt = len;
- memcpy(buf, s->buffer + s->readpos, cnt);
+ memcpy(buf, s->buffer + s->seq.readpos, cnt);
- s->readpos += cnt;
+ s->seq.readpos += cnt;
return cnt;
}
@@ -4315,6 +4316,8 @@ static int tracing_open_pipe(struct inode *inode, struct file *filp)
goto out;
}
+ trace_seq_init(&iter->seq);
+
/*
* We make a copy of the current tracer to avoid concurrent
* changes on it while we are reading.
@@ -4511,18 +4514,18 @@ waitagain:
trace_access_lock(iter->cpu_file);
while (trace_find_next_entry_inc(iter) != NULL) {
enum print_line_t ret;
- int len = iter->seq.len;
+ int len = iter->seq.seq.len;
ret = print_trace_line(iter);
if (ret == TRACE_TYPE_PARTIAL_LINE) {
/* don't print partial lines */
- iter->seq.len = len;
+ iter->seq.seq.len = len;
break;
}
if (ret != TRACE_TYPE_NO_CONSUME)
trace_consume(iter);
- if (iter->seq.len >= cnt)
+ if (iter->seq.seq.len >= cnt)
break;
/*
@@ -4538,7 +4541,7 @@ waitagain:
/* Now copy what we have to the user */
sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
- if (iter->seq.readpos >= iter->seq.len)
+ if (iter->seq.seq.readpos >= iter->seq.seq.len)
trace_seq_init(&iter->seq);
/*
@@ -4576,16 +4579,16 @@ tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
/* Seq buffer is page-sized, exactly what we need. */
for (;;) {
- count = iter->seq.len;
+ count = iter->seq.seq.len;
ret = print_trace_line(iter);
- count = iter->seq.len - count;
+ count = iter->seq.seq.len - count;
if (rem < count) {
rem = 0;
- iter->seq.len -= count;
+ iter->seq.seq.len -= count;
break;
}
if (ret == TRACE_TYPE_PARTIAL_LINE) {
- iter->seq.len -= count;
+ iter->seq.seq.len -= count;
break;
}
@@ -4666,13 +4669,13 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
/* Copy the data into the page, so we can start over. */
ret = trace_seq_to_buffer(&iter->seq,
page_address(spd.pages[i]),
- iter->seq.len);
+ iter->seq.seq.len);
if (ret < 0) {
__free_page(spd.pages[i]);
break;
}
spd.partial[i].offset = 0;
- spd.partial[i].len = iter->seq.len;
+ spd.partial[i].len = iter->seq.seq.len;
trace_seq_init(&iter->seq);
}
@@ -5673,7 +5676,7 @@ tracing_stats_read(struct file *filp, char __user *ubuf,
cnt = ring_buffer_read_events_cpu(trace_buf->buffer, cpu);
trace_seq_printf(s, "read events: %ld\n", cnt);
- count = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->len);
+ count = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->seq.len);
kfree(s);
@@ -6636,11 +6639,11 @@ void
trace_printk_seq(struct trace_seq *s)
{
/* Probably should print a warning here. */
- if (s->len >= TRACE_MAX_PRINT)
- s->len = TRACE_MAX_PRINT;
+ if (s->seq.len >= TRACE_MAX_PRINT)
+ s->seq.len = TRACE_MAX_PRINT;
/* should be zero ended, but we are paranoid. */
- s->buffer[s->len] = 0;
+ s->buffer[s->seq.len] = 0;
printk(KERN_TRACE "%s", s->buffer);
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index f9d0cbe014b7..4d0067dd7f88 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1044,7 +1044,7 @@ event_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
mutex_unlock(&event_mutex);
if (file)
- r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->len);
+ r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->seq.len);
kfree(s);
@@ -1210,7 +1210,7 @@ subsystem_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
trace_seq_init(s);
print_subsystem_event_filter(system, s);
- r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->len);
+ r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->seq.len);
kfree(s);
@@ -1265,7 +1265,7 @@ show_header(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
trace_seq_init(s);
func(s);
- r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->len);
+ r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->seq.len);
kfree(s);
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 100288d10e1f..6d1342ae7a44 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -1154,9 +1154,9 @@ print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
}
/* Strip ending newline */
- if (s->buffer[s->len - 1] == '\n') {
- s->buffer[s->len - 1] = '\0';
- s->len--;
+ if (s->buffer[s->seq.len - 1] == '\n') {
+ s->buffer[s->seq.len - 1] = '\0';
+ s->seq.len--;
}
trace_seq_puts(s, " */\n");
diff --git a/kernel/trace/trace_seq.c b/kernel/trace/trace_seq.c
index fabfa0f190a3..8c0c54fe674b 100644
--- a/kernel/trace/trace_seq.c
+++ b/kernel/trace/trace_seq.c
@@ -27,10 +27,19 @@
#include <linux/trace_seq.h>
/* How much buffer is left on the trace_seq? */
-#define TRACE_SEQ_BUF_LEFT(s) ((PAGE_SIZE - 1) - (s)->len)
+#define TRACE_SEQ_BUF_LEFT(s) seq_buf_buffer_left(&(s)->seq)
/* How much buffer is written? */
-#define TRACE_SEQ_BUF_USED(s) min((s)->len, (unsigned int)(PAGE_SIZE - 1))
+#define TRACE_SEQ_BUF_USED(s) min((s)->seq.len, (unsigned int)(PAGE_SIZE - 1))
+
+/*
+ * trace_seq should work with being initialized with 0s.
+ */
+static inline void __trace_seq_init(struct trace_seq *s)
+{
+ if (unlikely(!s->seq.size))
+ trace_seq_init(s);
+}
/**
* trace_print_seq - move the contents of trace_seq into a seq_file
@@ -43,10 +52,11 @@
*/
int trace_print_seq(struct seq_file *m, struct trace_seq *s)
{
- unsigned int len = TRACE_SEQ_BUF_USED(s);
int ret;
- ret = seq_write(m, s->buffer, len);
+ __trace_seq_init(s);
+
+ ret = seq_buf_print_seq(m, &s->seq);
/*
* Only reset this buffer if we successfully wrote to the
@@ -72,24 +82,23 @@ int trace_print_seq(struct seq_file *m, struct trace_seq *s)
*/
void trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
{
- unsigned int len = TRACE_SEQ_BUF_LEFT(s);
+ unsigned int save_len = s->seq.len;
va_list ap;
- int ret;
- if (s->full || !len)
+ if (s->full)
return;
+ __trace_seq_init(s);
+
va_start(ap, fmt);
- ret = vsnprintf(s->buffer + s->len, len, fmt, ap);
+ seq_buf_vprintf(&s->seq, fmt, ap);
va_end(ap);
/* If we can't write it all, don't bother writing anything */
- if (ret >= len) {
+ if (unlikely(seq_buf_has_overflowed(&s->seq))) {
+ s->seq.len = save_len;
s->full = 1;
- return;
}
-
- s->len += ret;
}
EXPORT_SYMBOL_GPL(trace_seq_printf);
@@ -104,14 +113,19 @@ EXPORT_SYMBOL_GPL(trace_seq_printf);
void trace_seq_bitmask(struct trace_seq *s, const unsigned long *maskp,
int nmaskbits)
{
- unsigned int len = TRACE_SEQ_BUF_LEFT(s);
- int ret;
+ unsigned int save_len = s->seq.len;
- if (s->full || !len)
+ if (s->full)
return;
- ret = bitmap_scnprintf(s->buffer + s->len, len, maskp, nmaskbits);
- s->len += ret;
+ __trace_seq_init(s);
+
+ seq_buf_bitmask(&s->seq, maskp, nmaskbits);
+
+ if (unlikely(seq_buf_has_overflowed(&s->seq))) {
+ s->seq.len = save_len;
+ s->full = 1;
+ }
}
EXPORT_SYMBOL_GPL(trace_seq_bitmask);
@@ -128,21 +142,20 @@ EXPORT_SYMBOL_GPL(trace_seq_bitmask);
*/
void trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args)
{
- unsigned int len = TRACE_SEQ_BUF_LEFT(s);
- int ret;
+ unsigned int save_len = s->seq.len;
- if (s->full || !len)
+ if (s->full)
return;
- ret = vsnprintf(s->buffer + s->len, len, fmt, args);
+ __trace_seq_init(s);
+
+ seq_buf_vprintf(&s->seq, fmt, args);
/* If we can't write it all, don't bother writing anything */
- if (ret >= len) {
+ if (unlikely(seq_buf_has_overflowed(&s->seq))) {
+ s->seq.len = save_len;
s->full = 1;
- return;
}
-
- s->len += ret;
}
EXPORT_SYMBOL_GPL(trace_seq_vprintf);
@@ -163,21 +176,21 @@ EXPORT_SYMBOL_GPL(trace_seq_vprintf);
*/
void trace_seq_bprintf(struct trace_seq *s, const char *fmt, const u32 *binary)
{
- unsigned int len = TRACE_SEQ_BUF_LEFT(s);
- int ret;
+ unsigned int save_len = s->seq.len;
- if (s->full || !len)
+ if (s->full)
return;
- ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
+ __trace_seq_init(s);
+
+ seq_buf_bprintf(&s->seq, fmt, binary);
/* If we can't write it all, don't bother writing anything */
- if (ret >= len) {
+ if (unlikely(seq_buf_has_overflowed(&s->seq))) {
+ s->seq.len = save_len;
s->full = 1;
return;
}
-
- s->len += ret;
}
EXPORT_SYMBOL_GPL(trace_seq_bprintf);
@@ -198,13 +211,14 @@ void trace_seq_puts(struct trace_seq *s, const char *str)
if (s->full)
return;
+ __trace_seq_init(s);
+
if (len > TRACE_SEQ_BUF_LEFT(s)) {
s->full = 1;
return;
}
- memcpy(s->buffer + s->len, str, len);
- s->len += len;
+ seq_buf_putmem(&s->seq, str, len);
}
EXPORT_SYMBOL_GPL(trace_seq_puts);
@@ -223,12 +237,14 @@ void trace_seq_putc(struct trace_seq *s, unsigned char c)
if (s->full)
return;
+ __trace_seq_init(s);
+
if (TRACE_SEQ_BUF_LEFT(s) < 1) {
s->full = 1;
return;
}
- s->buffer[s->len++] = c;
+ seq_buf_putc(&s->seq, c);
}
EXPORT_SYMBOL_GPL(trace_seq_putc);
@@ -247,19 +263,17 @@ void trace_seq_putmem(struct trace_seq *s, const void *mem, unsigned int len)
if (s->full)
return;
+ __trace_seq_init(s);
+
if (len > TRACE_SEQ_BUF_LEFT(s)) {
s->full = 1;
return;
}
- memcpy(s->buffer + s->len, mem, len);
- s->len += len;
+ seq_buf_putmem(&s->seq, mem, len);
}
EXPORT_SYMBOL_GPL(trace_seq_putmem);
-#define MAX_MEMHEX_BYTES 8U
-#define HEX_CHARS (MAX_MEMHEX_BYTES*2 + 1)
-
/**
* trace_seq_putmem_hex - write raw memory into the buffer in ASCII hex
* @s: trace sequence descriptor
@@ -273,32 +287,26 @@ EXPORT_SYMBOL_GPL(trace_seq_putmem);
void trace_seq_putmem_hex(struct trace_seq *s, const void *mem,
unsigned int len)
{
- unsigned char hex[HEX_CHARS];
- const unsigned char *data = mem;
- unsigned int start_len;
- int i, j;
+ unsigned int save_len = s->seq.len;
if (s->full)
return;
- while (len) {
- start_len = min(len, HEX_CHARS - 1);
-#ifdef __BIG_ENDIAN
- for (i = 0, j = 0; i < start_len; i++) {
-#else
- for (i = start_len-1, j = 0; i >= 0; i--) {
-#endif
- hex[j++] = hex_asc_hi(data[i]);
- hex[j++] = hex_asc_lo(data[i]);
- }
- if (WARN_ON_ONCE(j == 0 || j/2 > len))
- break;
-
- /* j increments twice per loop */
- len -= j / 2;
- hex[j++] = ' ';
-
- trace_seq_putmem(s, hex, j);
+ __trace_seq_init(s);
+
+ /* Each byte is represented by two chars */
+ if (len * 2 > TRACE_SEQ_BUF_LEFT(s)) {
+ s->full = 1;
+ return;
+ }
+
+ /* The added spaces can still cause an overflow */
+ seq_buf_putmem_hex(&s->seq, mem, len);
+
+ if (unlikely(seq_buf_has_overflowed(&s->seq))) {
+ s->seq.len = save_len;
+ s->full = 1;
+ return;
}
}
EXPORT_SYMBOL_GPL(trace_seq_putmem_hex);
@@ -317,30 +325,28 @@ EXPORT_SYMBOL_GPL(trace_seq_putmem_hex);
*/
int trace_seq_path(struct trace_seq *s, const struct path *path)
{
- unsigned char *p;
+ unsigned int save_len = s->seq.len;
+ int ret;
if (s->full)
return 0;
+ __trace_seq_init(s);
+
if (TRACE_SEQ_BUF_LEFT(s) < 1) {
s->full = 1;
return 0;
}
- p = d_path(path, s->buffer + s->len, PAGE_SIZE - s->len);
- if (!IS_ERR(p)) {
- p = mangle_path(s->buffer + s->len, p, "\n");
- if (p) {
- s->len = p - s->buffer;
- return 1;
- }
- } else {
- s->buffer[s->len++] = '?';
- return 1;
+ ret = seq_buf_path(&s->seq, path);
+
+ if (unlikely(seq_buf_has_overflowed(&s->seq))) {
+ s->seq.len = save_len;
+ s->full = 1;
+ return 0;
}
- s->full = 1;
- return 0;
+ return ret;
}
EXPORT_SYMBOL_GPL(trace_seq_path);
@@ -366,25 +372,7 @@ EXPORT_SYMBOL_GPL(trace_seq_path);
*/
int trace_seq_to_user(struct trace_seq *s, char __user *ubuf, int cnt)
{
- int len;
- int ret;
-
- if (!cnt)
- return 0;
-
- if (s->len <= s->readpos)
- return -EBUSY;
-
- len = s->len - s->readpos;
- if (cnt > len)
- cnt = len;
- ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
- if (ret == cnt)
- return -EFAULT;
-
- cnt -= ret;
-
- s->readpos += cnt;
- return cnt;
+ __trace_seq_init(s);
+ return seq_buf_to_user(&s->seq, ubuf, cnt);
}
EXPORT_SYMBOL_GPL(trace_seq_to_user);
--
2.1.1
^ permalink raw reply related [flat|nested] 16+ messages in thread
* [for-next][PATCH 02/15] tracing: Convert seq_buf_path() to be like seq_path()
2014-11-20 15:21 [for-next][PATCH 00/15] tracing/seq-buf/printk: New seq-buf utility from trace_seq for printk in NMI Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 01/15] tracing: Create seq_buf layer in trace_seq Steven Rostedt
@ 2014-11-20 15:21 ` Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 03/15] tracing: Convert seq_buf fields to be like seq_file fields Steven Rostedt
` (12 subsequent siblings)
14 siblings, 0 replies; 16+ messages in thread
From: Steven Rostedt @ 2014-11-20 15:21 UTC (permalink / raw)
To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek
[-- Attachment #1: 0002-tracing-Convert-seq_buf_path-to-be-like-seq_path.patch --]
[-- Type: text/plain, Size: 3639 bytes --]
From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
Rewrite seq_buf_path() like it is done in seq_path() and allow
it to accept any escape character instead of just "\n".
Making seq_buf_path() like seq_path() will help prevent problems
when converting seq_file to use the seq_buf logic.
Link: http://lkml.kernel.org/r/20141104160222.048795666@goodmis.org
Link: http://lkml.kernel.org/r/20141114011412.338523371@goodmis.org
Tested-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
include/linux/seq_buf.h | 2 +-
kernel/trace/seq_buf.c | 28 ++++++++++++++++------------
kernel/trace/trace_seq.c | 5 ++---
3 files changed, 19 insertions(+), 16 deletions(-)
diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h
index 4f7a96a9d71a..38770688a627 100644
--- a/include/linux/seq_buf.h
+++ b/include/linux/seq_buf.h
@@ -73,7 +73,7 @@ extern int seq_buf_putc(struct seq_buf *s, unsigned char c);
extern int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len);
extern int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
unsigned int len);
-extern int seq_buf_path(struct seq_buf *s, const struct path *path);
+extern int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc);
extern int seq_buf_bitmask(struct seq_buf *s, const unsigned long *maskp,
int nmaskbits);
diff --git a/kernel/trace/seq_buf.c b/kernel/trace/seq_buf.c
index e9a7861595d2..7dac34d1235b 100644
--- a/kernel/trace/seq_buf.c
+++ b/kernel/trace/seq_buf.c
@@ -272,28 +272,32 @@ int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
* seq_buf_path - copy a path into the sequence buffer
* @s: seq_buf descriptor
* @path: path to write into the sequence buffer.
+ * @esc: set of characters to escape in the output
*
* Write a path name into the sequence buffer.
*
- * Returns zero on success, -1 on overflow
+ * Returns the number of written bytes on success, -1 on overflow
*/
-int seq_buf_path(struct seq_buf *s, const struct path *path)
+int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc)
{
- unsigned int len = seq_buf_buffer_left(s);
- unsigned char *p;
+ char *buf = s->buffer + s->len;
+ size_t size = seq_buf_buffer_left(s);
+ int res = -1;
WARN_ON(s->size == 0);
- p = d_path(path, s->buffer + s->len, len);
- if (!IS_ERR(p)) {
- p = mangle_path(s->buffer + s->len, p, "\n");
- if (p) {
- s->len = p - s->buffer;
- return 0;
+ if (size) {
+ char *p = d_path(path, buf, size);
+ if (!IS_ERR(p)) {
+ char *end = mangle_path(buf, p, esc);
+ if (end)
+ res = end - buf;
}
}
- seq_buf_set_overflow(s);
- return -1;
+ if (res > 0)
+ s->len += res;
+
+ return res;
}
/**
diff --git a/kernel/trace/trace_seq.c b/kernel/trace/trace_seq.c
index 8c0c54fe674b..74cacc930c24 100644
--- a/kernel/trace/trace_seq.c
+++ b/kernel/trace/trace_seq.c
@@ -326,7 +326,6 @@ EXPORT_SYMBOL_GPL(trace_seq_putmem_hex);
int trace_seq_path(struct trace_seq *s, const struct path *path)
{
unsigned int save_len = s->seq.len;
- int ret;
if (s->full)
return 0;
@@ -338,7 +337,7 @@ int trace_seq_path(struct trace_seq *s, const struct path *path)
return 0;
}
- ret = seq_buf_path(&s->seq, path);
+ seq_buf_path(&s->seq, path, "\n");
if (unlikely(seq_buf_has_overflowed(&s->seq))) {
s->seq.len = save_len;
@@ -346,7 +345,7 @@ int trace_seq_path(struct trace_seq *s, const struct path *path)
return 0;
}
- return ret;
+ return 1;
}
EXPORT_SYMBOL_GPL(trace_seq_path);
--
2.1.1
^ permalink raw reply related [flat|nested] 16+ messages in thread
* [for-next][PATCH 03/15] tracing: Convert seq_buf fields to be like seq_file fields
2014-11-20 15:21 [for-next][PATCH 00/15] tracing/seq-buf/printk: New seq-buf utility from trace_seq for printk in NMI Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 01/15] tracing: Create seq_buf layer in trace_seq Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 02/15] tracing: Convert seq_buf_path() to be like seq_path() Steven Rostedt
@ 2014-11-20 15:21 ` Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 04/15] tracing: Add a seq_buf_clear() helper and clear len and readpos in init Steven Rostedt
` (11 subsequent siblings)
14 siblings, 0 replies; 16+ messages in thread
From: Steven Rostedt @ 2014-11-20 15:21 UTC (permalink / raw)
To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek
[-- Attachment #1: 0003-tracing-Convert-seq_buf-fields-to-be-like-seq_file-f.patch --]
[-- Type: text/plain, Size: 975 bytes --]
From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
In facilitating the conversion of seq_file to use seq_buf,
have the seq_buf fields match the types used by seq_file.
Link: http://lkml.kernel.org/r/20141104160222.195301024@goodmis.org
Tested-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
include/linux/seq_buf.h | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h
index 38770688a627..d14dc9023dde 100644
--- a/include/linux/seq_buf.h
+++ b/include/linux/seq_buf.h
@@ -16,10 +16,10 @@
* @readpos: The next position to read in the buffer.
*/
struct seq_buf {
- unsigned char *buffer;
- unsigned int size;
- unsigned int len;
- unsigned int readpos;
+ char *buffer;
+ size_t size;
+ size_t len;
+ loff_t readpos;
};
static inline void
--
2.1.1
^ permalink raw reply related [flat|nested] 16+ messages in thread
* [for-next][PATCH 04/15] tracing: Add a seq_buf_clear() helper and clear len and readpos in init
2014-11-20 15:21 [for-next][PATCH 00/15] tracing/seq-buf/printk: New seq-buf utility from trace_seq for printk in NMI Steven Rostedt
` (2 preceding siblings ...)
2014-11-20 15:21 ` [for-next][PATCH 03/15] tracing: Convert seq_buf fields to be like seq_file fields Steven Rostedt
@ 2014-11-20 15:21 ` Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 05/15] seq_buf: Create seq_buf_used() to find out how much was written Steven Rostedt
` (10 subsequent siblings)
14 siblings, 0 replies; 16+ messages in thread
From: Steven Rostedt @ 2014-11-20 15:21 UTC (permalink / raw)
To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek
[-- Attachment #1: 0004-tracing-Add-a-seq_buf_clear-helper-and-clear-len-and.patch --]
[-- Type: text/plain, Size: 1114 bytes --]
From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
Add a helper function seq_buf_clear() that resets the len and readpos
fields of a seq_buf. Currently it is only used in the seq_buf_init()
but will be used later when updating the seq_file code.
Link: http://lkml.kernel.org/r/20141104160222.352309995@goodmis.org
Tested-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
include/linux/seq_buf.h | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h
index d14dc9023dde..5d91262433e2 100644
--- a/include/linux/seq_buf.h
+++ b/include/linux/seq_buf.h
@@ -22,13 +22,18 @@ struct seq_buf {
loff_t readpos;
};
+static inline void seq_buf_clear(struct seq_buf *s)
+{
+ s->len = 0;
+ s->readpos = 0;
+}
+
static inline void
seq_buf_init(struct seq_buf *s, unsigned char *buf, unsigned int size)
{
s->buffer = buf;
s->size = size;
- s->len = 0;
- s->readpos = 0;
+ seq_buf_clear(s);
}
/*
--
2.1.1
^ permalink raw reply related [flat|nested] 16+ messages in thread
* [for-next][PATCH 05/15] seq_buf: Create seq_buf_used() to find out how much was written
2014-11-20 15:21 [for-next][PATCH 00/15] tracing/seq-buf/printk: New seq-buf utility from trace_seq for printk in NMI Steven Rostedt
` (3 preceding siblings ...)
2014-11-20 15:21 ` [for-next][PATCH 04/15] tracing: Add a seq_buf_clear() helper and clear len and readpos in init Steven Rostedt
@ 2014-11-20 15:21 ` Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 06/15] tracing: Clean up tracing_fill_pipe_page() Steven Rostedt
` (9 subsequent siblings)
14 siblings, 0 replies; 16+ messages in thread
From: Steven Rostedt @ 2014-11-20 15:21 UTC (permalink / raw)
To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek
[-- Attachment #1: 0005-seq_buf-Create-seq_buf_used-to-find-out-how-much-was.patch --]
[-- Type: text/plain, Size: 1755 bytes --]
From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
Add a helper function seq_buf_used() that replaces the SEQ_BUF_USED()
private macro to let callers have a method to know how much of the
seq_buf was written to.
Link: http://lkml.kernel.org/r/20141114011412.170377300@goodmis.org
Link: http://lkml.kernel.org/r/20141114011413.321654244@goodmis.org
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
include/linux/seq_buf.h | 6 ++++++
kernel/trace/seq_buf.c | 5 +----
2 files changed, 7 insertions(+), 4 deletions(-)
diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h
index 5d91262433e2..93718e570d4c 100644
--- a/include/linux/seq_buf.h
+++ b/include/linux/seq_buf.h
@@ -64,6 +64,12 @@ seq_buf_buffer_left(struct seq_buf *s)
return (s->size - 1) - s->len;
}
+/* How much buffer was written? */
+static inline unsigned int seq_buf_used(struct seq_buf *s)
+{
+ return min(s->len, s->size);
+}
+
extern __printf(2, 3)
int seq_buf_printf(struct seq_buf *s, const char *fmt, ...);
extern __printf(2, 0)
diff --git a/kernel/trace/seq_buf.c b/kernel/trace/seq_buf.c
index 7dac34d1235b..9ec5305d9da7 100644
--- a/kernel/trace/seq_buf.c
+++ b/kernel/trace/seq_buf.c
@@ -16,9 +16,6 @@
#include <linux/seq_file.h>
#include <linux/seq_buf.h>
-/* How much buffer is written? */
-#define SEQ_BUF_USED(s) min((s)->len, (s)->size - 1)
-
/**
* seq_buf_print_seq - move the contents of seq_buf into a seq_file
* @m: the seq_file descriptor that is the destination
@@ -28,7 +25,7 @@
*/
int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s)
{
- unsigned int len = SEQ_BUF_USED(s);
+ unsigned int len = seq_buf_used(s);
return seq_write(m, s->buffer, len);
}
--
2.1.1
^ permalink raw reply related [flat|nested] 16+ messages in thread
* [for-next][PATCH 06/15] tracing: Clean up tracing_fill_pipe_page()
2014-11-20 15:21 [for-next][PATCH 00/15] tracing/seq-buf/printk: New seq-buf utility from trace_seq for printk in NMI Steven Rostedt
` (4 preceding siblings ...)
2014-11-20 15:21 ` [for-next][PATCH 05/15] seq_buf: Create seq_buf_used() to find out how much was written Steven Rostedt
@ 2014-11-20 15:21 ` Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 07/15] tracing: Use trace_seq_used() and seq_buf_used() instead of len Steven Rostedt
` (8 subsequent siblings)
14 siblings, 0 replies; 16+ messages in thread
From: Steven Rostedt @ 2014-11-20 15:21 UTC (permalink / raw)
To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek
[-- Attachment #1: 0006-tracing-Clean-up-tracing_fill_pipe_page.patch --]
[-- Type: text/plain, Size: 1956 bytes --]
From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
The function tracing_fill_pipe_page() logic is a little confusing with the
use of count saving the seq.len and reusing it.
Instead of subtracting a number that is calculated from the saved
value of the seq.len from seq.len, just save the seq.len at the start
and if we need to reset it, just assign it again.
When the seq_buf overflow is len == size + 1, the current logic will
break. Changing it to use a saved length for resetting back to the
original value is more robust and will work when we change the way
seq_buf sets the overflow.
Link: http://lkml.kernel.org/r/20141118161546.GJ23958@pathway.suse.cz
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/trace.c | 25 +++++++++++++++++++------
1 file changed, 19 insertions(+), 6 deletions(-)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 7d7a07e9b9e9..0aa75be843a0 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4575,20 +4575,33 @@ static size_t
tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
{
size_t count;
+ int save_len;
int ret;
/* Seq buffer is page-sized, exactly what we need. */
for (;;) {
- count = iter->seq.seq.len;
+ save_len = iter->seq.seq.len;
ret = print_trace_line(iter);
- count = iter->seq.seq.len - count;
- if (rem < count) {
- rem = 0;
- iter->seq.seq.len -= count;
+
+ if (trace_seq_has_overflowed(&iter->seq)) {
+ iter->seq.seq.len = save_len;
break;
}
+
+ /*
+ * This should not be hit, because it should only
+ * be set if the iter->seq overflowed. But check it
+ * anyway to be safe.
+ */
if (ret == TRACE_TYPE_PARTIAL_LINE) {
- iter->seq.seq.len -= count;
+ iter->seq.seq.len = save_len;
+ break;
+ }
+
+ count = iter->seq.seq.len - save_len;
+ if (rem < count) {
+ rem = 0;
+ iter->seq.seq.len = save_len;
break;
}
--
2.1.1
^ permalink raw reply related [flat|nested] 16+ messages in thread
* [for-next][PATCH 07/15] tracing: Use trace_seq_used() and seq_buf_used() instead of len
2014-11-20 15:21 [for-next][PATCH 00/15] tracing/seq-buf/printk: New seq-buf utility from trace_seq for printk in NMI Steven Rostedt
` (5 preceding siblings ...)
2014-11-20 15:21 ` [for-next][PATCH 06/15] tracing: Clean up tracing_fill_pipe_page() Steven Rostedt
@ 2014-11-20 15:21 ` Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 08/15] tracing: Add paranoid size check in trace_printk_seq() Steven Rostedt
` (7 subsequent siblings)
14 siblings, 0 replies; 16+ messages in thread
From: Steven Rostedt @ 2014-11-20 15:21 UTC (permalink / raw)
To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek
[-- Attachment #1: 0007-tracing-Use-trace_seq_used-and-seq_buf_used-instead-.patch --]
[-- Type: text/plain, Size: 7209 bytes --]
From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
As the seq_buf->len will soon be +1 size when there's an overflow, we
must use trace_seq_used() or seq_buf_used() methods to get the real
length. This will prevent buffer overflow issues if just the len
of the seq_buf descriptor is used to copy memory.
Link: http://lkml.kernel.org/r/20141114121911.09ba3d38@gandalf.local.home
Reported-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
include/linux/trace_seq.h | 20 +++++++++++++++++++-
kernel/trace/seq_buf.c | 2 +-
kernel/trace/trace.c | 21 +++++++++++----------
kernel/trace/trace_events.c | 9 ++++++---
kernel/trace/trace_functions_graph.c | 5 ++++-
kernel/trace/trace_seq.c | 2 +-
6 files changed, 42 insertions(+), 17 deletions(-)
diff --git a/include/linux/trace_seq.h b/include/linux/trace_seq.h
index 85d37106be3d..cfaf5a1d4bad 100644
--- a/include/linux/trace_seq.h
+++ b/include/linux/trace_seq.h
@@ -24,6 +24,24 @@ trace_seq_init(struct trace_seq *s)
}
/**
+ * trace_seq_used - amount of actual data written to buffer
+ * @s: trace sequence descriptor
+ *
+ * Returns the amount of data written to the buffer.
+ *
+ * IMPORTANT!
+ *
+ * Use this instead of @s->seq.len if you need to pass the amount
+ * of data from the buffer to another buffer (userspace, or what not).
+ * The @s->seq.len on overflow is bigger than the buffer size and
+ * using it can cause access to undefined memory.
+ */
+static inline int trace_seq_used(struct trace_seq *s)
+{
+ return seq_buf_used(&s->seq);
+}
+
+/**
* trace_seq_buffer_ptr - return pointer to next location in buffer
* @s: trace sequence descriptor
*
@@ -35,7 +53,7 @@ trace_seq_init(struct trace_seq *s)
static inline unsigned char *
trace_seq_buffer_ptr(struct trace_seq *s)
{
- return s->buffer + s->seq.len;
+ return s->buffer + seq_buf_used(&s->seq);
}
/**
diff --git a/kernel/trace/seq_buf.c b/kernel/trace/seq_buf.c
index 9ec5305d9da7..ce17f65268ed 100644
--- a/kernel/trace/seq_buf.c
+++ b/kernel/trace/seq_buf.c
@@ -328,7 +328,7 @@ int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, int cnt)
if (s->len <= s->readpos)
return -EBUSY;
- len = s->len - s->readpos;
+ len = seq_buf_used(s) - s->readpos;
if (cnt > len)
cnt = len;
ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 0aa75be843a0..9023446b2c2b 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -944,10 +944,10 @@ static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
{
int len;
- if (s->seq.len <= s->seq.readpos)
+ if (trace_seq_used(s) <= s->seq.readpos)
return -EBUSY;
- len = s->seq.len - s->seq.readpos;
+ len = trace_seq_used(s) - s->seq.readpos;
if (cnt > len)
cnt = len;
memcpy(buf, s->buffer + s->seq.readpos, cnt);
@@ -4514,18 +4514,18 @@ waitagain:
trace_access_lock(iter->cpu_file);
while (trace_find_next_entry_inc(iter) != NULL) {
enum print_line_t ret;
- int len = iter->seq.seq.len;
+ int save_len = iter->seq.seq.len;
ret = print_trace_line(iter);
if (ret == TRACE_TYPE_PARTIAL_LINE) {
/* don't print partial lines */
- iter->seq.seq.len = len;
+ iter->seq.seq.len = save_len;
break;
}
if (ret != TRACE_TYPE_NO_CONSUME)
trace_consume(iter);
- if (iter->seq.seq.len >= cnt)
+ if (trace_seq_used(&iter->seq) >= cnt)
break;
/*
@@ -4541,7 +4541,7 @@ waitagain:
/* Now copy what we have to the user */
sret = trace_seq_to_user(&iter->seq, ubuf, cnt);
- if (iter->seq.seq.readpos >= iter->seq.seq.len)
+ if (iter->seq.seq.readpos >= trace_seq_used(&iter->seq))
trace_seq_init(&iter->seq);
/*
@@ -4598,7 +4598,7 @@ tracing_fill_pipe_page(size_t rem, struct trace_iterator *iter)
break;
}
- count = iter->seq.seq.len - save_len;
+ count = trace_seq_used(&iter->seq) - save_len;
if (rem < count) {
rem = 0;
iter->seq.seq.len = save_len;
@@ -4682,13 +4682,13 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
/* Copy the data into the page, so we can start over. */
ret = trace_seq_to_buffer(&iter->seq,
page_address(spd.pages[i]),
- iter->seq.seq.len);
+ trace_seq_used(&iter->seq));
if (ret < 0) {
__free_page(spd.pages[i]);
break;
}
spd.partial[i].offset = 0;
- spd.partial[i].len = iter->seq.seq.len;
+ spd.partial[i].len = trace_seq_used(&iter->seq);
trace_seq_init(&iter->seq);
}
@@ -5689,7 +5689,8 @@ tracing_stats_read(struct file *filp, char __user *ubuf,
cnt = ring_buffer_read_events_cpu(trace_buf->buffer, cpu);
trace_seq_printf(s, "read events: %ld\n", cnt);
- count = simple_read_from_buffer(ubuf, count, ppos, s->buffer, s->seq.len);
+ count = simple_read_from_buffer(ubuf, count, ppos,
+ s->buffer, trace_seq_used(s));
kfree(s);
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 4d0067dd7f88..935cbea78532 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1044,7 +1044,8 @@ event_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
mutex_unlock(&event_mutex);
if (file)
- r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->seq.len);
+ r = simple_read_from_buffer(ubuf, cnt, ppos,
+ s->buffer, trace_seq_used(s));
kfree(s);
@@ -1210,7 +1211,8 @@ subsystem_filter_read(struct file *filp, char __user *ubuf, size_t cnt,
trace_seq_init(s);
print_subsystem_event_filter(system, s);
- r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->seq.len);
+ r = simple_read_from_buffer(ubuf, cnt, ppos,
+ s->buffer, trace_seq_used(s));
kfree(s);
@@ -1265,7 +1267,8 @@ show_header(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
trace_seq_init(s);
func(s);
- r = simple_read_from_buffer(ubuf, cnt, ppos, s->buffer, s->seq.len);
+ r = simple_read_from_buffer(ubuf, cnt, ppos,
+ s->buffer, trace_seq_used(s));
kfree(s);
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 6d1342ae7a44..ec35468349a7 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -1153,6 +1153,9 @@ print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
return ret;
}
+ if (trace_seq_has_overflowed(s))
+ goto out;
+
/* Strip ending newline */
if (s->buffer[s->seq.len - 1] == '\n') {
s->buffer[s->seq.len - 1] = '\0';
@@ -1160,7 +1163,7 @@ print_graph_comment(struct trace_seq *s, struct trace_entry *ent,
}
trace_seq_puts(s, " */\n");
-
+ out:
return trace_handle_return(s);
}
diff --git a/kernel/trace/trace_seq.c b/kernel/trace/trace_seq.c
index 74cacc930c24..f8b45d8792f9 100644
--- a/kernel/trace/trace_seq.c
+++ b/kernel/trace/trace_seq.c
@@ -30,7 +30,7 @@
#define TRACE_SEQ_BUF_LEFT(s) seq_buf_buffer_left(&(s)->seq)
/* How much buffer is written? */
-#define TRACE_SEQ_BUF_USED(s) min((s)->seq.len, (unsigned int)(PAGE_SIZE - 1))
+#define TRACE_SEQ_BUF_USED(s) seq_buf_used(&(s)->seq)
/*
* trace_seq should work with being initialized with 0s.
--
2.1.1
^ permalink raw reply related [flat|nested] 16+ messages in thread
* [for-next][PATCH 08/15] tracing: Add paranoid size check in trace_printk_seq()
2014-11-20 15:21 [for-next][PATCH 00/15] tracing/seq-buf/printk: New seq-buf utility from trace_seq for printk in NMI Steven Rostedt
` (6 preceding siblings ...)
2014-11-20 15:21 ` [for-next][PATCH 07/15] tracing: Use trace_seq_used() and seq_buf_used() instead of len Steven Rostedt
@ 2014-11-20 15:21 ` Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 09/15] seq_buf: Add seq_buf_can_fit() helper function Steven Rostedt
` (6 subsequent siblings)
14 siblings, 0 replies; 16+ messages in thread
From: Steven Rostedt @ 2014-11-20 15:21 UTC (permalink / raw)
To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek
[-- Attachment #1: 0008-tracing-Add-paranoid-size-check-in-trace_printk_seq.patch --]
[-- Type: text/plain, Size: 1083 bytes --]
From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
To be really paranoid about writing out of bound data in
trace_printk_seq(), add another check of len compared to size.
Link: http://lkml.kernel.org/r/20141119144004.GB2332@dhcp128.suse.cz
Suggested-by: Petr Mladek <pmladek@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/trace.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 9023446b2c2b..26facec4625e 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -6656,6 +6656,14 @@ trace_printk_seq(struct trace_seq *s)
if (s->seq.len >= TRACE_MAX_PRINT)
s->seq.len = TRACE_MAX_PRINT;
+ /*
+ * More paranoid code. Although the buffer size is set to
+ * PAGE_SIZE, and TRACE_MAX_PRINT is 1000, this is just
+ * an extra layer of protection.
+ */
+ if (WARN_ON_ONCE(s->seq.len >= s->seq.size))
+ s->seq.len = s->seq.size - 1;
+
/* should be zero ended, but we are paranoid. */
s->buffer[s->seq.len] = 0;
--
2.1.1
^ permalink raw reply related [flat|nested] 16+ messages in thread
* [for-next][PATCH 09/15] seq_buf: Add seq_buf_can_fit() helper function
2014-11-20 15:21 [for-next][PATCH 00/15] tracing/seq-buf/printk: New seq-buf utility from trace_seq for printk in NMI Steven Rostedt
` (7 preceding siblings ...)
2014-11-20 15:21 ` [for-next][PATCH 08/15] tracing: Add paranoid size check in trace_printk_seq() Steven Rostedt
@ 2014-11-20 15:21 ` Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 10/15] tracing: Have seq_buf use full buffer Steven Rostedt
` (5 subsequent siblings)
14 siblings, 0 replies; 16+ messages in thread
From: Steven Rostedt @ 2014-11-20 15:21 UTC (permalink / raw)
To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek
[-- Attachment #1: 0009-seq_buf-Add-seq_buf_can_fit-helper-function.patch --]
[-- Type: text/plain, Size: 2576 bytes --]
From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
Add a seq_buf_can_fit() helper function that removes the possible mistakes
of comparing the seq_buf length plus added data compared to the size of
the buffer.
Link: http://lkml.kernel.org/r/20141118164025.GL23958@pathway.suse.cz
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/seq_buf.c | 23 ++++++++++++++++++-----
1 file changed, 18 insertions(+), 5 deletions(-)
diff --git a/kernel/trace/seq_buf.c b/kernel/trace/seq_buf.c
index ce17f65268ed..6fc9d021cbef 100644
--- a/kernel/trace/seq_buf.c
+++ b/kernel/trace/seq_buf.c
@@ -17,6 +17,19 @@
#include <linux/seq_buf.h>
/**
+ * seq_buf_can_fit - can the new data fit in the current buffer?
+ * @s: the seq_buf descriptor
+ * @len: The length to see if it can fit in the current buffer
+ *
+ * Returns true if there's enough unused space in the seq_buf buffer
+ * to fit the amount of new data according to @len.
+ */
+static bool seq_buf_can_fit(struct seq_buf *s, size_t len)
+{
+ return s->len + len < s->size;
+}
+
+/**
* seq_buf_print_seq - move the contents of seq_buf into a seq_file
* @m: the seq_file descriptor that is the destination
* @s: the seq_buf descriptor that is the source.
@@ -48,7 +61,7 @@ int seq_buf_vprintf(struct seq_buf *s, const char *fmt, va_list args)
if (s->len < s->size) {
len = vsnprintf(s->buffer + s->len, s->size - s->len, fmt, args);
- if (s->len + len < s->size) {
+ if (seq_buf_can_fit(s, len)) {
s->len += len;
return 0;
}
@@ -137,7 +150,7 @@ int seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary)
if (s->len < s->size) {
ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
- if (s->len + ret < s->size) {
+ if (seq_buf_can_fit(s, ret)) {
s->len += ret;
return 0;
}
@@ -161,7 +174,7 @@ int seq_buf_puts(struct seq_buf *s, const char *str)
WARN_ON(s->size == 0);
- if (s->len + len < s->size) {
+ if (seq_buf_can_fit(s, len)) {
memcpy(s->buffer + s->len, str, len);
s->len += len;
return 0;
@@ -183,7 +196,7 @@ int seq_buf_putc(struct seq_buf *s, unsigned char c)
{
WARN_ON(s->size == 0);
- if (s->len + 1 < s->size) {
+ if (seq_buf_can_fit(s, 1)) {
s->buffer[s->len++] = c;
return 0;
}
@@ -207,7 +220,7 @@ int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len)
{
WARN_ON(s->size == 0);
- if (s->len + len < s->size) {
+ if (seq_buf_can_fit(s, len)) {
memcpy(s->buffer + s->len, mem, len);
s->len += len;
return 0;
--
2.1.1
^ permalink raw reply related [flat|nested] 16+ messages in thread
* [for-next][PATCH 10/15] tracing: Have seq_buf use full buffer
2014-11-20 15:21 [for-next][PATCH 00/15] tracing/seq-buf/printk: New seq-buf utility from trace_seq for printk in NMI Steven Rostedt
` (8 preceding siblings ...)
2014-11-20 15:21 ` [for-next][PATCH 09/15] seq_buf: Add seq_buf_can_fit() helper function Steven Rostedt
@ 2014-11-20 15:21 ` Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 11/15] tracing: Add seq_buf_get_buf() and seq_buf_commit() helper functions Steven Rostedt
` (4 subsequent siblings)
14 siblings, 0 replies; 16+ messages in thread
From: Steven Rostedt @ 2014-11-20 15:21 UTC (permalink / raw)
To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek
[-- Attachment #1: 0010-tracing-Have-seq_buf-use-full-buffer.patch --]
[-- Type: text/plain, Size: 2517 bytes --]
From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
Currently seq_buf is full when all but one byte of the buffer is
filled. Change it so that the seq_buf is full when all of the
buffer is filled.
Some of the functions would fill the buffer completely and report
everything was fine. This was inconsistent with the max of size - 1.
Changing this to be max of size makes all functions consistent.
Link: http://lkml.kernel.org/r/20141104160222.502133196@goodmis.org
Link: http://lkml.kernel.org/r/20141114011412.811957882@goodmis.org
Tested-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
include/linux/seq_buf.h | 6 +++---
kernel/trace/seq_buf.c | 9 ++++++---
2 files changed, 9 insertions(+), 6 deletions(-)
diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h
index 93718e570d4c..0800a24b4348 100644
--- a/include/linux/seq_buf.h
+++ b/include/linux/seq_buf.h
@@ -43,13 +43,13 @@ seq_buf_init(struct seq_buf *s, unsigned char *buf, unsigned int size)
static inline bool
seq_buf_has_overflowed(struct seq_buf *s)
{
- return s->len == s->size;
+ return s->len > s->size;
}
static inline void
seq_buf_set_overflow(struct seq_buf *s)
{
- s->len = s->size;
+ s->len = s->size + 1;
}
/*
@@ -61,7 +61,7 @@ seq_buf_buffer_left(struct seq_buf *s)
if (seq_buf_has_overflowed(s))
return 0;
- return (s->size - 1) - s->len;
+ return s->size - s->len;
}
/* How much buffer was written? */
diff --git a/kernel/trace/seq_buf.c b/kernel/trace/seq_buf.c
index 6fc9d021cbef..c53f1d5088e8 100644
--- a/kernel/trace/seq_buf.c
+++ b/kernel/trace/seq_buf.c
@@ -26,7 +26,7 @@
*/
static bool seq_buf_can_fit(struct seq_buf *s, size_t len)
{
- return s->len + len < s->size;
+ return s->len + len <= s->size;
}
/**
@@ -110,8 +110,11 @@ int seq_buf_bitmask(struct seq_buf *s, const unsigned long *maskp,
WARN_ON(s->size == 0);
/*
- * The last byte of the buffer is used to determine if we
- * overflowed or not.
+ * Note, because bitmap_scnprintf() only returns the number of bytes
+ * written and not the number that would be written, we use the last
+ * byte of the buffer to let us know if we overflowed. There's a small
+ * chance that the bitmap could have fit exactly inside the buffer, but
+ * it's not that critical if that does happen.
*/
if (len > 1) {
ret = bitmap_scnprintf(s->buffer + s->len, len, maskp, nmaskbits);
--
2.1.1
^ permalink raw reply related [flat|nested] 16+ messages in thread
* [for-next][PATCH 11/15] tracing: Add seq_buf_get_buf() and seq_buf_commit() helper functions
2014-11-20 15:21 [for-next][PATCH 00/15] tracing/seq-buf/printk: New seq-buf utility from trace_seq for printk in NMI Steven Rostedt
` (9 preceding siblings ...)
2014-11-20 15:21 ` [for-next][PATCH 10/15] tracing: Have seq_buf use full buffer Steven Rostedt
@ 2014-11-20 15:21 ` Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 12/15] seq-buf: Make seq_buf_bprintf() conditional on CONFIG_BINARY_PRINTF Steven Rostedt
` (3 subsequent siblings)
14 siblings, 0 replies; 16+ messages in thread
From: Steven Rostedt @ 2014-11-20 15:21 UTC (permalink / raw)
To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek
[-- Attachment #1: 0011-tracing-Add-seq_buf_get_buf-and-seq_buf_commit-helpe.patch --]
[-- Type: text/plain, Size: 2922 bytes --]
From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
Add two helper functions; seq_buf_get_buf() and seq_buf_commit() that
are used by seq_buf_path(). This makes the code similar to the
seq_file: seq_path() function, and will help to be able to consolidate
the functions between seq_file and trace_seq.
Link: http://lkml.kernel.org/r/20141104160222.644881406@goodmis.org
Link: http://lkml.kernel.org/r/20141114011412.977571447@goodmis.org
Tested-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
include/linux/seq_buf.h | 41 +++++++++++++++++++++++++++++++++++++++++
kernel/trace/seq_buf.c | 7 +++----
2 files changed, 44 insertions(+), 4 deletions(-)
diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h
index 0800a24b4348..12c64282aa98 100644
--- a/include/linux/seq_buf.h
+++ b/include/linux/seq_buf.h
@@ -70,6 +70,47 @@ static inline unsigned int seq_buf_used(struct seq_buf *s)
return min(s->len, s->size);
}
+/**
+ * seq_buf_get_buf - get buffer to write arbitrary data to
+ * @s: the seq_buf handle
+ * @bufp: the beginning of the buffer is stored here
+ *
+ * Return the number of bytes available in the buffer, or zero if
+ * there's no space.
+ */
+static inline size_t seq_buf_get_buf(struct seq_buf *s, char **bufp)
+{
+ WARN_ON(s->len > s->size + 1);
+
+ if (s->len < s->size) {
+ *bufp = s->buffer + s->len;
+ return s->size - s->len;
+ }
+
+ *bufp = NULL;
+ return 0;
+}
+
+/**
+ * seq_buf_commit - commit data to the buffer
+ * @s: the seq_buf handle
+ * @num: the number of bytes to commit
+ *
+ * Commit @num bytes of data written to a buffer previously acquired
+ * by seq_buf_get. To signal an error condition, or that the data
+ * didn't fit in the available space, pass a negative @num value.
+ */
+static inline void seq_buf_commit(struct seq_buf *s, int num)
+{
+ if (num < 0) {
+ seq_buf_set_overflow(s);
+ } else {
+ /* num must be negative on overflow */
+ BUG_ON(s->len + num > s->size);
+ s->len += num;
+ }
+}
+
extern __printf(2, 3)
int seq_buf_printf(struct seq_buf *s, const char *fmt, ...);
extern __printf(2, 0)
diff --git a/kernel/trace/seq_buf.c b/kernel/trace/seq_buf.c
index c53f1d5088e8..086f594ac890 100644
--- a/kernel/trace/seq_buf.c
+++ b/kernel/trace/seq_buf.c
@@ -293,8 +293,8 @@ int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
*/
int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc)
{
- char *buf = s->buffer + s->len;
- size_t size = seq_buf_buffer_left(s);
+ char *buf;
+ size_t size = seq_buf_get_buf(s, &buf);
int res = -1;
WARN_ON(s->size == 0);
@@ -307,8 +307,7 @@ int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc)
res = end - buf;
}
}
- if (res > 0)
- s->len += res;
+ seq_buf_commit(s, res);
return res;
}
--
2.1.1
^ permalink raw reply related [flat|nested] 16+ messages in thread
* [for-next][PATCH 12/15] seq-buf: Make seq_buf_bprintf() conditional on CONFIG_BINARY_PRINTF
2014-11-20 15:21 [for-next][PATCH 00/15] tracing/seq-buf/printk: New seq-buf utility from trace_seq for printk in NMI Steven Rostedt
` (10 preceding siblings ...)
2014-11-20 15:21 ` [for-next][PATCH 11/15] tracing: Add seq_buf_get_buf() and seq_buf_commit() helper functions Steven Rostedt
@ 2014-11-20 15:21 ` Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 13/15] seq_buf: Move the seq_buf code to lib/ Steven Rostedt
` (2 subsequent siblings)
14 siblings, 0 replies; 16+ messages in thread
From: Steven Rostedt @ 2014-11-20 15:21 UTC (permalink / raw)
To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek
[-- Attachment #1: 0012-seq-buf-Make-seq_buf_bprintf-conditional-on-CONFIG_B.patch --]
[-- Type: text/plain, Size: 2612 bytes --]
From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
The function bstr_printf() from lib/vsprnintf.c is only available if
CONFIG_BINARY_PRINTF is defined. This is due to the only user currently
being the tracing infrastructure, which needs to select this config
when tracing is configured. Until there is another user of the binary
printf formats, this will continue to be the case.
Since seq_buf.c is now lives in lib/ and is compiled even without
tracing, it must encompass its use of bstr_printf() which is used
by seq_buf_printf(). This too is only used by the tracing infrastructure
and is still encapsulated by the CONFIG_BINARY_PRINTF.
Link: http://lkml.kernel.org/r/20141104160222.969013383@goodmis.org
Tested-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
include/linux/seq_buf.h | 7 +++++--
kernel/trace/seq_buf.c | 2 ++
2 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h
index 12c64282aa98..9aafe0e24c68 100644
--- a/include/linux/seq_buf.h
+++ b/include/linux/seq_buf.h
@@ -115,8 +115,6 @@ extern __printf(2, 3)
int seq_buf_printf(struct seq_buf *s, const char *fmt, ...);
extern __printf(2, 0)
int seq_buf_vprintf(struct seq_buf *s, const char *fmt, va_list args);
-extern int
-seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary);
extern int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s);
extern int seq_buf_to_user(struct seq_buf *s, char __user *ubuf,
int cnt);
@@ -130,4 +128,9 @@ extern int seq_buf_path(struct seq_buf *s, const struct path *path, const char *
extern int seq_buf_bitmask(struct seq_buf *s, const unsigned long *maskp,
int nmaskbits);
+#ifdef CONFIG_BINARY_PRINTF
+extern int
+seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary);
+#endif
+
#endif /* _LINUX_SEQ_BUF_H */
diff --git a/kernel/trace/seq_buf.c b/kernel/trace/seq_buf.c
index 086f594ac890..4eedfedb9e31 100644
--- a/kernel/trace/seq_buf.c
+++ b/kernel/trace/seq_buf.c
@@ -127,6 +127,7 @@ int seq_buf_bitmask(struct seq_buf *s, const unsigned long *maskp,
return -1;
}
+#ifdef CONFIG_BINARY_PRINTF
/**
* seq_buf_bprintf - Write the printf string from binary arguments
* @s: seq_buf descriptor
@@ -161,6 +162,7 @@ int seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary)
seq_buf_set_overflow(s);
return -1;
}
+#endif /* CONFIG_BINARY_PRINTF */
/**
* seq_buf_puts - sequence printing of simple string
--
2.1.1
^ permalink raw reply related [flat|nested] 16+ messages in thread
* [for-next][PATCH 13/15] seq_buf: Move the seq_buf code to lib/
2014-11-20 15:21 [for-next][PATCH 00/15] tracing/seq-buf/printk: New seq-buf utility from trace_seq for printk in NMI Steven Rostedt
` (11 preceding siblings ...)
2014-11-20 15:21 ` [for-next][PATCH 12/15] seq-buf: Make seq_buf_bprintf() conditional on CONFIG_BINARY_PRINTF Steven Rostedt
@ 2014-11-20 15:21 ` Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 14/15] printk: Add per_cpu printk func to allow printk to be diverted Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 15/15] x86/nmi: Perform a safe NMI stack trace on all CPUs Steven Rostedt
14 siblings, 0 replies; 16+ messages in thread
From: Steven Rostedt @ 2014-11-20 15:21 UTC (permalink / raw)
To: linux-kernel; +Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek
[-- Attachment #1: 0013-seq_buf-Move-the-seq_buf-code-to-lib.patch --]
[-- Type: text/plain, Size: 21821 bytes --]
From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
The seq_buf functions are rather useful outside of tracing. Instead
of having it be dependent on CONFIG_TRACING, move the code into lib/
and allow other users to have access to it even when tracing is not
configured.
The seq_buf utility is similar to the seq_file utility, but instead of
writing sending data back up to userland, it writes it into a buffer
defined at seq_buf_init(). This allows us to send a descriptor around
that writes printf() formatted strings into it that can be retrieved
later.
It is currently used by the tracing facility for such things like trace
events to convert its binary saved data in the ring buffer into an
ASCII human readable context to be displayed in /sys/kernel/debug/trace.
It can also be used for doing NMI prints safely from NMI context into
the seq_buf and retrieved later and dumped to printk() safely. Doing
printk() from an NMI context is dangerous because an NMI can preempt
a current printk() and deadlock on it.
Link: http://lkml.kernel.org/p/20140619213952.058255809@goodmis.org
Tested-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/trace/Makefile | 1 -
kernel/trace/seq_buf.c | 359 -------------------------------------------------
lib/Makefile | 2 +-
lib/seq_buf.c | 359 +++++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 360 insertions(+), 361 deletions(-)
delete mode 100644 kernel/trace/seq_buf.c
create mode 100644 lib/seq_buf.c
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index edc98c72a634..67d6369ddf83 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -29,7 +29,6 @@ obj-$(CONFIG_RING_BUFFER_BENCHMARK) += ring_buffer_benchmark.o
obj-$(CONFIG_TRACING) += trace.o
obj-$(CONFIG_TRACING) += trace_output.o
obj-$(CONFIG_TRACING) += trace_seq.o
-obj-$(CONFIG_TRACING) += seq_buf.o
obj-$(CONFIG_TRACING) += trace_stat.o
obj-$(CONFIG_TRACING) += trace_printk.o
obj-$(CONFIG_CONTEXT_SWITCH_TRACER) += trace_sched_switch.o
diff --git a/kernel/trace/seq_buf.c b/kernel/trace/seq_buf.c
deleted file mode 100644
index 4eedfedb9e31..000000000000
--- a/kernel/trace/seq_buf.c
+++ /dev/null
@@ -1,359 +0,0 @@
-/*
- * seq_buf.c
- *
- * Copyright (C) 2014 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
- *
- * The seq_buf is a handy tool that allows you to pass a descriptor around
- * to a buffer that other functions can write to. It is similar to the
- * seq_file functionality but has some differences.
- *
- * To use it, the seq_buf must be initialized with seq_buf_init().
- * This will set up the counters within the descriptor. You can call
- * seq_buf_init() more than once to reset the seq_buf to start
- * from scratch.
- */
-#include <linux/uaccess.h>
-#include <linux/seq_file.h>
-#include <linux/seq_buf.h>
-
-/**
- * seq_buf_can_fit - can the new data fit in the current buffer?
- * @s: the seq_buf descriptor
- * @len: The length to see if it can fit in the current buffer
- *
- * Returns true if there's enough unused space in the seq_buf buffer
- * to fit the amount of new data according to @len.
- */
-static bool seq_buf_can_fit(struct seq_buf *s, size_t len)
-{
- return s->len + len <= s->size;
-}
-
-/**
- * seq_buf_print_seq - move the contents of seq_buf into a seq_file
- * @m: the seq_file descriptor that is the destination
- * @s: the seq_buf descriptor that is the source.
- *
- * Returns zero on success, non zero otherwise
- */
-int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s)
-{
- unsigned int len = seq_buf_used(s);
-
- return seq_write(m, s->buffer, len);
-}
-
-/**
- * seq_buf_vprintf - sequence printing of information.
- * @s: seq_buf descriptor
- * @fmt: printf format string
- * @args: va_list of arguments from a printf() type function
- *
- * Writes a vnprintf() format into the sequencce buffer.
- *
- * Returns zero on success, -1 on overflow.
- */
-int seq_buf_vprintf(struct seq_buf *s, const char *fmt, va_list args)
-{
- int len;
-
- WARN_ON(s->size == 0);
-
- if (s->len < s->size) {
- len = vsnprintf(s->buffer + s->len, s->size - s->len, fmt, args);
- if (seq_buf_can_fit(s, len)) {
- s->len += len;
- return 0;
- }
- }
- seq_buf_set_overflow(s);
- return -1;
-}
-
-/**
- * seq_buf_printf - sequence printing of information
- * @s: seq_buf descriptor
- * @fmt: printf format string
- *
- * Writes a printf() format into the sequence buffer.
- *
- * Returns zero on success, -1 on overflow.
- */
-int seq_buf_printf(struct seq_buf *s, const char *fmt, ...)
-{
- va_list ap;
- int ret;
-
- va_start(ap, fmt);
- ret = seq_buf_vprintf(s, fmt, ap);
- va_end(ap);
-
- return ret;
-}
-
-/**
- * seq_buf_bitmask - write a bitmask array in its ASCII representation
- * @s: seq_buf descriptor
- * @maskp: points to an array of unsigned longs that represent a bitmask
- * @nmaskbits: The number of bits that are valid in @maskp
- *
- * Writes a ASCII representation of a bitmask string into @s.
- *
- * Returns zero on success, -1 on overflow.
- */
-int seq_buf_bitmask(struct seq_buf *s, const unsigned long *maskp,
- int nmaskbits)
-{
- unsigned int len = seq_buf_buffer_left(s);
- int ret;
-
- WARN_ON(s->size == 0);
-
- /*
- * Note, because bitmap_scnprintf() only returns the number of bytes
- * written and not the number that would be written, we use the last
- * byte of the buffer to let us know if we overflowed. There's a small
- * chance that the bitmap could have fit exactly inside the buffer, but
- * it's not that critical if that does happen.
- */
- if (len > 1) {
- ret = bitmap_scnprintf(s->buffer + s->len, len, maskp, nmaskbits);
- if (ret < len) {
- s->len += ret;
- return 0;
- }
- }
- seq_buf_set_overflow(s);
- return -1;
-}
-
-#ifdef CONFIG_BINARY_PRINTF
-/**
- * seq_buf_bprintf - Write the printf string from binary arguments
- * @s: seq_buf descriptor
- * @fmt: The format string for the @binary arguments
- * @binary: The binary arguments for @fmt.
- *
- * When recording in a fast path, a printf may be recorded with just
- * saving the format and the arguments as they were passed to the
- * function, instead of wasting cycles converting the arguments into
- * ASCII characters. Instead, the arguments are saved in a 32 bit
- * word array that is defined by the format string constraints.
- *
- * This function will take the format and the binary array and finish
- * the conversion into the ASCII string within the buffer.
- *
- * Returns zero on success, -1 on overflow.
- */
-int seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary)
-{
- unsigned int len = seq_buf_buffer_left(s);
- int ret;
-
- WARN_ON(s->size == 0);
-
- if (s->len < s->size) {
- ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
- if (seq_buf_can_fit(s, ret)) {
- s->len += ret;
- return 0;
- }
- }
- seq_buf_set_overflow(s);
- return -1;
-}
-#endif /* CONFIG_BINARY_PRINTF */
-
-/**
- * seq_buf_puts - sequence printing of simple string
- * @s: seq_buf descriptor
- * @str: simple string to record
- *
- * Copy a simple string into the sequence buffer.
- *
- * Returns zero on success, -1 on overflow
- */
-int seq_buf_puts(struct seq_buf *s, const char *str)
-{
- unsigned int len = strlen(str);
-
- WARN_ON(s->size == 0);
-
- if (seq_buf_can_fit(s, len)) {
- memcpy(s->buffer + s->len, str, len);
- s->len += len;
- return 0;
- }
- seq_buf_set_overflow(s);
- return -1;
-}
-
-/**
- * seq_buf_putc - sequence printing of simple character
- * @s: seq_buf descriptor
- * @c: simple character to record
- *
- * Copy a single character into the sequence buffer.
- *
- * Returns zero on success, -1 on overflow
- */
-int seq_buf_putc(struct seq_buf *s, unsigned char c)
-{
- WARN_ON(s->size == 0);
-
- if (seq_buf_can_fit(s, 1)) {
- s->buffer[s->len++] = c;
- return 0;
- }
- seq_buf_set_overflow(s);
- return -1;
-}
-
-/**
- * seq_buf_putmem - write raw data into the sequenc buffer
- * @s: seq_buf descriptor
- * @mem: The raw memory to copy into the buffer
- * @len: The length of the raw memory to copy (in bytes)
- *
- * There may be cases where raw memory needs to be written into the
- * buffer and a strcpy() would not work. Using this function allows
- * for such cases.
- *
- * Returns zero on success, -1 on overflow
- */
-int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len)
-{
- WARN_ON(s->size == 0);
-
- if (seq_buf_can_fit(s, len)) {
- memcpy(s->buffer + s->len, mem, len);
- s->len += len;
- return 0;
- }
- seq_buf_set_overflow(s);
- return -1;
-}
-
-#define MAX_MEMHEX_BYTES 8U
-#define HEX_CHARS (MAX_MEMHEX_BYTES*2 + 1)
-
-/**
- * seq_buf_putmem_hex - write raw memory into the buffer in ASCII hex
- * @s: seq_buf descriptor
- * @mem: The raw memory to write its hex ASCII representation of
- * @len: The length of the raw memory to copy (in bytes)
- *
- * This is similar to seq_buf_putmem() except instead of just copying the
- * raw memory into the buffer it writes its ASCII representation of it
- * in hex characters.
- *
- * Returns zero on success, -1 on overflow
- */
-int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
- unsigned int len)
-{
- unsigned char hex[HEX_CHARS];
- const unsigned char *data = mem;
- unsigned int start_len;
- int i, j;
-
- WARN_ON(s->size == 0);
-
- while (len) {
- start_len = min(len, HEX_CHARS - 1);
-#ifdef __BIG_ENDIAN
- for (i = 0, j = 0; i < start_len; i++) {
-#else
- for (i = start_len-1, j = 0; i >= 0; i--) {
-#endif
- hex[j++] = hex_asc_hi(data[i]);
- hex[j++] = hex_asc_lo(data[i]);
- }
- if (WARN_ON_ONCE(j == 0 || j/2 > len))
- break;
-
- /* j increments twice per loop */
- len -= j / 2;
- hex[j++] = ' ';
-
- seq_buf_putmem(s, hex, j);
- if (seq_buf_has_overflowed(s))
- return -1;
- }
- return 0;
-}
-
-/**
- * seq_buf_path - copy a path into the sequence buffer
- * @s: seq_buf descriptor
- * @path: path to write into the sequence buffer.
- * @esc: set of characters to escape in the output
- *
- * Write a path name into the sequence buffer.
- *
- * Returns the number of written bytes on success, -1 on overflow
- */
-int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc)
-{
- char *buf;
- size_t size = seq_buf_get_buf(s, &buf);
- int res = -1;
-
- WARN_ON(s->size == 0);
-
- if (size) {
- char *p = d_path(path, buf, size);
- if (!IS_ERR(p)) {
- char *end = mangle_path(buf, p, esc);
- if (end)
- res = end - buf;
- }
- }
- seq_buf_commit(s, res);
-
- return res;
-}
-
-/**
- * seq_buf_to_user - copy the squence buffer to user space
- * @s: seq_buf descriptor
- * @ubuf: The userspace memory location to copy to
- * @cnt: The amount to copy
- *
- * Copies the sequence buffer into the userspace memory pointed to
- * by @ubuf. It starts from the last read position (@s->readpos)
- * and writes up to @cnt characters or till it reaches the end of
- * the content in the buffer (@s->len), which ever comes first.
- *
- * On success, it returns a positive number of the number of bytes
- * it copied.
- *
- * On failure it returns -EBUSY if all of the content in the
- * sequence has been already read, which includes nothing in the
- * sequence (@s->len == @s->readpos).
- *
- * Returns -EFAULT if the copy to userspace fails.
- */
-int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, int cnt)
-{
- int len;
- int ret;
-
- if (!cnt)
- return 0;
-
- if (s->len <= s->readpos)
- return -EBUSY;
-
- len = seq_buf_used(s) - s->readpos;
- if (cnt > len)
- cnt = len;
- ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
- if (ret == cnt)
- return -EFAULT;
-
- cnt -= ret;
-
- s->readpos += cnt;
- return cnt;
-}
diff --git a/lib/Makefile b/lib/Makefile
index 7512dc978f18..a1aa1e81ed36 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -13,7 +13,7 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \
sha1.o md5.o irq_regs.o reciprocal_div.o argv_split.o \
proportions.o flex_proportions.o ratelimit.o show_mem.o \
is_single_threaded.o plist.o decompress.o kobject_uevent.o \
- earlycpio.o
+ earlycpio.o seq_buf.o
obj-$(CONFIG_ARCH_HAS_DEBUG_STRICT_USER_COPY_CHECKS) += usercopy.o
lib-$(CONFIG_MMU) += ioremap.o
diff --git a/lib/seq_buf.c b/lib/seq_buf.c
new file mode 100644
index 000000000000..4eedfedb9e31
--- /dev/null
+++ b/lib/seq_buf.c
@@ -0,0 +1,359 @@
+/*
+ * seq_buf.c
+ *
+ * Copyright (C) 2014 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
+ *
+ * The seq_buf is a handy tool that allows you to pass a descriptor around
+ * to a buffer that other functions can write to. It is similar to the
+ * seq_file functionality but has some differences.
+ *
+ * To use it, the seq_buf must be initialized with seq_buf_init().
+ * This will set up the counters within the descriptor. You can call
+ * seq_buf_init() more than once to reset the seq_buf to start
+ * from scratch.
+ */
+#include <linux/uaccess.h>
+#include <linux/seq_file.h>
+#include <linux/seq_buf.h>
+
+/**
+ * seq_buf_can_fit - can the new data fit in the current buffer?
+ * @s: the seq_buf descriptor
+ * @len: The length to see if it can fit in the current buffer
+ *
+ * Returns true if there's enough unused space in the seq_buf buffer
+ * to fit the amount of new data according to @len.
+ */
+static bool seq_buf_can_fit(struct seq_buf *s, size_t len)
+{
+ return s->len + len <= s->size;
+}
+
+/**
+ * seq_buf_print_seq - move the contents of seq_buf into a seq_file
+ * @m: the seq_file descriptor that is the destination
+ * @s: the seq_buf descriptor that is the source.
+ *
+ * Returns zero on success, non zero otherwise
+ */
+int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s)
+{
+ unsigned int len = seq_buf_used(s);
+
+ return seq_write(m, s->buffer, len);
+}
+
+/**
+ * seq_buf_vprintf - sequence printing of information.
+ * @s: seq_buf descriptor
+ * @fmt: printf format string
+ * @args: va_list of arguments from a printf() type function
+ *
+ * Writes a vnprintf() format into the sequencce buffer.
+ *
+ * Returns zero on success, -1 on overflow.
+ */
+int seq_buf_vprintf(struct seq_buf *s, const char *fmt, va_list args)
+{
+ int len;
+
+ WARN_ON(s->size == 0);
+
+ if (s->len < s->size) {
+ len = vsnprintf(s->buffer + s->len, s->size - s->len, fmt, args);
+ if (seq_buf_can_fit(s, len)) {
+ s->len += len;
+ return 0;
+ }
+ }
+ seq_buf_set_overflow(s);
+ return -1;
+}
+
+/**
+ * seq_buf_printf - sequence printing of information
+ * @s: seq_buf descriptor
+ * @fmt: printf format string
+ *
+ * Writes a printf() format into the sequence buffer.
+ *
+ * Returns zero on success, -1 on overflow.
+ */
+int seq_buf_printf(struct seq_buf *s, const char *fmt, ...)
+{
+ va_list ap;
+ int ret;
+
+ va_start(ap, fmt);
+ ret = seq_buf_vprintf(s, fmt, ap);
+ va_end(ap);
+
+ return ret;
+}
+
+/**
+ * seq_buf_bitmask - write a bitmask array in its ASCII representation
+ * @s: seq_buf descriptor
+ * @maskp: points to an array of unsigned longs that represent a bitmask
+ * @nmaskbits: The number of bits that are valid in @maskp
+ *
+ * Writes a ASCII representation of a bitmask string into @s.
+ *
+ * Returns zero on success, -1 on overflow.
+ */
+int seq_buf_bitmask(struct seq_buf *s, const unsigned long *maskp,
+ int nmaskbits)
+{
+ unsigned int len = seq_buf_buffer_left(s);
+ int ret;
+
+ WARN_ON(s->size == 0);
+
+ /*
+ * Note, because bitmap_scnprintf() only returns the number of bytes
+ * written and not the number that would be written, we use the last
+ * byte of the buffer to let us know if we overflowed. There's a small
+ * chance that the bitmap could have fit exactly inside the buffer, but
+ * it's not that critical if that does happen.
+ */
+ if (len > 1) {
+ ret = bitmap_scnprintf(s->buffer + s->len, len, maskp, nmaskbits);
+ if (ret < len) {
+ s->len += ret;
+ return 0;
+ }
+ }
+ seq_buf_set_overflow(s);
+ return -1;
+}
+
+#ifdef CONFIG_BINARY_PRINTF
+/**
+ * seq_buf_bprintf - Write the printf string from binary arguments
+ * @s: seq_buf descriptor
+ * @fmt: The format string for the @binary arguments
+ * @binary: The binary arguments for @fmt.
+ *
+ * When recording in a fast path, a printf may be recorded with just
+ * saving the format and the arguments as they were passed to the
+ * function, instead of wasting cycles converting the arguments into
+ * ASCII characters. Instead, the arguments are saved in a 32 bit
+ * word array that is defined by the format string constraints.
+ *
+ * This function will take the format and the binary array and finish
+ * the conversion into the ASCII string within the buffer.
+ *
+ * Returns zero on success, -1 on overflow.
+ */
+int seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary)
+{
+ unsigned int len = seq_buf_buffer_left(s);
+ int ret;
+
+ WARN_ON(s->size == 0);
+
+ if (s->len < s->size) {
+ ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
+ if (seq_buf_can_fit(s, ret)) {
+ s->len += ret;
+ return 0;
+ }
+ }
+ seq_buf_set_overflow(s);
+ return -1;
+}
+#endif /* CONFIG_BINARY_PRINTF */
+
+/**
+ * seq_buf_puts - sequence printing of simple string
+ * @s: seq_buf descriptor
+ * @str: simple string to record
+ *
+ * Copy a simple string into the sequence buffer.
+ *
+ * Returns zero on success, -1 on overflow
+ */
+int seq_buf_puts(struct seq_buf *s, const char *str)
+{
+ unsigned int len = strlen(str);
+
+ WARN_ON(s->size == 0);
+
+ if (seq_buf_can_fit(s, len)) {
+ memcpy(s->buffer + s->len, str, len);
+ s->len += len;
+ return 0;
+ }
+ seq_buf_set_overflow(s);
+ return -1;
+}
+
+/**
+ * seq_buf_putc - sequence printing of simple character
+ * @s: seq_buf descriptor
+ * @c: simple character to record
+ *
+ * Copy a single character into the sequence buffer.
+ *
+ * Returns zero on success, -1 on overflow
+ */
+int seq_buf_putc(struct seq_buf *s, unsigned char c)
+{
+ WARN_ON(s->size == 0);
+
+ if (seq_buf_can_fit(s, 1)) {
+ s->buffer[s->len++] = c;
+ return 0;
+ }
+ seq_buf_set_overflow(s);
+ return -1;
+}
+
+/**
+ * seq_buf_putmem - write raw data into the sequenc buffer
+ * @s: seq_buf descriptor
+ * @mem: The raw memory to copy into the buffer
+ * @len: The length of the raw memory to copy (in bytes)
+ *
+ * There may be cases where raw memory needs to be written into the
+ * buffer and a strcpy() would not work. Using this function allows
+ * for such cases.
+ *
+ * Returns zero on success, -1 on overflow
+ */
+int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len)
+{
+ WARN_ON(s->size == 0);
+
+ if (seq_buf_can_fit(s, len)) {
+ memcpy(s->buffer + s->len, mem, len);
+ s->len += len;
+ return 0;
+ }
+ seq_buf_set_overflow(s);
+ return -1;
+}
+
+#define MAX_MEMHEX_BYTES 8U
+#define HEX_CHARS (MAX_MEMHEX_BYTES*2 + 1)
+
+/**
+ * seq_buf_putmem_hex - write raw memory into the buffer in ASCII hex
+ * @s: seq_buf descriptor
+ * @mem: The raw memory to write its hex ASCII representation of
+ * @len: The length of the raw memory to copy (in bytes)
+ *
+ * This is similar to seq_buf_putmem() except instead of just copying the
+ * raw memory into the buffer it writes its ASCII representation of it
+ * in hex characters.
+ *
+ * Returns zero on success, -1 on overflow
+ */
+int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
+ unsigned int len)
+{
+ unsigned char hex[HEX_CHARS];
+ const unsigned char *data = mem;
+ unsigned int start_len;
+ int i, j;
+
+ WARN_ON(s->size == 0);
+
+ while (len) {
+ start_len = min(len, HEX_CHARS - 1);
+#ifdef __BIG_ENDIAN
+ for (i = 0, j = 0; i < start_len; i++) {
+#else
+ for (i = start_len-1, j = 0; i >= 0; i--) {
+#endif
+ hex[j++] = hex_asc_hi(data[i]);
+ hex[j++] = hex_asc_lo(data[i]);
+ }
+ if (WARN_ON_ONCE(j == 0 || j/2 > len))
+ break;
+
+ /* j increments twice per loop */
+ len -= j / 2;
+ hex[j++] = ' ';
+
+ seq_buf_putmem(s, hex, j);
+ if (seq_buf_has_overflowed(s))
+ return -1;
+ }
+ return 0;
+}
+
+/**
+ * seq_buf_path - copy a path into the sequence buffer
+ * @s: seq_buf descriptor
+ * @path: path to write into the sequence buffer.
+ * @esc: set of characters to escape in the output
+ *
+ * Write a path name into the sequence buffer.
+ *
+ * Returns the number of written bytes on success, -1 on overflow
+ */
+int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc)
+{
+ char *buf;
+ size_t size = seq_buf_get_buf(s, &buf);
+ int res = -1;
+
+ WARN_ON(s->size == 0);
+
+ if (size) {
+ char *p = d_path(path, buf, size);
+ if (!IS_ERR(p)) {
+ char *end = mangle_path(buf, p, esc);
+ if (end)
+ res = end - buf;
+ }
+ }
+ seq_buf_commit(s, res);
+
+ return res;
+}
+
+/**
+ * seq_buf_to_user - copy the squence buffer to user space
+ * @s: seq_buf descriptor
+ * @ubuf: The userspace memory location to copy to
+ * @cnt: The amount to copy
+ *
+ * Copies the sequence buffer into the userspace memory pointed to
+ * by @ubuf. It starts from the last read position (@s->readpos)
+ * and writes up to @cnt characters or till it reaches the end of
+ * the content in the buffer (@s->len), which ever comes first.
+ *
+ * On success, it returns a positive number of the number of bytes
+ * it copied.
+ *
+ * On failure it returns -EBUSY if all of the content in the
+ * sequence has been already read, which includes nothing in the
+ * sequence (@s->len == @s->readpos).
+ *
+ * Returns -EFAULT if the copy to userspace fails.
+ */
+int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, int cnt)
+{
+ int len;
+ int ret;
+
+ if (!cnt)
+ return 0;
+
+ if (s->len <= s->readpos)
+ return -EBUSY;
+
+ len = seq_buf_used(s) - s->readpos;
+ if (cnt > len)
+ cnt = len;
+ ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
+ if (ret == cnt)
+ return -EFAULT;
+
+ cnt -= ret;
+
+ s->readpos += cnt;
+ return cnt;
+}
--
2.1.1
^ permalink raw reply related [flat|nested] 16+ messages in thread
* [for-next][PATCH 14/15] printk: Add per_cpu printk func to allow printk to be diverted
2014-11-20 15:21 [for-next][PATCH 00/15] tracing/seq-buf/printk: New seq-buf utility from trace_seq for printk in NMI Steven Rostedt
` (12 preceding siblings ...)
2014-11-20 15:21 ` [for-next][PATCH 13/15] seq_buf: Move the seq_buf code to lib/ Steven Rostedt
@ 2014-11-20 15:21 ` Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 15/15] x86/nmi: Perform a safe NMI stack trace on all CPUs Steven Rostedt
14 siblings, 0 replies; 16+ messages in thread
From: Steven Rostedt @ 2014-11-20 15:21 UTC (permalink / raw)
To: linux-kernel
Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek, Paul E. McKenney
[-- Attachment #1: 0014-printk-Add-per_cpu-printk-func-to-allow-printk-to-be.patch --]
[-- Type: text/plain, Size: 3548 bytes --]
From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
Being able to divert printk to call another function besides the normal
logging is useful for such things like NMI handling. If some functions
are to be called from NMI that does printk() it is possible to lock up
the box if the nmi handler triggers when another printk is happening.
One example of this use is to perform a stack trace on all CPUs via NMI.
But if the NMI is to do the printk() it can cause the system to lock up.
By allowing the printk to be diverted to another function that can safely
record the printk output and then print it when it in a safe context
then NMIs will be safe to call these functions like show_regs().
Link: http://lkml.kernel.org/p/20140619213952.209176403@goodmis.org
Tested-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
include/linux/percpu.h | 3 +++
include/linux/printk.h | 2 ++
kernel/printk/printk.c | 38 +++++++++++++++++++++++++++++---------
3 files changed, 34 insertions(+), 9 deletions(-)
diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index a3aa63e47637..ba2e85a0ff5b 100644
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -134,4 +134,7 @@ extern phys_addr_t per_cpu_ptr_to_phys(void *addr);
(typeof(type) __percpu *)__alloc_percpu(sizeof(type), \
__alignof__(type))
+/* To avoid include hell, as printk can not declare this, we declare it here */
+DECLARE_PER_CPU(printk_func_t, printk_func);
+
#endif /* __LINUX_PERCPU_H */
diff --git a/include/linux/printk.h b/include/linux/printk.h
index d78125f73ac4..3bbd979d32fb 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -162,6 +162,8 @@ extern int kptr_restrict;
extern void wake_up_klogd(void);
+typedef int(*printk_func_t)(const char *fmt, va_list args);
+
void log_buf_kexec_setup(void);
void __init setup_log_buf(int early);
void dump_stack_set_arch_desc(const char *fmt, ...);
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index ced2b84b1cb7..f7b723f98cb9 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1807,6 +1807,30 @@ asmlinkage int printk_emit(int facility, int level,
}
EXPORT_SYMBOL(printk_emit);
+int vprintk_default(const char *fmt, va_list args)
+{
+ int r;
+
+#ifdef CONFIG_KGDB_KDB
+ if (unlikely(kdb_trap_printk)) {
+ r = vkdb_printf(fmt, args);
+ return r;
+ }
+#endif
+ r = vprintk_emit(0, -1, NULL, 0, fmt, args);
+
+ return r;
+}
+EXPORT_SYMBOL_GPL(vprintk_default);
+
+/*
+ * This allows printk to be diverted to another function per cpu.
+ * This is useful for calling printk functions from within NMI
+ * without worrying about race conditions that can lock up the
+ * box.
+ */
+DEFINE_PER_CPU(printk_func_t, printk_func) = vprintk_default;
+
/**
* printk - print a kernel message
* @fmt: format string
@@ -1830,19 +1854,15 @@ EXPORT_SYMBOL(printk_emit);
*/
asmlinkage __visible int printk(const char *fmt, ...)
{
+ printk_func_t vprintk_func;
va_list args;
int r;
-#ifdef CONFIG_KGDB_KDB
- if (unlikely(kdb_trap_printk)) {
- va_start(args, fmt);
- r = vkdb_printf(fmt, args);
- va_end(args);
- return r;
- }
-#endif
va_start(args, fmt);
- r = vprintk_emit(0, -1, NULL, 0, fmt, args);
+ preempt_disable();
+ vprintk_func = this_cpu_read(printk_func);
+ r = vprintk_func(fmt, args);
+ preempt_enable();
va_end(args);
return r;
--
2.1.1
^ permalink raw reply related [flat|nested] 16+ messages in thread
* [for-next][PATCH 15/15] x86/nmi: Perform a safe NMI stack trace on all CPUs
2014-11-20 15:21 [for-next][PATCH 00/15] tracing/seq-buf/printk: New seq-buf utility from trace_seq for printk in NMI Steven Rostedt
` (13 preceding siblings ...)
2014-11-20 15:21 ` [for-next][PATCH 14/15] printk: Add per_cpu printk func to allow printk to be diverted Steven Rostedt
@ 2014-11-20 15:21 ` Steven Rostedt
14 siblings, 0 replies; 16+ messages in thread
From: Steven Rostedt @ 2014-11-20 15:21 UTC (permalink / raw)
To: linux-kernel
Cc: Ingo Molnar, Andrew Morton, Jiri Kosina, Petr Mladek, Paul E. McKenney
[-- Attachment #1: 0015-x86-nmi-Perform-a-safe-NMI-stack-trace-on-all-CPUs.patch --]
[-- Type: text/plain, Size: 5451 bytes --]
From: "Steven Rostedt (Red Hat)" <rostedt@goodmis.org>
When trigger_all_cpu_backtrace() is called on x86, it will trigger an
NMI on each CPU and call show_regs(). But this can lead to a hard lock
up if the NMI comes in on another printk().
In order to avoid this, when the NMI triggers, it switches the printk
routine for that CPU to call a NMI safe printk function that records the
printk in a per_cpu seq_buf descriptor. After all NMIs have finished
recording its data, the seq_bufs are printed in a safe context.
Link: http://lkml.kernel.org/p/20140619213952.360076309@goodmis.org
Link: http://lkml.kernel.org/r/20141115050605.055232587@goodmis.org
Tested-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Petr Mladek <pmladek@suse.cz>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
arch/x86/kernel/apic/hw_nmi.c | 91 ++++++++++++++++++++++++++++++++++++++++---
1 file changed, 86 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kernel/apic/hw_nmi.c b/arch/x86/kernel/apic/hw_nmi.c
index 6a1e71bde323..c95c3e9ce196 100644
--- a/arch/x86/kernel/apic/hw_nmi.c
+++ b/arch/x86/kernel/apic/hw_nmi.c
@@ -18,6 +18,7 @@
#include <linux/nmi.h>
#include <linux/module.h>
#include <linux/delay.h>
+#include <linux/seq_buf.h>
#ifdef CONFIG_HARDLOCKUP_DETECTOR
u64 hw_nmi_get_sample_period(int watchdog_thresh)
@@ -29,14 +30,35 @@ u64 hw_nmi_get_sample_period(int watchdog_thresh)
#ifdef arch_trigger_all_cpu_backtrace
/* For reliability, we're prepared to waste bits here. */
static DECLARE_BITMAP(backtrace_mask, NR_CPUS) __read_mostly;
+static cpumask_var_t printtrace_mask;
+
+#define NMI_BUF_SIZE 4096
+
+struct nmi_seq_buf {
+ unsigned char buffer[NMI_BUF_SIZE];
+ struct seq_buf seq;
+};
+
+/* Safe printing in NMI context */
+static DEFINE_PER_CPU(struct nmi_seq_buf, nmi_print_seq);
/* "in progress" flag of arch_trigger_all_cpu_backtrace */
static unsigned long backtrace_flag;
+static void print_seq_line(struct nmi_seq_buf *s, int start, int end)
+{
+ const char *buf = s->buffer + start;
+
+ printk("%.*s", (end - start) + 1, buf);
+}
+
void arch_trigger_all_cpu_backtrace(bool include_self)
{
+ struct nmi_seq_buf *s;
+ int len;
+ int cpu;
int i;
- int cpu = get_cpu();
+ int this_cpu = get_cpu();
if (test_and_set_bit(0, &backtrace_flag)) {
/*
@@ -49,7 +71,17 @@ void arch_trigger_all_cpu_backtrace(bool include_self)
cpumask_copy(to_cpumask(backtrace_mask), cpu_online_mask);
if (!include_self)
- cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
+ cpumask_clear_cpu(this_cpu, to_cpumask(backtrace_mask));
+
+ cpumask_copy(printtrace_mask, to_cpumask(backtrace_mask));
+ /*
+ * Set up per_cpu seq_buf buffers that the NMIs running on the other
+ * CPUs will write to.
+ */
+ for_each_cpu(cpu, to_cpumask(backtrace_mask)) {
+ s = &per_cpu(nmi_print_seq, cpu);
+ seq_buf_init(&s->seq, s->buffer, NMI_BUF_SIZE);
+ }
if (!cpumask_empty(to_cpumask(backtrace_mask))) {
pr_info("sending NMI to %s CPUs:\n",
@@ -65,11 +97,58 @@ void arch_trigger_all_cpu_backtrace(bool include_self)
touch_softlockup_watchdog();
}
+ /*
+ * Now that all the NMIs have triggered, we can dump out their
+ * back traces safely to the console.
+ */
+ for_each_cpu(cpu, printtrace_mask) {
+ int last_i = 0;
+
+ s = &per_cpu(nmi_print_seq, cpu);
+ len = seq_buf_used(&s->seq);
+ if (!len)
+ continue;
+
+ /* Print line by line. */
+ for (i = 0; i < len; i++) {
+ if (s->buffer[i] == '\n') {
+ print_seq_line(s, last_i, i);
+ last_i = i + 1;
+ }
+ }
+ /* Check if there was a partial line. */
+ if (last_i < len) {
+ print_seq_line(s, last_i, len - 1);
+ pr_cont("\n");
+ }
+ }
+
clear_bit(0, &backtrace_flag);
smp_mb__after_atomic();
put_cpu();
}
+/*
+ * It is not safe to call printk() directly from NMI handlers.
+ * It may be fine if the NMI detected a lock up and we have no choice
+ * but to do so, but doing a NMI on all other CPUs to get a back trace
+ * can be done with a sysrq-l. We don't want that to lock up, which
+ * can happen if the NMI interrupts a printk in progress.
+ *
+ * Instead, we redirect the vprintk() to this nmi_vprintk() that writes
+ * the content into a per cpu seq_buf buffer. Then when the NMIs are
+ * all done, we can safely dump the contents of the seq_buf to a printk()
+ * from a non NMI context.
+ */
+static int nmi_vprintk(const char *fmt, va_list args)
+{
+ struct nmi_seq_buf *s = this_cpu_ptr(&nmi_print_seq);
+ unsigned int len = seq_buf_used(&s->seq);
+
+ seq_buf_vprintf(&s->seq, fmt, args);
+ return seq_buf_used(&s->seq) - len;
+}
+
static int
arch_trigger_all_cpu_backtrace_handler(unsigned int cmd, struct pt_regs *regs)
{
@@ -78,12 +157,14 @@ arch_trigger_all_cpu_backtrace_handler(unsigned int cmd, struct pt_regs *regs)
cpu = smp_processor_id();
if (cpumask_test_cpu(cpu, to_cpumask(backtrace_mask))) {
- static arch_spinlock_t lock = __ARCH_SPIN_LOCK_UNLOCKED;
+ printk_func_t printk_func_save = this_cpu_read(printk_func);
- arch_spin_lock(&lock);
+ /* Replace printk to write into the NMI seq */
+ this_cpu_write(printk_func, nmi_vprintk);
printk(KERN_WARNING "NMI backtrace for cpu %d\n", cpu);
show_regs(regs);
- arch_spin_unlock(&lock);
+ this_cpu_write(printk_func, printk_func_save);
+
cpumask_clear_cpu(cpu, to_cpumask(backtrace_mask));
return NMI_HANDLED;
}
--
2.1.1
^ permalink raw reply related [flat|nested] 16+ messages in thread
end of thread, other threads:[~2014-11-20 15:32 UTC | newest]
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2014-11-20 15:21 [for-next][PATCH 00/15] tracing/seq-buf/printk: New seq-buf utility from trace_seq for printk in NMI Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 01/15] tracing: Create seq_buf layer in trace_seq Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 02/15] tracing: Convert seq_buf_path() to be like seq_path() Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 03/15] tracing: Convert seq_buf fields to be like seq_file fields Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 04/15] tracing: Add a seq_buf_clear() helper and clear len and readpos in init Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 05/15] seq_buf: Create seq_buf_used() to find out how much was written Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 06/15] tracing: Clean up tracing_fill_pipe_page() Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 07/15] tracing: Use trace_seq_used() and seq_buf_used() instead of len Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 08/15] tracing: Add paranoid size check in trace_printk_seq() Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 09/15] seq_buf: Add seq_buf_can_fit() helper function Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 10/15] tracing: Have seq_buf use full buffer Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 11/15] tracing: Add seq_buf_get_buf() and seq_buf_commit() helper functions Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 12/15] seq-buf: Make seq_buf_bprintf() conditional on CONFIG_BINARY_PRINTF Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 13/15] seq_buf: Move the seq_buf code to lib/ Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 14/15] printk: Add per_cpu printk func to allow printk to be diverted Steven Rostedt
2014-11-20 15:21 ` [for-next][PATCH 15/15] x86/nmi: Perform a safe NMI stack trace on all CPUs Steven Rostedt
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