KERN_<LEVEL> currently takes up 3 bytes.
Shrink the kernel size by using an ASCII SOH and then the level byte.
Remove the need for KERN_CONT.
Convert directly embedded uses of <.> to KERN_<LEVEL>
Joe Perches (8):
printk: Add generic functions to find KERN_<LEVEL> headers
printk: Add kern_levels.h to make KERN_<LEVEL> available for asm use
arch: Remove direct definitions of KERN_<LEVEL> uses
btrfs: Use printk_get_level and printk_skip_level, add __printf, fix fallout
sound: Use printk_get_level and printk_skip_level
staging: wlags49_h2: Remove direct declarations of KERN_<LEVEL> prefixes
printk: Convert the format for KERN_<LEVEL> to a 2 byte pattern
printk: Remove the now unnecessary "C" annotation for KERN_CONT
arch/arm/lib/io-acorn.S | 3 +-
arch/arm/vfp/vfphw.S | 7 +++--
arch/frv/kernel/kernel_thread.S | 2 +-
drivers/staging/wlags49_h2/hcf.c | 8 +++---
drivers/staging/wlags49_h2/wl_main.c | 4 +-
fs/btrfs/ctree.h | 13 ++++++++++
fs/btrfs/disk-io.c | 2 +-
fs/btrfs/relocation.c | 2 +-
fs/btrfs/super.c | 41 +++++++++++++++++++++++++++++-----
include/linux/kern_levels.h | 25 ++++++++++++++++++++
include/linux/printk.h | 41 +++++++++++++++++++--------------
kernel/printk.c | 14 +++++++----
sound/core/misc.c | 13 +++++++---
13 files changed, 130 insertions(+), 45 deletions(-)
create mode 100644 include/linux/kern_levels.h
--
1.7.8.111.gad25c.dirty
The current form of a KERN_<LEVEL> is "<.>".
Add printk_get_level and printk_skip_level functions
to handle these formats.
These functions centralize tests of KERN_<LEVEL> so a future
modification can change the KERN_<LEVEL> style and shorten
the number of bytes consumed by these headers.
Signed-off-by: Joe Perches <[email protected]>
---
include/linux/printk.h | 26 ++++++++++++++++++++++++++
kernel/printk.c | 13 ++++++++-----
2 files changed, 34 insertions(+), 5 deletions(-)
diff --git a/include/linux/printk.h b/include/linux/printk.h
index 1bec2f7..6e12e1f 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -24,6 +24,32 @@ extern const char linux_proc_banner[];
*/
#define KERN_CONT "<c>"
+static inline int printk_get_level(const char *buffer)
+{
+ if (buffer[0] == '<' && buffer[1] && buffer[2] == '>') {
+ switch (buffer[1]) {
+ case '0' ... '7':
+ case 'd': /* KERN_DEFAULT */
+ case 'c': /* KERN_CONT */
+ return buffer[1];
+ }
+ }
+ return 0;
+}
+
+static inline const char *printk_skip_level(const char *buffer)
+{
+ if (printk_get_level(buffer)) {
+ switch (buffer[1]) {
+ case '0' ... '7':
+ case 'd': /* KERN_DEFAULT */
+ case 'c': /* KERN_CONT */
+ return buffer + 3;
+ }
+ }
+ return buffer;
+}
+
extern int console_printk[];
#define console_loglevel (console_printk[0])
diff --git a/kernel/printk.c b/kernel/printk.c
index 32462d2..7cce9c5 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -1267,6 +1267,7 @@ asmlinkage int vprintk_emit(int facility, int level,
static char cont_buf[LOG_LINE_MAX];
static size_t cont_len;
static int cont_level;
+ int kern_level;
static struct task_struct *cont_task;
static char textbuf[LOG_LINE_MAX];
char *text = textbuf;
@@ -1329,17 +1330,19 @@ asmlinkage int vprintk_emit(int facility, int level,
}
/* strip syslog prefix and extract log level or control flags */
- if (text[0] == '<' && text[1] && text[2] == '>') {
- switch (text[1]) {
+ kern_level = printk_get_level(text);
+ if (kern_level) {
+ const char *end_of_header = printk_skip_level(text);
+ switch (kern_level) {
case '0' ... '7':
if (level == -1)
- level = text[1] - '0';
+ level = kern_level - '0';
case 'd': /* KERN_DEFAULT */
prefix = true;
case 'c': /* KERN_CONT */
- text += 3;
- text_len -= 3;
}
+ text_len -= end_of_header - text;
+ text = end_of_header;
}
if (level == -1)
--
1.7.8.111.gad25c.dirty
Separate the printk.h file into 2 pieces so the definitions
can be used in asm files.
Signed-off-by: Joe Perches <[email protected]>
---
include/linux/kern_levels.h | 22 ++++++++++++++++++++++
include/linux/printk.h | 19 +------------------
2 files changed, 23 insertions(+), 18 deletions(-)
create mode 100644 include/linux/kern_levels.h
diff --git a/include/linux/kern_levels.h b/include/linux/kern_levels.h
new file mode 100644
index 0000000..337e56f
--- /dev/null
+++ b/include/linux/kern_levels.h
@@ -0,0 +1,22 @@
+#ifndef __KERN_LEVELS_H__
+#define __KERN_LEVELS_H__
+
+#define KERN_EMERG "<0>" /* system is unusable */
+#define KERN_ALERT "<1>" /* action must be taken immediately */
+#define KERN_CRIT "<2>" /* critical conditions */
+#define KERN_ERR "<3>" /* error conditions */
+#define KERN_WARNING "<4>" /* warning conditions */
+#define KERN_NOTICE "<5>" /* normal but significant condition */
+#define KERN_INFO "<6>" /* informational */
+#define KERN_DEBUG "<7>" /* debug-level messages */
+
+/* Use the default kernel loglevel */
+#define KERN_DEFAULT "<d>"
+/*
+ * Annotation for a "continued" line of log printout (only done after a
+ * line that had no enclosing \n). Only to be used by core/arch code
+ * during early bootup (a continued line is not SMP-safe otherwise).
+ */
+#define KERN_CONT "<c>"
+
+#endif
diff --git a/include/linux/printk.h b/include/linux/printk.h
index 6e12e1f..fea2de3 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -2,28 +2,11 @@
#define __KERNEL_PRINTK__
#include <linux/init.h>
+#include <linux/kern_levels.h>
extern const char linux_banner[];
extern const char linux_proc_banner[];
-#define KERN_EMERG "<0>" /* system is unusable */
-#define KERN_ALERT "<1>" /* action must be taken immediately */
-#define KERN_CRIT "<2>" /* critical conditions */
-#define KERN_ERR "<3>" /* error conditions */
-#define KERN_WARNING "<4>" /* warning conditions */
-#define KERN_NOTICE "<5>" /* normal but significant condition */
-#define KERN_INFO "<6>" /* informational */
-#define KERN_DEBUG "<7>" /* debug-level messages */
-
-/* Use the default kernel loglevel */
-#define KERN_DEFAULT "<d>"
-/*
- * Annotation for a "continued" line of log printout (only done after a
- * line that had no enclosing \n). Only to be used by core/arch code
- * during early bootup (a continued line is not SMP-safe otherwise).
- */
-#define KERN_CONT "<c>"
-
static inline int printk_get_level(const char *buffer)
{
if (buffer[0] == '<' && buffer[1] && buffer[2] == '>') {
--
1.7.8.111.gad25c.dirty
Add #include <linux/kern_levels.h> so that the #define KERN_<LEVEL>
macros don't have to be duplicated.
Signed-off-by: Joe Perches <[email protected]>
---
arch/arm/lib/io-acorn.S | 3 ++-
arch/arm/vfp/vfphw.S | 7 ++++---
arch/frv/kernel/kernel_thread.S | 2 +-
3 files changed, 7 insertions(+), 5 deletions(-)
diff --git a/arch/arm/lib/io-acorn.S b/arch/arm/lib/io-acorn.S
index 1b197ea..69719ba 100644
--- a/arch/arm/lib/io-acorn.S
+++ b/arch/arm/lib/io-acorn.S
@@ -11,13 +11,14 @@
*
*/
#include <linux/linkage.h>
+#include <linux/kern_levels.h>
#include <asm/assembler.h>
.text
.align
.Liosl_warning:
- .ascii "<4>insl/outsl not implemented, called from %08lX\0"
+ .ascii KERN_WARNING "insl/outsl not implemented, called from %08lX\0"
.align
/*
diff --git a/arch/arm/vfp/vfphw.S b/arch/arm/vfp/vfphw.S
index 2d30c7f..d50f0e4 100644
--- a/arch/arm/vfp/vfphw.S
+++ b/arch/arm/vfp/vfphw.S
@@ -16,6 +16,7 @@
*/
#include <asm/thread_info.h>
#include <asm/vfpmacros.h>
+#include <linux/kern_levels.h>
#include "../kernel/entry-header.S"
.macro DBGSTR, str
@@ -24,7 +25,7 @@
add r0, pc, #4
bl printk
b 1f
- .asciz "<7>VFP: \str\n"
+ .asciz KERN_DEBUG "VFP: \str\n"
.balign 4
1: ldmfd sp!, {r0-r3, ip, lr}
#endif
@@ -37,7 +38,7 @@
add r0, pc, #4
bl printk
b 1f
- .asciz "<7>VFP: \str\n"
+ .asciz KERN_DEBUG "VFP: \str\n"
.balign 4
1: ldmfd sp!, {r0-r3, ip, lr}
#endif
@@ -52,7 +53,7 @@
add r0, pc, #4
bl printk
b 1f
- .asciz "<7>VFP: \str\n"
+ .asciz KERN_DEBUG "VFP: \str\n"
.balign 4
1: ldmfd sp!, {r0-r3, ip, lr}
#endif
diff --git a/arch/frv/kernel/kernel_thread.S b/arch/frv/kernel/kernel_thread.S
index 4531c83..f0e5294 100644
--- a/arch/frv/kernel/kernel_thread.S
+++ b/arch/frv/kernel/kernel_thread.S
@@ -10,10 +10,10 @@
*/
#include <linux/linkage.h>
+#include <linux/kern_levels.h>
#include <asm/unistd.h>
#define CLONE_VM 0x00000100 /* set if VM shared between processes */
-#define KERN_ERR "<3>"
.section .rodata
kernel_thread_emsg:
--
1.7.8.111.gad25c.dirty
Use the generic printk_get_level function to search a message
for a kern_level. Add __printf to verify format and arguments.
Fix a few messages that had mismatches in format and arguments.
Add #ifdef CONFIG_PRINTK blocks to shrink the object size a bit
when not using printk.
Signed-off-by: Joe Perches <[email protected]>
---
fs/btrfs/ctree.h | 13 +++++++++++++
fs/btrfs/disk-io.c | 2 +-
fs/btrfs/relocation.c | 2 +-
fs/btrfs/super.c | 41 +++++++++++++++++++++++++++++++++++------
4 files changed, 50 insertions(+), 8 deletions(-)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 0236d03..590b519 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -3046,10 +3046,22 @@ ssize_t btrfs_listxattr(struct dentry *dentry, char *buffer, size_t size);
/* super.c */
int btrfs_parse_options(struct btrfs_root *root, char *options);
int btrfs_sync_fs(struct super_block *sb, int wait);
+
+#ifdef CONFIG_PRINTK
+__printf(2, 3)
void btrfs_printk(struct btrfs_fs_info *fs_info, const char *fmt, ...);
+#else
+static inline __printf(2, 3)
+void btrfs_printk(struct btrfs_fs_info *fs_info, const char *fmt, ...)
+{
+}
+#endif
+
+__printf(5, 6)
void __btrfs_std_error(struct btrfs_fs_info *fs_info, const char *function,
unsigned int line, int errno, const char *fmt, ...);
+
void __btrfs_abort_transaction(struct btrfs_trans_handle *trans,
struct btrfs_root *root, const char *function,
unsigned int line, int errno);
@@ -3073,6 +3085,7 @@ do { \
(errno), fmt, ##args); \
} while (0)
+__printf(5, 6)
void __btrfs_panic(struct btrfs_fs_info *fs_info, const char *function,
unsigned int line, int errno, const char *fmt, ...);
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 7ae51de..f02bba5 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1113,7 +1113,7 @@ void clean_tree_block(struct btrfs_trans_handle *trans, struct btrfs_root *root,
spin_unlock(&root->fs_info->delalloc_lock);
btrfs_panic(root->fs_info, -EOVERFLOW,
"Can't clear %lu bytes from "
- " dirty_mdatadata_bytes (%lu)",
+ " dirty_mdatadata_bytes (%llu)",
buf->len,
root->fs_info->dirty_metadata_bytes);
}
diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 646ee21..790f492 100644
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -1242,7 +1242,7 @@ static int __must_check __add_reloc_root(struct btrfs_root *root)
kfree(node);
btrfs_panic(root->fs_info, -EEXIST, "Duplicate root found "
"for start=%llu while inserting into relocation "
- "tree\n");
+ "tree\n", node->bytenr);
}
list_add_tail(&root->root_list, &rc->reloc_roots);
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 96eb9fe..a84529d 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -124,6 +124,7 @@ static void btrfs_handle_error(struct btrfs_fs_info *fs_info)
}
}
+#ifdef CONFIG_PRINTK
/*
* __btrfs_std_error decodes expected errors from the caller and
* invokes the approciate error response.
@@ -166,7 +167,7 @@ void __btrfs_std_error(struct btrfs_fs_info *fs_info, const char *function,
va_end(args);
}
-const char *logtypes[] = {
+static const char *logtypes[] = {
"emergency",
"alert",
"critical",
@@ -184,22 +185,50 @@ void btrfs_printk(struct btrfs_fs_info *fs_info, const char *fmt, ...)
struct va_format vaf;
va_list args;
const char *type = logtypes[4];
+ int kern_level;
va_start(args, fmt);
- if (fmt[0] == '<' && isdigit(fmt[1]) && fmt[2] == '>') {
- memcpy(lvl, fmt, 3);
- lvl[3] = '\0';
- fmt += 3;
- type = logtypes[fmt[1] - '0'];
+ kern_level = printk_get_level(fmt);
+ if (kern_level) {
+ size_t size = printk_skip_level(fmt) - fmt;
+ memcpy(lvl, fmt, size);
+ lvl[size] = '\0';
+ fmt += size;
+ type = logtypes[kern_level - '0'];
} else
*lvl = '\0';
vaf.fmt = fmt;
vaf.va = &args;
+
printk("%sBTRFS %s (device %s): %pV", lvl, type, sb->s_id, &vaf);
+
+ va_end(args);
}
+#else
+
+void __btrfs_std_error(struct btrfs_fs_info *fs_info, const char *function,
+ unsigned int line, int errno, const char *fmt, ...)
+{
+ struct super_block *sb = fs_info->sb;
+
+ /*
+ * Special case: if the error is EROFS, and we're already
+ * under MS_RDONLY, then it is safe here.
+ */
+ if (errno == -EROFS && (sb->s_flags & MS_RDONLY))
+ return;
+
+ /* Don't go through full error handling during mount */
+ if (sb->s_flags & MS_BORN) {
+ save_error_info(fs_info);
+ btrfs_handle_error(fs_info);
+ }
+}
+#endif
+
/*
* We only mark the transaction aborted and then set the file system read-only.
* This will prevent new transactions from starting or trying to join this
--
1.7.8.111.gad25c.dirty
Make the output logging routine independent of the
KERN_<LEVEL> style.
Signed-off-by: Joe Perches <[email protected]>
---
sound/core/misc.c | 13 +++++++++----
1 files changed, 9 insertions(+), 4 deletions(-)
diff --git a/sound/core/misc.c b/sound/core/misc.c
index 7681679..30e027e 100644
--- a/sound/core/misc.c
+++ b/sound/core/misc.c
@@ -68,6 +68,7 @@ void __snd_printk(unsigned int level, const char *path, int line,
{
va_list args;
#ifdef CONFIG_SND_VERBOSE_PRINTK
+ int kern_level;
struct va_format vaf;
char verbose_fmt[] = KERN_DEFAULT "ALSA %s:%d %pV";
#endif
@@ -81,12 +82,16 @@ void __snd_printk(unsigned int level, const char *path, int line,
#ifdef CONFIG_SND_VERBOSE_PRINTK
vaf.fmt = format;
vaf.va = &args;
- if (format[0] == '<' && format[2] == '>') {
- memcpy(verbose_fmt, format, 3);
- vaf.fmt = format + 3;
+
+ kern_level = printk_get_level(format);
+ if (kern_level) {
+ const char *end_of_header = printk_skip_level(format);
+ memcpy(verbose_fmt, format, end_of_header - format);
+ vaf.fmt = end_of_header;
} else if (level)
- memcpy(verbose_fmt, KERN_DEBUG, 3);
+ memcpy(verbose_fmt, KERN_DEBUG, sizeof(KERN_DEBUG) - 1);
printk(verbose_fmt, sanity_file_name(path), line, &vaf);
+
#else
vprintk(format, args);
#endif
--
1.7.8.111.gad25c.dirty
Use the standard KERN_<LEVEL> #defines instead of "<.>"
Signed-off-by: Joe Perches <[email protected]>
---
drivers/staging/wlags49_h2/hcf.c | 8 ++++----
drivers/staging/wlags49_h2/wl_main.c | 4 ++--
2 files changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/staging/wlags49_h2/hcf.c b/drivers/staging/wlags49_h2/hcf.c
index 366e4a4..4235446 100644
--- a/drivers/staging/wlags49_h2/hcf.c
+++ b/drivers/staging/wlags49_h2/hcf.c
@@ -705,7 +705,7 @@ hcf_action( IFBP ifbp, hcf_16 action )
// 800 us latency before FW switches to high power
MSF_WAIT(800); // MSF-defined function to wait n microseconds.
//OOR if ( ifbp->IFB_DSLinkStat & CFG_LINK_STAT_DS_OOR ) { // OutOfRange
-// printk( "<5>ACT_INT_OFF: Deepsleep phase terminated, enable and go to AwaitConnection\n" ); //;?remove me 1 day
+// printk(KERN_NOTICE "ACT_INT_OFF: Deepsleep phase terminated, enable and go to AwaitConnection\n" ); //;?remove me 1 day
// hcf_cntl( ifbp, HCF_CNTL_ENABLE );
// }
// ifbp->IFB_DSLinkStat &= ~( CFG_LINK_STAT_DS_IR | CFG_LINK_STAT_DS_OOR); //clear IR/OOR state
@@ -2979,7 +2979,7 @@ hcf_service_nic( IFBP ifbp, wci_bufp bufp, unsigned int len )
ltv.typ = CFG_DDS_TICK_TIME;
ltv.tick_time = ( ( ifbp->IFB_DSLinkStat & CFG_LINK_STAT_TIMER ) + 0x10 ) *64; //78 is more right
hcf_put_info( ifbp, (LTVP)<v );
- printk( "<5>Preparing for sleep, link_status: %04X, timer : %d\n",
+ printk(KERN_NOTICE "Preparing for sleep, link_status: %04X, timer : %d\n",
ifbp->IFB_DSLinkStat, ltv.tick_time );//;?remove me 1 day
ifbp->IFB_TickCnt++; //;?just to make sure we do not keep on printing above message
if ( ltv.tick_time < 300 * 125 ) ifbp->IFB_DSLinkStat += 0x0010;
@@ -4221,11 +4221,11 @@ isr_info( IFBP ifbp )
// /*4*/ if ( info[1] == CFG_LINK_STAT ) {
// ifbp->IFB_DSLinkStat = IPW( HREG_DATA_1 ) | CFG_LINK_STAT_CHANGE; //corrupts BAP !! ;?
// ifbp->IFB_LinkStat = ifbp->IFB_DSLinkStat & CFG_LINK_STAT_FW; //;? to be obsoleted
-// printk( "<4>linkstatus: %04x\n", ifbp->IFB_DSLinkStat ); //;?remove me 1 day
+// printk(KERN_ERR "linkstatus: %04x\n", ifbp->IFB_DSLinkStat ); //;?remove me 1 day
// #if (HCF_SLEEP) & HCF_DDS
// if ( ( ifbp->IFB_DSLinkStat & CFG_LINK_STAT_CONNECTED ) == 0 ) { //even values are disconnected etc.
// ifbp->IFB_TickCnt = 0; //start 2 second period (with 1 tick uncertanty)
-// printk( "<5>isr_info: AwaitConnection phase started, IFB_TickCnt = 0\n" ); //;?remove me 1 day
+// printk(KERN_NOTICE "isr_info: AwaitConnection phase started, IFB_TickCnt = 0\n" ); //;?remove me 1 day
// }
// #endif // HCF_DDS
// }
diff --git a/drivers/staging/wlags49_h2/wl_main.c b/drivers/staging/wlags49_h2/wl_main.c
index d5bf0a7..2041078 100644
--- a/drivers/staging/wlags49_h2/wl_main.c
+++ b/drivers/staging/wlags49_h2/wl_main.c
@@ -3822,7 +3822,7 @@ static int write_int(struct file *file, const char *buffer, unsigned long count,
lp->timer_oor.data = (unsigned long)lp;
lp->timer_oor.expires = RUN_AT( 3 * HZ );
add_timer( &lp->timer_oor );
- printk( "<5>wl_enable: %ld\n", jiffies ); //;?remove me 1 day
+ printk(KERN_NOTICE "wl_enable: %ld\n", jiffies ); //;?remove me 1 day
#endif //DN554
#ifdef DN554
/*******************************************************************************
@@ -3852,7 +3852,7 @@ void timer_oor( u_long arg )
DBG_ENTER( DbgInfo );
DBG_PARAM( DbgInfo, "arg", "0x%08lx", arg );
- printk( "<5>timer_oor: %ld 0x%04X\n", jiffies, lp->timer_oor_cnt ); //;?remove me 1 day
+ printk(KERN_NOTICE "timer_oor: %ld 0x%04X\n", jiffies, lp->timer_oor_cnt ); //;?remove me 1 day
lp->timer_oor_cnt += 10;
if ( (lp->timer_oor_cnt & ~DS_OOR) > 300 ) {
lp->timer_oor_cnt = 300;
--
1.7.8.111.gad25c.dirty
Instead of "<.>", use an ASCII SOH for the KERN_<LEVEL>
prefix initiator.
This saves 1 byte per printk, thousands of bytes in a normal kernel.
No output changes are produced as vprintk_emit converts these
uses to "<.>".
Signed-off-by: Joe Perches <[email protected]>
---
include/linux/kern_levels.h | 25 ++++++++++++++-----------
include/linux/printk.h | 4 ++--
kernel/printk.c | 3 ++-
3 files changed, 18 insertions(+), 14 deletions(-)
diff --git a/include/linux/kern_levels.h b/include/linux/kern_levels.h
index 337e56f..8c719a9 100644
--- a/include/linux/kern_levels.h
+++ b/include/linux/kern_levels.h
@@ -1,22 +1,25 @@
#ifndef __KERN_LEVELS_H__
#define __KERN_LEVELS_H__
-#define KERN_EMERG "<0>" /* system is unusable */
-#define KERN_ALERT "<1>" /* action must be taken immediately */
-#define KERN_CRIT "<2>" /* critical conditions */
-#define KERN_ERR "<3>" /* error conditions */
-#define KERN_WARNING "<4>" /* warning conditions */
-#define KERN_NOTICE "<5>" /* normal but significant condition */
-#define KERN_INFO "<6>" /* informational */
-#define KERN_DEBUG "<7>" /* debug-level messages */
+#define KERN_SOH "\001" /* ASCII Start Of Header */
+#define KERN_SOH_ASCII '\001'
+
+#define KERN_EMERG KERN_SOH "0" /* system is unusable */
+#define KERN_ALERT KERN_SOH "1" /* action must be taken immediately */
+#define KERN_CRIT KERN_SOH "2" /* critical conditions */
+#define KERN_ERR KERN_SOH "3" /* error conditions */
+#define KERN_WARNING KERN_SOH "4" /* warning conditions */
+#define KERN_NOTICE KERN_SOH "5" /* normal but significant condition */
+#define KERN_INFO KERN_SOH "6" /* informational */
+#define KERN_DEBUG KERN_SOH "7" /* debug-level messages */
+
+#define KERN_DEFAULT KERN_SOH "d" /* the default kernel loglevel */
-/* Use the default kernel loglevel */
-#define KERN_DEFAULT "<d>"
/*
* Annotation for a "continued" line of log printout (only done after a
* line that had no enclosing \n). Only to be used by core/arch code
* during early bootup (a continued line is not SMP-safe otherwise).
*/
-#define KERN_CONT "<c>"
+#define KERN_CONT KERN_SOH "c"
#endif
diff --git a/include/linux/printk.h b/include/linux/printk.h
index fea2de3..93a231f 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -9,7 +9,7 @@ extern const char linux_proc_banner[];
static inline int printk_get_level(const char *buffer)
{
- if (buffer[0] == '<' && buffer[1] && buffer[2] == '>') {
+ if (buffer[0] == KERN_SOH_ASCII && buffer[1]) {
switch (buffer[1]) {
case '0' ... '7':
case 'd': /* KERN_DEFAULT */
@@ -27,7 +27,7 @@ static inline const char *printk_skip_level(const char *buffer)
case '0' ... '7':
case 'd': /* KERN_DEFAULT */
case 'c': /* KERN_CONT */
- return buffer + 3;
+ return buffer + 2;
}
}
return buffer;
diff --git a/kernel/printk.c b/kernel/printk.c
index 7cce9c5..5cd73f7 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -1340,9 +1340,10 @@ asmlinkage int vprintk_emit(int facility, int level,
case 'd': /* KERN_DEFAULT */
prefix = true;
case 'c': /* KERN_CONT */
+ break;
}
text_len -= end_of_header - text;
- text = end_of_header;
+ text = (char *)end_of_header;
}
if (level == -1)
--
1.7.8.111.gad25c.dirty
Now that all KERN_<LEVEL> uses are prefixed with ASCII SOH,
there is no need for a KERN_CONT. Keep it backward compatible
by adding #define KERN_CONT ""
Reduces kernel image size a thousand bytes.
Signed-off-by: Joe Perches <[email protected]>
---
include/linux/kern_levels.h | 2 +-
include/linux/printk.h | 2 --
2 files changed, 1 insertions(+), 3 deletions(-)
diff --git a/include/linux/kern_levels.h b/include/linux/kern_levels.h
index 8c719a9..866caaa 100644
--- a/include/linux/kern_levels.h
+++ b/include/linux/kern_levels.h
@@ -20,6 +20,6 @@
* line that had no enclosing \n). Only to be used by core/arch code
* during early bootup (a continued line is not SMP-safe otherwise).
*/
-#define KERN_CONT KERN_SOH "c"
+#define KERN_CONT ""
#endif
diff --git a/include/linux/printk.h b/include/linux/printk.h
index 93a231f..9afc01e 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -13,7 +13,6 @@ static inline int printk_get_level(const char *buffer)
switch (buffer[1]) {
case '0' ... '7':
case 'd': /* KERN_DEFAULT */
- case 'c': /* KERN_CONT */
return buffer[1];
}
}
@@ -26,7 +25,6 @@ static inline const char *printk_skip_level(const char *buffer)
switch (buffer[1]) {
case '0' ... '7':
case 'd': /* KERN_DEFAULT */
- case 'c': /* KERN_CONT */
return buffer + 2;
}
}
--
1.7.8.111.gad25c.dirty
On Tue, 5 Jun 2012 02:46:29 -0700
Joe Perches <[email protected]> wrote:
> KERN_<LEVEL> currently takes up 3 bytes.
> Shrink the kernel size by using an ASCII SOH and then the level byte.
> Remove the need for KERN_CONT.
> Convert directly embedded uses of <.> to KERN_<LEVEL>
What an epic patchset. I guess that saving a byte per printk does make
the world a better place, and forcibly ensuring that nothing is
dependent upon the internal format of the KERN_foo strings is nice.
Unfortunately the <n> thing is part of the kernel ABI:
echo "<4>foo" > /dev/kmsg
devkmsg_writev() does weird and wonderful things with
facilities/levels. That function incorrectly returns "success" when
copy_from_user() faults, btw. It also babbles on about LOG_USER and
LOG_KERN without ever defining these things. I guess they're
userspace-only concepts and are hardwired to 0 and 1 in the kernel. Or
not.
So what to do about /dev/kmsg? I'd say "nothing": we retain "<n>" as
the externally-presented kernel format for a facility level, and the
fact that the kernel internally uses a different encoding is hidden
from userspace.
And if the user does
echo "\0014foo" > /dev/kmsg
then I guess we should pass it straight through, retaining the \0014.
But from my reading of your code, this doesn't work - vprintk_emit()
will go ahead and strip and interpret the \0014, evading the stuff
which devkmsg_writev() did.
On Tue, Jun 5, 2012 at 11:28 PM, Andrew Morton
<[email protected]> wrote:
> On Tue, 5 Jun 2012 02:46:29 -0700
> Joe Perches <[email protected]> wrote:
>
>> KERN_<LEVEL> currently takes up 3 bytes.
>> Shrink the kernel size by using an ASCII SOH and then the level byte.
>> Remove the need for KERN_CONT.
>> Convert directly embedded uses of <.> to KERN_<LEVEL>
>
> What an epic patchset. I guess that saving a byte per printk does make
> the world a better place, and forcibly ensuring that nothing is
> dependent upon the internal format of the KERN_foo strings is nice.
>
>
> Unfortunately the <n> thing is part of the kernel ABI:
>
> echo "<4>foo" > /dev/kmsg
>
> devkmsg_writev() does weird and wonderful things with
> facilities/levels. That function incorrectly returns "success" when
> copy_from_user() faults, btw. It also babbles on about LOG_USER and
> LOG_KERN without ever defining these things. I guess they're
> userspace-only concepts and are hardwired to 0 and 1 in the kernel. Or
> not.
It's as old as BSD, defined by syslog(3), used by glibc. The whole
<%u> prefix notation and the LOG_* names come from there.
The kernel is just user/facility == 0, so it never really was apparent
that the whole concept has more than a log level in that number.
Userspace syslog defines these pretty stupid numbers:
/* facility codes */
#define LOG_KERN (0<<3) /* kernel messages */
#define LOG_USER (1<<3) /* random user-level messages */
#define LOG_MAIL (2<<3) /* mail system */
#define LOG_DAEMON (3<<3) /* system daemons */
#define LOG_AUTH (4<<3) /* security/authorization messages */
#define LOG_SYSLOG (5<<3) /* messages generated internally by syslogd */
#define LOG_LPR (6<<3) /* line printer subsystem */
#define LOG_NEWS (7<<3) /* network news subsystem */
#define LOG_UUCP (8<<3) /* UUCP subsystem */
#define LOG_CRON (9<<3) /* clock daemon */
#define LOG_AUTHPRIV (10<<3) /* security/authorization messages
(private) */
#define LOG_FTP (11<<3) /* ftp daemon */
but it *can* still all be pretty useful, and people *can* get creative
with facility numbers if they want to, as we have like 13 bits at the
moment to use for the facility which is stored in the kernel log
buffer. :)
/dev/kmsg just enforces LOG_USER, if userspace tries to inject stuff
with LOG_KERN, which it should not be allowed. The non-LOG_KERN number
itself has not much meaning it just says: "this is not from the
kernel" which is important to keep in the message.
Als, dmesg(1) has a -k option, that filters out all userspace-injected stuff.
> So what to do about /dev/kmsg? I'd say "nothing": we retain "<n>" as
> the externally-presented kernel format for a facility level, and the
> fact that the kernel internally uses a different encoding is hidden
> from userspace.
Yeah, I think so.
Yeah, we strip the <> at printk() time, add the <> back at output
time; they are not stored internally anymore, so that should not
affect the current behaviour.
> And if the user does
>
> echo "\0014foo" > /dev/kmsg
>
> then I guess we should pass it straight through, retaining the \0014.
> But from my reading of your code, this doesn't work - vprintk_emit()
> will go ahead and strip and interpret the \0014, evading the stuff
> which devkmsg_writev() did.
We should make it not accept faked prefixes, yes. It should be
impossible to let messages look like they originated from the kernel,
just like the current code enforces a non-LOG_KERN <> prefix.
Kay
On Tue, 2012-06-05 at 14:28 -0700, Andrew Morton wrote:
> Unfortunately the <n> thing is part of the kernel ABI:
>
> echo "<4>foo" > /dev/kmsg
Which works the same way it did before.
On Tue, 05 Jun 2012 15:11:43 -0700
Joe Perches <[email protected]> wrote:
> On Tue, 2012-06-05 at 14:28 -0700, Andrew Morton wrote:
> > Unfortunately the <n> thing is part of the kernel ABI:
> >
> > echo "<4>foo" > /dev/kmsg
>
> Which works the same way it did before.
I didn't say it didn't.
What I did say is that echo "\0014">/dev/kmsg will subvert the intent
of the new logging code. Or might. But you just ignored all that,
forcing me to repeat myself, irritatedly.
On Tue, 2012-06-05 at 15:17 -0700, Andrew Morton wrote:
> On Tue, 05 Jun 2012 15:11:43 -0700
> Joe Perches <[email protected]> wrote:
>
> > On Tue, 2012-06-05 at 14:28 -0700, Andrew Morton wrote:
> > > Unfortunately the <n> thing is part of the kernel ABI:
> > >
> > > echo "<4>foo" > /dev/kmsg
> >
> > Which works the same way it did before.
>
> I didn't say it didn't.
>
> What I did say is that echo "\0014">/dev/kmsg will subvert the intent
> of the new logging code. Or might. But you just ignored all that,
> forcing me to repeat myself, irritatedly.
It works the same way before and after the patch.
Any write to /dev/kmsg without a KERN_<LEVEL>
emits at (1 << 3) + KERN_DEFAULT.
Writes with <n> values >= 8 are emitted at
that level.
On Tue, 2012-06-05 at 14:28 -0700, Andrew Morton wrote:
> devkmsg_writev() does weird and wonderful things with
> facilities/levels. That function incorrectly returns "success" when
> copy_from_user() faults, btw.
Oh. Better?
Thanks,
Kay
From: Kay Sievers <[email protected]>
Subject: kmsg: /dev/kmsg - properly return possible copy_from_user() failure
Reported-By: Andrew Morton <[email protected]>
Signed-off-by: Kay Sievers <[email protected]
---
printk.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/kernel/printk.c b/kernel/printk.c
index 32462d2..6bdacab 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -365,8 +365,10 @@ static ssize_t devkmsg_writev(struct kiocb *iocb, const struct iovec *iv,
line = buf;
for (i = 0; i < count; i++) {
- if (copy_from_user(line, iv[i].iov_base, iv[i].iov_len))
+ if (copy_from_user(line, iv[i].iov_base, iv[i].iov_len)) {
+ ret = -EFAULT;
goto out;
+ }
line += iv[i].iov_len;
}
On Wed, 06 Jun 2012 00:55:00 +0200
Kay Sievers <[email protected]> wrote:
> On Tue, 2012-06-05 at 14:28 -0700, Andrew Morton wrote:
>
> > devkmsg_writev() does weird and wonderful things with
> > facilities/levels. That function incorrectly returns "success" when
> > copy_from_user() faults, btw.
>
> Oh. Better?
>
> Thanks,
> Kay
>
>
> From: Kay Sievers <[email protected]>
> Subject: kmsg: /dev/kmsg - properly return possible copy_from_user() failure
>
> Reported-By: Andrew Morton <[email protected]>
> Signed-off-by: Kay Sievers <[email protected]
> ---
> printk.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/printk.c b/kernel/printk.c
> index 32462d2..6bdacab 100644
> --- a/kernel/printk.c
> +++ b/kernel/printk.c
> @@ -365,8 +365,10 @@ static ssize_t devkmsg_writev(struct kiocb *iocb, const struct iovec *iv,
>
> line = buf;
> for (i = 0; i < count; i++) {
> - if (copy_from_user(line, iv[i].iov_base, iv[i].iov_len))
> + if (copy_from_user(line, iv[i].iov_base, iv[i].iov_len)) {
> + ret = -EFAULT;
> goto out;
> + }
> line += iv[i].iov_len;
> }
Strictly speaking, when write() encounters an error it should return
number-of-bytes-written, or an errno if it wrote zero bytes. So
something like
--- a/kernel/printk.c~a
+++ a/kernel/printk.c
@@ -355,7 +355,7 @@ static ssize_t devkmsg_writev(struct kio
int level = default_message_loglevel;
int facility = 1; /* LOG_USER */
size_t len = iov_length(iv, count);
- ssize_t ret = len;
+ ssize_t ret;
if (len > LOG_LINE_MAX)
return -EINVAL;
@@ -365,8 +365,12 @@ static ssize_t devkmsg_writev(struct kio
line = buf;
for (i = 0; i < count; i++) {
- if (copy_from_user(line, iv[i].iov_base, iv[i].iov_len))
+ if (copy_from_user(line, iv[i].iov_base, iv[i].iov_len)) {
+ ret = line - buf;
+ if (!ret)
+ ret = -EFAULT;
goto out;
+ }
line += iv[i].iov_len;
}
@@ -396,6 +400,7 @@ static ssize_t devkmsg_writev(struct kio
line[len] = '\0';
printk_emit(facility, level, NULL, 0, "%s", line);
+ ret = 0;
out:
kfree(buf);
return ret;
_
On Tue, 05 Jun 2012 15:49:32 -0700
Joe Perches <[email protected]> wrote:
> On Tue, 2012-06-05 at 15:17 -0700, Andrew Morton wrote:
> > On Tue, 05 Jun 2012 15:11:43 -0700
> > Joe Perches <[email protected]> wrote:
> >
> > > On Tue, 2012-06-05 at 14:28 -0700, Andrew Morton wrote:
> > > > Unfortunately the <n> thing is part of the kernel ABI:
> > > >
> > > > echo "<4>foo" > /dev/kmsg
> > >
> > > Which works the same way it did before.
> >
> > I didn't say it didn't.
> >
> > What I did say is that echo "\0014">/dev/kmsg will subvert the intent
> > of the new logging code. Or might. But you just ignored all that,
> > forcing me to repeat myself, irritatedly.
>
> It works the same way before and after the patch.
>
> Any write to /dev/kmsg without a KERN_<LEVEL>
> emits at (1 << 3) + KERN_DEFAULT.
>
> Writes with <n> values >= 8 are emitted at
> that level.
What about writes starting with \001n? AFACIT, that will be stripped
away and the printk level will be altered. This is new behavior.
On Tue, 2012-06-05 at 16:29 -0700, Andrew Morton wrote:
> What about writes starting with \001n? AFACIT, that will be stripped
> away and the printk level will be altered. This is new behavior.
Nope.
# echo "\001Hello Andrew" > /dev/kmsg
/dev/kmsg has
12,774,2462339252;\001Hello Andrew
12 is 8 + KERN_DEFAULT
# echo "<1>Hello Andrew" > /dev/kmsg
/dev/kmsg has:
9,775,2516023444;Hello Andrew
On Wed, Jun 6, 2012 at 1:35 AM, Joe Perches <[email protected]> wrote:
> On Tue, 2012-06-05 at 16:29 -0700, Andrew Morton wrote:
>> What about writes starting with \001n? AFACIT, that will be stripped
>> away and the printk level will be altered. This is new behavior.
>
> Nope.
>
> # echo "\001Hello Andrew" > /dev/kmsg
> /dev/kmsg has
> 12,774,2462339252;\001Hello Andrew
Try "echo -e"? The stuff is copied verbatim otherwise.
Kay
On Wed, 2012-06-06 at 01:39 +0200, Kay Sievers wrote:
> On Wed, Jun 6, 2012 at 1:35 AM, Joe Perches <[email protected]> wrote:
> > On Tue, 2012-06-05 at 16:29 -0700, Andrew Morton wrote:
> >> What about writes starting with \001n? AFACIT, that will be stripped
> >> away and the printk level will be altered. This is new behavior.
> >
> > Nope.
> >
> > # echo "\001Hello Andrew" > /dev/kmsg
> > /dev/kmsg has
> > 12,774,2462339252;\001Hello Andrew
>
> Try "echo -e"? The stuff is copied verbatim otherwise.
# echo -e "\001Hello Kay" > /dev/kmsg
gives
12,776,3046752764;\x01Hello Kay
On Wed, 2012-06-06 at 01:39 +0200, Kay Sievers wrote:
> Try "echo -e"? The stuff is copied verbatim otherwise.
btw: I didn't change the devkmsg_writev function
which does the decoding of any "<n>" prefix for
printk_emit.
On Wed, Jun 6, 2012 at 1:43 AM, Joe Perches <[email protected]> wrote:
> On Wed, 2012-06-06 at 01:39 +0200, Kay Sievers wrote:
>> > # echo "\001Hello Andrew" > /dev/kmsg
>> > /dev/kmsg has
>> > 12,774,2462339252;\001Hello Andrew
>>
>> Try "echo -e"? The stuff is copied verbatim otherwise.
>
> # echo -e "\001Hello Kay" > /dev/kmsg
> gives
> 12,776,3046752764;\x01Hello Kay
Don't you need two bytes to trigger the logic?
Kay
On Wed, 2012-06-06 at 01:48 +0200, Kay Sievers wrote:
> On Wed, Jun 6, 2012 at 1:43 AM, Joe Perches <[email protected]> wrote:
> > On Wed, 2012-06-06 at 01:39 +0200, Kay Sievers wrote:
>
> >> > # echo "\001Hello Andrew" > /dev/kmsg
> >> > /dev/kmsg has
> >> > 12,774,2462339252;\001Hello Andrew
> >>
> >> Try "echo -e"? The stuff is copied verbatim otherwise.
> >
> > # echo -e "\001Hello Kay" > /dev/kmsg
> > gives
> > 12,776,3046752764;\x01Hello Kay
>
> Don't you need two bytes to trigger the logic?
Yes. Angle brackets fore and aft.
If you use a "<n>" prefix for write to /dev/kmsg,
then it's supported just like before.
Otherwise, it's emitted at KERN_DEFAULT.
cheers, Joe
On Tue, 05 Jun 2012 16:52:25 -0700
Joe Perches <[email protected]> wrote:
> On Wed, 2012-06-06 at 01:48 +0200, Kay Sievers wrote:
> > On Wed, Jun 6, 2012 at 1:43 AM, Joe Perches <[email protected]> wrote:
> > > On Wed, 2012-06-06 at 01:39 +0200, Kay Sievers wrote:
> >
> > >> > # echo "\001Hello Andrew" > /dev/kmsg
> > >> > /dev/kmsg has
> > >> > 12,774,2462339252;\001Hello Andrew
> > >>
> > >> Try "echo -e"? The stuff is copied verbatim otherwise.
> > >
> > > # echo -e "\001Hello Kay" > /dev/kmsg
> > > gives
> > > 12,776,3046752764;\x01Hello Kay
> >
> > Don't you need two bytes to trigger the logic?
>
> Yes. Angle brackets fore and aft.
he means
echo "\0014Hello Joe" > /dev/kmsg
^
It needs one of [0-7cd] to trigger the prefix handling.
On Tue, 2012-06-05 at 16:58 -0700, Andrew Morton wrote:
> echo "\0014Hello Joe" > /dev/kmsg
# echo -e "\x014Hello Me" > /dev/kmsg
gives:
12,778,4057982669;Hello Me
#echo -e "\x011Hello Me_2" > /dev/kmsg
gives:
12,779,4140452093;Hello Me_2
I didn't change devkmsg_writev so the
original parsing style for "<.>" is
unchanged.
from printk.c:
static ssize_t devkmsg_writev(struct kiocb *iocb, const struct iovec *iv,
unsigned long count, loff_t pos)
[...]
int level = default_message_loglevel;
[...]
if (line[0] == '<') {
char *endp = NULL;
i = simple_strtoul(line+1, &endp, 10);
if (endp && endp[0] == '>') {
level = i & 7;
if (i >> 3)
facility = i >> 3;
endp++;
len -= endp - line;
line = endp;
}
}
line[len] = '\0';
printk_emit(facility, level, NULL, 0, "%s", line);
[]
level is what matters.
from dmesg -r
<12>[ 2462.339252] \001Hello Andrew
<9>[ 2516.023444] Hello Andrew
<12>[ 3046.752764] \x01Hello Kay
<12>[ 3940.871850] \x01Hello Kay
<12>[ 4057.982669] Hello Me
<12>[ 4140.452093] Hello Me_2
On Wed, Jun 6, 2012 at 2:07 AM, Joe Perches <[email protected]> wrote:
> On Tue, 2012-06-05 at 16:58 -0700, Andrew Morton wrote:
>> echo "\0014Hello Joe" > /dev/kmsg
>
> # echo -e "\x014Hello Me" > /dev/kmsg
> gives:
> 12,778,4057982669;Hello Me
>
> #echo -e "\x011Hello Me_2" > /dev/kmsg
> gives:
> 12,779,4140452093;Hello Me_2
>
> I didn't change devkmsg_writev so the
> original parsing style for "<.>" is
> unchanged.
>
> from printk.c:
>
> static ssize_t devkmsg_writev(struct kiocb *iocb, const struct iovec *iv,
> unsigned long count, loff_t pos)
> [...]
> int level = default_message_loglevel;
> [...]
> if (line[0] == '<') {
> char *endp = NULL;
>
> i = simple_strtoul(line+1, &endp, 10);
> if (endp && endp[0] == '>') {
> level = i & 7;
> if (i >> 3)
> facility = i >> 3;
> endp++;
> len -= endp - line;
> line = endp;
> }
> }
> line[len] = '\0';
>
> printk_emit(facility, level, NULL, 0, "%s", line);
> []
>
> level is what matters.
>
> from dmesg -r
>
> <12>[ 2462.339252] \001Hello Andrew
> <9>[ 2516.023444] Hello Andrew
> <12>[ 3046.752764] \x01Hello Kay
> <12>[ 3940.871850] \x01Hello Kay
> <12>[ 4057.982669] Hello Me
> <12>[ 4140.452093] Hello Me_2
The question is what happens if you inject your new binary two-byte
prefix, like:
echo -e "\x01\x02Hello" > /dev/kmsg
And if that changes the log-level to "2" instead of the default "4"?
(assuming that I read your patch right, otherwise please correct the
bytes, but use the full sequence which your patch will recognize as an
internal level marker; seems your examples are all not triggering that)
Kay
On Wed, 2012-06-06 at 02:13 +0200, Kay Sievers wrote:
> The question is what happens if you inject your new binary two-byte
> prefix, like:
> echo -e "\x01\x02Hello" > /dev/kmsg
It's not a 2 byte binary.
It's a leading ascii SOH and a standard ascii char
'0' ... '7' or 'd'.
#define KERN_EMERG KERN_SOH "0" /* system is unusable */
#define KERN_ALERT KERN_SOH "1" /* action must be taken immediately */
etc...
> And if that changes the log-level to "2" instead of the default "4"?
No it doesn't.
It's not triggering that because devkmsg_writev does
prefix parsing only on the old "<n>" form.
On Wed, Jun 6, 2012 at 2:19 AM, Joe Perches <[email protected]> wrote:
> On Wed, 2012-06-06 at 02:13 +0200, Kay Sievers wrote:
>> The question is what happens if you inject your new binary two-byte
>> prefix, like:
>> echo -e "\x01\x02Hello" > /dev/kmsg
>
> It's not a 2 byte binary.
> It's a leading ascii SOH and a standard ascii char
> '0' ... '7' or 'd'.
>
> #define KERN_EMERG KERN_SOH "0" /* system is unusable */
> #define KERN_ALERT KERN_SOH "1" /* action must be taken immediately */
> etc...
Ok.
>> And if that changes the log-level to "2" instead of the default "4"?
>
> No it doesn't.
So:
echo -e "\x012Hello" > /dev/kmsg
is still level 4? Sounds all fine then.
> It's not triggering that because devkmsg_writev does
> prefix parsing only on the old "<n>" form.
Yeah, but printk_emit() will not try to parse it? I did not check, but
with your change, the prefix parsing in printk_emit() is still skipped
if a level is given as a parameter to printk_emit(), right?
Kay
On Tue, 05 Jun 2012 17:07:27 -0700 Joe Perches <[email protected]> wrote:
> On Tue, 2012-06-05 at 16:58 -0700, Andrew Morton wrote:
> > echo "\0014Hello Joe" > /dev/kmsg
>
> # echo -e "\x014Hello Me" > /dev/kmsg
> gives:
> 12,778,4057982669;Hello Me
That's changed behavior.
On Wed, 6 Jun 2012 02:28:39 +0200 Kay Sievers <[email protected]> wrote:
> Yeah, but printk_emit() will not try to parse it? I did not check, but
> with your change, the prefix parsing in printk_emit() is still skipped
> if a level is given as a parameter to printk_emit(), right?
printk_emit() does parse the leading \0014, and then skips over it,
removing it from the output stream. printk_emit() then throws away the
resulting level because devkmsg_writev() did not pass in level==-1.
On Wed, 2012-06-06 at 02:28 +0200, Kay Sievers wrote:
> On Wed, Jun 6, 2012 at 2:19 AM, Joe Perches <[email protected]> wrote:
> > On Wed, 2012-06-06 at 02:13 +0200, Kay Sievers wrote:
> >> The question is what happens if you inject your new binary two-byte
> >> prefix, like:
> >> echo -e "\x01\x02Hello" > /dev/kmsg
> >
> > It's not a 2 byte binary.
> > It's a leading ascii SOH and a standard ascii char
> > '0' ... '7' or 'd'.
> >
> > #define KERN_EMERG KERN_SOH "0" /* system is unusable */
> > #define KERN_ALERT KERN_SOH "1" /* action must be taken immediately */
> > etc...
>
> Ok.
>
> >> And if that changes the log-level to "2" instead of the default "4"?
> >
> > No it doesn't.
>
> So:
> echo -e "\x012Hello" > /dev/kmsg
> is still level 4? Sounds all fine then.
Yes.
# echo -e "\x012Hello again Kay" > /dev/kmsg
gives:
12,780,6031964979;Hello again Kay
> > It's not triggering that because devkmsg_writev does
> > prefix parsing only on the old "<n>" form.
>
> Yeah, but printk_emit() will not try to parse it? I did not check, but
> with your change, the prefix parsing in printk_emit() is still skipped
> if a level is given as a parameter to printk_emit(), right?
If level is not -1, then whatever prefix level the
string has is ignored by vprintk_emit.
from vprintk_emit:
/* strip syslog prefix and extract log level or control flags */
kern_level = printk_get_level(text);
if (kern_level) {
const char *end_of_header = printk_skip_level(text);
switch (kern_level) {
case '0' ... '7':
if (level == -1)
level = kern_level - '0';
case 'd': /* Strip d KERN_DEFAULT, start new line */
plen = 0;
default:
if (!new_text_line) {
log_buf_emit_char('\n');
new_text_line = 1;
}
}
text_len -= end_of_header - text;
text = (char *)end_of_header;
}
Only level == -1 will use the prefix level.
devkmsg_writev always passes a non -1 level.
cheers, Joe
On Tue, 2012-06-05 at 17:37 -0700, Andrew Morton wrote:
> On Tue, 05 Jun 2012 17:07:27 -0700 Joe Perches <[email protected]> wrote:
>
> > On Tue, 2012-06-05 at 16:58 -0700, Andrew Morton wrote:
> > > echo "\0014Hello Joe" > /dev/kmsg
> >
> > # echo -e "\x014Hello Me" > /dev/kmsg
> > gives:
> > 12,778,4057982669;Hello Me
>
> That's changed behavior.
Which is an improvement too.
I very much doubt a single app will change
because of this.
> printk_emit() does parse the leading \0014, and then skips over it,
> removing it from the output stream. printk_emit() then throws away the
> resulting level because devkmsg_writev() did not pass in level==-1.
I'm glad you know how it works now.
cheers, Joe
On Tue, 05 Jun 2012 17:40:05 -0700 Joe Perches <[email protected]> wrote:
> On Tue, 2012-06-05 at 17:37 -0700, Andrew Morton wrote:
> > On Tue, 05 Jun 2012 17:07:27 -0700 Joe Perches <[email protected]> wrote:
> >
> > > On Tue, 2012-06-05 at 16:58 -0700, Andrew Morton wrote:
> > > > echo "\0014Hello Joe" > /dev/kmsg
> > >
> > > # echo -e "\x014Hello Me" > /dev/kmsg
> > > gives:
> > > 12,778,4057982669;Hello Me
> >
> > That's changed behavior.
>
> Which is an improvement too.
No it isn't. It exposes internal kernel implementation details in
random weird inexplicable ways. It doesn't seem at all important
though.
> I very much doubt a single app will change
> because of this.
I doubt it as well.
> > printk_emit() does parse the leading \0014, and then skips over it,
> > removing it from the output stream. printk_emit() then throws away the
> > resulting level because devkmsg_writev() did not pass in level==-1.
>
> I'm glad you know how it works now.
It's nice to see you learning about it as well.
On Wed, Jun 6, 2012 at 2:46 AM, Andrew Morton <[email protected]> wrote:
> On Tue, 05 Jun 2012 17:40:05 -0700 Joe Perches <[email protected]> wrote:
>
>> On Tue, 2012-06-05 at 17:37 -0700, Andrew Morton wrote:
>> > On Tue, 05 Jun 2012 17:07:27 -0700 Joe Perches <[email protected]> wrote:
>> >
>> > > On Tue, 2012-06-05 at 16:58 -0700, Andrew Morton wrote:
>> > > > echo "\0014Hello Joe" > /dev/kmsg
>> > >
>> > > # echo -e "\x014Hello Me" > /dev/kmsg
>> > > gives:
>> > > 12,778,4057982669;Hello Me
>> >
>> > That's changed behavior.
>>
>> Which is an improvement too.
>
> No it isn't. It exposes internal kernel implementation details in
> random weird inexplicable ways. It doesn't seem at all important
> though.
>
>> I very much doubt a single app will change
>> because of this.
>
> I doubt it as well.
Yeah, the value of injecting such binary data is kind of questionable. :)
Joe, maybe you can change printk_emit() to skip the prefix
detection/stripping if a prefix is already passed to the function?
Kay
On Wed, 2012-06-06 at 03:10 +0200, Kay Sievers wrote:
> On Wed, Jun 6, 2012 at 2:46 AM, Andrew Morton <[email protected]> wrote:
> > On Tue, 05 Jun 2012 17:40:05 -0700 Joe Perches <[email protected]> wrote:
> >
> >> On Tue, 2012-06-05 at 17:37 -0700, Andrew Morton wrote:
> >> > On Tue, 05 Jun 2012 17:07:27 -0700 Joe Perches <[email protected]> wrote:
> >> >
> >> > > On Tue, 2012-06-05 at 16:58 -0700, Andrew Morton wrote:
> >> > > > echo "\0014Hello Joe" > /dev/kmsg
> >> > >
> >> > > # echo -e "\x014Hello Me" > /dev/kmsg
> >> > > gives:
> >> > > 12,778,4057982669;Hello Me
> >> >
> >> > That's changed behavior.
> >>
> >> Which is an improvement too.
> >
> > No it isn't. It exposes internal kernel implementation details in
> > random weird inexplicable ways. It doesn't seem at all important
> > though.
> >
> >> I very much doubt a single app will change
> >> because of this.
> >
> > I doubt it as well.
>
> Yeah, the value of injecting such binary data is kind of questionable. :)
>
> Joe, maybe you can change printk_emit() to skip the prefix
> detection/stripping if a prefix is already passed to the function?
Sure, it's pretty trivial.
Perhaps all binary data data should be elided.
Maybe print . for all non-printable ascii chars.
vprintk_emit prefix parsing should only be done for internal
kernel messages. This allows existing behavior to be kept
in all cases.
Signed-off-by: Joe Perches <[email protected]>
---
kernel/printk.c | 32 +++++++++++++++++---------------
1 files changed, 17 insertions(+), 15 deletions(-)
diff --git a/kernel/printk.c b/kernel/printk.c
index 5cd73f7..4e72c07 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -1267,7 +1267,6 @@ asmlinkage int vprintk_emit(int facility, int level,
static char cont_buf[LOG_LINE_MAX];
static size_t cont_len;
static int cont_level;
- int kern_level;
static struct task_struct *cont_task;
static char textbuf[LOG_LINE_MAX];
char *text = textbuf;
@@ -1329,21 +1328,24 @@ asmlinkage int vprintk_emit(int facility, int level,
newline = true;
}
- /* strip syslog prefix and extract log level or control flags */
- kern_level = printk_get_level(text);
- if (kern_level) {
- const char *end_of_header = printk_skip_level(text);
- switch (kern_level) {
- case '0' ... '7':
- if (level == -1)
- level = kern_level - '0';
- case 'd': /* KERN_DEFAULT */
- prefix = true;
- case 'c': /* KERN_CONT */
- break;
+ /* strip kernel syslog prefix and extract log level or control flags */
+ if (facility == 0) {
+ int kern_level = printk_get_level(text);
+
+ if (kern_level) {
+ const char *end_of_header = printk_skip_level(text);
+ switch (kern_level) {
+ case '0' ... '7':
+ if (level == -1)
+ level = kern_level - '0';
+ case 'd': /* KERN_DEFAULT */
+ prefix = true;
+ case 'c': /* KERN_CONT */
+ break;
+ }
+ text_len -= end_of_header - text;
+ text = (char *)end_of_header;
}
- text_len -= end_of_header - text;
- text = (char *)end_of_header;
}
if (level == -1)