[PATCH v9 0/3] x86/earlyprintk: setup serial earlyprintk as early as possible

[PATCH v9 0/3] x86/earlyprintk: setup serial earlyprintk as early as possible

[Alexander Kuleshov]

The early_printk function is usable only after the setup_early_printk will
be executed. We pass 'earlyprintk' through the kernel command line. So, it
means that earlyprintk will be usable only after the 'parse_early_param'
will be executed or in another words earlyprintk is usable only during early
boot, kernel decompression and after call of the parse_early_param. But
there are many stuff after the kernel decompression and before the
parse_early_param will be called as memblock usage, early cpu initialization,
early ioremap initialization and etc... So earlyprintk allows us to see
what's going on there.

Patchset was tested for both x86 and x86_64 architectures with the qemu.
It also provides call of the earlyprintk function right after the early
initialization of the serial console, so it must prints the debug string.

These patchset provides following changes:

1. Move handling of the builtin command line to the separate function
from the setup_arch. Now we can call it from the arch/x86/kernel/head{32,64}.c,
and find 'earlyprintk' kernel command line paramter there.

2. Provide setup_serial_console function to setup serial earlyprintk in the
arch/x86/kernel/head{32,64}.c

v9:

* Add call of the lockdep_init to the arch/x86/kernel/head{32,64}.c
before the serial console initialization to prevent:

[    0.000000] WARNING: lockdep init error! lock-(console_sem).lock was acquiredbefore lockdep_init
[    0.000000] Call stack leading to lockdep invocation was:
[    0.000000]  [<ffffffff81013f0f>] save_stack_trace+0x2f/0x50
[    0.000000]  [<ffffffff810a364c>] __lock_acquire+0xa2c/0xf00
[    0.000000]  [<ffffffff810a440b>] lock_acquire+0xdb/0x2b0
[    0.000000]  [<ffffffff81676b33>] _raw_spin_lock_irqsave+0x53/0x90
[    0.000000]  [<ffffffff8109b146>] down+0x16/0x50
[    0.000000]  [<ffffffff810b4d49>] console_lock+0x19/0x60
[    0.000000]  [<ffffffff810b78e6>] register_console+0x116/0x350
[    0.000000]  [<ffffffff81c36162>] setup_early_printk+0x165/0x467
[    0.000000]  [<ffffffff81c364ba>] setup_early_serial_console+0x56/0x58
[    0.000000]  [<ffffffff81c24565>] x86_64_start_kernel+0xce/0x110
[    0.000000]  [<ffffffffffffffff>] 0xffffffffffffffff
[    0.000000] ------------------------

during early serial console initialization.

* Add additional check to the earlyprintk initialization to protect
double initialization of the early_serial_console.

* Fixed comment.

v8:

* Fixed warning with the definition of the setup_early_serial_console
in the arch/x86/include/asm/setup.h

v7:

* Move setup_early_serial_console to the the arch/x86/include/setup.h
* Add ifdefs to prevent setup_serial_console if CONFIG_EARLY_PRINTK
is not set.

v6:

* Style fixes.
* Call of the suetp_builtin_cmdline moved to the separate patch.

v5:

* Call setup_builtin_cmdline instead of setup_cmdline

v4:

* Move setup_early_serial_console from the include/linux/printk.h
to the arch/x86/include/asm/serial.h, because this function is only
for x86 now.

v3:

* Call setup_cmdline before setup_early_printk;
* setup_early_printk call wrapped with the setup_early_serial_console which
checks that 'serial' given to the earlyprintk command line option. This
prevents call of the setup_early_printk with the given pciserial/dbgp/efi,
because they are using early_ioremap.

v2:

* Comment added before the setup_early_printk call;
* Added information about testing to the commit message.

Alexander Kuleshov (3):
  x86/setup: introduce setup_bultin_cmdline
  x86/setup: handle builtin command line as early as possible
  x86/earlyprintk: setup earlyprintk as early as possible

 arch/x86/include/asm/setup.h   |  8 ++++++++
 arch/x86/kernel/early_printk.c | 24 ++++++++++++++++++++++++
 arch/x86/kernel/head32.c       |  7 +++++++
 arch/x86/kernel/head64.c       |  7 +++++++
 arch/x86/kernel/setup.c        | 33 ++++++++++++++++++---------------
 5 files changed, 64 insertions(+), 15 deletions(-)

--
2.4.0.350.g9532ead

[PATCH v9 1/3] x86/setup: introduce setup_bultin_cmdline

[Alexander Kuleshov]

This patch introduces the setup_builtin_cmdline function which appends or
overrides boot_command_line with the builtin_cmdline if CONFIG_CMDLINE_BOOL
is set.

Previously this functional was in the setup_arch, but we need to move
it for getting actual command line as early as possible in the
arch/x86/kernel/head{32,64}.c for the earlyprintk setup.

Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
---
 arch/x86/include/asm/setup.h |  1 +
 arch/x86/kernel/setup.c      | 34 +++++++++++++++++++---------------
 2 files changed, 20 insertions(+), 15 deletions(-)

diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h
index f69e06b..59efd0d 100644
--- a/arch/x86/include/asm/setup.h
+++ b/arch/x86/include/asm/setup.h
@@ -119,6 +119,7 @@ asmlinkage void __init x86_64_start_kernel(char *real_mode);
 asmlinkage void __init x86_64_start_reservations(char *real_mode_data);
 
 #endif /* __i386__ */
+void __init setup_builtin_cmdline(void);
 #endif /* _SETUP */
 #else
 #define RESERVE_BRK(name,sz)				\
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index d74ac33..28dea1c 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -733,7 +733,7 @@ static void __init trim_snb_memory(void)
 	 * already been reserved.
 	 */
 	memblock_reserve(0, 1<<20);
-	
+
 	for (i = 0; i < ARRAY_SIZE(bad_pages); i++) {
 		if (memblock_reserve(bad_pages[i], PAGE_SIZE))
 			printk(KERN_WARNING "failed to reserve 0x%08lx\n",
@@ -825,7 +825,7 @@ static void __init trim_low_memory_range(void)
 {
 	memblock_reserve(0, ALIGN(reserve_low, PAGE_SIZE));
 }
-	
+
 /*
  * Dump out kernel offset information on panic.
  */
@@ -845,6 +845,22 @@ dump_kernel_offset(struct notifier_block *self, unsigned long v, void *p)
 	return 0;
 }
 
+void __init setup_builtin_cmdline(void)
+{
+#ifdef CONFIG_CMDLINE_BOOL
+#ifdef CONFIG_CMDLINE_OVERRIDE
+	strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
+#else
+	if (builtin_cmdline[0]) {
+		/* append boot loader cmdline to builtin */
+		strlcat(builtin_cmdline, " ", COMMAND_LINE_SIZE);
+		strlcat(builtin_cmdline, boot_command_line, COMMAND_LINE_SIZE);
+		strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
+	}
+#endif
+#endif
+}
+
 /*
  * Determine if we were loaded by an EFI loader.  If so, then we have also been
  * passed the efi memmap, systab, etc., so we should use these data structures
@@ -973,19 +989,7 @@ void __init setup_arch(char **cmdline_p)
 	bss_resource.start = __pa_symbol(__bss_start);
 	bss_resource.end = __pa_symbol(__bss_stop)-1;
 
-#ifdef CONFIG_CMDLINE_BOOL
-#ifdef CONFIG_CMDLINE_OVERRIDE
-	strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
-#else
-	if (builtin_cmdline[0]) {
-		/* append boot loader cmdline to builtin */
-		strlcat(builtin_cmdline, " ", COMMAND_LINE_SIZE);
-		strlcat(builtin_cmdline, boot_command_line, COMMAND_LINE_SIZE);
-		strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
-	}
-#endif
-#endif
-
+	setup_builtin_cmdline();
 	strlcpy(command_line, boot_command_line, COMMAND_LINE_SIZE);
 	*cmdline_p = command_line;
 
--
2.4.0.GIT

Re: [PATCH v9 1/3] x86/setup: introduce setup_bultin_cmdline

[Andy Shevchenko]

On Wed, 2015-06-03 at 13:55 +0600, Alexander Kuleshov wrote:
> This patch introduces the setup_builtin_cmdline function which appends or
> overrides boot_command_line with the builtin_cmdline if CONFIG_CMDLINE_BOOL
> is set.

> Previously this functional was in the setup_arch, but we need to move
> it for getting actual command line as early as possible in the
> arch/x86/kernel/head{32,64}.c for the earlyprintk setup.

[]


> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -733,7 +733,7 @@ static void __init trim_snb_memory(void)
>  	 * already been reserved.
>  	 */
>  	memblock_reserve(0, 1<<20);
> -	
> +
>  	for (i = 0; i < ARRAY_SIZE(bad_pages); i++) {
>  		if (memblock_reserve(bad_pages[i], PAGE_SIZE))
>  			printk(KERN_WARNING "failed to reserve 0x%08lx\n",
> @@ -825,7 +825,7 @@ static void __init trim_low_memory_range(void)
>  {
>  	memblock_reserve(0, ALIGN(reserve_low, PAGE_SIZE));
>  }
> -	
> +
>  /*
>   * Dump out kernel offset information on panic.
>   */

You again mixed things in one patch. Style thing if you wish shall go
separately.

-- 
Andy Shevchenko <andriy.shevchenko@intel.com>
Intel Finland Oy

Re: [PATCH v9 1/3] x86/setup: introduce setup_bultin_cmdline

[Alexander Kuleshov]

Hello Andy,

2015-06-03 15:30 GMT+06:00 Andy Shevchenko <andriy.shevchenko@linux.intel.com>:
> On Wed, 2015-06-03 at 13:55 +0600, Alexander Kuleshov wrote:
>> This patch introduces the setup_builtin_cmdline function which appends or
>> overrides boot_command_line with the builtin_cmdline if CONFIG_CMDLINE_BOOL
>> is set.
>
>> Previously this functional was in the setup_arch, but we need to move
>> it for getting actual command line as early as possible in the
>> arch/x86/kernel/head{32,64}.c for the earlyprintk setup.
>
> []

?

>> --- a/arch/x86/kernel/setup.c
>> +++ b/arch/x86/kernel/setup.c
>> @@ -733,7 +733,7 @@ static void __init trim_snb_memory(void)
>>        * already been reserved.
>>        */
>>       memblock_reserve(0, 1<<20);
>> -
>> +
>>       for (i = 0; i < ARRAY_SIZE(bad_pages); i++) {
>>               if (memblock_reserve(bad_pages[i], PAGE_SIZE))
>>                       printk(KERN_WARNING "failed to reserve 0x%08lx\n",
>> @@ -825,7 +825,7 @@ static void __init trim_low_memory_range(void)
>>  {
>>       memblock_reserve(0, ALIGN(reserve_low, PAGE_SIZE));
>>  }
>> -
>> +
>>  /*
>>   * Dump out kernel offset information on panic.
>>   */
>
> You again mixed things in one patch. Style thing if you wish shall go
> separately.

It is not style stuff. And I do not remember that I've touched this place.
Seems some problems with my editor.

Re: [PATCH v9 1/3] x86/setup: introduce setup_bultin_cmdline

[Andy Shevchenko]

On Fri, 2015-06-05 at 13:51 +0600, Alexander Kuleshov wrote:
> Hello Andy,
> 
> 2015-06-03 15:30 GMT+06:00 Andy Shevchenko <andriy.shevchenko@linux.intel.com>:
> > On Wed, 2015-06-03 at 13:55 +0600, Alexander Kuleshov wrote:
> >> This patch introduces the setup_builtin_cmdline function which appends or
> >> overrides boot_command_line with the builtin_cmdline if CONFIG_CMDLINE_BOOL
> >> is set.
> >
> >> Previously this functional was in the setup_arch, but we need to move
> >> it for getting actual command line as early as possible in the
> >> arch/x86/kernel/head{32,64}.c for the earlyprintk setup.
> >
> > []
> 
> ?

This means "skipped several lines of the message".

> >> --- a/arch/x86/kernel/setup.c
> >> +++ b/arch/x86/kernel/setup.c
> >> @@ -733,7 +733,7 @@ static void __init trim_snb_memory(void)
> >>        * already been reserved.
> >>        */
> >>       memblock_reserve(0, 1<<20);
> >> -
> >> +
> >>       for (i = 0; i < ARRAY_SIZE(bad_pages); i++) {
> >>               if (memblock_reserve(bad_pages[i], PAGE_SIZE))
> >>                       printk(KERN_WARNING "failed to reserve 0x%08lx\n",
> >> @@ -825,7 +825,7 @@ static void __init trim_low_memory_range(void)
> >>  {
> >>       memblock_reserve(0, ALIGN(reserve_low, PAGE_SIZE));
> >>  }
> >> -
> >> +
> >>  /*
> >>   * Dump out kernel offset information on panic.
> >>   */
> >
> > You again mixed things in one patch. Style thing if you wish shall go
> > separately.
> 
> It is not style stuff. And I do not remember that I've touched this place.
> Seems some problems with my editor.

Then perhaps a good idea to read mail before send.

-- 
Andy Shevchenko <andriy.shevchenko@intel.com>
Intel Finland Oy

Re: [PATCH v9 1/3] x86/setup: introduce setup_bultin_cmdline

[Alexander Kuleshov]

2015-06-03 15:30 GMT+06:00 Andy Shevchenko <andriy.shevchenko@linux.intel.com>:
> On Wed, 2015-06-03 at 13:55 +0600, Alexander Kuleshov wrote:
>> This patch introduces the setup_builtin_cmdline function which appends or
>> overrides boot_command_line with the builtin_cmdline if CONFIG_CMDLINE_BOOL
>> is set.
>
>> Previously this functional was in the setup_arch, but we need to move
>> it for getting actual command line as early as possible in the
>> arch/x86/kernel/head{32,64}.c for the earlyprintk setup.
>
> []
>

And what's wrong with this?

[PATCH v9 2/3] x86/setup: handle builtin command line as early as possible

[Alexander Kuleshov]

This patch adds the call of the setup_builtin_cmdline to
handle builtin command line before we will setup earlyprintk.

Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
---
 arch/x86/kernel/head32.c | 1 +
 arch/x86/kernel/head64.c | 2 ++
 arch/x86/kernel/setup.c  | 1 -
 3 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/head32.c b/arch/x86/kernel/head32.c
index 2911ef3..92e8b5f 100644
--- a/arch/x86/kernel/head32.c
+++ b/arch/x86/kernel/head32.c
@@ -31,6 +31,7 @@ static void __init i386_default_early_setup(void)
 
 asmlinkage __visible void __init i386_start_kernel(void)
 {
+	setup_builtin_cmdline();
 	cr4_init_shadow();
 	sanitize_boot_params(&boot_params);
 
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 2b55ee6..346a042 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -172,6 +172,8 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
 
 	copy_bootdata(__va(real_mode_data));
 
+	setup_builtin_cmdline();
+
 	/*
 	 * Load microcode early on BSP.
 	 */
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 28dea1c..12124df 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -989,7 +989,6 @@ void __init setup_arch(char **cmdline_p)
 	bss_resource.start = __pa_symbol(__bss_start);
 	bss_resource.end = __pa_symbol(__bss_stop)-1;
 
-	setup_builtin_cmdline();
 	strlcpy(command_line, boot_command_line, COMMAND_LINE_SIZE);
 	*cmdline_p = command_line;
 
--
2.4.0.GIT

[PATCH v9 3/3] x86/earlyprintk: setup earlyprintk as early as possible

[Alexander Kuleshov]

The early_printk function is usable only after the setup_early_printk will
be executed. We pass 'earlyprintk' through the kernel command line, so it
will be usable only after the 'parse_early_param' will be executed. This means
that we have usable earlyprintk only during early boot, kernel decompression
and after call of the 'parse_early_param'. This patchset makes earlyprintk
usable before the call of the 'parse_early_param'.

This patch makes the setup_early_printk visible for head{32,64}.c. So the
'early_printk' function will be usabable after decompression of the
kernel and before parse_early_param will be called. It also must be
safe if CONFIG_CMDLINE_BOOL and CONFIG_CMDLINE_OVERRIDE are set, because
setup_cmdline function will be called before setup_early_printk.

It provides earlyprintk only for serial console, because other needs in
ioremap which is not initialized yet.

Tested it with qemu, so early_printk() is usable and prints to serial
console right after setup_early_printk function called.

Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
---
 arch/x86/include/asm/setup.h   |  7 +++++++
 arch/x86/kernel/early_printk.c | 30 ++++++++++++++++++++++++++++--
 arch/x86/kernel/head32.c       |  7 +++++++
 arch/x86/kernel/head64.c       |  6 ++++++
 4 files changed, 48 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h
index 59efd0d..201eda0 100644
--- a/arch/x86/include/asm/setup.h
+++ b/arch/x86/include/asm/setup.h
@@ -120,6 +120,13 @@ asmlinkage void __init x86_64_start_reservations(char *real_mode_data);
 
 #endif /* __i386__ */
 void __init setup_builtin_cmdline(void);
+
+#ifdef CONFIG_EARLY_PRINTK
+/* used by arch/x86/kernel/head{32,64}.c */
+extern int __init setup_early_serial_console(void);
+#else
+static inline int __init setup_early_serial_console(void) { return 0; }
+#endif /* CONFIG_EARLY_PRINTK */
 #endif /* _SETUP */
 #else
 #define RESERVE_BRK(name,sz)				\
diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c
index 89427d8..5373298 100644
--- a/arch/x86/kernel/early_printk.c
+++ b/arch/x86/kernel/early_printk.c
@@ -342,14 +342,16 @@ static int __init setup_early_printk(char *buf)
 	keep = (strstr(buf, "keep") != NULL);
 
 	while (*buf != '\0') {
-		if (!strncmp(buf, "serial", 6)) {
+		if (!strncmp(buf, "serial", 6) &&
+		    early_serial_console.index == -1) {
 			buf += 6;
 			early_serial_init(buf);
 			early_console_register(&early_serial_console, keep);
 			if (!strncmp(buf, ",ttyS", 5))
 				buf += 5;
 		}
-		if (!strncmp(buf, "ttyS", 4)) {
+		if (!strncmp(buf, "ttyS", 4) &&
+		    early_serial_console.index == -1) {
 			early_serial_init(buf + 4);
 			early_console_register(&early_serial_console, keep);
 		}
@@ -385,4 +387,28 @@ static int __init setup_early_printk(char *buf)
 	return 0;
 }
 
+int __init setup_early_serial_console(void)
+{
+	char *arg;
+
+	/*
+	 * make sure that we have:
+	 *      "serial,0x3f8,115200"
+	 *      "serial,ttyS0,115200"
+	 *      "ttyS0,115200"
+	 */
+	arg = strstr(boot_command_line, "earlyprintk=serial");
+	if (!arg)
+		arg = strstr(boot_command_line, "earlyprintk=ttyS");
+	if (!arg)
+		return -1;
+
+	arg = strstr(boot_command_line, "earlyprintk=");
+
+	/* += strlen("earlyprintk="); */
+	arg += 12;
+
+	return setup_early_printk(arg);
+}
+
 early_param("earlyprintk", setup_early_printk);
diff --git a/arch/x86/kernel/head32.c b/arch/x86/kernel/head32.c
index 92e8b5f..6969d97 100644
--- a/arch/x86/kernel/head32.c
+++ b/arch/x86/kernel/head32.c
@@ -32,6 +32,13 @@ static void __init i386_default_early_setup(void)
 asmlinkage __visible void __init i386_start_kernel(void)
 {
 	setup_builtin_cmdline();
+
+	lockdep_init();
+
+	setup_early_serial_console();
+
+	early_printk("Early printk is initialized\n");
+
 	cr4_init_shadow();
 	sanitize_boot_params(&boot_params);
 
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 346a042..35dd00f 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -174,6 +174,12 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
 
 	setup_builtin_cmdline();
 
+	lockdep_init();
+
+	setup_early_serial_console();
+
+	early_printk("Early printk is initialized\n");
+
 	/*
 	 * Load microcode early on BSP.
 	 */
--
2.4.0.GIT