[PATCH v14 0/4] x86/earlyprintk: setup serial earlyprintk as early as possible

[PATCH v14 0/4] 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.

Changelog:

v14:
  * style and commit messages fixes;
  * earlyprintk_late renamed to is_earlyprintk_late

v13:
  * do not setup pciserial from the arch/x86/kernel/head{32,64}.c, because
it uses ioremap and we can't do it really early;
  * style fixes;
  * patch for testing.

v12:
  * all changes from the v11 are reverted
  * setup_early_serial_console() renamed to the setup_earlyprintk_console()
 and refactored. Now it checks 'earlyprintk=' in the kernel command line, set
earlyprintk_late variable to false. This variable allows to know, do we
can setup early console for the certain device.

v11:
  * setup_log_buf moved to the arch/x86/kernel/head{32,64.c} from
the arch/x86/kernel/setup.c to setup early log_buf for the earlyprintl
  * Update log_buf in the early_printk function
  * Added additional patch for testing earlyprintk

v10:
  * Removed style issues which are not related to the patchset.

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] [] save_stack_trace+0x2f/0x50
[ 0.000000] [] __lock_acquire+0xa2c/0xf00
[ 0.000000] [] lock_acquire+0xdb/0x2b0
[ 0.000000] [] _raw_spin_lock_irqsave+0x53/0x90
[ 0.000000] [] down+0x16/0x50
[ 0.000000] [] console_lock+0x19/0x60
[ 0.000000] [] register_console+0x116/0x350
[ 0.000000] [] setup_early_printk+0x165/0x467
[ 0.000000] [] setup_early_serial_console+0x56/0x58
[ 0.000000] [] x86_64_start_kernel+0xce/0x110
[ 0.000000] [] 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 setup_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 (4):
  x86/setup: introduce setup_bultin_cmdline
  x86/setup: handle builtin command line as early as possible
  x86/earlyprintk: setup earlyprintk as early as possible
  x86/earlyprintk: add some early_printk for tests

 arch/x86/include/asm/setup.h   |  7 +++++++
 arch/x86/kernel/early_printk.c | 42 +++++++++++++++++++++++++++++++++++-------
 arch/x86/kernel/head32.c       |  5 +++++
 arch/x86/kernel/head64.c       |  7 +++++++
 arch/x86/kernel/setup.c        | 31 ++++++++++++++++++-------------
 init/main.c                    |  2 ++
 6 files changed, 74 insertions(+), 20 deletions(-)

-- 
2.4.0.GIT

[PATCH v14 1/4] 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. We are going to handle earlyprintk earlier than setup_arch() will be
called, so if earlyprintk will be passed through a builtin command line, it
will be handled in a correct way.

There is no functional change.

Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
---
 arch/x86/include/asm/setup.h |  1 +
 arch/x86/kernel/setup.c      | 30 +++++++++++++++++-------------
 2 files changed, 18 insertions(+), 13 deletions(-)

diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h
index 11af24e..68d8c05 100644
--- a/arch/x86/include/asm/setup.h
+++ b/arch/x86/include/asm/setup.h
@@ -126,6 +126,7 @@ 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 d3b95b8..5622972 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -847,6 +847,22 @@ 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
@@ -975,19 +991,7 @@ 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

[PATCH v14 2/4] 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.
The earlyprintk command line option can be passed through the
builtin command line, so we'll handle it before the
setup_earlyprintk_console() will be called.

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 5a46681..1e5f064 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 5622972..4b8d9cb 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -991,2 +991,2 @@ 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 v14 3/4] x86/earlyprintk: setup earlyprintk as early as possible

[Alexander Kuleshov]

The earlyprintk 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(), but sometimes it is very useful to
know what occurs in between. The earlyprintk can allow us to know what occurs
after kernel decompression and before parse_early_param() will be called.
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.

This patch provides the following stuff:

1. This patch introduces the setup_earlyprintk_console() function,
which called arch/x86/kernel/head{32,64}.c, parses kernel command line,
tries to find 'earlyprintk' option and calls setup_early_printk() depending
on the result.

2. As setup_earlyprintk_console() setups earlyprintk very early, we can't
use all console devices for now, but only serial and vga. There is
is_earlyprintk_late variable which determines ability to setup earlyprintk
for the certain device.

3. Call of the lockdep_init() added to the arch/x86/kernel/head{32,64}.c
to prevent call of the register_console before the initialization of lockdep.

In other way there we will get:

[ 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] [] save_stack_trace+0x2f/0x50
[ 0.000000] [] __lock_acquire+0xa2c/0xf00
[ 0.000000] [] lock_acquire+0xdb/0x2b0
[ 0.000000] [] _raw_spin_lock_irqsave+0x53/0x90
[ 0.000000] [] down+0x16/0x50
[ 0.000000] [] console_lock+0x19/0x60
[ 0.000000] [] register_console+0x116/0x350
[ 0.000000] [] setup_early_printk+0x165/0x467
[ 0.000000] [] setup_early_serial_console+0x56/0x58
[ 0.000000] [] x86_64_start_kernel+0xce/0x110
[ 0.000000] [] 0xffffffffffffffff
[ 0.000000] ------------------------

This patch adds lockdep_init() to the arch/x86/kernel/head{32,64}.c, but
not removed it from the init/main.c, because there is a couple of architectures
which have support of the lockdep, but do not call lockdep_init() in their
architecture-dependent code.

4. As setup_earlyprintk_console can be called twice: from
setup_earlyprintk_console() and parse_early_param(), additional check is added
to the really early consoles to prevent initialization of already initialized
consoles.

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

We will not see earlyprintk messages in the dmesg buffer, because
it is too early to initialized log_buf.

Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
---
 arch/x86/include/asm/setup.h   |  6 ++++++
 arch/x86/kernel/early_printk.c | 42 +++++++++++++++++++++++++++++++++++-------
 arch/x86/kernel/head32.c       |  4 ++++
 arch/x86/kernel/head64.c       |  5 +++++
 4 files changed, 50 insertions(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h
index 68d8c05..44f7059 100644
--- a/arch/x86/include/asm/setup.h
+++ b/arch/x86/include/asm/setup.h
@@ -127,0 +127,0 @@ 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_earlyprintk_console(void);
+#else
+static inline int __init setup_earlyprintk_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..10d4d82 100644
--- a/arch/x86/kernel/early_printk.c
+++ b/arch/x86/kernel/early_printk.c
@@ -329,6 +329,14 @@ static inline void early_console_register(struct console *con, int keep_early)
 	register_console(early_console);
 }
 
+/*
+ * The setup_early_printk can be called from two places: from the
+ * setup_earlyprintk_console() and the parse_early_param(). In the
+ * first case it is too early to setup earlyprintk for some devices
+ * as efi, pciserial and etc., but it can be set for vga and serial.
+ */
+static bool is_earlyprintk_late = true;
+
 static int __init setup_early_printk(char *buf)
 {
 	int keep;
@@ -342,47 +350,67 @@ 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);
 		}
 #ifdef CONFIG_PCI
-		if (!strncmp(buf, "pciserial", 9)) {
+		if (!strncmp(buf, "pciserial", 9) && is_earlyprintk_late) {
 			early_pci_serial_init(buf + 9);
 			early_console_register(&early_serial_console, keep);
 			buf += 9; /* Keep from match the above "serial" */
 		}
 #endif
 		if (!strncmp(buf, "vga", 3) &&
-		    boot_params.screen_info.orig_video_isVGA == 1) {
+		    boot_params.screen_info.orig_video_isVGA == 1 &&
+		    early_vga_console.index == -1) {
 			max_xpos = boot_params.screen_info.orig_video_cols;
 			max_ypos = boot_params.screen_info.orig_video_lines;
 			current_ypos = boot_params.screen_info.orig_y;
 			early_console_register(&early_vga_console, keep);
 		}
 #ifdef CONFIG_EARLY_PRINTK_DBGP
-		if (!strncmp(buf, "dbgp", 4) && !early_dbgp_init(buf + 4))
+		if (!strncmp(buf, "dbgp", 4) && !early_dbgp_init(buf + 4) &&
+		    is_earlyprintk_late)
 			early_console_register(&early_dbgp_console, keep);
 #endif
 #ifdef CONFIG_HVC_XEN
-		if (!strncmp(buf, "xen", 3))
+		if (!strncmp(buf, "xen", 3) && is_earlyprintk_late)
 			early_console_register(&xenboot_console, keep);
 #endif
 #ifdef CONFIG_EARLY_PRINTK_EFI
-		if (!strncmp(buf, "efi", 3))
+		if (!strncmp(buf, "efi", 3) && is_earlyprintk_late)
 			early_console_register(&early_efi_console, keep);
 #endif
 
 		buf++;
 	}
+
+	is_earlyprintk_late = true;
+
 	return 0;
 }
 
 early_param("earlyprintk", setup_early_printk);
+
+int __init setup_earlyprintk_console(void)
+{
+	char *arg;
+
+	arg = strstr(boot_command_line, "earlyprintk=");
+	if (!arg)
+		return -1;
+
+	is_earlyprintk_late = false;
+
+	return setup_early_printk(arg);
+}
diff --git a/arch/x86/kernel/head32.c b/arch/x86/kernel/head32.c
index 92e8b5f..64554be 100644
--- a/arch/x86/kernel/head32.c
+++ b/arch/x86/kernel/head32.c
@@ -32,2 +32,2 @@ static void __init i386_default_early_setup(void)
 asmlinkage __visible void __init i386_start_kernel(void)
 {
	setup_builtin_cmdline();
+	lockdep_init();
+	setup_earlyprintk_console();
+	early_printk("earlyprintk 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 1e5f064..e61e5a8 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -174,0 +174,0 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)

 	setup_builtin_cmdline();
 
+	lockdep_init();
+	setup_earlyprintk_console();
+	early_printk("earlyprintk is initialized\n");
+
 	/*
 	 * Load microcode early on BSP.
 	 */
-- 
2.4.0.GIT

[PATCH v14 4/4] x86/earlyprintk: add some early_printk for tests

[Alexander Kuleshov]

This patch is only for test of the full patch series. It provides
a couple calls of the early_printk() function.

[Not for applying, only for testing]

Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
---
 arch/x86/kernel/setup.c | 2 ++
 init/main.c             | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 4b8d9cb..419835b 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -878,6 +878,8 @@ void __init setup_builtin_cmdline(void)
 
 void __init setup_arch(char **cmdline_p)
 {
+	early_printk("Beginning of the x86 specific setup\n");
+
 	memblock_reserve(__pa_symbol(_text),
 			 (unsigned long)__bss_stop - (unsigned long)_text);
 
diff --git a/init/main.c b/init/main.c
index c599aea..deeb2a2 100644
--- a/init/main.c
+++ b/init/main.c
@@ -499,6 +499,8 @@ asmlinkage __visible void __init start_kernel(void)
 	char *command_line;
 	char *after_dashes;
 
+	early_printk("start_kernel from init/main.c started to work\n");
+
 	/*
 	 * Need to run as early as possible, to initialize the
 	 * lockdep hash:
-- 
2.4.0.GIT