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. We have usable earlyprintk only during early boot, kernel
decompression and after call of the 'parse_early_param'. This patchset makes
serial earlyprintk usable before the call of the 'parse_early_param'.
Patchset was tested for both x86 and x86_64 architectures with the qemu.
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
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
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 <[email protected]>
---
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;
--
2.4.0.350.g9532ead
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 <[email protected]>
---
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;
--
2.4.0.350.g9532ead
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 <[email protected]>
---
arch/x86/include/asm/setup.h | 7 +++++++
arch/x86/kernel/early_printk.c | 24 ++++++++++++++++++++++++
arch/x86/kernel/head32.c | 6 ++++++
arch/x86/kernel/head64.c | 5 +++++
4 files changed, 42 insertions(+)
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..0b2a626 100644
--- a/arch/x86/kernel/early_printk.c
+++ b/arch/x86/kernel/early_printk.c
@@ -385,4 +385,28 @@ 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..759d115 100644
--- a/arch/x86/kernel/head32.c
+++ b/arch/x86/kernel/head32.c
@@ -32,6 +32,12 @@ static void __init i386_default_early_setup(void)
asmlinkage __visible void __init i386_start_kernel(void)
{
setup_builtin_cmdline();
+
+ setup_early_serial_console();
+
+ if (console_loglevel >= CONSOLE_LOGLEVEL_DEBUG)
+ 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..6b7529a 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -174,6 +174,11 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
setup_builtin_cmdline();
+ setup_early_serial_console();
+
+ if (console_loglevel >= CONSOLE_LOGLEVEL_DEBUG)
+ early_printk("Early printk is initialized\n");
+
/*
* Load microcode early on BSP.
*/
--
2.4.0.350.g9532ead
On Tue, May 26, 2015 at 07:06:47PM +0600, Alexander Kuleshov wrote:
> 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. We have usable earlyprintk only during early boot, kernel
> decompression and after call of the 'parse_early_param'. This patchset makes
> serial earlyprintk usable before the call of the 'parse_early_param'.
... and?
Why do we need it usable before parse_early_param()? Use case?
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
--
2015-05-26 19:17 GMT+06:00 Borislav Petkov <[email protected]>:
> On Tue, May 26, 2015 at 07:06:47PM +0600, Alexander Kuleshov wrote:
>> 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. We have usable earlyprintk only during early boot, kernel
>> decompression and after call of the 'parse_early_param'. This patchset makes
>> serial earlyprintk usable before the call of the 'parse_early_param'.
>
> ... and?
>
> Why do we need it usable before parse_early_param()? Use case?
>
To be able to use early_printk and serial console between kernel
decompression and
parse_eary_param.
On Tue, May 26, 2015 at 07:20:02PM +0600, Alexander Kuleshov wrote:
> To be able to use early_printk and serial console between kernel
> decompression and parse_eary_param.
So no real use case - only a "just because we can" case.
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
--
2015-05-26 19:57 GMT+06:00 Borislav Petkov <[email protected]>:
> On Tue, May 26, 2015 at 07:20:02PM +0600, Alexander Kuleshov wrote:
>> To be able to use early_printk and serial console between kernel
>> decompression and parse_eary_param.
>
> So no real use case - only a "just because we can" case.
>
It is not "just because we can". There is some code after kernel decompression
and before parse_early_param and earlyprintk can be useful for
printing debugging information
in this case.
On Tue, 2015-05-26 at 20:11 +0600, Alexander Kuleshov wrote:
> 2015-05-26 19:57 GMT+06:00 Borislav Petkov <[email protected]>:
> > On Tue, May 26, 2015 at 07:20:02PM +0600, Alexander Kuleshov wrote:
> >> To be able to use early_printk and serial console between kernel
> >> decompression and parse_eary_param.
> >
> > So no real use case - only a "just because we can" case.
> >
>
> It is not "just because we can". There is some code after kernel decompression
> and before parse_early_param and earlyprintk can be useful for
> printing debugging information
> in this case.
So, what is *yours* use case? From here you describe a *potential* use
case, not a real one.
--
Andy Shevchenko <[email protected]>
Intel Finland Oy
On Tue, May 26, 2015 at 08:11:07PM +0600, Alexander Kuleshov wrote:
> It is not "just because we can". There is some code after kernel
> decompression and before parse_early_param and earlyprintk can be
> useful for printing debugging information in this case.
Which code? Please show me.
Because *that* would be a use case.
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
--
2015-05-29 22:55 GMT+06:00 Borislav Petkov <[email protected]>:
>
> You can boot with "ignore_loglevel" to see that message. Provided
> ignore_loglevel is even parsed that early.
>
But ignore_loglevel is early_param too...
>
> Yes, I meant a testing patch which is used only for testing and which
> issues a bunch of early_printk() calls.
>
Maybe I just remove 'if' clause and just leave:
early_printk("Early printk is initialized\n");
In the arch/x86/kernel/head{32,64}.c? Call of the early_printk
is safe here, even earlyprintk is not enabled and it must
be good for testing this patchset.
> But, before you do that, your patchset has more problems. Booting in
> qemu+kvm gives this:
>
> early console in setup code
> early console in decompress_kernel
>
> Decompressing Linux... Parsing ELF... done.
> Booting the kernel.
> [ 0.000000] bootconsole [earlyser0] enabled
> [ 0.000000] ERROR: earlyprintk= earlyser already used
> ^^^^^^
Yes, thanks. This is because we go though a buffer in a loop
and after the earlyprintk=ttyS0, it finds console=ttyS0. So,
I think we can add additional check, something like this:
if (!strncmp(buf, "serial", 6) &&
early_serial_console.index == -1) {
...
...
...
}
and for the "ttyS...". Just tested it and it works without
"ERROR: earlyprintk= earlyser already used".
>
> [ 0.000000] per task-struct memory footprint: 2688 bytes
> [ 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] ------------------------
>
> This last one shows that you'd need to look into lockdep first. It also
> shows that early boot order is pretty fragile so one has to be very
> careful when changing stuff there.
>
What if I add call of the lockdep_init before the setup_early_serial_console?
It must be safe because there is check in the lockdep_init:
if (lockdep_initialized)
return;
and some architectures (powerpc, microblaze, s390) already do it in
the same way.
What do you think about it?
Thank you.