ARM: 7897/1: kexec: Use the right ISA for relocate_new_kernel

Message ID 1411638824-66243-1-git-send-email-sdu.liu@huawei.com
State New
Headers show

Commit Message

Liu hua Sept. 25, 2014, 9:53 a.m.
From: Dave Martin <dave.martin@linaro.org>

Hi Greg,

commit e2ccba49085ab5d71b092de2a5176eb9b19cc876 upstream

Copying a function with memcpy() and then trying to execute the
result isn't trivially portable to Thumb.

This patch modifies the kexec soft restart code to copy its
assembler trampoline relocate_new_kernel() using fncpy() instead,
so that relocate_new_kernel can be in the same ISA as the rest of
the kernel without problems.

Without this patch THUMB2 kernel can not go through kdump process.
I have test it  on 3.10. This patch applies to v3.13+. 3.10 stable
and 3.12stable need it.

(1) A separate backport is needed for 3.10;
(2) it can apply to 3.12 stable directly.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Reported-by: Taras Kondratiuk <taras.kondratiuk@linaro.org>
Tested-by: Taras Kondratiuk <taras.kondratiuk@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Integrated-by: Liu Hua <sdu.liu@huawei.com>
Signed-off-by: Liu Hua <sdu.liu@huawei.com>
---
 arch/arm/kernel/machine_kexec.c   | 17 ++++++++++-------
 arch/arm/kernel/relocate_kernel.S |  8 ++++++--
 2 files changed, 16 insertions(+), 9 deletions(-)

Comments

Li Zefan Sept. 25, 2014, 12:10 p.m. | #1
On 2014/9/25 17:53, Liu Hua wrote:
> From: Dave Martin <dave.martin@linaro.org>
> 
> Hi Greg,
> 
> commit e2ccba49085ab5d71b092de2a5176eb9b19cc876 upstream

commit XXX upstream.  <-- don't forget the dot

> 
> Copying a function with memcpy() and then trying to execute the
> result isn't trivially portable to Thumb.
> 
> This patch modifies the kexec soft restart code to copy its
> assembler trampoline relocate_new_kernel() using fncpy() instead,
> so that relocate_new_kernel can be in the same ISA as the rest of
> the kernel without problems.
> 
> Without this patch THUMB2 kernel can not go through kdump process.
> I have test it  on 3.10. This patch applies to v3.13+. 3.10 stable
> and 3.12stable need it.
> 

Please don't stuff this into the middle of the original changelog...

> (1) A separate backport is needed for 3.10;

Then send out the backport.

> (2) it can apply to 3.12 stable directly.

3.12 is maintained by Jiri.

> 
> Signed-off-by: Dave Martin <Dave.Martin@arm.com>
> Acked-by: Will Deacon <will.deacon@arm.com>
> Reported-by: Taras Kondratiuk <taras.kondratiuk@linaro.org>
> Tested-by: Taras Kondratiuk <taras.kondratiuk@linaro.org>
> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
> Integrated-by: Liu Hua <sdu.liu@huawei.com>

Please remove this line.

> Signed-off-by: Liu Hua <sdu.liu@huawei.com>

If the commit can be cherry-picked cleanly, just tell the stable
maintainer the commit ID, otherwise you should add changelog
for what you did to the original patch.

Like this:

https://lkml.org/lkml/2014/9/22/818

[lizf: Backported to 3.4:
 - Drop changes to arch/arm/include/asm/cacheflush.h and
   arch/arm/mach-exynos/mcpm-exynos.c]
Signed-off-by: Zefan Li <lizefan@huawei.com>]

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Liu hua Sept. 26, 2014, 4:22 a.m. | #2
于 2014/9/25 20:10, Zefan Li 写道:
> On 2014/9/25 17:53, Liu Hua wrote:
>> From: Dave Martin <dave.martin@linaro.org>
>>
>> Hi Greg,
>>
>> commit e2ccba49085ab5d71b092de2a5176eb9b19cc876 upstream
> 
> commit XXX upstream.  <-- don't forget the dot

Thanks, I will change this.
> 
>>
>> Copying a function with memcpy() and then trying to execute the
>> result isn't trivially portable to Thumb.
>>
>> This patch modifies the kexec soft restart code to copy its
>> assembler trampoline relocate_new_kernel() using fncpy() instead,
>> so that relocate_new_kernel can be in the same ISA as the rest of
>> the kernel without problems.
>>
>> Without this patch THUMB2 kernel can not go through kdump process.
>> I have test it  on 3.10. This patch applies to v3.13+. 3.10 stable
>> and 3.12stable need it.
>>
> 
> Please don't stuff this into the middle of the original changelog...
> 
>> (1) A separate backport is needed for 3.10;
> 
> Then send out the backport.
> 
>> (2) it can apply to 3.12 stable directly.
> 
> 3.12 is maintained by Jiri.

 This is to say I should send two mails for this upstreamed patch ?
> 
>>
>> Signed-off-by: Dave Martin <Dave.Martin@arm.com>
>> Acked-by: Will Deacon <will.deacon@arm.com>
>> Reported-by: Taras Kondratiuk <taras.kondratiuk@linaro.org>
>> Tested-by: Taras Kondratiuk <taras.kondratiuk@linaro.org>
>> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
>> Integrated-by: Liu Hua <sdu.liu@huawei.com>
> 
> Please remove this line.
> 
>> Signed-off-by: Liu Hua <sdu.liu@huawei.com>
> 
> If the commit can be cherry-picked cleanly, just tell the stable
> maintainer the commit ID, otherwise you should add changelog
> for what you did to the original patch.
> 
> Like this:
> 
> https://lkml.org/lkml/2014/9/22/818
> 
> [lizf: Backported to 3.4:
>  - Drop changes to arch/arm/include/asm/cacheflush.h and
>    arch/arm/mach-exynos/mcpm-exynos.c]
> Signed-off-by: Zefan Li <lizefan@huawei.com>]
Thank you very much, I will resend the patch?
> 
> 
> .
> 


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Patch

diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c
index c3ef920..70ae735 100644
--- a/arch/arm/kernel/machine_kexec.c
+++ b/arch/arm/kernel/machine_kexec.c
@@ -14,10 +14,11 @@ 
 #include <asm/pgalloc.h>
 #include <asm/mmu_context.h>
 #include <asm/cacheflush.h>
+#include <asm/fncpy.h>
 #include <asm/mach-types.h>
 #include <asm/system_misc.h>
 
-extern const unsigned char relocate_new_kernel[];
+extern void relocate_new_kernel(void);
 extern const unsigned int relocate_new_kernel_size;
 
 extern unsigned long kexec_start_address;
@@ -133,6 +134,8 @@  void machine_kexec(struct kimage *image)
 {
 	unsigned long page_list;
 	unsigned long reboot_code_buffer_phys;
+	unsigned long reboot_entry = (unsigned long)relocate_new_kernel;
+	unsigned long reboot_entry_phys;
 	void *reboot_code_buffer;
 
 	if (num_online_cpus() > 1) {
@@ -156,18 +159,18 @@  void machine_kexec(struct kimage *image)
 
 
 	/* copy our kernel relocation code to the control code page */
-	memcpy(reboot_code_buffer,
-	       relocate_new_kernel, relocate_new_kernel_size);
+	reboot_entry = fncpy(reboot_code_buffer,
+			     reboot_entry,
+			     relocate_new_kernel_size);
+	reboot_entry_phys = (unsigned long)reboot_entry +
+		(reboot_code_buffer_phys - (unsigned long)reboot_code_buffer);
 
-
-	flush_icache_range((unsigned long) reboot_code_buffer,
-			   (unsigned long) reboot_code_buffer + KEXEC_CONTROL_PAGE_SIZE);
 	printk(KERN_INFO "Bye!\n");
 
 	if (kexec_reinit)
 		kexec_reinit();
 
-	soft_restart(reboot_code_buffer_phys);
+	soft_restart(reboot_entry_phys);
 }
 
 void arch_crash_save_vmcoreinfo(void)
diff --git a/arch/arm/kernel/relocate_kernel.S b/arch/arm/kernel/relocate_kernel.S
index d0cdedf..9585896 100644
--- a/arch/arm/kernel/relocate_kernel.S
+++ b/arch/arm/kernel/relocate_kernel.S
@@ -2,10 +2,12 @@ 
  * relocate_kernel.S - put the kernel image in place to boot
  */
 
+#include <linux/linkage.h>
 #include <asm/kexec.h>
 
-	.globl relocate_new_kernel
-relocate_new_kernel:
+	.align	3	/* not needed for this code, but keeps fncpy() happy */
+
+ENTRY(relocate_new_kernel)
 
 	ldr	r0,kexec_indirection_page
 	ldr	r1,kexec_start_address
@@ -79,6 +81,8 @@  kexec_mach_type:
 kexec_boot_atags:
 	.long	0x0
 
+ENDPROC(relocate_new_kernel)
+
 relocate_new_kernel_end:
 
 	.globl relocate_new_kernel_size