diff mbox series

[v12,13/16] arm64: kexec_file: invoke the kernel without purgatory

Message ID 20180724065759.19186-14-takahiro.akashi@linaro.org (mailing list archive)
State New, archived
Headers show
Series arm64: kexec: add kexec_file_load() support | expand

Commit Message

AKASHI Takahiro July 24, 2018, 6:57 a.m. UTC 
On arm64, purgatory would do almost nothing. So just invoke secondary
kernel directly by jumping into its entry code.

While, in this case, cpu_soft_restart() must be called with dtb address
in the fifth argument, the behavior still stays compatible with kexec_load
case as long as the argument is null.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: James Morse <james.morse@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
---
 arch/arm64/kernel/cpu-reset.S       |  8 ++++----
 arch/arm64/kernel/machine_kexec.c   | 12 ++++++++++--
 arch/arm64/kernel/relocate_kernel.S |  3 ++-
 3 files changed, 16 insertions(+), 7 deletions(-)

Comments

James Morse July 26, 2018, 1:36 p.m. UTC | #1 
Hi Akashi,

On 24/07/18 07:57, AKASHI Takahiro wrote:
> On arm64, purgatory would do almost nothing. So just invoke secondary
> kernel directly by jumping into its entry code.
> 
> While, in this case, cpu_soft_restart() must be called with dtb address
> in the fifth argument, the behavior still stays compatible with kexec_load
> case as long as the argument is null.

This patch conflicts with commit 76f4e2da45b4 ("arm64: kexec: always reset to
EL2 if present") in the arm64 tree.

Thanks,

James

> diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c
> index f76ea92dff91..830a5063e09d 100644
> --- a/arch/arm64/kernel/machine_kexec.c
> +++ b/arch/arm64/kernel/machine_kexec.c
> @@ -205,10 +205,18 @@ void machine_kexec(struct kimage *kimage)
>  	 * uses physical addressing to relocate the new image to its final
>  	 * position and transfers control to the image entry point when the
>  	 * relocation is complete.
> +	 * In kexec case, kimage->start points to purgatory assuming that
> +	 * kernel entry and dtb address are embedded in purgatory by
> +	 * userspace (kexec-tools).
> +	 * In kexec_file case, the kernel starts directly without purgatory.
>  	 */
> -
>  	cpu_soft_restart(kimage != kexec_crash_image,
> -		reboot_code_buffer_phys, kimage->head, kimage->start, 0);
> +		reboot_code_buffer_phys, kimage->head, kimage->start,
> +#ifdef CONFIG_KEXEC_FILE
> +						kimage->arch.dtb_mem);
> +#else
> +						0);
> +#endif
>  
>  	BUG(); /* Should never get here. */
>  }
AKASHI Takahiro July 27, 2018, 7:22 a.m. UTC | #2 
On Thu, Jul 26, 2018 at 02:36:07PM +0100, James Morse wrote:
> Hi Akashi,
> 
> On 24/07/18 07:57, AKASHI Takahiro wrote:
> > On arm64, purgatory would do almost nothing. So just invoke secondary
> > kernel directly by jumping into its entry code.
> > 
> > While, in this case, cpu_soft_restart() must be called with dtb address
> > in the fifth argument, the behavior still stays compatible with kexec_load
> > case as long as the argument is null.
> 
> This patch conflicts with commit 76f4e2da45b4 ("arm64: kexec: always reset to
> EL2 if present") in the arm64 tree.

I haven't noticed Mark's patch.

I'm going to have to refresh my memory regarding why I introduced
el2_switch when I implemented kdump.
According to my current memory, however, I added
kvm_arch_hardware_enable/disable(), and associated functions, to gracefully
shutdown EL2 in case of kexec. Since we have no chance to call reset
function (via notifier) at kdump, I believed that el2_switch was necessary
for better chance of successful kdump.

Thanks,
-Takahiro AKASHI

> Thanks,
> 
> James
> 
> > diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c
> > index f76ea92dff91..830a5063e09d 100644
> > --- a/arch/arm64/kernel/machine_kexec.c
> > +++ b/arch/arm64/kernel/machine_kexec.c
> > @@ -205,10 +205,18 @@ void machine_kexec(struct kimage *kimage)
> >  	 * uses physical addressing to relocate the new image to its final
> >  	 * position and transfers control to the image entry point when the
> >  	 * relocation is complete.
> > +	 * In kexec case, kimage->start points to purgatory assuming that
> > +	 * kernel entry and dtb address are embedded in purgatory by
> > +	 * userspace (kexec-tools).
> > +	 * In kexec_file case, the kernel starts directly without purgatory.
> >  	 */
> > -
> >  	cpu_soft_restart(kimage != kexec_crash_image,
> > -		reboot_code_buffer_phys, kimage->head, kimage->start, 0);
> > +		reboot_code_buffer_phys, kimage->head, kimage->start,
> > +#ifdef CONFIG_KEXEC_FILE
> > +						kimage->arch.dtb_mem);
> > +#else
> > +						0);
> > +#endif
> >  
> >  	BUG(); /* Should never get here. */
> >  }
diff mbox series

Patch

diff --git a/arch/arm64/kernel/cpu-reset.S b/arch/arm64/kernel/cpu-reset.S
index 8021b46c9743..a2be30275a73 100644
--- a/arch/arm64/kernel/cpu-reset.S
+++ b/arch/arm64/kernel/cpu-reset.S
@@ -22,11 +22,11 @@ 
  * __cpu_soft_restart(el2_switch, entry, arg0, arg1, arg2) - Helper for
  * cpu_soft_restart.
  *
- * @el2_switch: Flag to indicate a swich to EL2 is needed.
+ * @el2_switch: Flag to indicate a switch to EL2 is needed.
  * @entry: Location to jump to for soft reset.
- * arg0: First argument passed to @entry.
- * arg1: Second argument passed to @entry.
- * arg2: Third argument passed to @entry.
+ * arg0: First argument passed to @entry. (relocation list)
+ * arg1: Second argument passed to @entry.(physical kernel entry)
+ * arg2: Third argument passed to @entry. (physical dtb address)
  *
  * Put the CPU into the same state as it would be if it had been reset, and
  * branch to what would be the reset vector. It must be executed with the
diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c
index f76ea92dff91..830a5063e09d 100644
--- a/arch/arm64/kernel/machine_kexec.c
+++ b/arch/arm64/kernel/machine_kexec.c
@@ -205,10 +205,18 @@  void machine_kexec(struct kimage *kimage)
 	 * uses physical addressing to relocate the new image to its final
 	 * position and transfers control to the image entry point when the
 	 * relocation is complete.
+	 * In kexec case, kimage->start points to purgatory assuming that
+	 * kernel entry and dtb address are embedded in purgatory by
+	 * userspace (kexec-tools).
+	 * In kexec_file case, the kernel starts directly without purgatory.
 	 */
-
 	cpu_soft_restart(kimage != kexec_crash_image,
-		reboot_code_buffer_phys, kimage->head, kimage->start, 0);
+		reboot_code_buffer_phys, kimage->head, kimage->start,
+#ifdef CONFIG_KEXEC_FILE
+						kimage->arch.dtb_mem);
+#else
+						0);
+#endif
 
 	BUG(); /* Should never get here. */
 }
diff --git a/arch/arm64/kernel/relocate_kernel.S b/arch/arm64/kernel/relocate_kernel.S
index f407e422a720..95fd94209aae 100644
--- a/arch/arm64/kernel/relocate_kernel.S
+++ b/arch/arm64/kernel/relocate_kernel.S
@@ -32,6 +32,7 @@ 
 ENTRY(arm64_relocate_new_kernel)
 
 	/* Setup the list loop variables. */
+	mov	x18, x2				/* x18 = dtb address */
 	mov	x17, x1				/* x17 = kimage_start */
 	mov	x16, x0				/* x16 = kimage_head */
 	raw_dcache_line_size x15, x0		/* x15 = dcache line size */
@@ -107,7 +108,7 @@  ENTRY(arm64_relocate_new_kernel)
 	isb
 
 	/* Start new image. */
-	mov	x0, xzr
+	mov	x0, x18
 	mov	x1, xzr
 	mov	x2, xzr
 	mov	x3, xzr