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Message-ID: <20210201160838.GH1463@shell.armlinux.org.uk>
Date: Mon, 1 Feb 2021 16:08:38 +0000
From: Russell King - ARM Linux admin <linux@...linux.org.uk>
To: Mark Rutland <mark.rutland@....com>
Cc: Giancarlo Ferrari <giancarlo.ferrari89@...il.com>,
linux-kernel@...r.kernel.org, penberg@...nel.org,
geert@...ux-m68k.org, linux-arm-kernel@...ts.infradead.org,
akpm@...ux-foundation.org, rppt@...nel.org,
giancarlo.ferrari@...ia.com
Subject: Re: [PATCH] ARM: kexec: Fix panic after TLB are invalidated
On Mon, Feb 01, 2021 at 01:57:14PM +0000, Mark Rutland wrote:
> We could simplify this slightly if we moved the kexec_& variables into a
> struct (using asm-offset KEXEC_VAR_* offsets and a KEXEC_VAR_SIZE region
> reserved in the asm), then here we could do something like:
>
> static struct kexec_vars *kexec_buffer_vars(void *buffer)
> {
> unsigned long code = ((unisigned long)relocate_new_kernel) & ~1;
> unsigned long vars - (unsigned long)relocate_vars;
> unsigned long offset = vars - code;
>
> return buffer + offset;
> }
>
> ... and in machine_kexec() do:
>
> struct kexec_vars *kv = kexec_buffer_vars(reboot_code_buffer);
>
> kv->start_address = image->start;
> kv->indirection_page = page_list;
> kv->mach_type = machine-arch_type;
> kv->boot_atags = arch.kernel_r2;
>
> ... if that looks any better to you?
Something like this?
diff --git a/arch/arm/include/asm/kexec-internal.h b/arch/arm/include/asm/kexec-internal.h
new file mode 100644
index 000000000000..ecc2322db7aa
--- /dev/null
+++ b/arch/arm/include/asm/kexec-internal.h
@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ARM_KEXEC_INTERNAL_H
+#define _ARM_KEXEC_INTERNAL_H
+
+struct kexec_relocate_data {
+ unsigned long kexec_start_address;
+ unsigned long kexec_indirection_page;
+ unsigned long kexec_mach_type;
+ unsigned long kexec_r2;
+};
+
+#endif
diff --git a/arch/arm/kernel/asm-offsets.c b/arch/arm/kernel/asm-offsets.c
index a1570c8bab25..be8050b0c3df 100644
--- a/arch/arm/kernel/asm-offsets.c
+++ b/arch/arm/kernel/asm-offsets.c
@@ -12,6 +12,7 @@
#include <linux/mm.h>
#include <linux/dma-mapping.h>
#include <asm/cacheflush.h>
+#include <asm/kexec-internal.h>
#include <asm/glue-df.h>
#include <asm/glue-pf.h>
#include <asm/mach/arch.h>
@@ -170,5 +171,9 @@ int main(void)
DEFINE(MPU_RGN_PRBAR, offsetof(struct mpu_rgn, prbar));
DEFINE(MPU_RGN_PRLAR, offsetof(struct mpu_rgn, prlar));
#endif
+ DEFINE(KEXEC_START_ADDR, offsetof(struct kexec_relocate_data, kexec_start_address));
+ DEFINE(KEXEC_INDIR_PAGE, offsetof(struct kexec_relocate_data, kexec_indirection_page));
+ DEFINE(KEXEC_MACH_TYPE, offsetof(struct kexec_relocate_data, kexec_mach_type));
+ DEFINE(KEXEC_R2, offsetof(struct kexec_relocate_data, kexec_r2));
return 0;
}
diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c
index 5d84ad333f05..2b09dad7935e 100644
--- a/arch/arm/kernel/machine_kexec.c
+++ b/arch/arm/kernel/machine_kexec.c
@@ -13,6 +13,7 @@
#include <linux/of_fdt.h>
#include <asm/mmu_context.h>
#include <asm/cacheflush.h>
+#include <asm/kexec-internal.h>
#include <asm/fncpy.h>
#include <asm/mach-types.h>
#include <asm/smp_plat.h>
@@ -22,11 +23,6 @@
extern void relocate_new_kernel(void);
extern const unsigned int relocate_new_kernel_size;
-extern unsigned long kexec_start_address;
-extern unsigned long kexec_indirection_page;
-extern unsigned long kexec_mach_type;
-extern unsigned long kexec_boot_atags;
-
static atomic_t waiting_for_crash_ipi;
/*
@@ -159,6 +155,7 @@ void (*kexec_reinit)(void);
void machine_kexec(struct kimage *image)
{
unsigned long page_list, reboot_entry_phys;
+ struct kexec_relocate_data *data;
void (*reboot_entry)(void);
void *reboot_code_buffer;
@@ -174,18 +171,17 @@ void machine_kexec(struct kimage *image)
reboot_code_buffer = page_address(image->control_code_page);
- /* Prepare parameters for reboot_code_buffer*/
- set_kernel_text_rw();
- kexec_start_address = image->start;
- kexec_indirection_page = page_list;
- kexec_mach_type = machine_arch_type;
- kexec_boot_atags = image->arch.kernel_r2;
-
/* copy our kernel relocation code to the control code page */
reboot_entry = fncpy(reboot_code_buffer,
&relocate_new_kernel,
relocate_new_kernel_size);
+ data = reboot_code_buffer + relocate_new_kernel_size;
+ data->kexec_start_address = image->start;
+ data->kexec_indirection_page = page_list;
+ data->kexec_mach_type = machine_arch_type;
+ data->kexec_r2 = image->arch.kernel_r2;
+
/* get the identity mapping physical address for the reboot code */
reboot_entry_phys = virt_to_idmap(reboot_entry);
diff --git a/arch/arm/kernel/relocate_kernel.S b/arch/arm/kernel/relocate_kernel.S
index 72a08786e16e..218d524360fc 100644
--- a/arch/arm/kernel/relocate_kernel.S
+++ b/arch/arm/kernel/relocate_kernel.S
@@ -5,14 +5,16 @@
#include <linux/linkage.h>
#include <asm/assembler.h>
+#include <asm/asm-offsets.h>
#include <asm/kexec.h>
.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
+ adr r7, relocate_new_kernel_end
+ ldr r0, [r7, #KEXEC_INDIR_PAGE]
+ ldr r1, [r7, #KEXEC_START_ADDR]
/*
* If there is no indirection page (we are doing crashdumps)
@@ -57,34 +59,16 @@ ENTRY(relocate_new_kernel)
2:
/* Jump to relocated kernel */
- mov lr,r1
- mov r0,#0
- ldr r1,kexec_mach_type
- ldr r2,kexec_boot_atags
- ARM( ret lr )
- THUMB( bx lr )
-
- .align
-
- .globl kexec_start_address
-kexec_start_address:
- .long 0x0
-
- .globl kexec_indirection_page
-kexec_indirection_page:
- .long 0x0
-
- .globl kexec_mach_type
-kexec_mach_type:
- .long 0x0
-
- /* phy addr of the atags for the new kernel */
- .globl kexec_boot_atags
-kexec_boot_atags:
- .long 0x0
+ mov lr, r1
+ mov r0, #0
+ ldr r1, [r7, #KEXEC_MACH_TYPE]
+ ldr r2, [r7, #KEXEC_R2]
+ ARM( ret lr )
+ THUMB( bx lr )
ENDPROC(relocate_new_kernel)
+ .align 3
relocate_new_kernel_end:
.globl relocate_new_kernel_size
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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