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Message-Id: <20210127172706.617195-2-pasha.tatashin@soleen.com>
Date: Wed, 27 Jan 2021 12:27:01 -0500
From: Pavel Tatashin <pasha.tatashin@...een.com>
To: pasha.tatashin@...een.com, jmorris@...ei.org, sashal@...nel.org,
ebiederm@...ssion.com, kexec@...ts.infradead.org,
linux-kernel@...r.kernel.org, corbet@....net,
catalin.marinas@....com, will@...nel.org,
linux-arm-kernel@...ts.infradead.org, maz@...nel.org,
james.morse@....com, vladimir.murzin@....com,
matthias.bgg@...il.com, linux-mm@...ck.org, mark.rutland@....com,
steve.capper@....com, rfontana@...hat.com, tglx@...utronix.de,
selindag@...il.com, tyhicks@...ux.microsoft.com
Subject: [PATCH v11 1/6] arm64: kexec: add expandable argument to relocation function
Currently, kexec relocation function (arm64_relocate_new_kernel) accepts
the following arguments:
head: start of array that contains relocation information.
entry: entry point for new kernel or purgatory.
dtb_mem: first and only argument to entry.
The number of arguments cannot be easily expended, because this
function is also called from HVC_SOFT_RESTART, which preserves only
three arguments (hypervisor abi). And, also arm64_relocate_new_kernel is
written in assembly but called without stack, thus no place to move extra
arguments to free registers.
Soon, we will need to pass more arguments: once we enable MMU we
will need to pass information about page tables.
Add a new struct: kern_reloc_arg, and place it in kexec safe page (i.e
memory that is not overwritten during relocation).
Thus, make arm64_relocate_new_kernel to only take one argument, that
contains all the needed information.
Note:
Another benefit of allowing this function to accept more arguments, is that
kernel can actually accept up to 4 arguments (x0-x3), however currently
only one is used, but if in the future we will need for more (for example,
pass information about when previous kernel exited to have a precise
measurement in time spent in purgatory), we won't be easilty do that
if arm64_relocate_new_kernel can't accept more arguments.
Signed-off-by: Pavel Tatashin <pasha.tatashin@...een.com>
---
arch/arm64/include/asm/kexec.h | 18 ++++++++++++++++++
arch/arm64/kernel/asm-offsets.c | 9 +++++++++
arch/arm64/kernel/cpu-reset.S | 11 +++--------
arch/arm64/kernel/cpu-reset.h | 8 +++-----
arch/arm64/kernel/machine_kexec.c | 27 +++++++++++++++++++++++++--
arch/arm64/kernel/relocate_kernel.S | 21 ++++++++-------------
6 files changed, 66 insertions(+), 28 deletions(-)
diff --git a/arch/arm64/include/asm/kexec.h b/arch/arm64/include/asm/kexec.h
index 9befcd87e9a8..990185744148 100644
--- a/arch/arm64/include/asm/kexec.h
+++ b/arch/arm64/include/asm/kexec.h
@@ -90,12 +90,30 @@ static inline void crash_prepare_suspend(void) {}
static inline void crash_post_resume(void) {}
#endif
+/*
+ * kern_reloc_arg is passed to kernel relocation function as an argument.
+ * head kimage->head, allows to traverse through relocation segments.
+ * entry_addr kimage->start, where to jump from relocation function (new
+ * kernel, or purgatory entry address).
+ * kern_arg0 first argument to kernel is its dtb address. The other
+ * arguments are currently unused, and must be set to 0
+ */
+struct kern_reloc_arg {
+ phys_addr_t head;
+ phys_addr_t entry_addr;
+ phys_addr_t kern_arg0;
+ phys_addr_t kern_arg1;
+ phys_addr_t kern_arg2;
+ phys_addr_t kern_arg3;
+};
+
#define ARCH_HAS_KIMAGE_ARCH
struct kimage_arch {
void *dtb;
phys_addr_t dtb_mem;
phys_addr_t kern_reloc;
+ phys_addr_t kern_reloc_arg;
/* Core ELF header buffer */
void *elf_headers;
unsigned long elf_headers_mem;
diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
index 301784463587..6067a288f568 100644
--- a/arch/arm64/kernel/asm-offsets.c
+++ b/arch/arm64/kernel/asm-offsets.c
@@ -23,6 +23,7 @@
#include <asm/suspend.h>
#include <linux/kbuild.h>
#include <linux/arm-smccc.h>
+#include <linux/kexec.h>
int main(void)
{
@@ -150,6 +151,14 @@ int main(void)
DEFINE(PTRAUTH_USER_KEY_APGA, offsetof(struct ptrauth_keys_user, apga));
DEFINE(PTRAUTH_KERNEL_KEY_APIA, offsetof(struct ptrauth_keys_kernel, apia));
BLANK();
+#endif
+#ifdef CONFIG_KEXEC_CORE
+ DEFINE(KEXEC_KRELOC_HEAD, offsetof(struct kern_reloc_arg, head));
+ DEFINE(KEXEC_KRELOC_ENTRY_ADDR, offsetof(struct kern_reloc_arg, entry_addr));
+ DEFINE(KEXEC_KRELOC_KERN_ARG0, offsetof(struct kern_reloc_arg, kern_arg0));
+ DEFINE(KEXEC_KRELOC_KERN_ARG1, offsetof(struct kern_reloc_arg, kern_arg1));
+ DEFINE(KEXEC_KRELOC_KERN_ARG2, offsetof(struct kern_reloc_arg, kern_arg2));
+ DEFINE(KEXEC_KRELOC_KERN_ARG3, offsetof(struct kern_reloc_arg, kern_arg3));
#endif
return 0;
}
diff --git a/arch/arm64/kernel/cpu-reset.S b/arch/arm64/kernel/cpu-reset.S
index 37721eb6f9a1..bbf70db43744 100644
--- a/arch/arm64/kernel/cpu-reset.S
+++ b/arch/arm64/kernel/cpu-reset.S
@@ -16,14 +16,11 @@
.pushsection .idmap.text, "awx"
/*
- * __cpu_soft_restart(el2_switch, entry, arg0, arg1, arg2) - Helper for
- * cpu_soft_restart.
+ * __cpu_soft_restart(el2_switch, entry, arg) - Helper for cpu_soft_restart.
*
* @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. (relocation list)
- * arg1: Second argument passed to @entry.(physical kernel entry)
- * arg2: Third argument passed to @entry. (physical dtb address)
+ * arg: Entry argument
*
* 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
@@ -47,9 +44,7 @@ SYM_CODE_START(__cpu_soft_restart)
hvc #0 // no return
1: mov x8, x1 // entry
- mov x0, x2 // arg0
- mov x1, x3 // arg1
- mov x2, x4 // arg2
+ mov x0, x2 // arg
br x8
SYM_CODE_END(__cpu_soft_restart)
diff --git a/arch/arm64/kernel/cpu-reset.h b/arch/arm64/kernel/cpu-reset.h
index ed50e9587ad8..7a8720ff186f 100644
--- a/arch/arm64/kernel/cpu-reset.h
+++ b/arch/arm64/kernel/cpu-reset.h
@@ -11,12 +11,10 @@
#include <asm/virt.h>
void __cpu_soft_restart(unsigned long el2_switch, unsigned long entry,
- unsigned long arg0, unsigned long arg1, unsigned long arg2);
+ unsigned long arg);
static inline void __noreturn cpu_soft_restart(unsigned long entry,
- unsigned long arg0,
- unsigned long arg1,
- unsigned long arg2)
+ unsigned long arg)
{
typeof(__cpu_soft_restart) *restart;
@@ -25,7 +23,7 @@ static inline void __noreturn cpu_soft_restart(unsigned long entry,
restart = (void *)__pa_symbol(__cpu_soft_restart);
cpu_install_idmap();
- restart(el2_switch, entry, arg0, arg1, arg2);
+ restart(el2_switch, entry, arg);
unreachable();
}
diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c
index 90a335c74442..679db3f1e0c5 100644
--- a/arch/arm64/kernel/machine_kexec.c
+++ b/arch/arm64/kernel/machine_kexec.c
@@ -43,6 +43,7 @@ static void _kexec_image_info(const char *func, int line,
pr_debug(" head: %lx\n", kimage->head);
pr_debug(" nr_segments: %lu\n", kimage->nr_segments);
pr_debug(" kern_reloc: %pa\n", &kimage->arch.kern_reloc);
+ pr_debug(" kern_reloc_arg: %pa\n", &kimage->arch.kern_reloc_arg);
for (i = 0; i < kimage->nr_segments; i++) {
pr_debug(" segment[%lu]: %016lx - %016lx, 0x%lx bytes, %lu pages\n",
@@ -59,19 +60,42 @@ void machine_kexec_cleanup(struct kimage *kimage)
/* Empty routine needed to avoid build errors. */
}
+/* Allocates pages for kexec page table */
+static void *kexec_page_alloc(void *arg)
+{
+ struct kimage *kimage = (struct kimage *)arg;
+ struct page *page = kimage_alloc_control_pages(kimage, 0);
+
+ if (!page)
+ return NULL;
+
+ memset(page_address(page), 0, PAGE_SIZE);
+
+ return page_address(page);
+}
+
int machine_kexec_post_load(struct kimage *kimage)
{
void *reloc_code = page_to_virt(kimage->control_code_page);
+ struct kern_reloc_arg *kern_reloc_arg = kexec_page_alloc(kimage);
+
+ if (!kern_reloc_arg)
+ return -ENOMEM;
memcpy(reloc_code, arm64_relocate_new_kernel,
arm64_relocate_new_kernel_size);
kimage->arch.kern_reloc = __pa(reloc_code);
+ kimage->arch.kern_reloc_arg = __pa(kern_reloc_arg);
+ kern_reloc_arg->head = kimage->head;
+ kern_reloc_arg->entry_addr = kimage->start;
+ kern_reloc_arg->kern_arg0 = kimage->arch.dtb_mem;
kexec_image_info(kimage);
/* Flush the reloc_code in preparation for its execution. */
__flush_dcache_area(reloc_code, arm64_relocate_new_kernel_size);
flush_icache_range((uintptr_t)reloc_code, (uintptr_t)reloc_code +
arm64_relocate_new_kernel_size);
+ __flush_dcache_area(kern_reloc_arg, sizeof(struct kern_reloc_arg));
return 0;
}
@@ -192,8 +216,7 @@ void machine_kexec(struct kimage *kimage)
* userspace (kexec-tools).
* In kexec_file case, the kernel starts directly without purgatory.
*/
- cpu_soft_restart(kimage->arch.kern_reloc, kimage->head, kimage->start,
- kimage->arch.dtb_mem);
+ cpu_soft_restart(kimage->arch.kern_reloc, kimage->arch.kern_reloc_arg);
BUG(); /* Should never get here. */
}
diff --git a/arch/arm64/kernel/relocate_kernel.S b/arch/arm64/kernel/relocate_kernel.S
index b78ea5de97a4..c92228aeddca 100644
--- a/arch/arm64/kernel/relocate_kernel.S
+++ b/arch/arm64/kernel/relocate_kernel.S
@@ -8,7 +8,7 @@
#include <linux/kexec.h>
#include <linux/linkage.h>
-
+#include <asm/asm-offsets.h>
#include <asm/assembler.h>
#include <asm/kexec.h>
#include <asm/page.h>
@@ -26,13 +26,8 @@
* safe memory that has been set up to be preserved during the copy operation.
*/
SYM_CODE_START(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 */
- mov x14, xzr /* x14 = entry ptr */
- mov x13, xzr /* x13 = copy dest */
/* Check if the new image needs relocation. */
+ ldr x16, [x0, #KEXEC_KRELOC_HEAD] /* x16 = kimage_head */
tbnz x16, IND_DONE_BIT, .Ldone
raw_dcache_line_size x15, x1 /* x15 = dcache line size */
.Lloop:
@@ -73,12 +68,12 @@ SYM_CODE_START(arm64_relocate_new_kernel)
isb
/* Start new image. */
- mov x0, x18
- mov x1, xzr
- mov x2, xzr
- mov x3, xzr
- br x17
-
+ ldr x4, [x0, #KEXEC_KRELOC_ENTRY_ADDR] /* x4 = kimage_start */
+ ldr x3, [x0, #KEXEC_KRELOC_KERN_ARG3]
+ ldr x2, [x0, #KEXEC_KRELOC_KERN_ARG2]
+ ldr x1, [x0, #KEXEC_KRELOC_KERN_ARG1]
+ ldr x0, [x0, #KEXEC_KRELOC_KERN_ARG0] /* x0 = dtb address */
+ br x4
SYM_CODE_END(arm64_relocate_new_kernel)
.align 3 /* To keep the 64-bit values below naturally aligned. */
--
2.25.1
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