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Subject[PATCH v9 07/11] arm64: kexec_file: add crash dump support
Date
Enabling crash dump (kdump) includes
* prepare contents of ELF header of a core dump file, /proc/vmcore,
using crash_prepare_elf64_headers(), and
* add two device tree properties, "linux,usable-memory-range" and
"linux,elfcorehdr", which represent repsectively a memory range
to be used by crash dump kernel and the header's location

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
---
arch/arm64/include/asm/kexec.h | 4 +
arch/arm64/kernel/kexec_image.c | 9 +-
arch/arm64/kernel/machine_kexec_file.c | 202 +++++++++++++++++++++++++
3 files changed, 213 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/kexec.h b/arch/arm64/include/asm/kexec.h
index 3cba4161818a..77f05bcf6a42 100644
--- a/arch/arm64/include/asm/kexec.h
+++ b/arch/arm64/include/asm/kexec.h
@@ -100,6 +100,10 @@ struct kimage_arch {
int kern_segment;
phys_addr_t dtb_mem;
void *dtb_buf;
+ /* Core ELF header buffer */
+ void *elf_headers;
+ unsigned long elf_headers_sz;
+ unsigned long elf_load_addr;
};

/**
diff --git a/arch/arm64/kernel/kexec_image.c b/arch/arm64/kernel/kexec_image.c
index 4dd524ad6611..2b3baf7285e0 100644
--- a/arch/arm64/kernel/kexec_image.c
+++ b/arch/arm64/kernel/kexec_image.c
@@ -39,8 +39,13 @@ static void *image_load(struct kimage *image,

/* Load the kernel */
kbuf.image = image;
- kbuf.buf_min = 0;
- kbuf.buf_max = ULONG_MAX;
+ if (image->type == KEXEC_TYPE_CRASH) {
+ kbuf.buf_min = crashk_res.start;
+ kbuf.buf_max = crashk_res.end + 1;
+ } else {
+ kbuf.buf_min = 0;
+ kbuf.buf_max = ULONG_MAX;
+ }
kbuf.top_down = false;

kbuf.buffer = kernel;
diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c
index 37c0a9dc2e47..ec674f4d267c 100644
--- a/arch/arm64/kernel/machine_kexec_file.c
+++ b/arch/arm64/kernel/machine_kexec_file.c
@@ -17,6 +17,7 @@
#include <linux/memblock.h>
#include <linux/of_fdt.h>
#include <linux/types.h>
+#include <linux/vmalloc.h>
#include <asm/byteorder.h>

static int __dt_root_addr_cells;
@@ -32,6 +33,10 @@ int arch_kimage_file_post_load_cleanup(struct kimage *image)
vfree(image->arch.dtb_buf);
image->arch.dtb_buf = NULL;

+ vfree(image->arch.elf_headers);
+ image->arch.elf_headers = NULL;
+ image->arch.elf_headers_sz = 0;
+
return kexec_image_post_load_cleanup_default(image);
}

@@ -76,6 +81,78 @@ int arch_kexec_walk_mem(struct kexec_buf *kbuf,
return ret;
}

+static int __init arch_kexec_file_init(void)
+{
+ /* Those values are used later on loading the kernel */
+ __dt_root_addr_cells = dt_root_addr_cells;
+ __dt_root_size_cells = dt_root_size_cells;
+
+ return 0;
+}
+late_initcall(arch_kexec_file_init);
+
+#define FDT_ALIGN(x, a) (((x) + (a) - 1) & ~((a) - 1))
+#define FDT_TAGALIGN(x) (FDT_ALIGN((x), FDT_TAGSIZE))
+
+static int fdt_prop_len(const char *prop_name, int len)
+{
+ return (strlen(prop_name) + 1) +
+ sizeof(struct fdt_property) +
+ FDT_TAGALIGN(len);
+}
+
+static bool cells_size_fitted(unsigned long base, unsigned long size)
+{
+ /* if *_cells >= 2, cells can hold 64-bit values anyway */
+ if ((__dt_root_addr_cells == 1) && (base >= (1ULL << 32)))
+ return false;
+
+ if ((__dt_root_size_cells == 1) && (size >= (1ULL << 32)))
+ return false;
+
+ return true;
+}
+
+static void fill_property(void *buf, u64 val64, int cells)
+{
+ u32 val32;
+
+ if (cells == 1) {
+ val32 = cpu_to_fdt32((u32)val64);
+ memcpy(buf, &val32, sizeof(val32));
+ } else {
+ memset(buf, 0, cells * sizeof(u32) - sizeof(u64));
+ buf += cells * sizeof(u32) - sizeof(u64);
+
+ val64 = cpu_to_fdt64(val64);
+ memcpy(buf, &val64, sizeof(val64));
+ }
+}
+
+static int fdt_setprop_range(void *fdt, int nodeoffset, const char *name,
+ unsigned long addr, unsigned long size)
+{
+ void *buf, *prop;
+ size_t buf_size;
+ int result;
+
+ buf_size = (__dt_root_addr_cells + __dt_root_size_cells) * sizeof(u32);
+ prop = buf = vmalloc(buf_size);
+ if (!buf)
+ return -ENOMEM;
+
+ fill_property(prop, addr, __dt_root_addr_cells);
+ prop += __dt_root_addr_cells * sizeof(u32);
+
+ fill_property(prop, size, __dt_root_size_cells);
+
+ result = fdt_setprop(fdt, nodeoffset, name, buf, buf_size);
+
+ vfree(buf);
+
+ return result;
+}
+
static int setup_dtb(struct kimage *image,
unsigned long initrd_load_addr, unsigned long initrd_len,
char *cmdline, unsigned long cmdline_len,
@@ -88,10 +165,26 @@ static int setup_dtb(struct kimage *image,
int range_len;
int ret;

+ /* check ranges against root's #address-cells and #size-cells */
+ if (image->type == KEXEC_TYPE_CRASH &&
+ (!cells_size_fitted(image->arch.elf_load_addr,
+ image->arch.elf_headers_sz) ||
+ !cells_size_fitted(crashk_res.start,
+ crashk_res.end - crashk_res.start + 1))) {
+ pr_err("Crash memory region doesn't fit into DT's root cell sizes.\n");
+ ret = -EINVAL;
+ goto out_err;
+ }
+
/* duplicate dt blob */
buf_size = fdt_totalsize(initial_boot_params);
range_len = (__dt_root_addr_cells + __dt_root_size_cells) * sizeof(u32);

+ if (image->type == KEXEC_TYPE_CRASH)
+ buf_size += fdt_prop_len("linux,elfcorehdr", range_len)
+ + fdt_prop_len("linux,usable-memory-range",
+ range_len);
+
if (initrd_load_addr)
buf_size += fdt_prop_len("linux,initrd-start", sizeof(u64))
+ fdt_prop_len("linux,initrd-end", sizeof(u64));
@@ -113,6 +206,23 @@ static int setup_dtb(struct kimage *image,
if (nodeoffset < 0)
goto out_err;

+ if (image->type == KEXEC_TYPE_CRASH) {
+ /* add linux,elfcorehdr */
+ ret = fdt_setprop_range(buf, nodeoffset, "linux,elfcorehdr",
+ image->arch.elf_load_addr,
+ image->arch.elf_headers_sz);
+ if (ret)
+ goto out_err;
+
+ /* add linux,usable-memory-range */
+ ret = fdt_setprop_range(buf, nodeoffset,
+ "linux,usable-memory-range",
+ crashk_res.start,
+ crashk_res.end - crashk_res.start + 1);
+ if (ret)
+ goto out_err;
+ }
+
/* add bootargs */
if (cmdline) {
ret = fdt_setprop(buf, nodeoffset, "bootargs",
@@ -148,17 +258,109 @@ static int setup_dtb(struct kimage *image,
return ret;
}

+static int get_nr_ranges_callback(struct resource *res, void *arg)
+{
+ unsigned int *nr_ranges = arg;
+
+ (*nr_ranges)++;
+ return 0;
+}
+
+static int add_mem_range_callback(struct resource *res, void *arg)
+{
+ struct crash_mem *cmem = arg;
+
+ cmem->ranges[cmem->nr_ranges].start = res->start;
+ cmem->ranges[cmem->nr_ranges].end = res->end;
+ cmem->nr_ranges++;
+
+ return 0;
+}
+
+static struct crash_mem *get_crash_memory_ranges(void)
+{
+ unsigned int nr_ranges;
+ struct crash_mem *cmem;
+
+ nr_ranges = 1; /* for exclusion of crashkernel region */
+ walk_system_ram_res(0, -1, &nr_ranges, get_nr_ranges_callback);
+
+ cmem = vmalloc(sizeof(struct crash_mem) +
+ sizeof(struct crash_mem_range) * nr_ranges);
+ if (!cmem)
+ return NULL;
+
+ cmem->max_nr_ranges = nr_ranges;
+ cmem->nr_ranges = 0;
+ walk_system_ram_res(0, -1, cmem, add_mem_range_callback);
+
+ /* Exclude crashkernel region */
+ if (crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end)) {
+ vfree(cmem);
+ return NULL;
+ }
+
+ return cmem;
+}
+
+static int prepare_elf_headers(void **addr, unsigned long *sz)
+{
+ struct crash_mem *cmem;
+ int ret = 0;
+
+ cmem = get_crash_memory_ranges();
+ if (!cmem)
+ return -ENOMEM;
+
+ ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
+
+ vfree(cmem);
+ return ret;
+}
+
int load_other_segments(struct kimage *image,
char *initrd, unsigned long initrd_len,
char *cmdline, unsigned long cmdline_len)
{
struct kexec_segment *kern_seg;
struct kexec_buf kbuf;
+ void *hdrs_addr;
+ unsigned long hdrs_sz;
unsigned long initrd_load_addr = 0;
char *dtb = NULL;
unsigned long dtb_len = 0;
int ret = 0;

+ /* load elf core header */
+ if (image->type == KEXEC_TYPE_CRASH) {
+ ret = prepare_elf_headers(&hdrs_addr, &hdrs_sz);
+ if (ret) {
+ pr_err("Preparing elf core header failed\n");
+ goto out_err;
+ }
+
+ kbuf.image = image;
+ kbuf.buffer = hdrs_addr;
+ kbuf.bufsz = hdrs_sz;
+ kbuf.memsz = hdrs_sz;
+ kbuf.buf_align = PAGE_SIZE;
+ kbuf.buf_min = crashk_res.start;
+ kbuf.buf_max = crashk_res.end + 1;
+ kbuf.top_down = true;
+
+ ret = kexec_add_buffer(&kbuf);
+ if (ret) {
+ vfree(hdrs_addr);
+ goto out_err;
+ }
+ image->arch.elf_headers = hdrs_addr;
+ image->arch.elf_headers_sz = hdrs_sz;
+ image->arch.elf_load_addr = kbuf.mem;
+
+ pr_debug("Loaded elf core header at 0x%lx bufsz=0x%lx memsz=0x%lx\n",
+ image->arch.elf_load_addr, hdrs_sz, hdrs_sz);
+ }
+
kern_seg = &image->segment[image->arch.kern_segment];
kbuf.image = image;
/* not allocate anything below the kernel */
--
2.17.0
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