[PATCH v2 5/7] x86: kexec_file: lift CRASH_MAX_RANGES limit on crash_mem buffer
AKASHI Takahiro
takahiro.akashi at linaro.org
Tue Mar 6 02:23:01 PST 2018
While CRASH_MAX_RANGES (== 16) seems to be good enough, fixed-number
array is not a good idea in general.
In this patch, size of crash_mem buffer is calculated as before and
the buffer is now dynamically allocated. This change also allows removing
crash_elf_data structure.
Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
Cc: Dave Young <dyoung at redhat.com>
Cc: Vivek Goyal <vgoyal at redhat.com>
Cc: Baoquan He <bhe at redhat.com>
---
arch/x86/kernel/crash.c | 82 +++++++++++++++++++------------------------------
1 file changed, 31 insertions(+), 51 deletions(-)
diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index b328153cee65..0f20a6330bd6 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -41,32 +41,14 @@
/* Alignment required for elf header segment */
#define ELF_CORE_HEADER_ALIGN 4096
-/* This primarily represents number of split ranges due to exclusion */
-#define CRASH_MAX_RANGES 16
-
struct crash_mem_range {
u64 start, end;
};
struct crash_mem {
- unsigned int nr_ranges;
- struct crash_mem_range ranges[CRASH_MAX_RANGES];
-};
-
-/* Misc data about ram ranges needed to prepare elf headers */
-struct crash_elf_data {
- struct kimage *image;
- /*
- * Total number of ram ranges we have after various adjustments for
- * crash reserved region, etc.
- */
unsigned int max_nr_ranges;
-
- /* Pointer to elf header */
- void *ehdr;
- /* Pointer to next phdr */
- void *bufp;
- struct crash_mem mem;
+ unsigned int nr_ranges;
+ struct crash_mem_range ranges[0];
};
/* Used while preparing memory map entries for second kernel */
@@ -217,26 +199,31 @@ static int get_nr_ram_ranges_callback(struct resource *res, void *arg)
return 0;
}
-
/* Gather all the required information to prepare elf headers for ram regions */
-static void fill_up_crash_elf_data(struct crash_elf_data *ced,
- struct kimage *image)
+static struct crash_mem *fill_up_crash_elf_data(void)
{
unsigned int nr_ranges = 0;
-
- ced->image = image;
+ struct crash_mem *cmem;
walk_system_ram_res(0, -1, &nr_ranges,
get_nr_ram_ranges_callback);
+ if (!nr_ranges)
+ return NULL;
- ced->max_nr_ranges = nr_ranges;
+ /*
+ * Exclusion of crash region and/or crashk_low_res may cause
+ * another range split. So add extra two slots here.
+ */
+ nr_ranges += 2;
+ cmem = vzalloc(sizeof(struct crash_mem) +
+ sizeof(struct crash_mem_range) * nr_ranges);
+ if (!cmem)
+ return NULL;
- /* Exclusion of crash region could split memory ranges */
- ced->max_nr_ranges++;
+ cmem->max_nr_ranges = nr_ranges;
+ cmem->nr_ranges = 0;
- /* If crashk_low_res is not 0, another range split possible */
- if (crashk_low_res.end)
- ced->max_nr_ranges++;
+ return cmem;
}
static int exclude_mem_range(struct crash_mem *mem,
@@ -293,10 +280,8 @@ static int exclude_mem_range(struct crash_mem *mem,
return 0;
/* Split happened */
- if (i == CRASH_MAX_RANGES - 1) {
- pr_err("Too many crash ranges after split\n");
+ if (i == mem->max_nr_ranges - 1)
return -ENOMEM;
- }
/* Location where new range should go */
j = i + 1;
@@ -314,11 +299,10 @@ static int exclude_mem_range(struct crash_mem *mem,
/*
* Look for any unwanted ranges between mstart, mend and remove them. This
- * might lead to split and split ranges are put in ced->mem.ranges[] array
+ * might lead to split and split ranges are put in cmem->ranges[] array
*/
-static int elf_header_exclude_ranges(struct crash_elf_data *ced)
+static int elf_header_exclude_ranges(struct crash_mem *cmem)
{
- struct crash_mem *cmem = &ced->mem;
int ret = 0;
/* Exclude crashkernel region */
@@ -337,8 +321,7 @@ static int elf_header_exclude_ranges(struct crash_elf_data *ced)
static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
{
- struct crash_elf_data *ced = arg;
- struct crash_mem *cmem = &ced->mem;
+ struct crash_mem *cmem = arg;
cmem->ranges[cmem->nr_ranges].start = res->start;
cmem->ranges[cmem->nr_ranges].end = res->end;
@@ -347,7 +330,7 @@ static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
return 0;
}
-static int prepare_elf64_headers(struct crash_elf_data *ced, bool kernel_map,
+static int prepare_elf64_headers(struct crash_mem *cmem, bool kernel_map,
void **addr, unsigned long *sz)
{
Elf64_Ehdr *ehdr;
@@ -356,12 +339,11 @@ static int prepare_elf64_headers(struct crash_elf_data *ced, bool kernel_map,
unsigned char *buf, *bufp;
unsigned int cpu, i;
unsigned long long notes_addr;
- struct crash_mem *cmem = &ced->mem;
unsigned long mstart, mend;
/* extra phdr for vmcoreinfo elf note */
nr_phdr = nr_cpus + 1;
- nr_phdr += ced->max_nr_ranges;
+ nr_phdr += cmem->nr_ranges;
/*
* kexec-tools creates an extra PT_LOAD phdr for kernel text mapping
@@ -455,29 +437,27 @@ static int prepare_elf64_headers(struct crash_elf_data *ced, bool kernel_map,
static int prepare_elf_headers(struct kimage *image, void **addr,
unsigned long *sz)
{
- struct crash_elf_data *ced;
+ struct crash_mem *cmem;
Elf64_Ehdr *ehdr;
Elf64_Phdr *phdr;
int ret, i;
- ced = kzalloc(sizeof(*ced), GFP_KERNEL);
- if (!ced)
+ cmem = fill_up_crash_elf_data();
+ if (!cmem)
return -ENOMEM;
- fill_up_crash_elf_data(ced, image);
-
- ret = walk_system_ram_res(0, -1, ced,
+ ret = walk_system_ram_res(0, -1, cmem,
prepare_elf64_ram_headers_callback);
if (ret)
goto out;
/* Exclude unwanted mem ranges */
- ret = elf_header_exclude_ranges(ced);
+ ret = elf_header_exclude_ranges(cmem);
if (ret)
goto out;
/* By default prepare 64bit headers */
- ret = prepare_elf64_headers(ced, IS_ENABLED(CONFIG_X86_64), addr, sz);
+ ret = prepare_elf64_headers(cmem, IS_ENABLED(CONFIG_X86_64), addr, sz);
if (ret)
goto out;
@@ -495,7 +475,7 @@ static int prepare_elf_headers(struct kimage *image, void **addr,
break;
}
out:
- kfree(ced);
+ vfree(cmem);
return ret;
}
--
2.16.2
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