[PATCH v8 2/5] crash: Exclude crash kernel memory in crash core

[PATCH v8 2/5] crash: Exclude crash kernel memory in crash core

[Jinjie Ruan]

The crash memory alloc, and the exclude of crashk_res, crashk_low_res
and crashk_cma memory are almost identical across different architectures,
handling them in the crash core would eliminate a lot of duplication, so
do them in the common code.

To achieve the above goal, three architecture-specific functions are
introduced:

- arch_get_system_nr_ranges(). Pre-counts the max number of memory ranges.

- arch_crash_populate_cmem(). Collects the memory ranges and fills them
  into cmem.

- arch_crash_exclude_ranges(). Architecture's additional crash memory
  ranges exclusion, defaulting to empty.

Acked-by: Baoquan He <bhe@redhat.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
 arch/arm64/kernel/machine_kexec_file.c     | 39 +++-------
 arch/loongarch/kernel/machine_kexec_file.c | 39 +++-------
 arch/riscv/kernel/machine_kexec_file.c     | 38 +++------
 arch/x86/kernel/crash.c                    | 89 +++-------------------
 include/linux/crash_core.h                 |  5 ++
 kernel/crash_core.c                        | 82 +++++++++++++++++++-
 6 files changed, 132 insertions(+), 160 deletions(-)

diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c
index fba260ad87a9..c338506a580b 100644
--- a/arch/arm64/kernel/machine_kexec_file.c
+++ b/arch/arm64/kernel/machine_kexec_file.c
@@ -40,23 +40,23 @@ int arch_kimage_file_post_load_cleanup(struct kimage *image)
 }
 
 #ifdef CONFIG_CRASH_DUMP
-static int prepare_elf_headers(void **addr, unsigned long *sz)
+unsigned int arch_get_system_nr_ranges(void)
 {
-	struct crash_mem *cmem;
-	unsigned int nr_ranges;
-	int ret;
-	u64 i;
+	unsigned int nr_ranges = 2; /* for exclusion of crashkernel region */
 	phys_addr_t start, end;
+	u64 i;
 
-	nr_ranges = 2; /* for exclusion of crashkernel region */
 	for_each_mem_range(i, &start, &end)
 		nr_ranges++;
 
-	cmem = kmalloc_flex(*cmem, ranges, nr_ranges);
-	if (!cmem)
-		return -ENOMEM;
+	return nr_ranges;
+}
+
+int arch_crash_populate_cmem(struct crash_mem *cmem)
+{
+	phys_addr_t start, end;
+	u64 i;
 
-	cmem->max_nr_ranges = nr_ranges;
 	cmem->nr_ranges = 0;
 	for_each_mem_range(i, &start, &end) {
 		cmem->ranges[cmem->nr_ranges].start = start;
@@ -64,22 +64,7 @@ static int prepare_elf_headers(void **addr, unsigned long *sz)
 		cmem->nr_ranges++;
 	}
 
-	/* Exclude crashkernel region */
-	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
-	if (ret)
-		goto out;
-
-	if (crashk_low_res.end) {
-		ret = crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
-		if (ret)
-			goto out;
-	}
-
-	ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
-
-out:
-	kfree(cmem);
-	return ret;
+	return 0;
 }
 #endif
 
@@ -109,7 +94,7 @@ int load_other_segments(struct kimage *image,
 	void *headers;
 	unsigned long headers_sz;
 	if (image->type == KEXEC_TYPE_CRASH) {
-		ret = prepare_elf_headers(&headers, &headers_sz);
+		ret = crash_prepare_headers(true, &headers, &headers_sz, NULL);
 		if (ret) {
 			pr_err("Preparing elf core header failed\n");
 			goto out_err;
diff --git a/arch/loongarch/kernel/machine_kexec_file.c b/arch/loongarch/kernel/machine_kexec_file.c
index 5584b798ba46..4b318a94b564 100644
--- a/arch/loongarch/kernel/machine_kexec_file.c
+++ b/arch/loongarch/kernel/machine_kexec_file.c
@@ -56,23 +56,23 @@ static void cmdline_add_initrd(struct kimage *image, unsigned long *cmdline_tmpl
 }
 
 #ifdef CONFIG_CRASH_DUMP
-
-static int prepare_elf_headers(void **addr, unsigned long *sz)
+unsigned int arch_get_system_nr_ranges(void)
 {
-	int ret, nr_ranges;
-	uint64_t i;
+	int nr_ranges = 2; /* for exclusion of crashkernel region */
 	phys_addr_t start, end;
-	struct crash_mem *cmem;
+	uint64_t i;
 
-	nr_ranges = 2; /* for exclusion of crashkernel region */
 	for_each_mem_range(i, &start, &end)
 		nr_ranges++;
 
-	cmem = kmalloc_flex(*cmem, ranges, nr_ranges);
-	if (!cmem)
-		return -ENOMEM;
+	return nr_ranges;
+}
+
+int arch_crash_populate_cmem(struct crash_mem *cmem)
+{
+	phys_addr_t start, end;
+	uint64_t i;
 
-	cmem->max_nr_ranges = nr_ranges;
 	cmem->nr_ranges = 0;
 	for_each_mem_range(i, &start, &end) {
 		cmem->ranges[cmem->nr_ranges].start = start;
@@ -80,22 +80,7 @@ static int prepare_elf_headers(void **addr, unsigned long *sz)
 		cmem->nr_ranges++;
 	}
 
-	/* Exclude crashkernel region */
-	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
-	if (ret < 0)
-		goto out;
-
-	if (crashk_low_res.end) {
-		ret = crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
-		if (ret < 0)
-			goto out;
-	}
-
-	ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
-
-out:
-	kfree(cmem);
-	return ret;
+	return 0;
 }
 
 /*
@@ -163,7 +148,7 @@ int load_other_segments(struct kimage *image,
 		void *headers;
 		unsigned long headers_sz;
 
-		ret = prepare_elf_headers(&headers, &headers_sz);
+		ret = crash_prepare_headers(true, &headers, &headers_sz, NULL);
 		if (ret < 0) {
 			pr_err("Preparing elf core header failed\n");
 			goto out_err;
diff --git a/arch/riscv/kernel/machine_kexec_file.c b/arch/riscv/kernel/machine_kexec_file.c
index 54e2d9552e93..d0e331d87155 100644
--- a/arch/riscv/kernel/machine_kexec_file.c
+++ b/arch/riscv/kernel/machine_kexec_file.c
@@ -44,6 +44,15 @@ static int get_nr_ram_ranges_callback(struct resource *res, void *arg)
 	return 0;
 }
 
+unsigned int arch_get_system_nr_ranges(void)
+{
+	unsigned int nr_ranges = 1; /* For exclusion of crashkernel region */
+
+	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
+
+	return nr_ranges;
+}
+
 static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
 {
 	struct crash_mem *cmem = arg;
@@ -55,33 +64,10 @@ static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
 	return 0;
 }
 
-static int prepare_elf_headers(void **addr, unsigned long *sz)
+int arch_crash_populate_cmem(struct crash_mem *cmem)
 {
-	struct crash_mem *cmem;
-	unsigned int nr_ranges;
-	int ret;
-
-	nr_ranges = 1; /* For exclusion of crashkernel region */
-	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
-
-	cmem = kmalloc_flex(*cmem, ranges, nr_ranges);
-	if (!cmem)
-		return -ENOMEM;
-
-	cmem->max_nr_ranges = nr_ranges;
 	cmem->nr_ranges = 0;
-	ret = walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
-	if (ret)
-		goto out;
-
-	/* Exclude crashkernel region */
-	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
-	if (!ret)
-		ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
-
-out:
-	kfree(cmem);
-	return ret;
+	return walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
 }
 
 static char *setup_kdump_cmdline(struct kimage *image, char *cmdline,
@@ -273,7 +259,7 @@ int load_extra_segments(struct kimage *image, unsigned long kernel_start,
 	if (image->type == KEXEC_TYPE_CRASH) {
 		void *headers;
 		unsigned long headers_sz;
-		ret = prepare_elf_headers(&headers, &headers_sz);
+		ret = crash_prepare_headers(true, &headers, &headers_sz, NULL);
 		if (ret) {
 			pr_err("Preparing elf core header failed\n");
 			goto out;
diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index 335fd2ee9766..3ad3f8b758a4 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -152,16 +152,8 @@ 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 struct crash_mem *fill_up_crash_elf_data(void)
+unsigned int arch_get_system_nr_ranges(void)
 {
-	unsigned int nr_ranges = 0;
-	struct crash_mem *cmem;
-
-	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
-	if (!nr_ranges)
-		return NULL;
-
 	/*
 	 * Exclusion of crash region, crashk_low_res and/or crashk_cma_ranges
 	 * may cause range splits. So add extra slots here.
@@ -176,49 +168,16 @@ static struct crash_mem *fill_up_crash_elf_data(void)
 	 * But in order to lest the low 1M could be changed in the future,
 	 * (e.g. [start, 1M]), add a extra slot.
 	 */
-	nr_ranges += 3 + crashk_cma_cnt;
-	cmem = vzalloc(struct_size(cmem, ranges, nr_ranges));
-	if (!cmem)
-		return NULL;
-
-	cmem->max_nr_ranges = nr_ranges;
+	unsigned int nr_ranges = 3 + crashk_cma_cnt;
 
-	return cmem;
+	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
+	return nr_ranges;
 }
 
-/*
- * Look for any unwanted ranges between mstart, mend and remove them. This
- * might lead to split and split ranges are put in cmem->ranges[] array
- */
-static int elf_header_exclude_ranges(struct crash_mem *cmem)
+int arch_crash_exclude_ranges(struct crash_mem *cmem)
 {
-	int ret = 0;
-	int i;
-
 	/* Exclude the low 1M because it is always reserved */
-	ret = crash_exclude_mem_range(cmem, 0, SZ_1M - 1);
-	if (ret)
-		return ret;
-
-	/* Exclude crashkernel region */
-	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
-	if (ret)
-		return ret;
-
-	if (crashk_low_res.end)
-		ret = crash_exclude_mem_range(cmem, crashk_low_res.start,
-					      crashk_low_res.end);
-	if (ret)
-		return ret;
-
-	for (i = 0; i < crashk_cma_cnt; ++i) {
-		ret = crash_exclude_mem_range(cmem, crashk_cma_ranges[i].start,
-					      crashk_cma_ranges[i].end);
-		if (ret)
-			return ret;
-	}
-
-	return 0;
+	return crash_exclude_mem_range(cmem, 0, SZ_1M - 1);
 }
 
 static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
@@ -232,35 +191,9 @@ static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
 	return 0;
 }
 
-/* Prepare elf headers. Return addr and size */
-static int prepare_elf_headers(void **addr, unsigned long *sz,
-			       unsigned long *nr_mem_ranges)
+int arch_crash_populate_cmem(struct crash_mem *cmem)
 {
-	struct crash_mem *cmem;
-	int ret;
-
-	cmem = fill_up_crash_elf_data();
-	if (!cmem)
-		return -ENOMEM;
-
-	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(cmem);
-	if (ret)
-		goto out;
-
-	/* Return the computed number of memory ranges, for hotplug usage */
-	*nr_mem_ranges = cmem->nr_ranges;
-
-	/* By default prepare 64bit headers */
-	ret = crash_prepare_elf64_headers(cmem, IS_ENABLED(CONFIG_X86_64), addr, sz);
-
-out:
-	vfree(cmem);
-	return ret;
+	return walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
 }
 #endif
 
@@ -418,7 +351,8 @@ int crash_load_segments(struct kimage *image)
 				  .buf_max = ULONG_MAX, .top_down = false };
 
 	/* Prepare elf headers and add a segment */
-	ret = prepare_elf_headers(&kbuf.buffer, &kbuf.bufsz, &pnum);
+	ret = crash_prepare_headers(IS_ENABLED(CONFIG_X86_64), &kbuf.buffer,
+				    &kbuf.bufsz, &pnum);
 	if (ret)
 		return ret;
 
@@ -529,7 +463,8 @@ void arch_crash_handle_hotplug_event(struct kimage *image, void *arg)
 	 * Create the new elfcorehdr reflecting the changes to CPU and/or
 	 * memory resources.
 	 */
-	if (prepare_elf_headers(&elfbuf, &elfsz, &nr_mem_ranges)) {
+	if (crash_prepare_headers(IS_ENABLED(CONFIG_X86_64), &elfbuf, &elfsz,
+				  &nr_mem_ranges)) {
 		pr_err("unable to create new elfcorehdr");
 		goto out;
 	}
diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
index d35726d6a415..033b20204aca 100644
--- a/include/linux/crash_core.h
+++ b/include/linux/crash_core.h
@@ -66,6 +66,8 @@ extern int crash_exclude_mem_range(struct crash_mem *mem,
 				   unsigned long long mend);
 extern int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
 				       void **addr, unsigned long *sz);
+extern int crash_prepare_headers(int need_kernel_map, void **addr,
+				 unsigned long *sz, unsigned long *nr_mem_ranges);
 
 struct kimage;
 struct kexec_segment;
@@ -83,6 +85,9 @@ int kexec_should_crash(struct task_struct *p);
 int kexec_crash_loaded(void);
 void crash_save_cpu(struct pt_regs *regs, int cpu);
 extern int kimage_crash_copy_vmcoreinfo(struct kimage *image);
+extern unsigned int arch_get_system_nr_ranges(void);
+extern int arch_crash_populate_cmem(struct crash_mem *cmem);
+extern int arch_crash_exclude_ranges(struct crash_mem *cmem);
 
 #else /* !CONFIG_CRASH_DUMP*/
 struct pt_regs;
diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index 2c1a3791e410..96a96e511f5a 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -170,9 +170,6 @@ static inline resource_size_t crash_resource_size(const struct resource *res)
 	return !res->end ? 0 : resource_size(res);
 }
 
-
-
-
 int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
 			  void **addr, unsigned long *sz)
 {
@@ -274,6 +271,85 @@ int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
 	return 0;
 }
 
+static struct crash_mem *alloc_cmem(unsigned int nr_ranges)
+{
+	struct crash_mem *cmem;
+
+	cmem = kvzalloc_flex(*cmem, ranges, nr_ranges);
+	if (!cmem)
+		return NULL;
+
+	cmem->max_nr_ranges = nr_ranges;
+	return cmem;
+}
+
+unsigned int __weak arch_get_system_nr_ranges(void) { return 0; }
+int __weak arch_crash_populate_cmem(struct crash_mem *cmem) { return -1; }
+int __weak arch_crash_exclude_ranges(struct crash_mem *cmem) { return 0; }
+
+static int crash_exclude_core_ranges(struct crash_mem *cmem)
+{
+	int ret, i;
+
+	/* Exclude crashkernel region */
+	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
+	if (ret)
+		return ret;
+
+	if (crashk_low_res.end) {
+		ret = crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
+		if (ret)
+			return ret;
+	}
+
+	for (i = 0; i < crashk_cma_cnt; ++i) {
+		ret = crash_exclude_mem_range(cmem, crashk_cma_ranges[i].start,
+					      crashk_cma_ranges[i].end);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+int crash_prepare_headers(int need_kernel_map, void **addr, unsigned long *sz,
+			  unsigned long *nr_mem_ranges)
+{
+	unsigned int max_nr_ranges;
+	struct crash_mem *cmem;
+	int ret;
+
+	max_nr_ranges = arch_get_system_nr_ranges();
+	if (!max_nr_ranges)
+		return -ENOMEM;
+
+	cmem = alloc_cmem(max_nr_ranges);
+	if (!cmem)
+		return -ENOMEM;
+
+	ret = arch_crash_populate_cmem(cmem);
+	if (ret)
+		goto out;
+
+	ret = crash_exclude_core_ranges(cmem);
+	if (ret)
+		goto out;
+
+	ret = arch_crash_exclude_ranges(cmem);
+	if (ret)
+		goto out;
+
+	/* Return the computed number of memory ranges, for hotplug usage */
+	if (nr_mem_ranges)
+		*nr_mem_ranges = cmem->nr_ranges;
+
+	ret = crash_prepare_elf64_headers(cmem, need_kernel_map, addr, sz);
+
+out:
+	kvfree(cmem);
+	return ret;
+}
+
 /**
  * crash_exclude_mem_range - exclude a mem range for existing ranges
  * @mem: mem->range contains an array of ranges sorted in ascending order
-- 
2.34.1

[PATCH v8 2/5] crash: Exclude crash kernel memory in crash core

[Jinjie Ruan]

The crash memory alloc, and the exclude of crashk_res, crashk_low_res
and crashk_cma memory are almost identical across different architectures,
handling them in the crash core would eliminate a lot of duplication, so
do them in the common code.

To achieve the above goal, three architecture-specific functions are
introduced:

- arch_get_system_nr_ranges(). Pre-counts the max number of memory ranges.

- arch_crash_populate_cmem(). Collects the memory ranges and fills them
  into cmem.

- arch_crash_exclude_ranges(). Architecture's additional crash memory
  ranges exclusion, defaulting to empty.

Acked-by: Baoquan He <bhe@redhat.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
---
 arch/arm64/kernel/machine_kexec_file.c     | 39 +++-------
 arch/loongarch/kernel/machine_kexec_file.c | 39 +++-------
 arch/riscv/kernel/machine_kexec_file.c     | 38 +++------
 arch/x86/kernel/crash.c                    | 89 +++-------------------
 include/linux/crash_core.h                 |  5 ++
 kernel/crash_core.c                        | 82 +++++++++++++++++++-
 6 files changed, 132 insertions(+), 160 deletions(-)

diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c
index fba260ad87a9..c338506a580b 100644
--- a/arch/arm64/kernel/machine_kexec_file.c
+++ b/arch/arm64/kernel/machine_kexec_file.c
@@ -40,23 +40,23 @@ int arch_kimage_file_post_load_cleanup(struct kimage *image)
 }
 
 #ifdef CONFIG_CRASH_DUMP
-static int prepare_elf_headers(void **addr, unsigned long *sz)
+unsigned int arch_get_system_nr_ranges(void)
 {
-	struct crash_mem *cmem;
-	unsigned int nr_ranges;
-	int ret;
-	u64 i;
+	unsigned int nr_ranges = 2; /* for exclusion of crashkernel region */
 	phys_addr_t start, end;
+	u64 i;
 
-	nr_ranges = 2; /* for exclusion of crashkernel region */
 	for_each_mem_range(i, &start, &end)
 		nr_ranges++;
 
-	cmem = kmalloc_flex(*cmem, ranges, nr_ranges);
-	if (!cmem)
-		return -ENOMEM;
+	return nr_ranges;
+}
+
+int arch_crash_populate_cmem(struct crash_mem *cmem)
+{
+	phys_addr_t start, end;
+	u64 i;
 
-	cmem->max_nr_ranges = nr_ranges;
 	cmem->nr_ranges = 0;
 	for_each_mem_range(i, &start, &end) {
 		cmem->ranges[cmem->nr_ranges].start = start;
@@ -64,22 +64,7 @@ static int prepare_elf_headers(void **addr, unsigned long *sz)
 		cmem->nr_ranges++;
 	}
 
-	/* Exclude crashkernel region */
-	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
-	if (ret)
-		goto out;
-
-	if (crashk_low_res.end) {
-		ret = crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
-		if (ret)
-			goto out;
-	}
-
-	ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
-
-out:
-	kfree(cmem);
-	return ret;
+	return 0;
 }
 #endif
 
@@ -109,7 +94,7 @@ int load_other_segments(struct kimage *image,
 	void *headers;
 	unsigned long headers_sz;
 	if (image->type == KEXEC_TYPE_CRASH) {
-		ret = prepare_elf_headers(&headers, &headers_sz);
+		ret = crash_prepare_headers(true, &headers, &headers_sz, NULL);
 		if (ret) {
 			pr_err("Preparing elf core header failed\n");
 			goto out_err;
diff --git a/arch/loongarch/kernel/machine_kexec_file.c b/arch/loongarch/kernel/machine_kexec_file.c
index 5584b798ba46..4b318a94b564 100644
--- a/arch/loongarch/kernel/machine_kexec_file.c
+++ b/arch/loongarch/kernel/machine_kexec_file.c
@@ -56,23 +56,23 @@ static void cmdline_add_initrd(struct kimage *image, unsigned long *cmdline_tmpl
 }
 
 #ifdef CONFIG_CRASH_DUMP
-
-static int prepare_elf_headers(void **addr, unsigned long *sz)
+unsigned int arch_get_system_nr_ranges(void)
 {
-	int ret, nr_ranges;
-	uint64_t i;
+	int nr_ranges = 2; /* for exclusion of crashkernel region */
 	phys_addr_t start, end;
-	struct crash_mem *cmem;
+	uint64_t i;
 
-	nr_ranges = 2; /* for exclusion of crashkernel region */
 	for_each_mem_range(i, &start, &end)
 		nr_ranges++;
 
-	cmem = kmalloc_flex(*cmem, ranges, nr_ranges);
-	if (!cmem)
-		return -ENOMEM;
+	return nr_ranges;
+}
+
+int arch_crash_populate_cmem(struct crash_mem *cmem)
+{
+	phys_addr_t start, end;
+	uint64_t i;
 
-	cmem->max_nr_ranges = nr_ranges;
 	cmem->nr_ranges = 0;
 	for_each_mem_range(i, &start, &end) {
 		cmem->ranges[cmem->nr_ranges].start = start;
@@ -80,22 +80,7 @@ static int prepare_elf_headers(void **addr, unsigned long *sz)
 		cmem->nr_ranges++;
 	}
 
-	/* Exclude crashkernel region */
-	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
-	if (ret < 0)
-		goto out;
-
-	if (crashk_low_res.end) {
-		ret = crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
-		if (ret < 0)
-			goto out;
-	}
-
-	ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
-
-out:
-	kfree(cmem);
-	return ret;
+	return 0;
 }
 
 /*
@@ -163,7 +148,7 @@ int load_other_segments(struct kimage *image,
 		void *headers;
 		unsigned long headers_sz;
 
-		ret = prepare_elf_headers(&headers, &headers_sz);
+		ret = crash_prepare_headers(true, &headers, &headers_sz, NULL);
 		if (ret < 0) {
 			pr_err("Preparing elf core header failed\n");
 			goto out_err;
diff --git a/arch/riscv/kernel/machine_kexec_file.c b/arch/riscv/kernel/machine_kexec_file.c
index 54e2d9552e93..d0e331d87155 100644
--- a/arch/riscv/kernel/machine_kexec_file.c
+++ b/arch/riscv/kernel/machine_kexec_file.c
@@ -44,6 +44,15 @@ static int get_nr_ram_ranges_callback(struct resource *res, void *arg)
 	return 0;
 }
 
+unsigned int arch_get_system_nr_ranges(void)
+{
+	unsigned int nr_ranges = 1; /* For exclusion of crashkernel region */
+
+	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
+
+	return nr_ranges;
+}
+
 static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
 {
 	struct crash_mem *cmem = arg;
@@ -55,33 +64,10 @@ static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
 	return 0;
 }
 
-static int prepare_elf_headers(void **addr, unsigned long *sz)
+int arch_crash_populate_cmem(struct crash_mem *cmem)
 {
-	struct crash_mem *cmem;
-	unsigned int nr_ranges;
-	int ret;
-
-	nr_ranges = 1; /* For exclusion of crashkernel region */
-	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
-
-	cmem = kmalloc_flex(*cmem, ranges, nr_ranges);
-	if (!cmem)
-		return -ENOMEM;
-
-	cmem->max_nr_ranges = nr_ranges;
 	cmem->nr_ranges = 0;
-	ret = walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
-	if (ret)
-		goto out;
-
-	/* Exclude crashkernel region */
-	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
-	if (!ret)
-		ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
-
-out:
-	kfree(cmem);
-	return ret;
+	return walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
 }
 
 static char *setup_kdump_cmdline(struct kimage *image, char *cmdline,
@@ -273,7 +259,7 @@ int load_extra_segments(struct kimage *image, unsigned long kernel_start,
 	if (image->type == KEXEC_TYPE_CRASH) {
 		void *headers;
 		unsigned long headers_sz;
-		ret = prepare_elf_headers(&headers, &headers_sz);
+		ret = crash_prepare_headers(true, &headers, &headers_sz, NULL);
 		if (ret) {
 			pr_err("Preparing elf core header failed\n");
 			goto out;
diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index 335fd2ee9766..3ad3f8b758a4 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -152,16 +152,8 @@ 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 struct crash_mem *fill_up_crash_elf_data(void)
+unsigned int arch_get_system_nr_ranges(void)
 {
-	unsigned int nr_ranges = 0;
-	struct crash_mem *cmem;
-
-	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
-	if (!nr_ranges)
-		return NULL;
-
 	/*
 	 * Exclusion of crash region, crashk_low_res and/or crashk_cma_ranges
 	 * may cause range splits. So add extra slots here.
@@ -176,49 +168,16 @@ static struct crash_mem *fill_up_crash_elf_data(void)
 	 * But in order to lest the low 1M could be changed in the future,
 	 * (e.g. [start, 1M]), add a extra slot.
 	 */
-	nr_ranges += 3 + crashk_cma_cnt;
-	cmem = vzalloc(struct_size(cmem, ranges, nr_ranges));
-	if (!cmem)
-		return NULL;
-
-	cmem->max_nr_ranges = nr_ranges;
+	unsigned int nr_ranges = 3 + crashk_cma_cnt;
 
-	return cmem;
+	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
+	return nr_ranges;
 }
 
-/*
- * Look for any unwanted ranges between mstart, mend and remove them. This
- * might lead to split and split ranges are put in cmem->ranges[] array
- */
-static int elf_header_exclude_ranges(struct crash_mem *cmem)
+int arch_crash_exclude_ranges(struct crash_mem *cmem)
 {
-	int ret = 0;
-	int i;
-
 	/* Exclude the low 1M because it is always reserved */
-	ret = crash_exclude_mem_range(cmem, 0, SZ_1M - 1);
-	if (ret)
-		return ret;
-
-	/* Exclude crashkernel region */
-	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
-	if (ret)
-		return ret;
-
-	if (crashk_low_res.end)
-		ret = crash_exclude_mem_range(cmem, crashk_low_res.start,
-					      crashk_low_res.end);
-	if (ret)
-		return ret;
-
-	for (i = 0; i < crashk_cma_cnt; ++i) {
-		ret = crash_exclude_mem_range(cmem, crashk_cma_ranges[i].start,
-					      crashk_cma_ranges[i].end);
-		if (ret)
-			return ret;
-	}
-
-	return 0;
+	return crash_exclude_mem_range(cmem, 0, SZ_1M - 1);
 }
 
 static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
@@ -232,35 +191,9 @@ static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
 	return 0;
 }
 
-/* Prepare elf headers. Return addr and size */
-static int prepare_elf_headers(void **addr, unsigned long *sz,
-			       unsigned long *nr_mem_ranges)
+int arch_crash_populate_cmem(struct crash_mem *cmem)
 {
-	struct crash_mem *cmem;
-	int ret;
-
-	cmem = fill_up_crash_elf_data();
-	if (!cmem)
-		return -ENOMEM;
-
-	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(cmem);
-	if (ret)
-		goto out;
-
-	/* Return the computed number of memory ranges, for hotplug usage */
-	*nr_mem_ranges = cmem->nr_ranges;
-
-	/* By default prepare 64bit headers */
-	ret = crash_prepare_elf64_headers(cmem, IS_ENABLED(CONFIG_X86_64), addr, sz);
-
-out:
-	vfree(cmem);
-	return ret;
+	return walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
 }
 #endif
 
@@ -418,7 +351,8 @@ int crash_load_segments(struct kimage *image)
 				  .buf_max = ULONG_MAX, .top_down = false };
 
 	/* Prepare elf headers and add a segment */
-	ret = prepare_elf_headers(&kbuf.buffer, &kbuf.bufsz, &pnum);
+	ret = crash_prepare_headers(IS_ENABLED(CONFIG_X86_64), &kbuf.buffer,
+				    &kbuf.bufsz, &pnum);
 	if (ret)
 		return ret;
 
@@ -529,7 +463,8 @@ void arch_crash_handle_hotplug_event(struct kimage *image, void *arg)
 	 * Create the new elfcorehdr reflecting the changes to CPU and/or
 	 * memory resources.
 	 */
-	if (prepare_elf_headers(&elfbuf, &elfsz, &nr_mem_ranges)) {
+	if (crash_prepare_headers(IS_ENABLED(CONFIG_X86_64), &elfbuf, &elfsz,
+				  &nr_mem_ranges)) {
 		pr_err("unable to create new elfcorehdr");
 		goto out;
 	}
diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
index d35726d6a415..033b20204aca 100644
--- a/include/linux/crash_core.h
+++ b/include/linux/crash_core.h
@@ -66,6 +66,8 @@ extern int crash_exclude_mem_range(struct crash_mem *mem,
 				   unsigned long long mend);
 extern int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
 				       void **addr, unsigned long *sz);
+extern int crash_prepare_headers(int need_kernel_map, void **addr,
+				 unsigned long *sz, unsigned long *nr_mem_ranges);
 
 struct kimage;
 struct kexec_segment;
@@ -83,6 +85,9 @@ int kexec_should_crash(struct task_struct *p);
 int kexec_crash_loaded(void);
 void crash_save_cpu(struct pt_regs *regs, int cpu);
 extern int kimage_crash_copy_vmcoreinfo(struct kimage *image);
+extern unsigned int arch_get_system_nr_ranges(void);
+extern int arch_crash_populate_cmem(struct crash_mem *cmem);
+extern int arch_crash_exclude_ranges(struct crash_mem *cmem);
 
 #else /* !CONFIG_CRASH_DUMP*/
 struct pt_regs;
diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index 2c1a3791e410..96a96e511f5a 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -170,9 +170,6 @@ static inline resource_size_t crash_resource_size(const struct resource *res)
 	return !res->end ? 0 : resource_size(res);
 }
 
-
-
-
 int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
 			  void **addr, unsigned long *sz)
 {
@@ -274,6 +271,85 @@ int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
 	return 0;
 }
 
+static struct crash_mem *alloc_cmem(unsigned int nr_ranges)
+{
+	struct crash_mem *cmem;
+
+	cmem = kvzalloc_flex(*cmem, ranges, nr_ranges);
+	if (!cmem)
+		return NULL;
+
+	cmem->max_nr_ranges = nr_ranges;
+	return cmem;
+}
+
+unsigned int __weak arch_get_system_nr_ranges(void) { return 0; }
+int __weak arch_crash_populate_cmem(struct crash_mem *cmem) { return -1; }
+int __weak arch_crash_exclude_ranges(struct crash_mem *cmem) { return 0; }
+
+static int crash_exclude_core_ranges(struct crash_mem *cmem)
+{
+	int ret, i;
+
+	/* Exclude crashkernel region */
+	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
+	if (ret)
+		return ret;
+
+	if (crashk_low_res.end) {
+		ret = crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
+		if (ret)
+			return ret;
+	}
+
+	for (i = 0; i < crashk_cma_cnt; ++i) {
+		ret = crash_exclude_mem_range(cmem, crashk_cma_ranges[i].start,
+					      crashk_cma_ranges[i].end);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+int crash_prepare_headers(int need_kernel_map, void **addr, unsigned long *sz,
+			  unsigned long *nr_mem_ranges)
+{
+	unsigned int max_nr_ranges;
+	struct crash_mem *cmem;
+	int ret;
+
+	max_nr_ranges = arch_get_system_nr_ranges();
+	if (!max_nr_ranges)
+		return -ENOMEM;
+
+	cmem = alloc_cmem(max_nr_ranges);
+	if (!cmem)
+		return -ENOMEM;
+
+	ret = arch_crash_populate_cmem(cmem);
+	if (ret)
+		goto out;
+
+	ret = crash_exclude_core_ranges(cmem);
+	if (ret)
+		goto out;
+
+	ret = arch_crash_exclude_ranges(cmem);
+	if (ret)
+		goto out;
+
+	/* Return the computed number of memory ranges, for hotplug usage */
+	if (nr_mem_ranges)
+		*nr_mem_ranges = cmem->nr_ranges;
+
+	ret = crash_prepare_elf64_headers(cmem, need_kernel_map, addr, sz);
+
+out:
+	kvfree(cmem);
+	return ret;
+}
+
 /**
  * crash_exclude_mem_range - exclude a mem range for existing ranges
  * @mem: mem->range contains an array of ranges sorted in ascending order
-- 
2.34.1


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Re: [PATCH v8 2/5] crash: Exclude crash kernel memory in crash core

[Sourabh Jain]

Changes look good to me:

Reviewed-by: Sourabh Jain <sourabhjain@linux.ibm.com>

On 02/03/26 09:23, Jinjie Ruan wrote:
> The crash memory alloc, and the exclude of crashk_res, crashk_low_res
> and crashk_cma memory are almost identical across different architectures,
> handling them in the crash core would eliminate a lot of duplication, so
> do them in the common code.
>
> To achieve the above goal, three architecture-specific functions are
> introduced:
>
> - arch_get_system_nr_ranges(). Pre-counts the max number of memory ranges.
>
> - arch_crash_populate_cmem(). Collects the memory ranges and fills them
>    into cmem.
>
> - arch_crash_exclude_ranges(). Architecture's additional crash memory
>    ranges exclusion, defaulting to empty.
>
> Acked-by: Baoquan He <bhe@redhat.com>
> Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
> ---
>   arch/arm64/kernel/machine_kexec_file.c     | 39 +++-------
>   arch/loongarch/kernel/machine_kexec_file.c | 39 +++-------
>   arch/riscv/kernel/machine_kexec_file.c     | 38 +++------
>   arch/x86/kernel/crash.c                    | 89 +++-------------------
>   include/linux/crash_core.h                 |  5 ++
>   kernel/crash_core.c                        | 82 +++++++++++++++++++-
>   6 files changed, 132 insertions(+), 160 deletions(-)
>
> diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c
> index fba260ad87a9..c338506a580b 100644
> --- a/arch/arm64/kernel/machine_kexec_file.c
> +++ b/arch/arm64/kernel/machine_kexec_file.c
> @@ -40,23 +40,23 @@ int arch_kimage_file_post_load_cleanup(struct kimage *image)
>   }
>   
>   #ifdef CONFIG_CRASH_DUMP
> -static int prepare_elf_headers(void **addr, unsigned long *sz)
> +unsigned int arch_get_system_nr_ranges(void)
>   {
> -	struct crash_mem *cmem;
> -	unsigned int nr_ranges;
> -	int ret;
> -	u64 i;
> +	unsigned int nr_ranges = 2; /* for exclusion of crashkernel region */
>   	phys_addr_t start, end;
> +	u64 i;
>   
> -	nr_ranges = 2; /* for exclusion of crashkernel region */
>   	for_each_mem_range(i, &start, &end)
>   		nr_ranges++;
>   
> -	cmem = kmalloc_flex(*cmem, ranges, nr_ranges);
> -	if (!cmem)
> -		return -ENOMEM;
> +	return nr_ranges;
> +}
> +
> +int arch_crash_populate_cmem(struct crash_mem *cmem)
> +{
> +	phys_addr_t start, end;
> +	u64 i;
>   
> -	cmem->max_nr_ranges = nr_ranges;
>   	cmem->nr_ranges = 0;
>   	for_each_mem_range(i, &start, &end) {
>   		cmem->ranges[cmem->nr_ranges].start = start;
> @@ -64,22 +64,7 @@ static int prepare_elf_headers(void **addr, unsigned long *sz)
>   		cmem->nr_ranges++;
>   	}
>   
> -	/* Exclude crashkernel region */
> -	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
> -	if (ret)
> -		goto out;
> -
> -	if (crashk_low_res.end) {
> -		ret = crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
> -		if (ret)
> -			goto out;
> -	}
> -
> -	ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
> -
> -out:
> -	kfree(cmem);
> -	return ret;
> +	return 0;
>   }
>   #endif
>   
> @@ -109,7 +94,7 @@ int load_other_segments(struct kimage *image,
>   	void *headers;
>   	unsigned long headers_sz;
>   	if (image->type == KEXEC_TYPE_CRASH) {
> -		ret = prepare_elf_headers(&headers, &headers_sz);
> +		ret = crash_prepare_headers(true, &headers, &headers_sz, NULL);
>   		if (ret) {
>   			pr_err("Preparing elf core header failed\n");
>   			goto out_err;
> diff --git a/arch/loongarch/kernel/machine_kexec_file.c b/arch/loongarch/kernel/machine_kexec_file.c
> index 5584b798ba46..4b318a94b564 100644
> --- a/arch/loongarch/kernel/machine_kexec_file.c
> +++ b/arch/loongarch/kernel/machine_kexec_file.c
> @@ -56,23 +56,23 @@ static void cmdline_add_initrd(struct kimage *image, unsigned long *cmdline_tmpl
>   }
>   
>   #ifdef CONFIG_CRASH_DUMP
> -
> -static int prepare_elf_headers(void **addr, unsigned long *sz)
> +unsigned int arch_get_system_nr_ranges(void)
>   {
> -	int ret, nr_ranges;
> -	uint64_t i;
> +	int nr_ranges = 2; /* for exclusion of crashkernel region */
>   	phys_addr_t start, end;
> -	struct crash_mem *cmem;
> +	uint64_t i;
>   
> -	nr_ranges = 2; /* for exclusion of crashkernel region */
>   	for_each_mem_range(i, &start, &end)
>   		nr_ranges++;
>   
> -	cmem = kmalloc_flex(*cmem, ranges, nr_ranges);
> -	if (!cmem)
> -		return -ENOMEM;
> +	return nr_ranges;
> +}
> +
> +int arch_crash_populate_cmem(struct crash_mem *cmem)
> +{
> +	phys_addr_t start, end;
> +	uint64_t i;
>   
> -	cmem->max_nr_ranges = nr_ranges;
>   	cmem->nr_ranges = 0;
>   	for_each_mem_range(i, &start, &end) {
>   		cmem->ranges[cmem->nr_ranges].start = start;
> @@ -80,22 +80,7 @@ static int prepare_elf_headers(void **addr, unsigned long *sz)
>   		cmem->nr_ranges++;
>   	}
>   
> -	/* Exclude crashkernel region */
> -	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
> -	if (ret < 0)
> -		goto out;
> -
> -	if (crashk_low_res.end) {
> -		ret = crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
> -		if (ret < 0)
> -			goto out;
> -	}
> -
> -	ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
> -
> -out:
> -	kfree(cmem);
> -	return ret;
> +	return 0;
>   }
>   
>   /*
> @@ -163,7 +148,7 @@ int load_other_segments(struct kimage *image,
>   		void *headers;
>   		unsigned long headers_sz;
>   
> -		ret = prepare_elf_headers(&headers, &headers_sz);
> +		ret = crash_prepare_headers(true, &headers, &headers_sz, NULL);
>   		if (ret < 0) {
>   			pr_err("Preparing elf core header failed\n");
>   			goto out_err;
> diff --git a/arch/riscv/kernel/machine_kexec_file.c b/arch/riscv/kernel/machine_kexec_file.c
> index 54e2d9552e93..d0e331d87155 100644
> --- a/arch/riscv/kernel/machine_kexec_file.c
> +++ b/arch/riscv/kernel/machine_kexec_file.c
> @@ -44,6 +44,15 @@ static int get_nr_ram_ranges_callback(struct resource *res, void *arg)
>   	return 0;
>   }
>   
> +unsigned int arch_get_system_nr_ranges(void)
> +{
> +	unsigned int nr_ranges = 1; /* For exclusion of crashkernel region */
> +
> +	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
> +
> +	return nr_ranges;
> +}
> +
>   static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
>   {
>   	struct crash_mem *cmem = arg;
> @@ -55,33 +64,10 @@ static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
>   	return 0;
>   }
>   
> -static int prepare_elf_headers(void **addr, unsigned long *sz)
> +int arch_crash_populate_cmem(struct crash_mem *cmem)
>   {
> -	struct crash_mem *cmem;
> -	unsigned int nr_ranges;
> -	int ret;
> -
> -	nr_ranges = 1; /* For exclusion of crashkernel region */
> -	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
> -
> -	cmem = kmalloc_flex(*cmem, ranges, nr_ranges);
> -	if (!cmem)
> -		return -ENOMEM;
> -
> -	cmem->max_nr_ranges = nr_ranges;
>   	cmem->nr_ranges = 0;
> -	ret = walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
> -	if (ret)
> -		goto out;
> -
> -	/* Exclude crashkernel region */
> -	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
> -	if (!ret)
> -		ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
> -
> -out:
> -	kfree(cmem);
> -	return ret;
> +	return walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
>   }
>   
>   static char *setup_kdump_cmdline(struct kimage *image, char *cmdline,
> @@ -273,7 +259,7 @@ int load_extra_segments(struct kimage *image, unsigned long kernel_start,
>   	if (image->type == KEXEC_TYPE_CRASH) {
>   		void *headers;
>   		unsigned long headers_sz;
> -		ret = prepare_elf_headers(&headers, &headers_sz);
> +		ret = crash_prepare_headers(true, &headers, &headers_sz, NULL);
>   		if (ret) {
>   			pr_err("Preparing elf core header failed\n");
>   			goto out;
> diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
> index 335fd2ee9766..3ad3f8b758a4 100644
> --- a/arch/x86/kernel/crash.c
> +++ b/arch/x86/kernel/crash.c
> @@ -152,16 +152,8 @@ 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 struct crash_mem *fill_up_crash_elf_data(void)
> +unsigned int arch_get_system_nr_ranges(void)
>   {
> -	unsigned int nr_ranges = 0;
> -	struct crash_mem *cmem;
> -
> -	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
> -	if (!nr_ranges)
> -		return NULL;
> -
>   	/*
>   	 * Exclusion of crash region, crashk_low_res and/or crashk_cma_ranges
>   	 * may cause range splits. So add extra slots here.
> @@ -176,49 +168,16 @@ static struct crash_mem *fill_up_crash_elf_data(void)
>   	 * But in order to lest the low 1M could be changed in the future,
>   	 * (e.g. [start, 1M]), add a extra slot.
>   	 */
> -	nr_ranges += 3 + crashk_cma_cnt;
> -	cmem = vzalloc(struct_size(cmem, ranges, nr_ranges));
> -	if (!cmem)
> -		return NULL;
> -
> -	cmem->max_nr_ranges = nr_ranges;
> +	unsigned int nr_ranges = 3 + crashk_cma_cnt;
>   
> -	return cmem;
> +	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
> +	return nr_ranges;
>   }
>   
> -/*
> - * Look for any unwanted ranges between mstart, mend and remove them. This
> - * might lead to split and split ranges are put in cmem->ranges[] array
> - */
> -static int elf_header_exclude_ranges(struct crash_mem *cmem)
> +int arch_crash_exclude_ranges(struct crash_mem *cmem)
>   {
> -	int ret = 0;
> -	int i;
> -
>   	/* Exclude the low 1M because it is always reserved */
> -	ret = crash_exclude_mem_range(cmem, 0, SZ_1M - 1);
> -	if (ret)
> -		return ret;
> -
> -	/* Exclude crashkernel region */
> -	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
> -	if (ret)
> -		return ret;
> -
> -	if (crashk_low_res.end)
> -		ret = crash_exclude_mem_range(cmem, crashk_low_res.start,
> -					      crashk_low_res.end);
> -	if (ret)
> -		return ret;
> -
> -	for (i = 0; i < crashk_cma_cnt; ++i) {
> -		ret = crash_exclude_mem_range(cmem, crashk_cma_ranges[i].start,
> -					      crashk_cma_ranges[i].end);
> -		if (ret)
> -			return ret;
> -	}
> -
> -	return 0;
> +	return crash_exclude_mem_range(cmem, 0, SZ_1M - 1);
>   }
>   
>   static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
> @@ -232,35 +191,9 @@ static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
>   	return 0;
>   }
>   
> -/* Prepare elf headers. Return addr and size */
> -static int prepare_elf_headers(void **addr, unsigned long *sz,
> -			       unsigned long *nr_mem_ranges)
> +int arch_crash_populate_cmem(struct crash_mem *cmem)
>   {
> -	struct crash_mem *cmem;
> -	int ret;
> -
> -	cmem = fill_up_crash_elf_data();
> -	if (!cmem)
> -		return -ENOMEM;
> -
> -	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(cmem);
> -	if (ret)
> -		goto out;
> -
> -	/* Return the computed number of memory ranges, for hotplug usage */
> -	*nr_mem_ranges = cmem->nr_ranges;
> -
> -	/* By default prepare 64bit headers */
> -	ret = crash_prepare_elf64_headers(cmem, IS_ENABLED(CONFIG_X86_64), addr, sz);
> -
> -out:
> -	vfree(cmem);
> -	return ret;
> +	return walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
>   }
>   #endif
>   
> @@ -418,7 +351,8 @@ int crash_load_segments(struct kimage *image)
>   				  .buf_max = ULONG_MAX, .top_down = false };
>   
>   	/* Prepare elf headers and add a segment */
> -	ret = prepare_elf_headers(&kbuf.buffer, &kbuf.bufsz, &pnum);
> +	ret = crash_prepare_headers(IS_ENABLED(CONFIG_X86_64), &kbuf.buffer,
> +				    &kbuf.bufsz, &pnum);
>   	if (ret)
>   		return ret;
>   
> @@ -529,7 +463,8 @@ void arch_crash_handle_hotplug_event(struct kimage *image, void *arg)
>   	 * Create the new elfcorehdr reflecting the changes to CPU and/or
>   	 * memory resources.
>   	 */
> -	if (prepare_elf_headers(&elfbuf, &elfsz, &nr_mem_ranges)) {
> +	if (crash_prepare_headers(IS_ENABLED(CONFIG_X86_64), &elfbuf, &elfsz,
> +				  &nr_mem_ranges)) {
>   		pr_err("unable to create new elfcorehdr");
>   		goto out;
>   	}
> diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
> index d35726d6a415..033b20204aca 100644
> --- a/include/linux/crash_core.h
> +++ b/include/linux/crash_core.h
> @@ -66,6 +66,8 @@ extern int crash_exclude_mem_range(struct crash_mem *mem,
>   				   unsigned long long mend);
>   extern int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
>   				       void **addr, unsigned long *sz);
> +extern int crash_prepare_headers(int need_kernel_map, void **addr,
> +				 unsigned long *sz, unsigned long *nr_mem_ranges);
>   
>   struct kimage;
>   struct kexec_segment;
> @@ -83,6 +85,9 @@ int kexec_should_crash(struct task_struct *p);
>   int kexec_crash_loaded(void);
>   void crash_save_cpu(struct pt_regs *regs, int cpu);
>   extern int kimage_crash_copy_vmcoreinfo(struct kimage *image);
> +extern unsigned int arch_get_system_nr_ranges(void);
> +extern int arch_crash_populate_cmem(struct crash_mem *cmem);
> +extern int arch_crash_exclude_ranges(struct crash_mem *cmem);
>   
>   #else /* !CONFIG_CRASH_DUMP*/
>   struct pt_regs;
> diff --git a/kernel/crash_core.c b/kernel/crash_core.c
> index 2c1a3791e410..96a96e511f5a 100644
> --- a/kernel/crash_core.c
> +++ b/kernel/crash_core.c
> @@ -170,9 +170,6 @@ static inline resource_size_t crash_resource_size(const struct resource *res)
>   	return !res->end ? 0 : resource_size(res);
>   }
>   
> -
> -
> -
>   int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
>   			  void **addr, unsigned long *sz)
>   {
> @@ -274,6 +271,85 @@ int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
>   	return 0;
>   }
>   
> +static struct crash_mem *alloc_cmem(unsigned int nr_ranges)
> +{
> +	struct crash_mem *cmem;
> +
> +	cmem = kvzalloc_flex(*cmem, ranges, nr_ranges);
> +	if (!cmem)
> +		return NULL;
> +
> +	cmem->max_nr_ranges = nr_ranges;
> +	return cmem;
> +}
> +
> +unsigned int __weak arch_get_system_nr_ranges(void) { return 0; }
> +int __weak arch_crash_populate_cmem(struct crash_mem *cmem) { return -1; }
> +int __weak arch_crash_exclude_ranges(struct crash_mem *cmem) { return 0; }
> +
> +static int crash_exclude_core_ranges(struct crash_mem *cmem)
> +{
> +	int ret, i;
> +
> +	/* Exclude crashkernel region */
> +	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
> +	if (ret)
> +		return ret;
> +
> +	if (crashk_low_res.end) {
> +		ret = crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	for (i = 0; i < crashk_cma_cnt; ++i) {
> +		ret = crash_exclude_mem_range(cmem, crashk_cma_ranges[i].start,
> +					      crashk_cma_ranges[i].end);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +int crash_prepare_headers(int need_kernel_map, void **addr, unsigned long *sz,
> +			  unsigned long *nr_mem_ranges)
> +{
> +	unsigned int max_nr_ranges;
> +	struct crash_mem *cmem;
> +	int ret;
> +
> +	max_nr_ranges = arch_get_system_nr_ranges();
> +	if (!max_nr_ranges)
> +		return -ENOMEM;
> +
> +	cmem = alloc_cmem(max_nr_ranges);
> +	if (!cmem)
> +		return -ENOMEM;
> +
> +	ret = arch_crash_populate_cmem(cmem);
> +	if (ret)
> +		goto out;
> +
> +	ret = crash_exclude_core_ranges(cmem);
> +	if (ret)
> +		goto out;
> +
> +	ret = arch_crash_exclude_ranges(cmem);
> +	if (ret)
> +		goto out;
> +
> +	/* Return the computed number of memory ranges, for hotplug usage */
> +	if (nr_mem_ranges)
> +		*nr_mem_ranges = cmem->nr_ranges;
> +
> +	ret = crash_prepare_elf64_headers(cmem, need_kernel_map, addr, sz);
> +
> +out:
> +	kvfree(cmem);
> +	return ret;
> +}
> +
>   /**
>    * crash_exclude_mem_range - exclude a mem range for existing ranges
>    * @mem: mem->range contains an array of ranges sorted in ascending order

Re: [PATCH v8 2/5] crash: Exclude crash kernel memory in crash core

[Sourabh Jain]

Changes look good to me:

Reviewed-by: Sourabh Jain <sourabhjain@linux.ibm.com>

On 02/03/26 09:23, Jinjie Ruan wrote:
> The crash memory alloc, and the exclude of crashk_res, crashk_low_res
> and crashk_cma memory are almost identical across different architectures,
> handling them in the crash core would eliminate a lot of duplication, so
> do them in the common code.
>
> To achieve the above goal, three architecture-specific functions are
> introduced:
>
> - arch_get_system_nr_ranges(). Pre-counts the max number of memory ranges.
>
> - arch_crash_populate_cmem(). Collects the memory ranges and fills them
>    into cmem.
>
> - arch_crash_exclude_ranges(). Architecture's additional crash memory
>    ranges exclusion, defaulting to empty.
>
> Acked-by: Baoquan He <bhe@redhat.com>
> Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
> ---
>   arch/arm64/kernel/machine_kexec_file.c     | 39 +++-------
>   arch/loongarch/kernel/machine_kexec_file.c | 39 +++-------
>   arch/riscv/kernel/machine_kexec_file.c     | 38 +++------
>   arch/x86/kernel/crash.c                    | 89 +++-------------------
>   include/linux/crash_core.h                 |  5 ++
>   kernel/crash_core.c                        | 82 +++++++++++++++++++-
>   6 files changed, 132 insertions(+), 160 deletions(-)
>
> diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c
> index fba260ad87a9..c338506a580b 100644
> --- a/arch/arm64/kernel/machine_kexec_file.c
> +++ b/arch/arm64/kernel/machine_kexec_file.c
> @@ -40,23 +40,23 @@ int arch_kimage_file_post_load_cleanup(struct kimage *image)
>   }
>   
>   #ifdef CONFIG_CRASH_DUMP
> -static int prepare_elf_headers(void **addr, unsigned long *sz)
> +unsigned int arch_get_system_nr_ranges(void)
>   {
> -	struct crash_mem *cmem;
> -	unsigned int nr_ranges;
> -	int ret;
> -	u64 i;
> +	unsigned int nr_ranges = 2; /* for exclusion of crashkernel region */
>   	phys_addr_t start, end;
> +	u64 i;
>   
> -	nr_ranges = 2; /* for exclusion of crashkernel region */
>   	for_each_mem_range(i, &start, &end)
>   		nr_ranges++;
>   
> -	cmem = kmalloc_flex(*cmem, ranges, nr_ranges);
> -	if (!cmem)
> -		return -ENOMEM;
> +	return nr_ranges;
> +}
> +
> +int arch_crash_populate_cmem(struct crash_mem *cmem)
> +{
> +	phys_addr_t start, end;
> +	u64 i;
>   
> -	cmem->max_nr_ranges = nr_ranges;
>   	cmem->nr_ranges = 0;
>   	for_each_mem_range(i, &start, &end) {
>   		cmem->ranges[cmem->nr_ranges].start = start;
> @@ -64,22 +64,7 @@ static int prepare_elf_headers(void **addr, unsigned long *sz)
>   		cmem->nr_ranges++;
>   	}
>   
> -	/* Exclude crashkernel region */
> -	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
> -	if (ret)
> -		goto out;
> -
> -	if (crashk_low_res.end) {
> -		ret = crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
> -		if (ret)
> -			goto out;
> -	}
> -
> -	ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
> -
> -out:
> -	kfree(cmem);
> -	return ret;
> +	return 0;
>   }
>   #endif
>   
> @@ -109,7 +94,7 @@ int load_other_segments(struct kimage *image,
>   	void *headers;
>   	unsigned long headers_sz;
>   	if (image->type == KEXEC_TYPE_CRASH) {
> -		ret = prepare_elf_headers(&headers, &headers_sz);
> +		ret = crash_prepare_headers(true, &headers, &headers_sz, NULL);
>   		if (ret) {
>   			pr_err("Preparing elf core header failed\n");
>   			goto out_err;
> diff --git a/arch/loongarch/kernel/machine_kexec_file.c b/arch/loongarch/kernel/machine_kexec_file.c
> index 5584b798ba46..4b318a94b564 100644
> --- a/arch/loongarch/kernel/machine_kexec_file.c
> +++ b/arch/loongarch/kernel/machine_kexec_file.c
> @@ -56,23 +56,23 @@ static void cmdline_add_initrd(struct kimage *image, unsigned long *cmdline_tmpl
>   }
>   
>   #ifdef CONFIG_CRASH_DUMP
> -
> -static int prepare_elf_headers(void **addr, unsigned long *sz)
> +unsigned int arch_get_system_nr_ranges(void)
>   {
> -	int ret, nr_ranges;
> -	uint64_t i;
> +	int nr_ranges = 2; /* for exclusion of crashkernel region */
>   	phys_addr_t start, end;
> -	struct crash_mem *cmem;
> +	uint64_t i;
>   
> -	nr_ranges = 2; /* for exclusion of crashkernel region */
>   	for_each_mem_range(i, &start, &end)
>   		nr_ranges++;
>   
> -	cmem = kmalloc_flex(*cmem, ranges, nr_ranges);
> -	if (!cmem)
> -		return -ENOMEM;
> +	return nr_ranges;
> +}
> +
> +int arch_crash_populate_cmem(struct crash_mem *cmem)
> +{
> +	phys_addr_t start, end;
> +	uint64_t i;
>   
> -	cmem->max_nr_ranges = nr_ranges;
>   	cmem->nr_ranges = 0;
>   	for_each_mem_range(i, &start, &end) {
>   		cmem->ranges[cmem->nr_ranges].start = start;
> @@ -80,22 +80,7 @@ static int prepare_elf_headers(void **addr, unsigned long *sz)
>   		cmem->nr_ranges++;
>   	}
>   
> -	/* Exclude crashkernel region */
> -	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
> -	if (ret < 0)
> -		goto out;
> -
> -	if (crashk_low_res.end) {
> -		ret = crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
> -		if (ret < 0)
> -			goto out;
> -	}
> -
> -	ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
> -
> -out:
> -	kfree(cmem);
> -	return ret;
> +	return 0;
>   }
>   
>   /*
> @@ -163,7 +148,7 @@ int load_other_segments(struct kimage *image,
>   		void *headers;
>   		unsigned long headers_sz;
>   
> -		ret = prepare_elf_headers(&headers, &headers_sz);
> +		ret = crash_prepare_headers(true, &headers, &headers_sz, NULL);
>   		if (ret < 0) {
>   			pr_err("Preparing elf core header failed\n");
>   			goto out_err;
> diff --git a/arch/riscv/kernel/machine_kexec_file.c b/arch/riscv/kernel/machine_kexec_file.c
> index 54e2d9552e93..d0e331d87155 100644
> --- a/arch/riscv/kernel/machine_kexec_file.c
> +++ b/arch/riscv/kernel/machine_kexec_file.c
> @@ -44,6 +44,15 @@ static int get_nr_ram_ranges_callback(struct resource *res, void *arg)
>   	return 0;
>   }
>   
> +unsigned int arch_get_system_nr_ranges(void)
> +{
> +	unsigned int nr_ranges = 1; /* For exclusion of crashkernel region */
> +
> +	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
> +
> +	return nr_ranges;
> +}
> +
>   static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
>   {
>   	struct crash_mem *cmem = arg;
> @@ -55,33 +64,10 @@ static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
>   	return 0;
>   }
>   
> -static int prepare_elf_headers(void **addr, unsigned long *sz)
> +int arch_crash_populate_cmem(struct crash_mem *cmem)
>   {
> -	struct crash_mem *cmem;
> -	unsigned int nr_ranges;
> -	int ret;
> -
> -	nr_ranges = 1; /* For exclusion of crashkernel region */
> -	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
> -
> -	cmem = kmalloc_flex(*cmem, ranges, nr_ranges);
> -	if (!cmem)
> -		return -ENOMEM;
> -
> -	cmem->max_nr_ranges = nr_ranges;
>   	cmem->nr_ranges = 0;
> -	ret = walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
> -	if (ret)
> -		goto out;
> -
> -	/* Exclude crashkernel region */
> -	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
> -	if (!ret)
> -		ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
> -
> -out:
> -	kfree(cmem);
> -	return ret;
> +	return walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
>   }
>   
>   static char *setup_kdump_cmdline(struct kimage *image, char *cmdline,
> @@ -273,7 +259,7 @@ int load_extra_segments(struct kimage *image, unsigned long kernel_start,
>   	if (image->type == KEXEC_TYPE_CRASH) {
>   		void *headers;
>   		unsigned long headers_sz;
> -		ret = prepare_elf_headers(&headers, &headers_sz);
> +		ret = crash_prepare_headers(true, &headers, &headers_sz, NULL);
>   		if (ret) {
>   			pr_err("Preparing elf core header failed\n");
>   			goto out;
> diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
> index 335fd2ee9766..3ad3f8b758a4 100644
> --- a/arch/x86/kernel/crash.c
> +++ b/arch/x86/kernel/crash.c
> @@ -152,16 +152,8 @@ 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 struct crash_mem *fill_up_crash_elf_data(void)
> +unsigned int arch_get_system_nr_ranges(void)
>   {
> -	unsigned int nr_ranges = 0;
> -	struct crash_mem *cmem;
> -
> -	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
> -	if (!nr_ranges)
> -		return NULL;
> -
>   	/*
>   	 * Exclusion of crash region, crashk_low_res and/or crashk_cma_ranges
>   	 * may cause range splits. So add extra slots here.
> @@ -176,49 +168,16 @@ static struct crash_mem *fill_up_crash_elf_data(void)
>   	 * But in order to lest the low 1M could be changed in the future,
>   	 * (e.g. [start, 1M]), add a extra slot.
>   	 */
> -	nr_ranges += 3 + crashk_cma_cnt;
> -	cmem = vzalloc(struct_size(cmem, ranges, nr_ranges));
> -	if (!cmem)
> -		return NULL;
> -
> -	cmem->max_nr_ranges = nr_ranges;
> +	unsigned int nr_ranges = 3 + crashk_cma_cnt;
>   
> -	return cmem;
> +	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
> +	return nr_ranges;
>   }
>   
> -/*
> - * Look for any unwanted ranges between mstart, mend and remove them. This
> - * might lead to split and split ranges are put in cmem->ranges[] array
> - */
> -static int elf_header_exclude_ranges(struct crash_mem *cmem)
> +int arch_crash_exclude_ranges(struct crash_mem *cmem)
>   {
> -	int ret = 0;
> -	int i;
> -
>   	/* Exclude the low 1M because it is always reserved */
> -	ret = crash_exclude_mem_range(cmem, 0, SZ_1M - 1);
> -	if (ret)
> -		return ret;
> -
> -	/* Exclude crashkernel region */
> -	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
> -	if (ret)
> -		return ret;
> -
> -	if (crashk_low_res.end)
> -		ret = crash_exclude_mem_range(cmem, crashk_low_res.start,
> -					      crashk_low_res.end);
> -	if (ret)
> -		return ret;
> -
> -	for (i = 0; i < crashk_cma_cnt; ++i) {
> -		ret = crash_exclude_mem_range(cmem, crashk_cma_ranges[i].start,
> -					      crashk_cma_ranges[i].end);
> -		if (ret)
> -			return ret;
> -	}
> -
> -	return 0;
> +	return crash_exclude_mem_range(cmem, 0, SZ_1M - 1);
>   }
>   
>   static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
> @@ -232,35 +191,9 @@ static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
>   	return 0;
>   }
>   
> -/* Prepare elf headers. Return addr and size */
> -static int prepare_elf_headers(void **addr, unsigned long *sz,
> -			       unsigned long *nr_mem_ranges)
> +int arch_crash_populate_cmem(struct crash_mem *cmem)
>   {
> -	struct crash_mem *cmem;
> -	int ret;
> -
> -	cmem = fill_up_crash_elf_data();
> -	if (!cmem)
> -		return -ENOMEM;
> -
> -	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(cmem);
> -	if (ret)
> -		goto out;
> -
> -	/* Return the computed number of memory ranges, for hotplug usage */
> -	*nr_mem_ranges = cmem->nr_ranges;
> -
> -	/* By default prepare 64bit headers */
> -	ret = crash_prepare_elf64_headers(cmem, IS_ENABLED(CONFIG_X86_64), addr, sz);
> -
> -out:
> -	vfree(cmem);
> -	return ret;
> +	return walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
>   }
>   #endif
>   
> @@ -418,7 +351,8 @@ int crash_load_segments(struct kimage *image)
>   				  .buf_max = ULONG_MAX, .top_down = false };
>   
>   	/* Prepare elf headers and add a segment */
> -	ret = prepare_elf_headers(&kbuf.buffer, &kbuf.bufsz, &pnum);
> +	ret = crash_prepare_headers(IS_ENABLED(CONFIG_X86_64), &kbuf.buffer,
> +				    &kbuf.bufsz, &pnum);
>   	if (ret)
>   		return ret;
>   
> @@ -529,7 +463,8 @@ void arch_crash_handle_hotplug_event(struct kimage *image, void *arg)
>   	 * Create the new elfcorehdr reflecting the changes to CPU and/or
>   	 * memory resources.
>   	 */
> -	if (prepare_elf_headers(&elfbuf, &elfsz, &nr_mem_ranges)) {
> +	if (crash_prepare_headers(IS_ENABLED(CONFIG_X86_64), &elfbuf, &elfsz,
> +				  &nr_mem_ranges)) {
>   		pr_err("unable to create new elfcorehdr");
>   		goto out;
>   	}
> diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
> index d35726d6a415..033b20204aca 100644
> --- a/include/linux/crash_core.h
> +++ b/include/linux/crash_core.h
> @@ -66,6 +66,8 @@ extern int crash_exclude_mem_range(struct crash_mem *mem,
>   				   unsigned long long mend);
>   extern int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
>   				       void **addr, unsigned long *sz);
> +extern int crash_prepare_headers(int need_kernel_map, void **addr,
> +				 unsigned long *sz, unsigned long *nr_mem_ranges);
>   
>   struct kimage;
>   struct kexec_segment;
> @@ -83,6 +85,9 @@ int kexec_should_crash(struct task_struct *p);
>   int kexec_crash_loaded(void);
>   void crash_save_cpu(struct pt_regs *regs, int cpu);
>   extern int kimage_crash_copy_vmcoreinfo(struct kimage *image);
> +extern unsigned int arch_get_system_nr_ranges(void);
> +extern int arch_crash_populate_cmem(struct crash_mem *cmem);
> +extern int arch_crash_exclude_ranges(struct crash_mem *cmem);
>   
>   #else /* !CONFIG_CRASH_DUMP*/
>   struct pt_regs;
> diff --git a/kernel/crash_core.c b/kernel/crash_core.c
> index 2c1a3791e410..96a96e511f5a 100644
> --- a/kernel/crash_core.c
> +++ b/kernel/crash_core.c
> @@ -170,9 +170,6 @@ static inline resource_size_t crash_resource_size(const struct resource *res)
>   	return !res->end ? 0 : resource_size(res);
>   }
>   
> -
> -
> -
>   int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
>   			  void **addr, unsigned long *sz)
>   {
> @@ -274,6 +271,85 @@ int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
>   	return 0;
>   }
>   
> +static struct crash_mem *alloc_cmem(unsigned int nr_ranges)
> +{
> +	struct crash_mem *cmem;
> +
> +	cmem = kvzalloc_flex(*cmem, ranges, nr_ranges);
> +	if (!cmem)
> +		return NULL;
> +
> +	cmem->max_nr_ranges = nr_ranges;
> +	return cmem;
> +}
> +
> +unsigned int __weak arch_get_system_nr_ranges(void) { return 0; }
> +int __weak arch_crash_populate_cmem(struct crash_mem *cmem) { return -1; }
> +int __weak arch_crash_exclude_ranges(struct crash_mem *cmem) { return 0; }
> +
> +static int crash_exclude_core_ranges(struct crash_mem *cmem)
> +{
> +	int ret, i;
> +
> +	/* Exclude crashkernel region */
> +	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
> +	if (ret)
> +		return ret;
> +
> +	if (crashk_low_res.end) {
> +		ret = crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	for (i = 0; i < crashk_cma_cnt; ++i) {
> +		ret = crash_exclude_mem_range(cmem, crashk_cma_ranges[i].start,
> +					      crashk_cma_ranges[i].end);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +int crash_prepare_headers(int need_kernel_map, void **addr, unsigned long *sz,
> +			  unsigned long *nr_mem_ranges)
> +{
> +	unsigned int max_nr_ranges;
> +	struct crash_mem *cmem;
> +	int ret;
> +
> +	max_nr_ranges = arch_get_system_nr_ranges();
> +	if (!max_nr_ranges)
> +		return -ENOMEM;
> +
> +	cmem = alloc_cmem(max_nr_ranges);
> +	if (!cmem)
> +		return -ENOMEM;
> +
> +	ret = arch_crash_populate_cmem(cmem);
> +	if (ret)
> +		goto out;
> +
> +	ret = crash_exclude_core_ranges(cmem);
> +	if (ret)
> +		goto out;
> +
> +	ret = arch_crash_exclude_ranges(cmem);
> +	if (ret)
> +		goto out;
> +
> +	/* Return the computed number of memory ranges, for hotplug usage */
> +	if (nr_mem_ranges)
> +		*nr_mem_ranges = cmem->nr_ranges;
> +
> +	ret = crash_prepare_elf64_headers(cmem, need_kernel_map, addr, sz);
> +
> +out:
> +	kvfree(cmem);
> +	return ret;
> +}
> +
>   /**
>    * crash_exclude_mem_range - exclude a mem range for existing ranges
>    * @mem: mem->range contains an array of ranges sorted in ascending order


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Re: [PATCH v8 2/5] crash: Exclude crash kernel memory in crash core

[kernel test robot]

BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
In-Reply-To: <20260302035315.3892241-3-ruanjinjie@huawei.com>
References: <20260302035315.3892241-3-ruanjinjie@huawei.com>
TO: Jinjie Ruan <ruanjinjie@huawei.com>
TO: corbet@lwn.net
TO: skhan@linuxfoundation.org
TO: catalin.marinas@arm.com
TO: will@kernel.org
TO: chenhuacai@kernel.org
TO: kernel@xen0n.name
TO: maddy@linux.ibm.com
TO: mpe@ellerman.id.au
TO: npiggin@gmail.com
TO: chleroy@kernel.org
TO: pjw@kernel.org
TO: palmer@dabbelt.com
TO: aou@eecs.berkeley.edu
TO: alex@ghiti.fr
TO: tglx@kernel.org
TO: mingo@redhat.com
TO: bp@alien8.de
TO: dave.hansen@linux.intel.com
TO: hpa@zytor.com
TO: robh@kernel.org
TO: saravanak@kernel.org
TO: akpm@linux-foundation.org
TO: bhe@redhat.com
TO: vgoyal@redhat.com
TO: dyoung@redhat.com
TO: rdunlap@infradead.org
TO: pmladek@suse.com
TO: dapeng1.mi@linux.intel.com
TO: kees@kernel.org
TO: paulmck@kernel.org

Hi Jinjie,

kernel test robot noticed the following build warnings:

[auto build test WARNING on arm64/for-next/core]
[also build test WARNING on robh/for-next linus/master v7.0-rc2 next-20260305]
[cannot apply to powerpc/next powerpc/fixes]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Jinjie-Ruan/powerpc-crash-sort-crash-memory-ranges-before-preparing-elfcorehdr/20260302-115646
base:   https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-next/core
patch link:    https://lore.kernel.org/r/20260302035315.3892241-3-ruanjinjie%40huawei.com
patch subject: [PATCH v8 2/5] crash: Exclude crash kernel memory in crash core
:::::: branch date: 4 days ago
:::::: commit date: 4 days ago
config: i386-randconfig-141-20260305 (https://download.01.org/0day-ci/archive/20260306/202603060454.MeuKcrhO-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
smatch: v0.5.0-9004-gb810ac53

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <error27@gmail.com>
| Closes: https://lore.kernel.org/r/202603060454.MeuKcrhO-lkp@intel.com/

smatch warnings:
kernel/crash_core.c:305 crash_exclude_core_ranges() warn: we never enter this loop

vim +305 kernel/crash_core.c

747ee16995b671 Jinjie Ruan 2026-03-02  289  
747ee16995b671 Jinjie Ruan 2026-03-02  290  static int crash_exclude_core_ranges(struct crash_mem *cmem)
747ee16995b671 Jinjie Ruan 2026-03-02  291  {
747ee16995b671 Jinjie Ruan 2026-03-02  292  	int ret, i;
747ee16995b671 Jinjie Ruan 2026-03-02  293  
747ee16995b671 Jinjie Ruan 2026-03-02  294  	/* Exclude crashkernel region */
747ee16995b671 Jinjie Ruan 2026-03-02  295  	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
747ee16995b671 Jinjie Ruan 2026-03-02  296  	if (ret)
747ee16995b671 Jinjie Ruan 2026-03-02  297  		return ret;
747ee16995b671 Jinjie Ruan 2026-03-02  298  
747ee16995b671 Jinjie Ruan 2026-03-02  299  	if (crashk_low_res.end) {
747ee16995b671 Jinjie Ruan 2026-03-02  300  		ret = crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
747ee16995b671 Jinjie Ruan 2026-03-02  301  		if (ret)
747ee16995b671 Jinjie Ruan 2026-03-02  302  			return ret;
747ee16995b671 Jinjie Ruan 2026-03-02  303  	}
747ee16995b671 Jinjie Ruan 2026-03-02  304  
747ee16995b671 Jinjie Ruan 2026-03-02 @305  	for (i = 0; i < crashk_cma_cnt; ++i) {
747ee16995b671 Jinjie Ruan 2026-03-02  306  		ret = crash_exclude_mem_range(cmem, crashk_cma_ranges[i].start,
747ee16995b671 Jinjie Ruan 2026-03-02  307  					      crashk_cma_ranges[i].end);
747ee16995b671 Jinjie Ruan 2026-03-02  308  		if (ret)
747ee16995b671 Jinjie Ruan 2026-03-02  309  			return ret;
747ee16995b671 Jinjie Ruan 2026-03-02  310  	}
747ee16995b671 Jinjie Ruan 2026-03-02  311  
747ee16995b671 Jinjie Ruan 2026-03-02  312  	return 0;
747ee16995b671 Jinjie Ruan 2026-03-02  313  }
747ee16995b671 Jinjie Ruan 2026-03-02  314  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH v8 2/5] crash: Exclude crash kernel memory in crash core

[Jinjie Ruan]

On 2026/3/2 11:53, Jinjie Ruan wrote:
> The crash memory alloc, and the exclude of crashk_res, crashk_low_res
> and crashk_cma memory are almost identical across different architectures,
> handling them in the crash core would eliminate a lot of duplication, so
> do them in the common code.
> 
> To achieve the above goal, three architecture-specific functions are
> introduced:
> 
> - arch_get_system_nr_ranges(). Pre-counts the max number of memory ranges.
> 
> - arch_crash_populate_cmem(). Collects the memory ranges and fills them
>   into cmem.
> 
> - arch_crash_exclude_ranges(). Architecture's additional crash memory
>   ranges exclusion, defaulting to empty.
> 
> Acked-by: Baoquan He <bhe@redhat.com>
> Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
> ---
>  arch/arm64/kernel/machine_kexec_file.c     | 39 +++-------
>  arch/loongarch/kernel/machine_kexec_file.c | 39 +++-------
>  arch/riscv/kernel/machine_kexec_file.c     | 38 +++------
>  arch/x86/kernel/crash.c                    | 89 +++-------------------
>  include/linux/crash_core.h                 |  5 ++
>  kernel/crash_core.c                        | 82 +++++++++++++++++++-
>  6 files changed, 132 insertions(+), 160 deletions(-)
> 
> diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c
> index fba260ad87a9..c338506a580b 100644
> --- a/arch/arm64/kernel/machine_kexec_file.c
> +++ b/arch/arm64/kernel/machine_kexec_file.c
> @@ -40,23 +40,23 @@ int arch_kimage_file_post_load_cleanup(struct kimage *image)
>  }
>  
>  #ifdef CONFIG_CRASH_DUMP
> -static int prepare_elf_headers(void **addr, unsigned long *sz)
> +unsigned int arch_get_system_nr_ranges(void)
>  {
> -	struct crash_mem *cmem;
> -	unsigned int nr_ranges;
> -	int ret;
> -	u64 i;
> +	unsigned int nr_ranges = 2; /* for exclusion of crashkernel region */
>  	phys_addr_t start, end;
> +	u64 i;
>  
> -	nr_ranges = 2; /* for exclusion of crashkernel region */
>  	for_each_mem_range(i, &start, &end)
>  		nr_ranges++;
>  
> -	cmem = kmalloc_flex(*cmem, ranges, nr_ranges);
> -	if (!cmem)
> -		return -ENOMEM;
> +	return nr_ranges;
> +}
> +
> +int arch_crash_populate_cmem(struct crash_mem *cmem)
> +{
> +	phys_addr_t start, end;
> +	u64 i;
>  
> -	cmem->max_nr_ranges = nr_ranges;
>  	cmem->nr_ranges = 0;
>  	for_each_mem_range(i, &start, &end) {
>  		cmem->ranges[cmem->nr_ranges].start = start;
> @@ -64,22 +64,7 @@ static int prepare_elf_headers(void **addr, unsigned long *sz)
>  		cmem->nr_ranges++;
>  	}
>  
> -	/* Exclude crashkernel region */
> -	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
> -	if (ret)
> -		goto out;
> -
> -	if (crashk_low_res.end) {
> -		ret = crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
> -		if (ret)
> -			goto out;
> -	}
> -
> -	ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
> -
> -out:
> -	kfree(cmem);
> -	return ret;
> +	return 0;
>  }
>  #endif
>  
> @@ -109,7 +94,7 @@ int load_other_segments(struct kimage *image,
>  	void *headers;
>  	unsigned long headers_sz;
>  	if (image->type == KEXEC_TYPE_CRASH) {
> -		ret = prepare_elf_headers(&headers, &headers_sz);
> +		ret = crash_prepare_headers(true, &headers, &headers_sz, NULL);
>  		if (ret) {
>  			pr_err("Preparing elf core header failed\n");
>  			goto out_err;
> diff --git a/arch/loongarch/kernel/machine_kexec_file.c b/arch/loongarch/kernel/machine_kexec_file.c
> index 5584b798ba46..4b318a94b564 100644
> --- a/arch/loongarch/kernel/machine_kexec_file.c
> +++ b/arch/loongarch/kernel/machine_kexec_file.c
> @@ -56,23 +56,23 @@ static void cmdline_add_initrd(struct kimage *image, unsigned long *cmdline_tmpl
>  }
>  
>  #ifdef CONFIG_CRASH_DUMP
> -
> -static int prepare_elf_headers(void **addr, unsigned long *sz)
> +unsigned int arch_get_system_nr_ranges(void)
>  {
> -	int ret, nr_ranges;
> -	uint64_t i;
> +	int nr_ranges = 2; /* for exclusion of crashkernel region */
>  	phys_addr_t start, end;
> -	struct crash_mem *cmem;
> +	uint64_t i;
>  
> -	nr_ranges = 2; /* for exclusion of crashkernel region */
>  	for_each_mem_range(i, &start, &end)
>  		nr_ranges++;
>  
> -	cmem = kmalloc_flex(*cmem, ranges, nr_ranges);
> -	if (!cmem)
> -		return -ENOMEM;
> +	return nr_ranges;
> +}
> +
> +int arch_crash_populate_cmem(struct crash_mem *cmem)
> +{
> +	phys_addr_t start, end;
> +	uint64_t i;
>  
> -	cmem->max_nr_ranges = nr_ranges;
>  	cmem->nr_ranges = 0;
>  	for_each_mem_range(i, &start, &end) {
>  		cmem->ranges[cmem->nr_ranges].start = start;
> @@ -80,22 +80,7 @@ static int prepare_elf_headers(void **addr, unsigned long *sz)
>  		cmem->nr_ranges++;
>  	}
>  
> -	/* Exclude crashkernel region */
> -	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
> -	if (ret < 0)
> -		goto out;
> -
> -	if (crashk_low_res.end) {
> -		ret = crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
> -		if (ret < 0)
> -			goto out;
> -	}
> -
> -	ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
> -
> -out:
> -	kfree(cmem);
> -	return ret;
> +	return 0;
>  }
>  
>  /*
> @@ -163,7 +148,7 @@ int load_other_segments(struct kimage *image,
>  		void *headers;
>  		unsigned long headers_sz;
>  
> -		ret = prepare_elf_headers(&headers, &headers_sz);
> +		ret = crash_prepare_headers(true, &headers, &headers_sz, NULL);
>  		if (ret < 0) {
>  			pr_err("Preparing elf core header failed\n");
>  			goto out_err;
> diff --git a/arch/riscv/kernel/machine_kexec_file.c b/arch/riscv/kernel/machine_kexec_file.c
> index 54e2d9552e93..d0e331d87155 100644
> --- a/arch/riscv/kernel/machine_kexec_file.c
> +++ b/arch/riscv/kernel/machine_kexec_file.c
> @@ -44,6 +44,15 @@ static int get_nr_ram_ranges_callback(struct resource *res, void *arg)
>  	return 0;
>  }
>  
> +unsigned int arch_get_system_nr_ranges(void)
> +{
> +	unsigned int nr_ranges = 1; /* For exclusion of crashkernel region */
> +
> +	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
> +
> +	return nr_ranges;
> +}
> +
>  static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
>  {
>  	struct crash_mem *cmem = arg;
> @@ -55,33 +64,10 @@ static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
>  	return 0;
>  }
>  
> -static int prepare_elf_headers(void **addr, unsigned long *sz)
> +int arch_crash_populate_cmem(struct crash_mem *cmem)
>  {
> -	struct crash_mem *cmem;
> -	unsigned int nr_ranges;
> -	int ret;
> -
> -	nr_ranges = 1; /* For exclusion of crashkernel region */
> -	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
> -
> -	cmem = kmalloc_flex(*cmem, ranges, nr_ranges);
> -	if (!cmem)
> -		return -ENOMEM;
> -
> -	cmem->max_nr_ranges = nr_ranges;
>  	cmem->nr_ranges = 0;
> -	ret = walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
> -	if (ret)
> -		goto out;

Hi, Baoquan

While using AI tools to assist in the review, I noticed the following
issues in the RISC-V implementation:

riscv supports crashk_low_res in commit 5882e5acf18d ("riscv: kdump:
Implement crashkernel=X,[high,low]"),  so it should have excluded the
"crashk_low_res" reserved ranges from the crash kernel memory to prevent
them from being exported through /proc/vmcore, and the exclusion would
need an extra crash_mem range as below.

Should I include a fix for this in this patch set?

--- a/arch/riscv/kernel/machine_kexec_file.c
+++ b/arch/riscv/kernel/machine_kexec_file.c
@@ -61,7 +61,7 @@ static int prepare_elf_headers(void **addr, unsigned
long *sz)
        unsigned int nr_ranges;
        int ret;

-       nr_ranges = 1; /* For exclusion of crashkernel region */
+       nr_ranges = 2; /* For exclusion of crashkernel region */
        walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);

        cmem = kmalloc_flex(*cmem, ranges, nr_ranges);
@@ -76,8 +76,16 @@ static int prepare_elf_headers(void **addr, unsigned
long *sz)

        /* Exclude crashkernel region */
        ret = crash_exclude_mem_range(cmem, crashk_res.start,
crashk_res.end);
-       if (!ret)
-               ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
+       if (ret)
+               goto out;
+
+       if (crashk_low_res.end) {
+               ret = crash_exclude_mem_range(cmem,
crashk_low_res.start, crashk_low_res.end);
+               if (ret)
+                       goto out;
+       }
+
+       ret = crash_prepare_elf64_headers(cmem, true, addr, sz);

 out:
        kfree(cmem);



> -
> -	/* Exclude crashkernel region */
> -	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
> -	if (!ret)
> -		ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
> -
> -out:
> -	kfree(cmem);
> -	return ret;
> +	return walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
>  }
>  
>  static char *setup_kdump_cmdline(struct kimage *image, char *cmdline,
> @@ -273,7 +259,7 @@ int load_extra_segments(struct kimage *image, unsigned long kernel_start,
>  	if (image->type == KEXEC_TYPE_CRASH) {
>  		void *headers;
>  		unsigned long headers_sz;
> -		ret = prepare_elf_headers(&headers, &headers_sz);
> +		ret = crash_prepare_headers(true, &headers, &headers_sz, NULL);
>  		if (ret) {
>  			pr_err("Preparing elf core header failed\n");
>  			goto out;
> diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
> index 335fd2ee9766..3ad3f8b758a4 100644
> --- a/arch/x86/kernel/crash.c
> +++ b/arch/x86/kernel/crash.c
> @@ -152,16 +152,8 @@ 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 struct crash_mem *fill_up_crash_elf_data(void)
> +unsigned int arch_get_system_nr_ranges(void)
>  {
> -	unsigned int nr_ranges = 0;
> -	struct crash_mem *cmem;
> -
> -	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
> -	if (!nr_ranges)
> -		return NULL;
> -
>  	/*
>  	 * Exclusion of crash region, crashk_low_res and/or crashk_cma_ranges
>  	 * may cause range splits. So add extra slots here.
> @@ -176,49 +168,16 @@ static struct crash_mem *fill_up_crash_elf_data(void)
>  	 * But in order to lest the low 1M could be changed in the future,
>  	 * (e.g. [start, 1M]), add a extra slot.
>  	 */
> -	nr_ranges += 3 + crashk_cma_cnt;
> -	cmem = vzalloc(struct_size(cmem, ranges, nr_ranges));
> -	if (!cmem)
> -		return NULL;
> -
> -	cmem->max_nr_ranges = nr_ranges;
> +	unsigned int nr_ranges = 3 + crashk_cma_cnt;
>  
> -	return cmem;
> +	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
> +	return nr_ranges;
>  }
>  
> -/*
> - * Look for any unwanted ranges between mstart, mend and remove them. This
> - * might lead to split and split ranges are put in cmem->ranges[] array
> - */
> -static int elf_header_exclude_ranges(struct crash_mem *cmem)
> +int arch_crash_exclude_ranges(struct crash_mem *cmem)
>  {
> -	int ret = 0;
> -	int i;
> -
>  	/* Exclude the low 1M because it is always reserved */
> -	ret = crash_exclude_mem_range(cmem, 0, SZ_1M - 1);
> -	if (ret)
> -		return ret;
> -
> -	/* Exclude crashkernel region */
> -	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
> -	if (ret)
> -		return ret;
> -
> -	if (crashk_low_res.end)
> -		ret = crash_exclude_mem_range(cmem, crashk_low_res.start,
> -					      crashk_low_res.end);
> -	if (ret)
> -		return ret;
> -
> -	for (i = 0; i < crashk_cma_cnt; ++i) {
> -		ret = crash_exclude_mem_range(cmem, crashk_cma_ranges[i].start,
> -					      crashk_cma_ranges[i].end);
> -		if (ret)
> -			return ret;
> -	}
> -
> -	return 0;
> +	return crash_exclude_mem_range(cmem, 0, SZ_1M - 1);
>  }
>  
>  static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
> @@ -232,35 +191,9 @@ static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
>  	return 0;
>  }
>  
> -/* Prepare elf headers. Return addr and size */
> -static int prepare_elf_headers(void **addr, unsigned long *sz,
> -			       unsigned long *nr_mem_ranges)
> +int arch_crash_populate_cmem(struct crash_mem *cmem)
>  {
> -	struct crash_mem *cmem;
> -	int ret;
> -
> -	cmem = fill_up_crash_elf_data();
> -	if (!cmem)
> -		return -ENOMEM;
> -
> -	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(cmem);
> -	if (ret)
> -		goto out;
> -
> -	/* Return the computed number of memory ranges, for hotplug usage */
> -	*nr_mem_ranges = cmem->nr_ranges;
> -
> -	/* By default prepare 64bit headers */
> -	ret = crash_prepare_elf64_headers(cmem, IS_ENABLED(CONFIG_X86_64), addr, sz);
> -
> -out:
> -	vfree(cmem);
> -	return ret;
> +	return walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
>  }
>  #endif
>  
> @@ -418,7 +351,8 @@ int crash_load_segments(struct kimage *image)
>  				  .buf_max = ULONG_MAX, .top_down = false };
>  
>  	/* Prepare elf headers and add a segment */
> -	ret = prepare_elf_headers(&kbuf.buffer, &kbuf.bufsz, &pnum);
> +	ret = crash_prepare_headers(IS_ENABLED(CONFIG_X86_64), &kbuf.buffer,
> +				    &kbuf.bufsz, &pnum);
>  	if (ret)
>  		return ret;
>  
> @@ -529,7 +463,8 @@ void arch_crash_handle_hotplug_event(struct kimage *image, void *arg)
>  	 * Create the new elfcorehdr reflecting the changes to CPU and/or
>  	 * memory resources.
>  	 */
> -	if (prepare_elf_headers(&elfbuf, &elfsz, &nr_mem_ranges)) {
> +	if (crash_prepare_headers(IS_ENABLED(CONFIG_X86_64), &elfbuf, &elfsz,
> +				  &nr_mem_ranges)) {
>  		pr_err("unable to create new elfcorehdr");
>  		goto out;
>  	}
> diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
> index d35726d6a415..033b20204aca 100644
> --- a/include/linux/crash_core.h
> +++ b/include/linux/crash_core.h
> @@ -66,6 +66,8 @@ extern int crash_exclude_mem_range(struct crash_mem *mem,
>  				   unsigned long long mend);
>  extern int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
>  				       void **addr, unsigned long *sz);
> +extern int crash_prepare_headers(int need_kernel_map, void **addr,
> +				 unsigned long *sz, unsigned long *nr_mem_ranges);
>  
>  struct kimage;
>  struct kexec_segment;
> @@ -83,6 +85,9 @@ int kexec_should_crash(struct task_struct *p);
>  int kexec_crash_loaded(void);
>  void crash_save_cpu(struct pt_regs *regs, int cpu);
>  extern int kimage_crash_copy_vmcoreinfo(struct kimage *image);
> +extern unsigned int arch_get_system_nr_ranges(void);
> +extern int arch_crash_populate_cmem(struct crash_mem *cmem);
> +extern int arch_crash_exclude_ranges(struct crash_mem *cmem);
>  
>  #else /* !CONFIG_CRASH_DUMP*/
>  struct pt_regs;
> diff --git a/kernel/crash_core.c b/kernel/crash_core.c
> index 2c1a3791e410..96a96e511f5a 100644
> --- a/kernel/crash_core.c
> +++ b/kernel/crash_core.c
> @@ -170,9 +170,6 @@ static inline resource_size_t crash_resource_size(const struct resource *res)
>  	return !res->end ? 0 : resource_size(res);
>  }
>  
> -
> -
> -
>  int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
>  			  void **addr, unsigned long *sz)
>  {
> @@ -274,6 +271,85 @@ int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
>  	return 0;
>  }
>  
> +static struct crash_mem *alloc_cmem(unsigned int nr_ranges)
> +{
> +	struct crash_mem *cmem;
> +
> +	cmem = kvzalloc_flex(*cmem, ranges, nr_ranges);
> +	if (!cmem)
> +		return NULL;
> +
> +	cmem->max_nr_ranges = nr_ranges;
> +	return cmem;
> +}
> +
> +unsigned int __weak arch_get_system_nr_ranges(void) { return 0; }
> +int __weak arch_crash_populate_cmem(struct crash_mem *cmem) { return -1; }
> +int __weak arch_crash_exclude_ranges(struct crash_mem *cmem) { return 0; }
> +
> +static int crash_exclude_core_ranges(struct crash_mem *cmem)
> +{
> +	int ret, i;
> +
> +	/* Exclude crashkernel region */
> +	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
> +	if (ret)
> +		return ret;
> +
> +	if (crashk_low_res.end) {
> +		ret = crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	for (i = 0; i < crashk_cma_cnt; ++i) {
> +		ret = crash_exclude_mem_range(cmem, crashk_cma_ranges[i].start,
> +					      crashk_cma_ranges[i].end);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +int crash_prepare_headers(int need_kernel_map, void **addr, unsigned long *sz,
> +			  unsigned long *nr_mem_ranges)
> +{
> +	unsigned int max_nr_ranges;
> +	struct crash_mem *cmem;
> +	int ret;
> +
> +	max_nr_ranges = arch_get_system_nr_ranges();
> +	if (!max_nr_ranges)
> +		return -ENOMEM;
> +
> +	cmem = alloc_cmem(max_nr_ranges);
> +	if (!cmem)
> +		return -ENOMEM;
> +
> +	ret = arch_crash_populate_cmem(cmem);
> +	if (ret)
> +		goto out;
> +
> +	ret = crash_exclude_core_ranges(cmem);
> +	if (ret)
> +		goto out;
> +
> +	ret = arch_crash_exclude_ranges(cmem);
> +	if (ret)
> +		goto out;
> +
> +	/* Return the computed number of memory ranges, for hotplug usage */
> +	if (nr_mem_ranges)
> +		*nr_mem_ranges = cmem->nr_ranges;
> +
> +	ret = crash_prepare_elf64_headers(cmem, need_kernel_map, addr, sz);
> +
> +out:
> +	kvfree(cmem);
> +	return ret;
> +}
> +
>  /**
>   * crash_exclude_mem_range - exclude a mem range for existing ranges
>   * @mem: mem->range contains an array of ranges sorted in ascending order

Re: [PATCH v8 2/5] crash: Exclude crash kernel memory in crash core

[Jinjie Ruan]

On 2026/3/2 11:53, Jinjie Ruan wrote:
> The crash memory alloc, and the exclude of crashk_res, crashk_low_res
> and crashk_cma memory are almost identical across different architectures,
> handling them in the crash core would eliminate a lot of duplication, so
> do them in the common code.
> 
> To achieve the above goal, three architecture-specific functions are
> introduced:
> 
> - arch_get_system_nr_ranges(). Pre-counts the max number of memory ranges.
> 
> - arch_crash_populate_cmem(). Collects the memory ranges and fills them
>   into cmem.
> 
> - arch_crash_exclude_ranges(). Architecture's additional crash memory
>   ranges exclusion, defaulting to empty.
> 
> Acked-by: Baoquan He <bhe@redhat.com>
> Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
> ---
>  arch/arm64/kernel/machine_kexec_file.c     | 39 +++-------
>  arch/loongarch/kernel/machine_kexec_file.c | 39 +++-------
>  arch/riscv/kernel/machine_kexec_file.c     | 38 +++------
>  arch/x86/kernel/crash.c                    | 89 +++-------------------
>  include/linux/crash_core.h                 |  5 ++
>  kernel/crash_core.c                        | 82 +++++++++++++++++++-
>  6 files changed, 132 insertions(+), 160 deletions(-)
> 
> diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c
> index fba260ad87a9..c338506a580b 100644
> --- a/arch/arm64/kernel/machine_kexec_file.c
> +++ b/arch/arm64/kernel/machine_kexec_file.c
> @@ -40,23 +40,23 @@ int arch_kimage_file_post_load_cleanup(struct kimage *image)
>  }
>  
>  #ifdef CONFIG_CRASH_DUMP
> -static int prepare_elf_headers(void **addr, unsigned long *sz)
> +unsigned int arch_get_system_nr_ranges(void)
>  {
> -	struct crash_mem *cmem;
> -	unsigned int nr_ranges;
> -	int ret;
> -	u64 i;
> +	unsigned int nr_ranges = 2; /* for exclusion of crashkernel region */
>  	phys_addr_t start, end;
> +	u64 i;
>  
> -	nr_ranges = 2; /* for exclusion of crashkernel region */
>  	for_each_mem_range(i, &start, &end)
>  		nr_ranges++;
>  
> -	cmem = kmalloc_flex(*cmem, ranges, nr_ranges);
> -	if (!cmem)
> -		return -ENOMEM;
> +	return nr_ranges;
> +}
> +
> +int arch_crash_populate_cmem(struct crash_mem *cmem)
> +{
> +	phys_addr_t start, end;
> +	u64 i;
>  
> -	cmem->max_nr_ranges = nr_ranges;
>  	cmem->nr_ranges = 0;
>  	for_each_mem_range(i, &start, &end) {
>  		cmem->ranges[cmem->nr_ranges].start = start;
> @@ -64,22 +64,7 @@ static int prepare_elf_headers(void **addr, unsigned long *sz)
>  		cmem->nr_ranges++;
>  	}
>  
> -	/* Exclude crashkernel region */
> -	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
> -	if (ret)
> -		goto out;
> -
> -	if (crashk_low_res.end) {
> -		ret = crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
> -		if (ret)
> -			goto out;
> -	}
> -
> -	ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
> -
> -out:
> -	kfree(cmem);
> -	return ret;
> +	return 0;
>  }
>  #endif
>  
> @@ -109,7 +94,7 @@ int load_other_segments(struct kimage *image,
>  	void *headers;
>  	unsigned long headers_sz;
>  	if (image->type == KEXEC_TYPE_CRASH) {
> -		ret = prepare_elf_headers(&headers, &headers_sz);
> +		ret = crash_prepare_headers(true, &headers, &headers_sz, NULL);
>  		if (ret) {
>  			pr_err("Preparing elf core header failed\n");
>  			goto out_err;
> diff --git a/arch/loongarch/kernel/machine_kexec_file.c b/arch/loongarch/kernel/machine_kexec_file.c
> index 5584b798ba46..4b318a94b564 100644
> --- a/arch/loongarch/kernel/machine_kexec_file.c
> +++ b/arch/loongarch/kernel/machine_kexec_file.c
> @@ -56,23 +56,23 @@ static void cmdline_add_initrd(struct kimage *image, unsigned long *cmdline_tmpl
>  }
>  
>  #ifdef CONFIG_CRASH_DUMP
> -
> -static int prepare_elf_headers(void **addr, unsigned long *sz)
> +unsigned int arch_get_system_nr_ranges(void)
>  {
> -	int ret, nr_ranges;
> -	uint64_t i;
> +	int nr_ranges = 2; /* for exclusion of crashkernel region */
>  	phys_addr_t start, end;
> -	struct crash_mem *cmem;
> +	uint64_t i;
>  
> -	nr_ranges = 2; /* for exclusion of crashkernel region */
>  	for_each_mem_range(i, &start, &end)
>  		nr_ranges++;
>  
> -	cmem = kmalloc_flex(*cmem, ranges, nr_ranges);
> -	if (!cmem)
> -		return -ENOMEM;
> +	return nr_ranges;
> +}
> +
> +int arch_crash_populate_cmem(struct crash_mem *cmem)
> +{
> +	phys_addr_t start, end;
> +	uint64_t i;
>  
> -	cmem->max_nr_ranges = nr_ranges;
>  	cmem->nr_ranges = 0;
>  	for_each_mem_range(i, &start, &end) {
>  		cmem->ranges[cmem->nr_ranges].start = start;
> @@ -80,22 +80,7 @@ static int prepare_elf_headers(void **addr, unsigned long *sz)
>  		cmem->nr_ranges++;
>  	}
>  
> -	/* Exclude crashkernel region */
> -	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
> -	if (ret < 0)
> -		goto out;
> -
> -	if (crashk_low_res.end) {
> -		ret = crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
> -		if (ret < 0)
> -			goto out;
> -	}
> -
> -	ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
> -
> -out:
> -	kfree(cmem);
> -	return ret;
> +	return 0;
>  }
>  
>  /*
> @@ -163,7 +148,7 @@ int load_other_segments(struct kimage *image,
>  		void *headers;
>  		unsigned long headers_sz;
>  
> -		ret = prepare_elf_headers(&headers, &headers_sz);
> +		ret = crash_prepare_headers(true, &headers, &headers_sz, NULL);
>  		if (ret < 0) {
>  			pr_err("Preparing elf core header failed\n");
>  			goto out_err;
> diff --git a/arch/riscv/kernel/machine_kexec_file.c b/arch/riscv/kernel/machine_kexec_file.c
> index 54e2d9552e93..d0e331d87155 100644
> --- a/arch/riscv/kernel/machine_kexec_file.c
> +++ b/arch/riscv/kernel/machine_kexec_file.c
> @@ -44,6 +44,15 @@ static int get_nr_ram_ranges_callback(struct resource *res, void *arg)
>  	return 0;
>  }
>  
> +unsigned int arch_get_system_nr_ranges(void)
> +{
> +	unsigned int nr_ranges = 1; /* For exclusion of crashkernel region */
> +
> +	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
> +
> +	return nr_ranges;
> +}
> +
>  static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
>  {
>  	struct crash_mem *cmem = arg;
> @@ -55,33 +64,10 @@ static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
>  	return 0;
>  }
>  
> -static int prepare_elf_headers(void **addr, unsigned long *sz)
> +int arch_crash_populate_cmem(struct crash_mem *cmem)
>  {
> -	struct crash_mem *cmem;
> -	unsigned int nr_ranges;
> -	int ret;
> -
> -	nr_ranges = 1; /* For exclusion of crashkernel region */
> -	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
> -
> -	cmem = kmalloc_flex(*cmem, ranges, nr_ranges);
> -	if (!cmem)
> -		return -ENOMEM;
> -
> -	cmem->max_nr_ranges = nr_ranges;
>  	cmem->nr_ranges = 0;
> -	ret = walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
> -	if (ret)
> -		goto out;

Hi, Baoquan

While using AI tools to assist in the review, I noticed the following
issues in the RISC-V implementation:

riscv supports crashk_low_res in commit 5882e5acf18d ("riscv: kdump:
Implement crashkernel=X,[high,low]"),  so it should have excluded the
"crashk_low_res" reserved ranges from the crash kernel memory to prevent
them from being exported through /proc/vmcore, and the exclusion would
need an extra crash_mem range as below.

Should I include a fix for this in this patch set?

--- a/arch/riscv/kernel/machine_kexec_file.c
+++ b/arch/riscv/kernel/machine_kexec_file.c
@@ -61,7 +61,7 @@ static int prepare_elf_headers(void **addr, unsigned
long *sz)
        unsigned int nr_ranges;
        int ret;

-       nr_ranges = 1; /* For exclusion of crashkernel region */
+       nr_ranges = 2; /* For exclusion of crashkernel region */
        walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);

        cmem = kmalloc_flex(*cmem, ranges, nr_ranges);
@@ -76,8 +76,16 @@ static int prepare_elf_headers(void **addr, unsigned
long *sz)

        /* Exclude crashkernel region */
        ret = crash_exclude_mem_range(cmem, crashk_res.start,
crashk_res.end);
-       if (!ret)
-               ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
+       if (ret)
+               goto out;
+
+       if (crashk_low_res.end) {
+               ret = crash_exclude_mem_range(cmem,
crashk_low_res.start, crashk_low_res.end);
+               if (ret)
+                       goto out;
+       }
+
+       ret = crash_prepare_elf64_headers(cmem, true, addr, sz);

 out:
        kfree(cmem);



> -
> -	/* Exclude crashkernel region */
> -	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
> -	if (!ret)
> -		ret = crash_prepare_elf64_headers(cmem, true, addr, sz);
> -
> -out:
> -	kfree(cmem);
> -	return ret;
> +	return walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
>  }
>  
>  static char *setup_kdump_cmdline(struct kimage *image, char *cmdline,
> @@ -273,7 +259,7 @@ int load_extra_segments(struct kimage *image, unsigned long kernel_start,
>  	if (image->type == KEXEC_TYPE_CRASH) {
>  		void *headers;
>  		unsigned long headers_sz;
> -		ret = prepare_elf_headers(&headers, &headers_sz);
> +		ret = crash_prepare_headers(true, &headers, &headers_sz, NULL);
>  		if (ret) {
>  			pr_err("Preparing elf core header failed\n");
>  			goto out;
> diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
> index 335fd2ee9766..3ad3f8b758a4 100644
> --- a/arch/x86/kernel/crash.c
> +++ b/arch/x86/kernel/crash.c
> @@ -152,16 +152,8 @@ 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 struct crash_mem *fill_up_crash_elf_data(void)
> +unsigned int arch_get_system_nr_ranges(void)
>  {
> -	unsigned int nr_ranges = 0;
> -	struct crash_mem *cmem;
> -
> -	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
> -	if (!nr_ranges)
> -		return NULL;
> -
>  	/*
>  	 * Exclusion of crash region, crashk_low_res and/or crashk_cma_ranges
>  	 * may cause range splits. So add extra slots here.
> @@ -176,49 +168,16 @@ static struct crash_mem *fill_up_crash_elf_data(void)
>  	 * But in order to lest the low 1M could be changed in the future,
>  	 * (e.g. [start, 1M]), add a extra slot.
>  	 */
> -	nr_ranges += 3 + crashk_cma_cnt;
> -	cmem = vzalloc(struct_size(cmem, ranges, nr_ranges));
> -	if (!cmem)
> -		return NULL;
> -
> -	cmem->max_nr_ranges = nr_ranges;
> +	unsigned int nr_ranges = 3 + crashk_cma_cnt;
>  
> -	return cmem;
> +	walk_system_ram_res(0, -1, &nr_ranges, get_nr_ram_ranges_callback);
> +	return nr_ranges;
>  }
>  
> -/*
> - * Look for any unwanted ranges between mstart, mend and remove them. This
> - * might lead to split and split ranges are put in cmem->ranges[] array
> - */
> -static int elf_header_exclude_ranges(struct crash_mem *cmem)
> +int arch_crash_exclude_ranges(struct crash_mem *cmem)
>  {
> -	int ret = 0;
> -	int i;
> -
>  	/* Exclude the low 1M because it is always reserved */
> -	ret = crash_exclude_mem_range(cmem, 0, SZ_1M - 1);
> -	if (ret)
> -		return ret;
> -
> -	/* Exclude crashkernel region */
> -	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
> -	if (ret)
> -		return ret;
> -
> -	if (crashk_low_res.end)
> -		ret = crash_exclude_mem_range(cmem, crashk_low_res.start,
> -					      crashk_low_res.end);
> -	if (ret)
> -		return ret;
> -
> -	for (i = 0; i < crashk_cma_cnt; ++i) {
> -		ret = crash_exclude_mem_range(cmem, crashk_cma_ranges[i].start,
> -					      crashk_cma_ranges[i].end);
> -		if (ret)
> -			return ret;
> -	}
> -
> -	return 0;
> +	return crash_exclude_mem_range(cmem, 0, SZ_1M - 1);
>  }
>  
>  static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
> @@ -232,35 +191,9 @@ static int prepare_elf64_ram_headers_callback(struct resource *res, void *arg)
>  	return 0;
>  }
>  
> -/* Prepare elf headers. Return addr and size */
> -static int prepare_elf_headers(void **addr, unsigned long *sz,
> -			       unsigned long *nr_mem_ranges)
> +int arch_crash_populate_cmem(struct crash_mem *cmem)
>  {
> -	struct crash_mem *cmem;
> -	int ret;
> -
> -	cmem = fill_up_crash_elf_data();
> -	if (!cmem)
> -		return -ENOMEM;
> -
> -	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(cmem);
> -	if (ret)
> -		goto out;
> -
> -	/* Return the computed number of memory ranges, for hotplug usage */
> -	*nr_mem_ranges = cmem->nr_ranges;
> -
> -	/* By default prepare 64bit headers */
> -	ret = crash_prepare_elf64_headers(cmem, IS_ENABLED(CONFIG_X86_64), addr, sz);
> -
> -out:
> -	vfree(cmem);
> -	return ret;
> +	return walk_system_ram_res(0, -1, cmem, prepare_elf64_ram_headers_callback);
>  }
>  #endif
>  
> @@ -418,7 +351,8 @@ int crash_load_segments(struct kimage *image)
>  				  .buf_max = ULONG_MAX, .top_down = false };
>  
>  	/* Prepare elf headers and add a segment */
> -	ret = prepare_elf_headers(&kbuf.buffer, &kbuf.bufsz, &pnum);
> +	ret = crash_prepare_headers(IS_ENABLED(CONFIG_X86_64), &kbuf.buffer,
> +				    &kbuf.bufsz, &pnum);
>  	if (ret)
>  		return ret;
>  
> @@ -529,7 +463,8 @@ void arch_crash_handle_hotplug_event(struct kimage *image, void *arg)
>  	 * Create the new elfcorehdr reflecting the changes to CPU and/or
>  	 * memory resources.
>  	 */
> -	if (prepare_elf_headers(&elfbuf, &elfsz, &nr_mem_ranges)) {
> +	if (crash_prepare_headers(IS_ENABLED(CONFIG_X86_64), &elfbuf, &elfsz,
> +				  &nr_mem_ranges)) {
>  		pr_err("unable to create new elfcorehdr");
>  		goto out;
>  	}
> diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
> index d35726d6a415..033b20204aca 100644
> --- a/include/linux/crash_core.h
> +++ b/include/linux/crash_core.h
> @@ -66,6 +66,8 @@ extern int crash_exclude_mem_range(struct crash_mem *mem,
>  				   unsigned long long mend);
>  extern int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
>  				       void **addr, unsigned long *sz);
> +extern int crash_prepare_headers(int need_kernel_map, void **addr,
> +				 unsigned long *sz, unsigned long *nr_mem_ranges);
>  
>  struct kimage;
>  struct kexec_segment;
> @@ -83,6 +85,9 @@ int kexec_should_crash(struct task_struct *p);
>  int kexec_crash_loaded(void);
>  void crash_save_cpu(struct pt_regs *regs, int cpu);
>  extern int kimage_crash_copy_vmcoreinfo(struct kimage *image);
> +extern unsigned int arch_get_system_nr_ranges(void);
> +extern int arch_crash_populate_cmem(struct crash_mem *cmem);
> +extern int arch_crash_exclude_ranges(struct crash_mem *cmem);
>  
>  #else /* !CONFIG_CRASH_DUMP*/
>  struct pt_regs;
> diff --git a/kernel/crash_core.c b/kernel/crash_core.c
> index 2c1a3791e410..96a96e511f5a 100644
> --- a/kernel/crash_core.c
> +++ b/kernel/crash_core.c
> @@ -170,9 +170,6 @@ static inline resource_size_t crash_resource_size(const struct resource *res)
>  	return !res->end ? 0 : resource_size(res);
>  }
>  
> -
> -
> -
>  int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
>  			  void **addr, unsigned long *sz)
>  {
> @@ -274,6 +271,85 @@ int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
>  	return 0;
>  }
>  
> +static struct crash_mem *alloc_cmem(unsigned int nr_ranges)
> +{
> +	struct crash_mem *cmem;
> +
> +	cmem = kvzalloc_flex(*cmem, ranges, nr_ranges);
> +	if (!cmem)
> +		return NULL;
> +
> +	cmem->max_nr_ranges = nr_ranges;
> +	return cmem;
> +}
> +
> +unsigned int __weak arch_get_system_nr_ranges(void) { return 0; }
> +int __weak arch_crash_populate_cmem(struct crash_mem *cmem) { return -1; }
> +int __weak arch_crash_exclude_ranges(struct crash_mem *cmem) { return 0; }
> +
> +static int crash_exclude_core_ranges(struct crash_mem *cmem)
> +{
> +	int ret, i;
> +
> +	/* Exclude crashkernel region */
> +	ret = crash_exclude_mem_range(cmem, crashk_res.start, crashk_res.end);
> +	if (ret)
> +		return ret;
> +
> +	if (crashk_low_res.end) {
> +		ret = crash_exclude_mem_range(cmem, crashk_low_res.start, crashk_low_res.end);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	for (i = 0; i < crashk_cma_cnt; ++i) {
> +		ret = crash_exclude_mem_range(cmem, crashk_cma_ranges[i].start,
> +					      crashk_cma_ranges[i].end);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +int crash_prepare_headers(int need_kernel_map, void **addr, unsigned long *sz,
> +			  unsigned long *nr_mem_ranges)
> +{
> +	unsigned int max_nr_ranges;
> +	struct crash_mem *cmem;
> +	int ret;
> +
> +	max_nr_ranges = arch_get_system_nr_ranges();
> +	if (!max_nr_ranges)
> +		return -ENOMEM;
> +
> +	cmem = alloc_cmem(max_nr_ranges);
> +	if (!cmem)
> +		return -ENOMEM;
> +
> +	ret = arch_crash_populate_cmem(cmem);
> +	if (ret)
> +		goto out;
> +
> +	ret = crash_exclude_core_ranges(cmem);
> +	if (ret)
> +		goto out;
> +
> +	ret = arch_crash_exclude_ranges(cmem);
> +	if (ret)
> +		goto out;
> +
> +	/* Return the computed number of memory ranges, for hotplug usage */
> +	if (nr_mem_ranges)
> +		*nr_mem_ranges = cmem->nr_ranges;
> +
> +	ret = crash_prepare_elf64_headers(cmem, need_kernel_map, addr, sz);
> +
> +out:
> +	kvfree(cmem);
> +	return ret;
> +}
> +
>  /**
>   * crash_exclude_mem_range - exclude a mem range for existing ranges
>   * @mem: mem->range contains an array of ranges sorted in ascending order

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