[PATCH v2 0/8] kdump: use generic functions to simplify crashkernel reservation in arch

[PATCH v2 0/8] kdump: use generic functions to simplify crashkernel reservation in arch

[Baoquan He]

In the current arm64, crashkernel=,high support has been finished after
several rounds of posting and careful reviewing. The code in arm64 which
parses crashkernel kernel parameters firstly, then reserve memory can be
a good example for other ARCH to refer to.

Whereas in x86_64, the code mixing crashkernel parameter parsing and
memory reserving is twisted, and looks messy. Refactoring the code to
make it more readable maintainable is necessary.

Here, firstly abstract the crashkernel parameter parsing code into
parse_crashkernel() to make it be able to parse crashkernel=,high|low.
Then abstract the crashkernel memory reserving code into a generic
function reserve_crashkernel_generic(). Finally, in ARCH which
crashkernel=,high support is needed, a simple arch_reserve_crashkernel()
can be added to call above two functions. This can remove the duplicated
implmentation code in each ARCH, like arm64, x86_64.

I only change the arm64 and x86_64 implementation to make use of the
generic functions to simplify code. Risc-v can be done very easily refer
to the steps in arm64 and x86_64.

History:
- RFC patchset:
  https://lore.kernel.org/all/20230619055951.45620-1-bhe@redhat.com/T/#u
  [RFC PATCH 0/4] kdump: add generic functions to simplify crashkernel crashkernel in architecture
  Dave and Philipp commented the old parse_crashkernel_common() and
  parse_crashkernel_generic() are quite confusing. In this formal post,
  I made change to address the concern by unifying all crashkernel
  parsing into parse_crashkernel().

v1->v2:
- Change to add asm/crash_core.h into x86 and arm64 to contain those
  arch specific macro definitions for generic reservaton. This fixes the
  compiling error reported by LKP in v1.
  https://lore.kernel.org/all/202308272150.p3kRkMoF-lkp@intel.com/T/#u
- Fix a log typo in patch 8, thanks to Samuel.

Baoquan He (8):
  crash_core.c: remove unnecessary parameter of function
  crash_core: change the prototype of function parse_crashkernel()
  crash_core: change parse_crashkernel() to support
    crashkernel=,high|low parsing
  crash_core: add generic function to do reservation
  crash_core.h: include <asm/crash_core.h> if generic reservation is
    needed
  x86: kdump: use generic interface to simplify crashkernel reservation
    code
  arm64: kdump: use generic interface to simplify crashkernel
    reservation
  crash_core.c: remove unneeded functions

 arch/arm/kernel/setup.c              |   3 +-
 arch/arm64/Kconfig                   |   3 +
 arch/arm64/include/asm/crash_core.h  |  10 ++
 arch/arm64/mm/init.c                 | 140 ++--------------------
 arch/ia64/kernel/setup.c             |   2 +-
 arch/loongarch/kernel/setup.c        |   4 +-
 arch/mips/kernel/setup.c             |   3 +-
 arch/powerpc/kernel/fadump.c         |   2 +-
 arch/powerpc/kexec/core.c            |   2 +-
 arch/powerpc/mm/nohash/kaslr_booke.c |   2 +-
 arch/riscv/mm/init.c                 |   2 +-
 arch/s390/kernel/setup.c             |   4 +-
 arch/sh/kernel/machine_kexec.c       |   2 +-
 arch/x86/Kconfig                     |   3 +
 arch/x86/include/asm/crash_core.h    |  34 ++++++
 arch/x86/kernel/setup.c              | 143 +++-------------------
 include/linux/crash_core.h           |  38 +++++-
 kernel/crash_core.c                  | 170 +++++++++++++++++++++++----
 18 files changed, 269 insertions(+), 298 deletions(-)
 create mode 100644 arch/arm64/include/asm/crash_core.h
 create mode 100644 arch/x86/include/asm/crash_core.h

-- 
2.41.0

[PATCH v2 1/8] crash_core.c: remove unnecessary parameter of function

[Baoquan He]

In all call sites of __parse_crashkernel(), the parameter 'name' is
hardcoded as "crashkernel=". So remove the unnecessary parameter 'name',
add local varibale 'name' inside __parse_crashkernel() instead.

Signed-off-by: Baoquan He <bhe@redhat.com>
---
 kernel/crash_core.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index 90ce1dfd591c..f27b4e45d410 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -241,11 +241,11 @@ static int __init __parse_crashkernel(char *cmdline,
 			     unsigned long long system_ram,
 			     unsigned long long *crash_size,
 			     unsigned long long *crash_base,
-			     const char *name,
 			     const char *suffix)
 {
 	char	*first_colon, *first_space;
 	char	*ck_cmdline;
+	char	*name = "crashkernel=";
 
 	BUG_ON(!crash_size || !crash_base);
 	*crash_size = 0;
@@ -283,7 +283,7 @@ int __init parse_crashkernel(char *cmdline,
 			     unsigned long long *crash_base)
 {
 	return __parse_crashkernel(cmdline, system_ram, crash_size, crash_base,
-					"crashkernel=", NULL);
+				NULL);
 }
 
 int __init parse_crashkernel_high(char *cmdline,
@@ -292,7 +292,7 @@ int __init parse_crashkernel_high(char *cmdline,
 			     unsigned long long *crash_base)
 {
 	return __parse_crashkernel(cmdline, system_ram, crash_size, crash_base,
-				"crashkernel=", suffix_tbl[SUFFIX_HIGH]);
+				suffix_tbl[SUFFIX_HIGH]);
 }
 
 int __init parse_crashkernel_low(char *cmdline,
@@ -301,7 +301,7 @@ int __init parse_crashkernel_low(char *cmdline,
 			     unsigned long long *crash_base)
 {
 	return __parse_crashkernel(cmdline, system_ram, crash_size, crash_base,
-				"crashkernel=", suffix_tbl[SUFFIX_LOW]);
+				suffix_tbl[SUFFIX_LOW]);
 }
 
 /*
-- 
2.41.0

[PATCH v2 2/8] crash_core: change the prototype of function parse_crashkernel()

[Baoquan He]

Add two parameters 'low_size' and 'high' to function parse_crashkernel(),
later crashkernel=,high|low parsing will be added. Make adjustments in all
call sites of parse_crashkernel() in arch.

Signed-off-by: Baoquan He <bhe@redhat.com>
---
 arch/arm/kernel/setup.c              |  3 ++-
 arch/arm64/mm/init.c                 |  2 +-
 arch/ia64/kernel/setup.c             |  2 +-
 arch/loongarch/kernel/setup.c        |  4 +++-
 arch/mips/kernel/setup.c             |  3 ++-
 arch/powerpc/kernel/fadump.c         |  2 +-
 arch/powerpc/kexec/core.c            |  2 +-
 arch/powerpc/mm/nohash/kaslr_booke.c |  2 +-
 arch/riscv/mm/init.c                 |  2 +-
 arch/s390/kernel/setup.c             |  4 ++--
 arch/sh/kernel/machine_kexec.c       |  2 +-
 arch/x86/kernel/setup.c              |  3 ++-
 include/linux/crash_core.h           |  3 ++-
 kernel/crash_core.c                  | 15 ++++++++++++---
 14 files changed, 32 insertions(+), 17 deletions(-)

diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index c66b560562b3..e2bb7afd0683 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -1010,7 +1010,8 @@ static void __init reserve_crashkernel(void)
 
 	total_mem = get_total_mem();
 	ret = parse_crashkernel(boot_command_line, total_mem,
-				&crash_size, &crash_base);
+				&crash_size, &crash_base,
+				NULL, NULL);
 	/* invalid value specified or crashkernel=0 */
 	if (ret || !crash_size)
 		return;
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 4fcb88a445ef..4ad637508b75 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -142,7 +142,7 @@ static void __init reserve_crashkernel(void)
 
 	/* crashkernel=X[@offset] */
 	ret = parse_crashkernel(cmdline, memblock_phys_mem_size(),
-				&crash_size, &crash_base);
+				&crash_size, &crash_base, NULL, NULL);
 	if (ret == -ENOENT) {
 		ret = parse_crashkernel_high(cmdline, 0, &crash_size, &crash_base);
 		if (ret || !crash_size)
diff --git a/arch/ia64/kernel/setup.c b/arch/ia64/kernel/setup.c
index 5a55ac82c13a..4faea2d2cf07 100644
--- a/arch/ia64/kernel/setup.c
+++ b/arch/ia64/kernel/setup.c
@@ -277,7 +277,7 @@ static void __init setup_crashkernel(unsigned long total, int *n)
 	int ret;
 
 	ret = parse_crashkernel(boot_command_line, total,
-			&size, &base);
+			&size, &base, NULL, NULL);
 	if (ret == 0 && size > 0) {
 		if (!base) {
 			sort_regions(rsvd_region, *n);
diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
index 9d830ab4e302..776a068d8718 100644
--- a/arch/loongarch/kernel/setup.c
+++ b/arch/loongarch/kernel/setup.c
@@ -267,7 +267,9 @@ static void __init arch_parse_crashkernel(void)
 	unsigned long long crash_base, crash_size;
 
 	total_mem = memblock_phys_mem_size();
-	ret = parse_crashkernel(boot_command_line, total_mem, &crash_size, &crash_base);
+	ret = parse_crashkernel(boot_command_line, total_mem,
+				&crash_size, &crash_base,
+				NULL, NULL);
 	if (ret < 0 || crash_size <= 0)
 		return;
 
diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index cb871eb784a7..08321c945ac4 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -460,7 +460,8 @@ static void __init mips_parse_crashkernel(void)
 
 	total_mem = memblock_phys_mem_size();
 	ret = parse_crashkernel(boot_command_line, total_mem,
-				&crash_size, &crash_base);
+				&crash_size, &crash_base,
+				NULL, NULL);
 	if (ret != 0 || crash_size <= 0)
 		return;
 
diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index ea0a073abd96..7dbdeba56e74 100644
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -313,7 +313,7 @@ static __init u64 fadump_calculate_reserve_size(void)
 	 * memory at a predefined offset.
 	 */
 	ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
-				&size, &base);
+				&size, &base, NULL, NULL);
 	if (ret == 0 && size > 0) {
 		unsigned long max_size;
 
diff --git a/arch/powerpc/kexec/core.c b/arch/powerpc/kexec/core.c
index de64c7962991..9346c960b296 100644
--- a/arch/powerpc/kexec/core.c
+++ b/arch/powerpc/kexec/core.c
@@ -109,7 +109,7 @@ void __init reserve_crashkernel(void)
 	total_mem_sz = memory_limit ? memory_limit : memblock_phys_mem_size();
 	/* use common parsing */
 	ret = parse_crashkernel(boot_command_line, total_mem_sz,
-			&crash_size, &crash_base);
+			&crash_size, &crash_base, NULL, NULL);
 	if (ret == 0 && crash_size > 0) {
 		crashk_res.start = crash_base;
 		crashk_res.end = crash_base + crash_size - 1;
diff --git a/arch/powerpc/mm/nohash/kaslr_booke.c b/arch/powerpc/mm/nohash/kaslr_booke.c
index 2fb3edafe9ab..b4f2786a7d2b 100644
--- a/arch/powerpc/mm/nohash/kaslr_booke.c
+++ b/arch/powerpc/mm/nohash/kaslr_booke.c
@@ -178,7 +178,7 @@ static void __init get_crash_kernel(void *fdt, unsigned long size)
 	int ret;
 
 	ret = parse_crashkernel(boot_command_line, size, &crash_size,
-				&crash_base);
+				&crash_base, NULL, NULL);
 	if (ret != 0 || crash_size == 0)
 		return;
 	if (crash_base == 0)
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index e4c35ac2357f..a9ef0824f905 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -1332,7 +1332,7 @@ static void __init reserve_crashkernel(void)
 	}
 
 	ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
-				&crash_size, &crash_base);
+				&crash_size, &crash_base, NULL, NULL);
 	if (ret || !crash_size)
 		return;
 
diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index c744104e4a9c..98204a5f62b1 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -626,8 +626,8 @@ static void __init reserve_crashkernel(void)
 	phys_addr_t low, high;
 	int rc;
 
-	rc = parse_crashkernel(boot_command_line, ident_map_size, &crash_size,
-			       &crash_base);
+	rc = parse_crashkernel(boot_command_line, ident_map_size,
+			       &crash_size, &crash_base, NULL, NULL);
 
 	crash_base = ALIGN(crash_base, KEXEC_CRASH_MEM_ALIGN);
 	crash_size = ALIGN(crash_size, KEXEC_CRASH_MEM_ALIGN);
diff --git a/arch/sh/kernel/machine_kexec.c b/arch/sh/kernel/machine_kexec.c
index 223c14f44af7..fa3a7b36190a 100644
--- a/arch/sh/kernel/machine_kexec.c
+++ b/arch/sh/kernel/machine_kexec.c
@@ -154,7 +154,7 @@ void __init reserve_crashkernel(void)
 	int ret;
 
 	ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
-			&crash_size, &crash_base);
+			&crash_size, &crash_base, NULL, NULL);
 	if (ret == 0 && crash_size > 0) {
 		crashk_res.start = crash_base;
 		crashk_res.end = crash_base + crash_size - 1;
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index fd975a4a5200..382c66d2cf71 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -558,7 +558,8 @@ static void __init reserve_crashkernel(void)
 	total_mem = memblock_phys_mem_size();
 
 	/* crashkernel=XM */
-	ret = parse_crashkernel(boot_command_line, total_mem, &crash_size, &crash_base);
+	ret = parse_crashkernel(boot_command_line, total_mem,
+				&crash_size, &crash_base, NULL, NULL);
 	if (ret != 0 || crash_size <= 0) {
 		/* crashkernel=X,high */
 		ret = parse_crashkernel_high(boot_command_line, total_mem,
diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
index de62a722431e..2e76289699ff 100644
--- a/include/linux/crash_core.h
+++ b/include/linux/crash_core.h
@@ -78,7 +78,8 @@ Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
 void final_note(Elf_Word *buf);
 
 int __init parse_crashkernel(char *cmdline, unsigned long long system_ram,
-		unsigned long long *crash_size, unsigned long long *crash_base);
+		unsigned long long *crash_size, unsigned long long *crash_base,
+		unsigned long long *low_size, bool *high);
 int parse_crashkernel_high(char *cmdline, unsigned long long system_ram,
 		unsigned long long *crash_size, unsigned long long *crash_base);
 int parse_crashkernel_low(char *cmdline, unsigned long long system_ram,
diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index f27b4e45d410..f6a5c219e2e1 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -280,10 +280,19 @@ static int __init __parse_crashkernel(char *cmdline,
 int __init parse_crashkernel(char *cmdline,
 			     unsigned long long system_ram,
 			     unsigned long long *crash_size,
-			     unsigned long long *crash_base)
+			     unsigned long long *crash_base,
+			     unsigned long long *low_size,
+			     bool *high)
 {
-	return __parse_crashkernel(cmdline, system_ram, crash_size, crash_base,
-				NULL);
+	int ret;
+
+	/* crashkernel=X[@offset] */
+	ret = __parse_crashkernel(cmdline, system_ram, crash_size,
+				crash_base, NULL);
+	if (!high)
+		return ret;
+
+	return 0;
 }
 
 int __init parse_crashkernel_high(char *cmdline,
-- 
2.41.0

[PATCH v2 3/8] crash_core: change parse_crashkernel() to support crashkernel=,high|low parsing

[Baoquan He]

Now parse_crashkernel() is a real entry point for all kinds of
crahskernel parsing on any architecture.

And wrap the crahskernel=,high|low handling inside
CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION ifdeffery scope.

Signed-off-by: Baoquan He <bhe@redhat.com>
---
 include/linux/crash_core.h |  6 ++++++
 kernel/crash_core.c        | 28 +++++++++++++++++++++++++++-
 2 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
index 2e76289699ff..85260bf4a734 100644
--- a/include/linux/crash_core.h
+++ b/include/linux/crash_core.h
@@ -77,6 +77,12 @@ Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
 			  void *data, size_t data_len);
 void final_note(Elf_Word *buf);
 
+#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
+#ifndef DEFAULT_CRASH_KERNEL_LOW_SIZE
+#define DEFAULT_CRASH_KERNEL_LOW_SIZE  (128UL << 20)
+#endif
+#endif
+
 int __init parse_crashkernel(char *cmdline, unsigned long long system_ram,
 		unsigned long long *crash_size, unsigned long long *crash_base,
 		unsigned long long *low_size, bool *high);
diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index f6a5c219e2e1..355b0ab5189c 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -276,6 +276,9 @@ static int __init __parse_crashkernel(char *cmdline,
 /*
  * That function is the entry point for command line parsing and should be
  * called from the arch-specific code.
+ *
+ * If crashkernel=,high|low is supported on architecture, non-NULL values
+ * should be passed to parameters 'low_size' and 'high'.
  */
 int __init parse_crashkernel(char *cmdline,
 			     unsigned long long system_ram,
@@ -291,7 +294,30 @@ int __init parse_crashkernel(char *cmdline,
 				crash_base, NULL);
 	if (!high)
 		return ret;
-
+#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
+	else if (ret == -ENOENT) {
+		ret = __parse_crashkernel(cmdline, 0, crash_size,
+				crash_base, suffix_tbl[SUFFIX_HIGH]);
+		if (ret || !*crash_size)
+			return -1;
+
+		/*
+		 * crashkernel=Y,low can be specified or not, but invalid value
+		 * is not allowed.
+		 */
+		ret = __parse_crashkernel(cmdline, 0, low_size,
+				crash_base, suffix_tbl[SUFFIX_LOW]);
+		if (ret == -ENOENT)
+			*low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
+		else if (ret)
+			return -1;
+
+		*high = true;
+	} else if (ret || !*crash_size) {
+		/* The specified value is invalid */
+		return -1;
+	}
+#endif
 	return 0;
 }
 
-- 
2.41.0

[PATCH v2 4/8] crash_core: add generic function to do reservation

[Baoquan He]

In architecture like x86_64, arm64 and riscv, they have vast virtual
address space and usually have huge physical memory RAM. Their
crashkernel reservation doesn't have to be limited under 4G RAM,
but can be extended to the whole physical memory via crashkernel=,high
support.

Now add function reserve_crashkernel_generic() to reserve crashkernel
memory if users specify any case of kernel pamameters, like
crashkernel=xM[@offset] or crashkernel=,high|low.

This is preparation to simplify code of crashkernel=,high support
in architecutures.

Signed-off-by: Baoquan He <bhe@redhat.com>
---
 include/linux/crash_core.h |  34 ++++++++++--
 kernel/crash_core.c        | 109 ++++++++++++++++++++++++++++++++++++-
 2 files changed, 136 insertions(+), 7 deletions(-)

diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
index 85260bf4a734..2f732493e922 100644
--- a/include/linux/crash_core.h
+++ b/include/linux/crash_core.h
@@ -77,12 +77,6 @@ Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
 			  void *data, size_t data_len);
 void final_note(Elf_Word *buf);
 
-#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
-#ifndef DEFAULT_CRASH_KERNEL_LOW_SIZE
-#define DEFAULT_CRASH_KERNEL_LOW_SIZE  (128UL << 20)
-#endif
-#endif
-
 int __init parse_crashkernel(char *cmdline, unsigned long long system_ram,
 		unsigned long long *crash_size, unsigned long long *crash_base,
 		unsigned long long *low_size, bool *high);
@@ -91,4 +85,32 @@ int parse_crashkernel_high(char *cmdline, unsigned long long system_ram,
 int parse_crashkernel_low(char *cmdline, unsigned long long system_ram,
 		unsigned long long *crash_size, unsigned long long *crash_base);
 
+#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
+#ifndef DEFAULT_CRASH_KERNEL_LOW_SIZE
+#define DEFAULT_CRASH_KERNEL_LOW_SIZE	(128UL << 20)
+#endif
+#ifndef CRASH_ALIGN
+#define CRASH_ALIGN			SZ_2M
+#endif
+#ifndef CRASH_ADDR_LOW_MAX
+#define CRASH_ADDR_LOW_MAX		SZ_4G
+#endif
+#ifndef CRASH_ADDR_HIGH_MAX
+#define CRASH_ADDR_HIGH_MAX		memblock_end_of_DRAM()
+#endif
+
+void __init reserve_crashkernel_generic(char *cmdline,
+		unsigned long long crash_size,
+		unsigned long long crash_base,
+		unsigned long long crash_low_size,
+		bool high);
+#else
+static inline void __init reserve_crashkernel_generic(char *cmdline,
+		unsigned long long crash_size,
+		unsigned long long crash_base,
+		unsigned long long crash_low_size,
+		bool high)
+{}
+#endif
+
 #endif /* LINUX_CRASH_CORE_H */
diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index 355b0ab5189c..6bc00cc390b5 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -5,11 +5,13 @@
  */
 
 #include <linux/buildid.h>
-#include <linux/crash_core.h>
 #include <linux/init.h>
 #include <linux/utsname.h>
 #include <linux/vmalloc.h>
 #include <linux/sizes.h>
+#include <linux/memblock.h>
+#include <linux/kexec.h>
+#include <linux/kmemleak.h>
 
 #include <asm/page.h>
 #include <asm/sections.h>
@@ -349,6 +351,111 @@ static int __init parse_crashkernel_dummy(char *arg)
 }
 early_param("crashkernel", parse_crashkernel_dummy);
 
+#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
+static int __init reserve_crashkernel_low(unsigned long long low_size)
+{
+#ifdef CONFIG_64BIT
+	unsigned long long low_base;
+
+	low_base = memblock_phys_alloc_range(low_size, CRASH_ALIGN, 0, CRASH_ADDR_LOW_MAX);
+	if (!low_base) {
+		pr_err("cannot allocate crashkernel low memory (size:0x%llx).\n", low_size);
+		return -ENOMEM;
+	}
+
+	pr_info("crashkernel low memory reserved: 0x%08llx - 0x%08llx (%lld MB)\n",
+		low_base, low_base + low_size, low_size >> 20);
+
+	crashk_low_res.start = low_base;
+	crashk_low_res.end   = low_base + low_size - 1;
+	insert_resource(&iomem_resource, &crashk_low_res);
+#endif
+	return 0;
+}
+
+void __init reserve_crashkernel_generic(char *cmdline,
+			     unsigned long long crash_size,
+			     unsigned long long crash_base,
+			     unsigned long long crash_low_size,
+			     bool high)
+{
+	unsigned long long search_end = CRASH_ADDR_LOW_MAX, search_base = 0;
+	bool fixed_base = false;
+
+	/* User specifies base address explicitly. */
+	if (crash_base) {
+		fixed_base = true;
+		search_base = crash_base;
+		search_end = crash_base + crash_size;
+	}
+
+	if (high) {
+		search_base = CRASH_ADDR_LOW_MAX;
+		search_end = CRASH_ADDR_HIGH_MAX;
+	}
+
+retry:
+	crash_base = memblock_phys_alloc_range(crash_size, CRASH_ALIGN,
+					       search_base, search_end);
+	if (!crash_base) {
+		/*
+		 * For crashkernel=size[KMG]@offset[KMG], print out failure
+		 * message if can't reserve the specified region.
+		 */
+		if (fixed_base) {
+			pr_warn("crashkernel reservation failed - memory is in use.\n");
+			return;
+		}
+
+		/*
+		 * For crashkernel=size[KMG], if the first attempt was for
+		 * low memory, fall back to high memory, the minimum required
+		 * low memory will be reserved later.
+		 */
+		if (!high && search_end == CRASH_ADDR_LOW_MAX) {
+			search_end = CRASH_ADDR_HIGH_MAX;
+			search_base = CRASH_ADDR_LOW_MAX;
+			crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
+			goto retry;
+		}
+
+		/*
+		 * For crashkernel=size[KMG],high, if the first attempt was
+		 * for high memory, fall back to low memory.
+		 */
+		if (high && search_end == CRASH_ADDR_HIGH_MAX) {
+			search_end = CRASH_ADDR_LOW_MAX;
+			search_base = 0;
+			goto retry;
+		}
+		pr_warn("cannot allocate crashkernel (size:0x%llx)\n",
+			crash_size);
+		return;
+	}
+
+	if ((crash_base > CRASH_ADDR_LOW_MAX) &&
+	     crash_low_size && reserve_crashkernel_low(crash_low_size)) {
+		memblock_phys_free(crash_base, crash_size);
+		return;
+	}
+
+	pr_info("crashkernel reserved: 0x%016llx - 0x%016llx (%lld MB)\n",
+		crash_base, crash_base + crash_size, crash_size >> 20);
+
+	/*
+	 * The crashkernel memory will be removed from the kernel linear
+	 * map. Inform kmemleak so that it won't try to access it.
+	 */
+	kmemleak_ignore_phys(crash_base);
+	if (crashk_low_res.end)
+		kmemleak_ignore_phys(crashk_low_res.start);
+
+	crashk_res.start = crash_base;
+	crashk_res.end = crash_base + crash_size - 1;
+	insert_resource(&iomem_resource, &crashk_res);
+}
+#endif
+
 Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
 			  void *data, size_t data_len)
 {
-- 
2.41.0

[PATCH v2 5/8] crash_core.h: include <asm/crash_core.h> if generic reservation is needed

[Baoquan He]

In asm/crash_core.h, ARCH can provide its own macro definitions to
override DEFAULT_CRASH_KERNEL_LOW_SIZE, CRASH_ALIGN, CRASH_ADDR_LOW_MAX,
CRASH_ADDR_HIGH_MAX in <linux/crash_core.h> if needed.

Later, x86 and arm64 wil support the generic reservaton, so wrap the
including into CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION ifdeffery
scope to avoid compiling error in other ARCH-es which doesn't take the
generic reservation.

Signed-off-by: Baoquan He <bhe@redhat.com>
---
 include/linux/crash_core.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
index 2f732493e922..86e22e6a039f 100644
--- a/include/linux/crash_core.h
+++ b/include/linux/crash_core.h
@@ -5,6 +5,9 @@
 #include <linux/linkage.h>
 #include <linux/elfcore.h>
 #include <linux/elf.h>
+#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
+#include <asm/crash_core.h>
+#endif
 
 #define CRASH_CORE_NOTE_NAME	   "CORE"
 #define CRASH_CORE_NOTE_HEAD_BYTES ALIGN(sizeof(struct elf_note), 4)
-- 
2.41.0

[PATCH v2 6/8] x86: kdump: use generic interface to simplify crashkernel reservation code

[Baoquan He]

With the help of newly changed function parse_crashkernel() and
generic reserve_crashkernel_generic(), crashkernel reservation can be
simplified by steps:

1) Add a new header file <asm/crash_core.h>, and define CRASH_ALIGN,
   CRASH_ADDR_LOW_MAX, CRASH_ADDR_HIGH_MAX and
   DEFAULT_CRASH_KERNEL_LOW_SIZE in <asm/crash_core.h>;

2) Add arch_reserve_crashkernel() to call parse_crashkernel() and
   reserve_crashkernel_generic(), and do the ARCH specific work if
   needed.

3) Add ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION Kconfig in
   arch/x86/Kconfig.

When adding DEFAULT_CRASH_KERNEL_LOW_SIZE, add crash_low_size_default()
to calculate crashkernel low memory because x86_64 has special
requirement.

The old reserve_crashkernel_low() and reserve_crashkernel() can be
removed.

Signed-off-by: Baoquan He <bhe@redhat.com>
---
 arch/x86/Kconfig                  |   3 +
 arch/x86/include/asm/crash_core.h |  34 +++++++
 arch/x86/kernel/setup.c           | 144 ++++--------------------------
 3 files changed, 53 insertions(+), 128 deletions(-)
 create mode 100644 arch/x86/include/asm/crash_core.h

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 8d9e4b362572..c4539dc35985 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2037,6 +2037,9 @@ config KEXEC_FILE
 config ARCH_HAS_KEXEC_PURGATORY
 	def_bool KEXEC_FILE
 
+config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
+	def_bool CRASH_CORE
+
 config KEXEC_SIG
 	bool "Verify kernel signature during kexec_file_load() syscall"
 	depends on KEXEC_FILE
diff --git a/arch/x86/include/asm/crash_core.h b/arch/x86/include/asm/crash_core.h
new file mode 100644
index 000000000000..5fc5e4f94521
--- /dev/null
+++ b/arch/x86/include/asm/crash_core.h
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _X86_CRASH_CORE_H
+#define _X86_CRASH_CORE_H
+
+/* 16M alignment for crash kernel regions */
+#define CRASH_ALIGN             SZ_16M
+
+/*
+ * Keep the crash kernel below this limit.
+ *
+ * Earlier 32-bits kernels would limit the kernel to the low 512 MB range
+ * due to mapping restrictions.
+ *
+ * 64-bit kdump kernels need to be restricted to be under 64 TB, which is
+ * the upper limit of system RAM in 4-level paging mode. Since the kdump
+ * jump could be from 5-level paging to 4-level paging, the jump will fail if
+ * the kernel is put above 64 TB, and during the 1st kernel bootup there's
+ * no good way to detect the paging mode of the target kernel which will be
+ * loaded for dumping.
+ */
+
+#ifdef CONFIG_X86_32
+# define CRASH_ADDR_LOW_MAX     SZ_512M
+# define CRASH_ADDR_HIGH_MAX    SZ_512M
+#else
+# define CRASH_ADDR_LOW_MAX     SZ_4G
+# define CRASH_ADDR_HIGH_MAX    SZ_64T
+#endif
+
+# define DEFAULT_CRASH_KERNEL_LOW_SIZE crash_low_size_default()
+
+extern unsigned long crash_low_size_default(void);
+
+#endif /* _X86_CRASH_CORE_H */
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 382c66d2cf71..559a5c4141db 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -474,152 +474,40 @@ static void __init memblock_x86_reserve_range_setup_data(void)
 /*
  * --------- Crashkernel reservation ------------------------------
  */
-
-/* 16M alignment for crash kernel regions */
-#define CRASH_ALIGN		SZ_16M
-
-/*
- * Keep the crash kernel below this limit.
- *
- * Earlier 32-bits kernels would limit the kernel to the low 512 MB range
- * due to mapping restrictions.
- *
- * 64-bit kdump kernels need to be restricted to be under 64 TB, which is
- * the upper limit of system RAM in 4-level paging mode. Since the kdump
- * jump could be from 5-level paging to 4-level paging, the jump will fail if
- * the kernel is put above 64 TB, and during the 1st kernel bootup there's
- * no good way to detect the paging mode of the target kernel which will be
- * loaded for dumping.
- */
-#ifdef CONFIG_X86_32
-# define CRASH_ADDR_LOW_MAX	SZ_512M
-# define CRASH_ADDR_HIGH_MAX	SZ_512M
-#else
-# define CRASH_ADDR_LOW_MAX	SZ_4G
-# define CRASH_ADDR_HIGH_MAX	SZ_64T
-#endif
-
-static int __init reserve_crashkernel_low(void)
+unsigned long crash_low_size_default(void)
 {
 #ifdef CONFIG_X86_64
-	unsigned long long base, low_base = 0, low_size = 0;
-	unsigned long low_mem_limit;
-	int ret;
-
-	low_mem_limit = min(memblock_phys_mem_size(), CRASH_ADDR_LOW_MAX);
-
-	/* crashkernel=Y,low */
-	ret = parse_crashkernel_low(boot_command_line, low_mem_limit, &low_size, &base);
-	if (ret) {
-		/*
-		 * two parts from kernel/dma/swiotlb.c:
-		 * -swiotlb size: user-specified with swiotlb= or default.
-		 *
-		 * -swiotlb overflow buffer: now hardcoded to 32k. We round it
-		 * to 8M for other buffers that may need to stay low too. Also
-		 * make sure we allocate enough extra low memory so that we
-		 * don't run out of DMA buffers for 32-bit devices.
-		 */
-		low_size = max(swiotlb_size_or_default() + (8UL << 20), 256UL << 20);
-	} else {
-		/* passed with crashkernel=0,low ? */
-		if (!low_size)
-			return 0;
-	}
-
-	low_base = memblock_phys_alloc_range(low_size, CRASH_ALIGN, 0, CRASH_ADDR_LOW_MAX);
-	if (!low_base) {
-		pr_err("Cannot reserve %ldMB crashkernel low memory, please try smaller size.\n",
-		       (unsigned long)(low_size >> 20));
-		return -ENOMEM;
-	}
-
-	pr_info("Reserving %ldMB of low memory at %ldMB for crashkernel (low RAM limit: %ldMB)\n",
-		(unsigned long)(low_size >> 20),
-		(unsigned long)(low_base >> 20),
-		(unsigned long)(low_mem_limit >> 20));
-
-	crashk_low_res.start = low_base;
-	crashk_low_res.end   = low_base + low_size - 1;
-	insert_resource(&iomem_resource, &crashk_low_res);
-#endif
+	return max(swiotlb_size_or_default() + (8UL << 20), 256UL << 20);
+#else
 	return 0;
+#endif
 }
 
-static void __init reserve_crashkernel(void)
+static void __init arch_reserve_crashkernel(void)
 {
-	unsigned long long crash_size, crash_base, total_mem;
+	unsigned long long crash_base, crash_size, low_size = 0;
+	char *cmdline = boot_command_line;
 	bool high = false;
 	int ret;
 
 	if (!IS_ENABLED(CONFIG_KEXEC_CORE))
 		return;
 
-	total_mem = memblock_phys_mem_size();
-
-	/* crashkernel=XM */
-	ret = parse_crashkernel(boot_command_line, total_mem,
-				&crash_size, &crash_base, NULL, NULL);
-	if (ret != 0 || crash_size <= 0) {
-		/* crashkernel=X,high */
-		ret = parse_crashkernel_high(boot_command_line, total_mem,
-					     &crash_size, &crash_base);
-		if (ret != 0 || crash_size <= 0)
-			return;
-		high = true;
-	}
+	ret = parse_crashkernel(cmdline, memblock_phys_mem_size(),
+				&crash_size, &crash_base,
+				&low_size, &high);
+	if (ret)
+		return;
 
 	if (xen_pv_domain()) {
 		pr_info("Ignoring crashkernel for a Xen PV domain\n");
 		return;
 	}
 
-	/* 0 means: find the address automatically */
-	if (!crash_base) {
-		/*
-		 * Set CRASH_ADDR_LOW_MAX upper bound for crash memory,
-		 * crashkernel=x,high reserves memory over 4G, also allocates
-		 * 256M extra low memory for DMA buffers and swiotlb.
-		 * But the extra memory is not required for all machines.
-		 * So try low memory first and fall back to high memory
-		 * unless "crashkernel=size[KMG],high" is specified.
-		 */
-		if (!high)
-			crash_base = memblock_phys_alloc_range(crash_size,
-						CRASH_ALIGN, CRASH_ALIGN,
-						CRASH_ADDR_LOW_MAX);
-		if (!crash_base)
-			crash_base = memblock_phys_alloc_range(crash_size,
-						CRASH_ALIGN, CRASH_ALIGN,
-						CRASH_ADDR_HIGH_MAX);
-		if (!crash_base) {
-			pr_info("crashkernel reservation failed - No suitable area found.\n");
-			return;
-		}
-	} else {
-		unsigned long long start;
-
-		start = memblock_phys_alloc_range(crash_size, SZ_1M, crash_base,
-						  crash_base + crash_size);
-		if (start != crash_base) {
-			pr_info("crashkernel reservation failed - memory is in use.\n");
-			return;
-		}
-	}
-
-	if (crash_base >= (1ULL << 32) && reserve_crashkernel_low()) {
-		memblock_phys_free(crash_base, crash_size);
-		return;
-	}
-
-	pr_info("Reserving %ldMB of memory at %ldMB for crashkernel (System RAM: %ldMB)\n",
-		(unsigned long)(crash_size >> 20),
-		(unsigned long)(crash_base >> 20),
-		(unsigned long)(total_mem >> 20));
+	reserve_crashkernel_generic(cmdline, crash_size, crash_base,
+				    low_size, high);
 
-	crashk_res.start = crash_base;
-	crashk_res.end   = crash_base + crash_size - 1;
-	insert_resource(&iomem_resource, &crashk_res);
+	return;
 }
 
 static struct resource standard_io_resources[] = {
@@ -1231,7 +1119,7 @@ void __init setup_arch(char **cmdline_p)
 	 * Reserve memory for crash kernel after SRAT is parsed so that it
 	 * won't consume hotpluggable memory.
 	 */
-	reserve_crashkernel();
+	arch_reserve_crashkernel();
 
 	memblock_find_dma_reserve();
 
-- 
2.41.0

[PATCH v2 7/8] arm64: kdump: use generic interface to simplify crashkernel reservation

[Baoquan He]

With the help of newly changed function parse_crashkernel() and
generic reserve_crashkernel_generic(), crashkernel reservation can be
simplified by steps:

1) Add a new header file <asm/crash_core.h>, and define CRASH_ALIGN,
   CRASH_ADDR_LOW_MAX, CRASH_ADDR_HIGH_MAX and
   DEFAULT_CRASH_KERNEL_LOW_SIZE in <asm/crash_core.h>;

2) Add arch_reserve_crashkernel() to call parse_crashkernel() and
   reserve_crashkernel_generic();

3) Add ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION Kconfig in
   arch/arm64/Kconfig.

The old reserve_crashkernel_low() and reserve_crashkernel() can be
removed.

Signed-off-by: Baoquan He <bhe@redhat.com>
---
 arch/arm64/Kconfig                  |   3 +
 arch/arm64/include/asm/crash_core.h |  10 ++
 arch/arm64/mm/init.c                | 140 ++--------------------------
 3 files changed, 21 insertions(+), 132 deletions(-)
 create mode 100644 arch/arm64/include/asm/crash_core.h

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 29db061db9bb..07fb8c71339d 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1481,6 +1481,9 @@ config KEXEC_FILE
 	  for kernel and initramfs as opposed to list of segments as
 	  accepted by previous system call.
 
+config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
+	def_bool CRASH_CORE
+
 config KEXEC_SIG
 	bool "Verify kernel signature during kexec_file_load() syscall"
 	depends on KEXEC_FILE
diff --git a/arch/arm64/include/asm/crash_core.h b/arch/arm64/include/asm/crash_core.h
new file mode 100644
index 000000000000..9f5c8d339f44
--- /dev/null
+++ b/arch/arm64/include/asm/crash_core.h
@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef _ARM64_CRASH_CORE_H
+#define _ARM64_CRASH_CORE_H
+
+/* Current arm64 boot protocol requires 2MB alignment */
+#define CRASH_ALIGN                     SZ_2M
+
+#define CRASH_ADDR_LOW_MAX              arm64_dma_phys_limit
+#define CRASH_ADDR_HIGH_MAX             (PHYS_MASK + 1)
+#endif
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 4ad637508b75..48ab23531bb6 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -64,15 +64,6 @@ EXPORT_SYMBOL(memstart_addr);
  */
 phys_addr_t __ro_after_init arm64_dma_phys_limit;
 
-/* Current arm64 boot protocol requires 2MB alignment */
-#define CRASH_ALIGN			SZ_2M
-
-#define CRASH_ADDR_LOW_MAX		arm64_dma_phys_limit
-#define CRASH_ADDR_HIGH_MAX		(PHYS_MASK + 1)
-#define CRASH_HIGH_SEARCH_BASE		SZ_4G
-
-#define DEFAULT_CRASH_KERNEL_LOW_SIZE	(128UL << 20)
-
 /*
  * To make optimal use of block mappings when laying out the linear
  * mapping, round down the base of physical memory to a size that can
@@ -100,140 +91,25 @@ phys_addr_t __ro_after_init arm64_dma_phys_limit;
 #define ARM64_MEMSTART_ALIGN	(1UL << ARM64_MEMSTART_SHIFT)
 #endif
 
-static int __init reserve_crashkernel_low(unsigned long long low_size)
-{
-	unsigned long long low_base;
-
-	low_base = memblock_phys_alloc_range(low_size, CRASH_ALIGN, 0, CRASH_ADDR_LOW_MAX);
-	if (!low_base) {
-		pr_err("cannot allocate crashkernel low memory (size:0x%llx).\n", low_size);
-		return -ENOMEM;
-	}
-
-	pr_info("crashkernel low memory reserved: 0x%08llx - 0x%08llx (%lld MB)\n",
-		low_base, low_base + low_size, low_size >> 20);
-
-	crashk_low_res.start = low_base;
-	crashk_low_res.end   = low_base + low_size - 1;
-	insert_resource(&iomem_resource, &crashk_low_res);
-
-	return 0;
-}
-
-/*
- * reserve_crashkernel() - reserves memory for crash kernel
- *
- * This function reserves memory area given in "crashkernel=" kernel command
- * line parameter. The memory reserved is used by dump capture kernel when
- * primary kernel is crashing.
- */
-static void __init reserve_crashkernel(void)
+static void __init arch_reserve_crashkernel(void)
 {
-	unsigned long long crash_low_size = 0, search_base = 0;
-	unsigned long long crash_max = CRASH_ADDR_LOW_MAX;
+	unsigned long long low_size = 0;
 	unsigned long long crash_base, crash_size;
 	char *cmdline = boot_command_line;
-	bool fixed_base = false;
 	bool high = false;
 	int ret;
 
 	if (!IS_ENABLED(CONFIG_KEXEC_CORE))
 		return;
 
-	/* crashkernel=X[@offset] */
 	ret = parse_crashkernel(cmdline, memblock_phys_mem_size(),
-				&crash_size, &crash_base, NULL, NULL);
-	if (ret == -ENOENT) {
-		ret = parse_crashkernel_high(cmdline, 0, &crash_size, &crash_base);
-		if (ret || !crash_size)
-			return;
-
-		/*
-		 * crashkernel=Y,low can be specified or not, but invalid value
-		 * is not allowed.
-		 */
-		ret = parse_crashkernel_low(cmdline, 0, &crash_low_size, &crash_base);
-		if (ret == -ENOENT)
-			crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
-		else if (ret)
-			return;
-
-		search_base = CRASH_HIGH_SEARCH_BASE;
-		crash_max = CRASH_ADDR_HIGH_MAX;
-		high = true;
-	} else if (ret || !crash_size) {
-		/* The specified value is invalid */
+				&crash_size, &crash_base,
+				&low_size, &high);
+	if (ret)
 		return;
-	}
-
-	crash_size = PAGE_ALIGN(crash_size);
-
-	/* User specifies base address explicitly. */
-	if (crash_base) {
-		fixed_base = true;
-		search_base = crash_base;
-		crash_max = crash_base + crash_size;
-	}
-
-retry:
-	crash_base = memblock_phys_alloc_range(crash_size, CRASH_ALIGN,
-					       search_base, crash_max);
-	if (!crash_base) {
-		/*
-		 * For crashkernel=size[KMG]@offset[KMG], print out failure
-		 * message if can't reserve the specified region.
-		 */
-		if (fixed_base) {
-			pr_warn("crashkernel reservation failed - memory is in use.\n");
-			return;
-		}
-
-		/*
-		 * For crashkernel=size[KMG], if the first attempt was for
-		 * low memory, fall back to high memory, the minimum required
-		 * low memory will be reserved later.
-		 */
-		if (!high && crash_max == CRASH_ADDR_LOW_MAX) {
-			crash_max = CRASH_ADDR_HIGH_MAX;
-			search_base = CRASH_ADDR_LOW_MAX;
-			crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
-			goto retry;
-		}
-
-		/*
-		 * For crashkernel=size[KMG],high, if the first attempt was
-		 * for high memory, fall back to low memory.
-		 */
-		if (high && crash_max == CRASH_ADDR_HIGH_MAX) {
-			crash_max = CRASH_ADDR_LOW_MAX;
-			search_base = 0;
-			goto retry;
-		}
-		pr_warn("cannot allocate crashkernel (size:0x%llx)\n",
-			crash_size);
-		return;
-	}
-
-	if ((crash_base >= CRASH_ADDR_LOW_MAX) && crash_low_size &&
-	     reserve_crashkernel_low(crash_low_size)) {
-		memblock_phys_free(crash_base, crash_size);
-		return;
-	}
-
-	pr_info("crashkernel reserved: 0x%016llx - 0x%016llx (%lld MB)\n",
-		crash_base, crash_base + crash_size, crash_size >> 20);
-
-	/*
-	 * The crashkernel memory will be removed from the kernel linear
-	 * map. Inform kmemleak so that it won't try to access it.
-	 */
-	kmemleak_ignore_phys(crash_base);
-	if (crashk_low_res.end)
-		kmemleak_ignore_phys(crashk_low_res.start);
 
-	crashk_res.start = crash_base;
-	crashk_res.end = crash_base + crash_size - 1;
-	insert_resource(&iomem_resource, &crashk_res);
+	reserve_crashkernel_generic(cmdline, crash_size, crash_base,
+				    low_size, high);
 }
 
 /*
@@ -481,7 +357,7 @@ void __init bootmem_init(void)
 	 * request_standard_resources() depends on crashkernel's memory being
 	 * reserved, so do it here.
 	 */
-	reserve_crashkernel();
+	arch_reserve_crashkernel();
 
 	memblock_dump_all();
 }
-- 
2.41.0

[PATCH v2 8/8] crash_core.c: remove unneeded functions

[Baoquan He]

So far, nobody calls functions parse_crashkernel_high() and
parse_crashkernel_low(), remove both of them.

Signed-off-by: Baoquan He <bhe@redhat.com>
---
 include/linux/crash_core.h |  4 ----
 kernel/crash_core.c        | 18 ------------------
 2 files changed, 22 deletions(-)

diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
index 86e22e6a039f..d64006c4bd43 100644
--- a/include/linux/crash_core.h
+++ b/include/linux/crash_core.h
@@ -83,10 +83,6 @@ void final_note(Elf_Word *buf);
 int __init parse_crashkernel(char *cmdline, unsigned long long system_ram,
 		unsigned long long *crash_size, unsigned long long *crash_base,
 		unsigned long long *low_size, bool *high);
-int parse_crashkernel_high(char *cmdline, unsigned long long system_ram,
-		unsigned long long *crash_size, unsigned long long *crash_base);
-int parse_crashkernel_low(char *cmdline, unsigned long long system_ram,
-		unsigned long long *crash_size, unsigned long long *crash_base);
 
 #ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
 #ifndef DEFAULT_CRASH_KERNEL_LOW_SIZE
diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index 6bc00cc390b5..61a8ea3b23a2 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -323,24 +323,6 @@ int __init parse_crashkernel(char *cmdline,
 	return 0;
 }
 
-int __init parse_crashkernel_high(char *cmdline,
-			     unsigned long long system_ram,
-			     unsigned long long *crash_size,
-			     unsigned long long *crash_base)
-{
-	return __parse_crashkernel(cmdline, system_ram, crash_size, crash_base,
-				suffix_tbl[SUFFIX_HIGH]);
-}
-
-int __init parse_crashkernel_low(char *cmdline,
-			     unsigned long long system_ram,
-			     unsigned long long *crash_size,
-			     unsigned long long *crash_base)
-{
-	return __parse_crashkernel(cmdline, system_ram, crash_size, crash_base,
-				suffix_tbl[SUFFIX_LOW]);
-}
-
 /*
  * Add a dummy early_param handler to mark crashkernel= as a known command line
  * parameter and suppress incorrect warnings in init/main.c.
-- 
2.41.0

Re: [PATCH v2 6/8] x86: kdump: use generic interface to simplify crashkernel reservation code

[kernel test robot]

Hi Baoquan,

kernel test robot noticed the following build errors:

[auto build test ERROR on arm64/for-next/core]
[also build test ERROR on tip/x86/core powerpc/next powerpc/fixes linus/master v6.5]
[cannot apply to next-20230829]
[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/Baoquan-He/crash_core-c-remove-unnecessary-parameter-of-function/20230829-201942
base:   https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-next/core
patch link:    https://lore.kernel.org/r/20230829121610.138107-7-bhe%40redhat.com
patch subject: [PATCH v2 6/8] x86: kdump: use generic interface to simplify crashkernel reservation code
config: i386-randconfig-r026-20230830 (https://download.01.org/0day-ci/archive/20230830/202308300522.oOG0V3U3-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230830/202308300522.oOG0V3U3-lkp@intel.com/reproduce)

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>
| Closes: https://lore.kernel.org/oe-kbuild-all/202308300522.oOG0V3U3-lkp@intel.com/

All errors (new ones prefixed by >>):

   ld: kernel/crash_core.o: in function `reserve_crashkernel_generic':
>> kernel/crash_core.c:450: undefined reference to `crashk_low_res'
>> ld: kernel/crash_core.c:451: undefined reference to `crashk_low_res'
>> ld: kernel/crash_core.c:455: undefined reference to `crashk_res'
   ld: kernel/crash_core.c:453: undefined reference to `crashk_res'
   ld: kernel/crash_core.c:454: undefined reference to `crashk_res'


vim +450 kernel/crash_core.c

6bee83d29d2e09 Baoquan He 2023-08-29  375  
6bee83d29d2e09 Baoquan He 2023-08-29  376  void __init reserve_crashkernel_generic(char *cmdline,
6bee83d29d2e09 Baoquan He 2023-08-29  377  			     unsigned long long crash_size,
6bee83d29d2e09 Baoquan He 2023-08-29  378  			     unsigned long long crash_base,
6bee83d29d2e09 Baoquan He 2023-08-29  379  			     unsigned long long crash_low_size,
6bee83d29d2e09 Baoquan He 2023-08-29  380  			     bool high)
6bee83d29d2e09 Baoquan He 2023-08-29  381  {
6bee83d29d2e09 Baoquan He 2023-08-29  382  	unsigned long long search_end = CRASH_ADDR_LOW_MAX, search_base = 0;
6bee83d29d2e09 Baoquan He 2023-08-29  383  	bool fixed_base = false;
6bee83d29d2e09 Baoquan He 2023-08-29  384  
6bee83d29d2e09 Baoquan He 2023-08-29  385  	/* User specifies base address explicitly. */
6bee83d29d2e09 Baoquan He 2023-08-29  386  	if (crash_base) {
6bee83d29d2e09 Baoquan He 2023-08-29  387  		fixed_base = true;
6bee83d29d2e09 Baoquan He 2023-08-29  388  		search_base = crash_base;
6bee83d29d2e09 Baoquan He 2023-08-29  389  		search_end = crash_base + crash_size;
6bee83d29d2e09 Baoquan He 2023-08-29  390  	}
6bee83d29d2e09 Baoquan He 2023-08-29  391  
6bee83d29d2e09 Baoquan He 2023-08-29  392  	if (high) {
6bee83d29d2e09 Baoquan He 2023-08-29  393  		search_base = CRASH_ADDR_LOW_MAX;
6bee83d29d2e09 Baoquan He 2023-08-29  394  		search_end = CRASH_ADDR_HIGH_MAX;
6bee83d29d2e09 Baoquan He 2023-08-29  395  	}
6bee83d29d2e09 Baoquan He 2023-08-29  396  
6bee83d29d2e09 Baoquan He 2023-08-29  397  retry:
6bee83d29d2e09 Baoquan He 2023-08-29  398  	crash_base = memblock_phys_alloc_range(crash_size, CRASH_ALIGN,
6bee83d29d2e09 Baoquan He 2023-08-29  399  					       search_base, search_end);
6bee83d29d2e09 Baoquan He 2023-08-29  400  	if (!crash_base) {
6bee83d29d2e09 Baoquan He 2023-08-29  401  		/*
6bee83d29d2e09 Baoquan He 2023-08-29  402  		 * For crashkernel=size[KMG]@offset[KMG], print out failure
6bee83d29d2e09 Baoquan He 2023-08-29  403  		 * message if can't reserve the specified region.
6bee83d29d2e09 Baoquan He 2023-08-29  404  		 */
6bee83d29d2e09 Baoquan He 2023-08-29  405  		if (fixed_base) {
6bee83d29d2e09 Baoquan He 2023-08-29  406  			pr_warn("crashkernel reservation failed - memory is in use.\n");
6bee83d29d2e09 Baoquan He 2023-08-29  407  			return;
6bee83d29d2e09 Baoquan He 2023-08-29  408  		}
6bee83d29d2e09 Baoquan He 2023-08-29  409  
6bee83d29d2e09 Baoquan He 2023-08-29  410  		/*
6bee83d29d2e09 Baoquan He 2023-08-29  411  		 * For crashkernel=size[KMG], if the first attempt was for
6bee83d29d2e09 Baoquan He 2023-08-29  412  		 * low memory, fall back to high memory, the minimum required
6bee83d29d2e09 Baoquan He 2023-08-29  413  		 * low memory will be reserved later.
6bee83d29d2e09 Baoquan He 2023-08-29  414  		 */
6bee83d29d2e09 Baoquan He 2023-08-29  415  		if (!high && search_end == CRASH_ADDR_LOW_MAX) {
6bee83d29d2e09 Baoquan He 2023-08-29  416  			search_end = CRASH_ADDR_HIGH_MAX;
6bee83d29d2e09 Baoquan He 2023-08-29  417  			search_base = CRASH_ADDR_LOW_MAX;
6bee83d29d2e09 Baoquan He 2023-08-29  418  			crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
6bee83d29d2e09 Baoquan He 2023-08-29  419  			goto retry;
6bee83d29d2e09 Baoquan He 2023-08-29  420  		}
6bee83d29d2e09 Baoquan He 2023-08-29  421  
6bee83d29d2e09 Baoquan He 2023-08-29  422  		/*
6bee83d29d2e09 Baoquan He 2023-08-29  423  		 * For crashkernel=size[KMG],high, if the first attempt was
6bee83d29d2e09 Baoquan He 2023-08-29  424  		 * for high memory, fall back to low memory.
6bee83d29d2e09 Baoquan He 2023-08-29  425  		 */
6bee83d29d2e09 Baoquan He 2023-08-29  426  		if (high && search_end == CRASH_ADDR_HIGH_MAX) {
6bee83d29d2e09 Baoquan He 2023-08-29  427  			search_end = CRASH_ADDR_LOW_MAX;
6bee83d29d2e09 Baoquan He 2023-08-29  428  			search_base = 0;
6bee83d29d2e09 Baoquan He 2023-08-29  429  			goto retry;
6bee83d29d2e09 Baoquan He 2023-08-29  430  		}
6bee83d29d2e09 Baoquan He 2023-08-29  431  		pr_warn("cannot allocate crashkernel (size:0x%llx)\n",
6bee83d29d2e09 Baoquan He 2023-08-29  432  			crash_size);
6bee83d29d2e09 Baoquan He 2023-08-29  433  		return;
6bee83d29d2e09 Baoquan He 2023-08-29  434  	}
6bee83d29d2e09 Baoquan He 2023-08-29  435  
6bee83d29d2e09 Baoquan He 2023-08-29  436  	if ((crash_base > CRASH_ADDR_LOW_MAX) &&
6bee83d29d2e09 Baoquan He 2023-08-29  437  	     crash_low_size && reserve_crashkernel_low(crash_low_size)) {
6bee83d29d2e09 Baoquan He 2023-08-29  438  		memblock_phys_free(crash_base, crash_size);
6bee83d29d2e09 Baoquan He 2023-08-29  439  		return;
6bee83d29d2e09 Baoquan He 2023-08-29  440  	}
6bee83d29d2e09 Baoquan He 2023-08-29  441  
6bee83d29d2e09 Baoquan He 2023-08-29  442  	pr_info("crashkernel reserved: 0x%016llx - 0x%016llx (%lld MB)\n",
6bee83d29d2e09 Baoquan He 2023-08-29  443  		crash_base, crash_base + crash_size, crash_size >> 20);
6bee83d29d2e09 Baoquan He 2023-08-29  444  
6bee83d29d2e09 Baoquan He 2023-08-29  445  	/*
6bee83d29d2e09 Baoquan He 2023-08-29  446  	 * The crashkernel memory will be removed from the kernel linear
6bee83d29d2e09 Baoquan He 2023-08-29  447  	 * map. Inform kmemleak so that it won't try to access it.
6bee83d29d2e09 Baoquan He 2023-08-29  448  	 */
6bee83d29d2e09 Baoquan He 2023-08-29  449  	kmemleak_ignore_phys(crash_base);
6bee83d29d2e09 Baoquan He 2023-08-29 @450  	if (crashk_low_res.end)
6bee83d29d2e09 Baoquan He 2023-08-29 @451  		kmemleak_ignore_phys(crashk_low_res.start);
6bee83d29d2e09 Baoquan He 2023-08-29  452  
6bee83d29d2e09 Baoquan He 2023-08-29  453  	crashk_res.start = crash_base;
6bee83d29d2e09 Baoquan He 2023-08-29  454  	crashk_res.end = crash_base + crash_size - 1;
6bee83d29d2e09 Baoquan He 2023-08-29 @455  	insert_resource(&iomem_resource, &crashk_res);
6bee83d29d2e09 Baoquan He 2023-08-29  456  }
6bee83d29d2e09 Baoquan He 2023-08-29  457  #endif
6bee83d29d2e09 Baoquan He 2023-08-29  458  

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

Re: [PATCH v2 6/8] x86: kdump: use generic interface to simplify crashkernel reservation code

[kernel test robot]

Hi Baoquan,

kernel test robot noticed the following build errors:

[auto build test ERROR on arm64/for-next/core]
[also build test ERROR on tip/x86/core powerpc/next powerpc/fixes v6.5]
[cannot apply to linus/master next-20230829]
[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/Baoquan-He/crash_core-c-remove-unnecessary-parameter-of-function/20230829-201942
base:   https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-next/core
patch link:    https://lore.kernel.org/r/20230829121610.138107-7-bhe%40redhat.com
patch subject: [PATCH v2 6/8] x86: kdump: use generic interface to simplify crashkernel reservation code
config: x86_64-randconfig-r022-20230830 (https://download.01.org/0day-ci/archive/20230830/202308300910.e0i4piJT-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230830/202308300910.e0i4piJT-lkp@intel.com/reproduce)

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>
| Closes: https://lore.kernel.org/oe-kbuild-all/202308300910.e0i4piJT-lkp@intel.com/

All errors (new ones prefixed by >>):

   ld: vmlinux.o: in function `reserve_crashkernel_low':
   kernel/crash_core.c:369: undefined reference to `crashk_low_res'
   ld: kernel/crash_core.c:369: undefined reference to `crashk_low_res'
   ld: kernel/crash_core.c:370: undefined reference to `crashk_low_res'
   ld: kernel/crash_core.c:369: undefined reference to `crashk_low_res'
   ld: kernel/crash_core.c:370: undefined reference to `crashk_low_res'
   ld: vmlinux.o:kernel/crash_core.c:371: more undefined references to `crashk_low_res' follow
   ld: vmlinux.o: in function `reserve_crashkernel_generic':
>> kernel/crash_core.c:453: undefined reference to `crashk_res'
>> ld: kernel/crash_core.c:453: undefined reference to `crashk_res'
   ld: kernel/crash_core.c:454: undefined reference to `crashk_res'
>> ld: kernel/crash_core.c:453: undefined reference to `crashk_res'
   ld: kernel/crash_core.c:454: undefined reference to `crashk_res'
   ld: vmlinux.o:kernel/crash_core.c:454: more undefined references to `crashk_res' follow


vim +453 kernel/crash_core.c

71d2bcec2d4d69 Philipp Rudo 2021-12-24  353  
6bee83d29d2e09 Baoquan He   2023-08-29  354  #ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
6bee83d29d2e09 Baoquan He   2023-08-29  355  static int __init reserve_crashkernel_low(unsigned long long low_size)
6bee83d29d2e09 Baoquan He   2023-08-29  356  {
6bee83d29d2e09 Baoquan He   2023-08-29  357  #ifdef CONFIG_64BIT
6bee83d29d2e09 Baoquan He   2023-08-29  358  	unsigned long long low_base;
6bee83d29d2e09 Baoquan He   2023-08-29  359  
6bee83d29d2e09 Baoquan He   2023-08-29  360  	low_base = memblock_phys_alloc_range(low_size, CRASH_ALIGN, 0, CRASH_ADDR_LOW_MAX);
6bee83d29d2e09 Baoquan He   2023-08-29  361  	if (!low_base) {
6bee83d29d2e09 Baoquan He   2023-08-29  362  		pr_err("cannot allocate crashkernel low memory (size:0x%llx).\n", low_size);
6bee83d29d2e09 Baoquan He   2023-08-29  363  		return -ENOMEM;
6bee83d29d2e09 Baoquan He   2023-08-29  364  	}
6bee83d29d2e09 Baoquan He   2023-08-29  365  
6bee83d29d2e09 Baoquan He   2023-08-29  366  	pr_info("crashkernel low memory reserved: 0x%08llx - 0x%08llx (%lld MB)\n",
6bee83d29d2e09 Baoquan He   2023-08-29  367  		low_base, low_base + low_size, low_size >> 20);
6bee83d29d2e09 Baoquan He   2023-08-29  368  
6bee83d29d2e09 Baoquan He   2023-08-29 @369  	crashk_low_res.start = low_base;
6bee83d29d2e09 Baoquan He   2023-08-29  370  	crashk_low_res.end   = low_base + low_size - 1;
6bee83d29d2e09 Baoquan He   2023-08-29  371  	insert_resource(&iomem_resource, &crashk_low_res);
6bee83d29d2e09 Baoquan He   2023-08-29  372  #endif
6bee83d29d2e09 Baoquan He   2023-08-29  373  	return 0;
6bee83d29d2e09 Baoquan He   2023-08-29  374  }
6bee83d29d2e09 Baoquan He   2023-08-29  375  
6bee83d29d2e09 Baoquan He   2023-08-29  376  void __init reserve_crashkernel_generic(char *cmdline,
6bee83d29d2e09 Baoquan He   2023-08-29  377  			     unsigned long long crash_size,
6bee83d29d2e09 Baoquan He   2023-08-29  378  			     unsigned long long crash_base,
6bee83d29d2e09 Baoquan He   2023-08-29  379  			     unsigned long long crash_low_size,
6bee83d29d2e09 Baoquan He   2023-08-29  380  			     bool high)
6bee83d29d2e09 Baoquan He   2023-08-29  381  {
6bee83d29d2e09 Baoquan He   2023-08-29  382  	unsigned long long search_end = CRASH_ADDR_LOW_MAX, search_base = 0;
6bee83d29d2e09 Baoquan He   2023-08-29  383  	bool fixed_base = false;
6bee83d29d2e09 Baoquan He   2023-08-29  384  
6bee83d29d2e09 Baoquan He   2023-08-29  385  	/* User specifies base address explicitly. */
6bee83d29d2e09 Baoquan He   2023-08-29  386  	if (crash_base) {
6bee83d29d2e09 Baoquan He   2023-08-29  387  		fixed_base = true;
6bee83d29d2e09 Baoquan He   2023-08-29  388  		search_base = crash_base;
6bee83d29d2e09 Baoquan He   2023-08-29  389  		search_end = crash_base + crash_size;
6bee83d29d2e09 Baoquan He   2023-08-29  390  	}
6bee83d29d2e09 Baoquan He   2023-08-29  391  
6bee83d29d2e09 Baoquan He   2023-08-29  392  	if (high) {
6bee83d29d2e09 Baoquan He   2023-08-29  393  		search_base = CRASH_ADDR_LOW_MAX;
6bee83d29d2e09 Baoquan He   2023-08-29  394  		search_end = CRASH_ADDR_HIGH_MAX;
6bee83d29d2e09 Baoquan He   2023-08-29  395  	}
6bee83d29d2e09 Baoquan He   2023-08-29  396  
6bee83d29d2e09 Baoquan He   2023-08-29  397  retry:
6bee83d29d2e09 Baoquan He   2023-08-29  398  	crash_base = memblock_phys_alloc_range(crash_size, CRASH_ALIGN,
6bee83d29d2e09 Baoquan He   2023-08-29  399  					       search_base, search_end);
6bee83d29d2e09 Baoquan He   2023-08-29  400  	if (!crash_base) {
6bee83d29d2e09 Baoquan He   2023-08-29  401  		/*
6bee83d29d2e09 Baoquan He   2023-08-29  402  		 * For crashkernel=size[KMG]@offset[KMG], print out failure
6bee83d29d2e09 Baoquan He   2023-08-29  403  		 * message if can't reserve the specified region.
6bee83d29d2e09 Baoquan He   2023-08-29  404  		 */
6bee83d29d2e09 Baoquan He   2023-08-29  405  		if (fixed_base) {
6bee83d29d2e09 Baoquan He   2023-08-29  406  			pr_warn("crashkernel reservation failed - memory is in use.\n");
6bee83d29d2e09 Baoquan He   2023-08-29  407  			return;
6bee83d29d2e09 Baoquan He   2023-08-29  408  		}
6bee83d29d2e09 Baoquan He   2023-08-29  409  
6bee83d29d2e09 Baoquan He   2023-08-29  410  		/*
6bee83d29d2e09 Baoquan He   2023-08-29  411  		 * For crashkernel=size[KMG], if the first attempt was for
6bee83d29d2e09 Baoquan He   2023-08-29  412  		 * low memory, fall back to high memory, the minimum required
6bee83d29d2e09 Baoquan He   2023-08-29  413  		 * low memory will be reserved later.
6bee83d29d2e09 Baoquan He   2023-08-29  414  		 */
6bee83d29d2e09 Baoquan He   2023-08-29  415  		if (!high && search_end == CRASH_ADDR_LOW_MAX) {
6bee83d29d2e09 Baoquan He   2023-08-29  416  			search_end = CRASH_ADDR_HIGH_MAX;
6bee83d29d2e09 Baoquan He   2023-08-29  417  			search_base = CRASH_ADDR_LOW_MAX;
6bee83d29d2e09 Baoquan He   2023-08-29  418  			crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
6bee83d29d2e09 Baoquan He   2023-08-29  419  			goto retry;
6bee83d29d2e09 Baoquan He   2023-08-29  420  		}
6bee83d29d2e09 Baoquan He   2023-08-29  421  
6bee83d29d2e09 Baoquan He   2023-08-29  422  		/*
6bee83d29d2e09 Baoquan He   2023-08-29  423  		 * For crashkernel=size[KMG],high, if the first attempt was
6bee83d29d2e09 Baoquan He   2023-08-29  424  		 * for high memory, fall back to low memory.
6bee83d29d2e09 Baoquan He   2023-08-29  425  		 */
6bee83d29d2e09 Baoquan He   2023-08-29  426  		if (high && search_end == CRASH_ADDR_HIGH_MAX) {
6bee83d29d2e09 Baoquan He   2023-08-29  427  			search_end = CRASH_ADDR_LOW_MAX;
6bee83d29d2e09 Baoquan He   2023-08-29  428  			search_base = 0;
6bee83d29d2e09 Baoquan He   2023-08-29  429  			goto retry;
6bee83d29d2e09 Baoquan He   2023-08-29  430  		}
6bee83d29d2e09 Baoquan He   2023-08-29  431  		pr_warn("cannot allocate crashkernel (size:0x%llx)\n",
6bee83d29d2e09 Baoquan He   2023-08-29  432  			crash_size);
6bee83d29d2e09 Baoquan He   2023-08-29  433  		return;
6bee83d29d2e09 Baoquan He   2023-08-29  434  	}
6bee83d29d2e09 Baoquan He   2023-08-29  435  
6bee83d29d2e09 Baoquan He   2023-08-29  436  	if ((crash_base > CRASH_ADDR_LOW_MAX) &&
6bee83d29d2e09 Baoquan He   2023-08-29  437  	     crash_low_size && reserve_crashkernel_low(crash_low_size)) {
6bee83d29d2e09 Baoquan He   2023-08-29  438  		memblock_phys_free(crash_base, crash_size);
6bee83d29d2e09 Baoquan He   2023-08-29  439  		return;
6bee83d29d2e09 Baoquan He   2023-08-29  440  	}
6bee83d29d2e09 Baoquan He   2023-08-29  441  
6bee83d29d2e09 Baoquan He   2023-08-29  442  	pr_info("crashkernel reserved: 0x%016llx - 0x%016llx (%lld MB)\n",
6bee83d29d2e09 Baoquan He   2023-08-29  443  		crash_base, crash_base + crash_size, crash_size >> 20);
6bee83d29d2e09 Baoquan He   2023-08-29  444  
6bee83d29d2e09 Baoquan He   2023-08-29  445  	/*
6bee83d29d2e09 Baoquan He   2023-08-29  446  	 * The crashkernel memory will be removed from the kernel linear
6bee83d29d2e09 Baoquan He   2023-08-29  447  	 * map. Inform kmemleak so that it won't try to access it.
6bee83d29d2e09 Baoquan He   2023-08-29  448  	 */
6bee83d29d2e09 Baoquan He   2023-08-29  449  	kmemleak_ignore_phys(crash_base);
6bee83d29d2e09 Baoquan He   2023-08-29  450  	if (crashk_low_res.end)
6bee83d29d2e09 Baoquan He   2023-08-29  451  		kmemleak_ignore_phys(crashk_low_res.start);
6bee83d29d2e09 Baoquan He   2023-08-29  452  
6bee83d29d2e09 Baoquan He   2023-08-29 @453  	crashk_res.start = crash_base;
6bee83d29d2e09 Baoquan He   2023-08-29  454  	crashk_res.end = crash_base + crash_size - 1;
6bee83d29d2e09 Baoquan He   2023-08-29  455  	insert_resource(&iomem_resource, &crashk_res);
6bee83d29d2e09 Baoquan He   2023-08-29  456  }
6bee83d29d2e09 Baoquan He   2023-08-29  457  #endif
6bee83d29d2e09 Baoquan He   2023-08-29  458  

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

Re: [PATCH v2 6/8] x86: kdump: use generic interface to simplify crashkernel reservation code

[Baoquan He]

On 08/30/23 at 09:49am, kernel test robot wrote:
> Hi Baoquan,
> 
> kernel test robot noticed the following build errors:
> 
> [auto build test ERROR on arm64/for-next/core]
> [also build test ERROR on tip/x86/core powerpc/next powerpc/fixes v6.5]
> [cannot apply to linus/master next-20230829]
> [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/Baoquan-He/crash_core-c-remove-unnecessary-parameter-of-function/20230829-201942
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-next/core
> patch link:    https://lore.kernel.org/r/20230829121610.138107-7-bhe%40redhat.com
> patch subject: [PATCH v2 6/8] x86: kdump: use generic interface to simplify crashkernel reservation code
> config: x86_64-randconfig-r022-20230830 (https://download.01.org/0day-ci/archive/20230830/202308300910.e0i4piJT-lkp@intel.com/config)
> compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230830/202308300910.e0i4piJT-lkp@intel.com/reproduce)
> 
> 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>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202308300910.e0i4piJT-lkp@intel.com/
> 
> All errors (new ones prefixed by >>):
> 
>    ld: vmlinux.o: in function `reserve_crashkernel_low':
>    kernel/crash_core.c:369: undefined reference to `crashk_low_res'
>    ld: kernel/crash_core.c:369: undefined reference to `crashk_low_res'
>    ld: kernel/crash_core.c:370: undefined reference to `crashk_low_res'
>    ld: kernel/crash_core.c:369: undefined reference to `crashk_low_res'
>    ld: kernel/crash_core.c:370: undefined reference to `crashk_low_res'
>    ld: vmlinux.o:kernel/crash_core.c:371: more undefined references to `crashk_low_res' follow
>    ld: vmlinux.o: in function `reserve_crashkernel_generic':
> >> kernel/crash_core.c:453: undefined reference to `crashk_res'
> >> ld: kernel/crash_core.c:453: undefined reference to `crashk_res'
>    ld: kernel/crash_core.c:454: undefined reference to `crashk_res'
> >> ld: kernel/crash_core.c:453: undefined reference to `crashk_res'
>    ld: kernel/crash_core.c:454: undefined reference to `crashk_res'
>    ld: vmlinux.o:kernel/crash_core.c:454: more undefined references to `crashk_res' follow

Thanks for reporting. This one has the same root cause as the i386-randconfig
building. It's because crashk_res|crashk_low_res are defined in
kernel/kexec_core.c, but referenced in generic reservation code in
crash_core.c, while in this lkp's randconfig, CONFIG_KEXEC_CORE is
unset, CONFIG_CRASH_CORE=on. Then undefined reference to `crashk_res'
and `crashk_low_res' are reported.

Below patch can fix it. I will post v3 to contain this.

From 5a5bda3b5b1e370b789489d87516c8f1fb966c46 Mon Sep 17 00:00:00 2001
From: Baoquan He <bhe@redhat.com>
Date: Tue, 29 Aug 2023 22:38:15 -0400
Subject: [PATCH] crash_core: move crashk_res and crashk_low_res definition
 into crash_core.c
Content-type: text/plain

Both crashk_res and crashk_low_res are used to mark the reserved
crashkernel regions in iomem_resource tree. And later the generic
crashkernel resrvation which references them will be added into
crash_core.c. So move crashk_res and crashk_low_res definition into
crash_core.c to avoid compiling error when CONFIG_CRASH_CORE=on while
CONFIG_KEXEC_CORE is unset.

Signed-off-by: Baoquan He <bhe@redhat.com>
---
 include/linux/crash_core.h |  5 +++++
 include/linux/kexec.h      |  4 ----
 kernel/crash_core.c        | 16 ++++++++++++++++
 kernel/kexec_core.c        | 17 -----------------
 4 files changed, 21 insertions(+), 21 deletions(-)

diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
index d64006c4bd43..daa87b8730d3 100644
--- a/include/linux/crash_core.h
+++ b/include/linux/crash_core.h
@@ -9,6 +9,11 @@
 #include <asm/crash_core.h>
 #endif
 
+/* Location of a reserved region to hold the crash kernel.
+ */
+extern struct resource crashk_res;
+extern struct resource crashk_low_res;
+
 #define CRASH_CORE_NOTE_NAME	   "CORE"
 #define CRASH_CORE_NOTE_HEAD_BYTES ALIGN(sizeof(struct elf_note), 4)
 #define CRASH_CORE_NOTE_NAME_BYTES ALIGN(sizeof(CRASH_CORE_NOTE_NAME), 4)
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 22b5cd24f581..e762b0435c39 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -22,10 +22,6 @@
 #include <uapi/linux/kexec.h>
 #include <linux/verification.h>
 
-/* Location of a reserved region to hold the crash kernel.
- */
-extern struct resource crashk_res;
-extern struct resource crashk_low_res;
 extern note_buf_t __percpu *crash_notes;
 
 #ifdef CONFIG_KEXEC_CORE
diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index 61a8ea3b23a2..d76e7280c651 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -28,6 +28,22 @@ u32 *vmcoreinfo_note;
 /* trusted vmcoreinfo, e.g. we can make a copy in the crash memory */
 static unsigned char *vmcoreinfo_data_safecopy;
 
+/* Location of the reserved area for the crash kernel */
+struct resource crashk_res = {
+	.name  = "Crash kernel",
+	.start = 0,
+	.end   = 0,
+	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
+	.desc  = IORES_DESC_CRASH_KERNEL
+};
+struct resource crashk_low_res = {
+	.name  = "Crash kernel",
+	.start = 0,
+	.end   = 0,
+	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
+	.desc  = IORES_DESC_CRASH_KERNEL
+};
+
 /*
  * parsing the "crashkernel" commandline
  *
diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index e2f2574d8b74..03ee65546df6 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -55,23 +55,6 @@ note_buf_t __percpu *crash_notes;
 /* Flag to indicate we are going to kexec a new kernel */
 bool kexec_in_progress = false;
 
-
-/* Location of the reserved area for the crash kernel */
-struct resource crashk_res = {
-	.name  = "Crash kernel",
-	.start = 0,
-	.end   = 0,
-	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
-	.desc  = IORES_DESC_CRASH_KERNEL
-};
-struct resource crashk_low_res = {
-	.name  = "Crash kernel",
-	.start = 0,
-	.end   = 0,
-	.flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM,
-	.desc  = IORES_DESC_CRASH_KERNEL
-};
-
 int kexec_should_crash(struct task_struct *p)
 {
 	/*
-- 
2.41.0

Re: [PATCH v2 1/8] crash_core.c: remove unnecessary parameter of function

[Leizhen (ThunderTown)]

On 2023/8/29 20:16, Baoquan He wrote:
> In all call sites of __parse_crashkernel(), the parameter 'name' is
> hardcoded as "crashkernel=". So remove the unnecessary parameter 'name',
> add local varibale 'name' inside __parse_crashkernel() instead.

Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com>

> 
> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
>  kernel/crash_core.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/kernel/crash_core.c b/kernel/crash_core.c
> index 90ce1dfd591c..f27b4e45d410 100644
> --- a/kernel/crash_core.c
> +++ b/kernel/crash_core.c
> @@ -241,11 +241,11 @@ static int __init __parse_crashkernel(char *cmdline,
>  			     unsigned long long system_ram,
>  			     unsigned long long *crash_size,
>  			     unsigned long long *crash_base,
> -			     const char *name,
>  			     const char *suffix)
>  {
>  	char	*first_colon, *first_space;
>  	char	*ck_cmdline;
> +	char	*name = "crashkernel=";
>  
>  	BUG_ON(!crash_size || !crash_base);
>  	*crash_size = 0;
> @@ -283,7 +283,7 @@ int __init parse_crashkernel(char *cmdline,
>  			     unsigned long long *crash_base)
>  {
>  	return __parse_crashkernel(cmdline, system_ram, crash_size, crash_base,
> -					"crashkernel=", NULL);
> +				NULL);
>  }
>  
>  int __init parse_crashkernel_high(char *cmdline,
> @@ -292,7 +292,7 @@ int __init parse_crashkernel_high(char *cmdline,
>  			     unsigned long long *crash_base)
>  {
>  	return __parse_crashkernel(cmdline, system_ram, crash_size, crash_base,
> -				"crashkernel=", suffix_tbl[SUFFIX_HIGH]);
> +				suffix_tbl[SUFFIX_HIGH]);
>  }
>  
>  int __init parse_crashkernel_low(char *cmdline,
> @@ -301,7 +301,7 @@ int __init parse_crashkernel_low(char *cmdline,
>  			     unsigned long long *crash_base)
>  {
>  	return __parse_crashkernel(cmdline, system_ram, crash_size, crash_base,
> -				"crashkernel=", suffix_tbl[SUFFIX_LOW]);
> +				suffix_tbl[SUFFIX_LOW]);
>  }
>  
>  /*
> 

-- 
Regards,
  Zhen Lei

Re: [PATCH v2 2/8] crash_core: change the prototype of function parse_crashkernel()

[Leizhen (ThunderTown)]

On 2023/8/29 20:16, Baoquan He wrote:
> Add two parameters 'low_size' and 'high' to function parse_crashkernel(),
> later crashkernel=,high|low parsing will be added. Make adjustments in all
> call sites of parse_crashkernel() in arch.

Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com>

> 
> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
>  arch/arm/kernel/setup.c              |  3 ++-
>  arch/arm64/mm/init.c                 |  2 +-
>  arch/ia64/kernel/setup.c             |  2 +-
>  arch/loongarch/kernel/setup.c        |  4 +++-
>  arch/mips/kernel/setup.c             |  3 ++-
>  arch/powerpc/kernel/fadump.c         |  2 +-
>  arch/powerpc/kexec/core.c            |  2 +-
>  arch/powerpc/mm/nohash/kaslr_booke.c |  2 +-
>  arch/riscv/mm/init.c                 |  2 +-
>  arch/s390/kernel/setup.c             |  4 ++--
>  arch/sh/kernel/machine_kexec.c       |  2 +-
>  arch/x86/kernel/setup.c              |  3 ++-
>  include/linux/crash_core.h           |  3 ++-
>  kernel/crash_core.c                  | 15 ++++++++++++---
>  14 files changed, 32 insertions(+), 17 deletions(-)
> 
> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
> index c66b560562b3..e2bb7afd0683 100644
> --- a/arch/arm/kernel/setup.c
> +++ b/arch/arm/kernel/setup.c
> @@ -1010,7 +1010,8 @@ static void __init reserve_crashkernel(void)
>  
>  	total_mem = get_total_mem();
>  	ret = parse_crashkernel(boot_command_line, total_mem,
> -				&crash_size, &crash_base);
> +				&crash_size, &crash_base,
> +				NULL, NULL);
>  	/* invalid value specified or crashkernel=0 */
>  	if (ret || !crash_size)
>  		return;
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 4fcb88a445ef..4ad637508b75 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -142,7 +142,7 @@ static void __init reserve_crashkernel(void)
>  
>  	/* crashkernel=X[@offset] */
>  	ret = parse_crashkernel(cmdline, memblock_phys_mem_size(),
> -				&crash_size, &crash_base);
> +				&crash_size, &crash_base, NULL, NULL);
>  	if (ret == -ENOENT) {
>  		ret = parse_crashkernel_high(cmdline, 0, &crash_size, &crash_base);
>  		if (ret || !crash_size)
> diff --git a/arch/ia64/kernel/setup.c b/arch/ia64/kernel/setup.c
> index 5a55ac82c13a..4faea2d2cf07 100644
> --- a/arch/ia64/kernel/setup.c
> +++ b/arch/ia64/kernel/setup.c
> @@ -277,7 +277,7 @@ static void __init setup_crashkernel(unsigned long total, int *n)
>  	int ret;
>  
>  	ret = parse_crashkernel(boot_command_line, total,
> -			&size, &base);
> +			&size, &base, NULL, NULL);
>  	if (ret == 0 && size > 0) {
>  		if (!base) {
>  			sort_regions(rsvd_region, *n);
> diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
> index 9d830ab4e302..776a068d8718 100644
> --- a/arch/loongarch/kernel/setup.c
> +++ b/arch/loongarch/kernel/setup.c
> @@ -267,7 +267,9 @@ static void __init arch_parse_crashkernel(void)
>  	unsigned long long crash_base, crash_size;
>  
>  	total_mem = memblock_phys_mem_size();
> -	ret = parse_crashkernel(boot_command_line, total_mem, &crash_size, &crash_base);
> +	ret = parse_crashkernel(boot_command_line, total_mem,
> +				&crash_size, &crash_base,
> +				NULL, NULL);
>  	if (ret < 0 || crash_size <= 0)
>  		return;
>  
> diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
> index cb871eb784a7..08321c945ac4 100644
> --- a/arch/mips/kernel/setup.c
> +++ b/arch/mips/kernel/setup.c
> @@ -460,7 +460,8 @@ static void __init mips_parse_crashkernel(void)
>  
>  	total_mem = memblock_phys_mem_size();
>  	ret = parse_crashkernel(boot_command_line, total_mem,
> -				&crash_size, &crash_base);
> +				&crash_size, &crash_base,
> +				NULL, NULL);
>  	if (ret != 0 || crash_size <= 0)
>  		return;
>  
> diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
> index ea0a073abd96..7dbdeba56e74 100644
> --- a/arch/powerpc/kernel/fadump.c
> +++ b/arch/powerpc/kernel/fadump.c
> @@ -313,7 +313,7 @@ static __init u64 fadump_calculate_reserve_size(void)
>  	 * memory at a predefined offset.
>  	 */
>  	ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
> -				&size, &base);
> +				&size, &base, NULL, NULL);
>  	if (ret == 0 && size > 0) {
>  		unsigned long max_size;
>  
> diff --git a/arch/powerpc/kexec/core.c b/arch/powerpc/kexec/core.c
> index de64c7962991..9346c960b296 100644
> --- a/arch/powerpc/kexec/core.c
> +++ b/arch/powerpc/kexec/core.c
> @@ -109,7 +109,7 @@ void __init reserve_crashkernel(void)
>  	total_mem_sz = memory_limit ? memory_limit : memblock_phys_mem_size();
>  	/* use common parsing */
>  	ret = parse_crashkernel(boot_command_line, total_mem_sz,
> -			&crash_size, &crash_base);
> +			&crash_size, &crash_base, NULL, NULL);
>  	if (ret == 0 && crash_size > 0) {
>  		crashk_res.start = crash_base;
>  		crashk_res.end = crash_base + crash_size - 1;
> diff --git a/arch/powerpc/mm/nohash/kaslr_booke.c b/arch/powerpc/mm/nohash/kaslr_booke.c
> index 2fb3edafe9ab..b4f2786a7d2b 100644
> --- a/arch/powerpc/mm/nohash/kaslr_booke.c
> +++ b/arch/powerpc/mm/nohash/kaslr_booke.c
> @@ -178,7 +178,7 @@ static void __init get_crash_kernel(void *fdt, unsigned long size)
>  	int ret;
>  
>  	ret = parse_crashkernel(boot_command_line, size, &crash_size,
> -				&crash_base);
> +				&crash_base, NULL, NULL);
>  	if (ret != 0 || crash_size == 0)
>  		return;
>  	if (crash_base == 0)
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index e4c35ac2357f..a9ef0824f905 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -1332,7 +1332,7 @@ static void __init reserve_crashkernel(void)
>  	}
>  
>  	ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
> -				&crash_size, &crash_base);
> +				&crash_size, &crash_base, NULL, NULL);
>  	if (ret || !crash_size)
>  		return;
>  
> diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
> index c744104e4a9c..98204a5f62b1 100644
> --- a/arch/s390/kernel/setup.c
> +++ b/arch/s390/kernel/setup.c
> @@ -626,8 +626,8 @@ static void __init reserve_crashkernel(void)
>  	phys_addr_t low, high;
>  	int rc;
>  
> -	rc = parse_crashkernel(boot_command_line, ident_map_size, &crash_size,
> -			       &crash_base);
> +	rc = parse_crashkernel(boot_command_line, ident_map_size,
> +			       &crash_size, &crash_base, NULL, NULL);
>  
>  	crash_base = ALIGN(crash_base, KEXEC_CRASH_MEM_ALIGN);
>  	crash_size = ALIGN(crash_size, KEXEC_CRASH_MEM_ALIGN);
> diff --git a/arch/sh/kernel/machine_kexec.c b/arch/sh/kernel/machine_kexec.c
> index 223c14f44af7..fa3a7b36190a 100644
> --- a/arch/sh/kernel/machine_kexec.c
> +++ b/arch/sh/kernel/machine_kexec.c
> @@ -154,7 +154,7 @@ void __init reserve_crashkernel(void)
>  	int ret;
>  
>  	ret = parse_crashkernel(boot_command_line, memblock_phys_mem_size(),
> -			&crash_size, &crash_base);
> +			&crash_size, &crash_base, NULL, NULL);
>  	if (ret == 0 && crash_size > 0) {
>  		crashk_res.start = crash_base;
>  		crashk_res.end = crash_base + crash_size - 1;
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index fd975a4a5200..382c66d2cf71 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -558,7 +558,8 @@ static void __init reserve_crashkernel(void)
>  	total_mem = memblock_phys_mem_size();
>  
>  	/* crashkernel=XM */
> -	ret = parse_crashkernel(boot_command_line, total_mem, &crash_size, &crash_base);
> +	ret = parse_crashkernel(boot_command_line, total_mem,
> +				&crash_size, &crash_base, NULL, NULL);
>  	if (ret != 0 || crash_size <= 0) {
>  		/* crashkernel=X,high */
>  		ret = parse_crashkernel_high(boot_command_line, total_mem,
> diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
> index de62a722431e..2e76289699ff 100644
> --- a/include/linux/crash_core.h
> +++ b/include/linux/crash_core.h
> @@ -78,7 +78,8 @@ Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
>  void final_note(Elf_Word *buf);
>  
>  int __init parse_crashkernel(char *cmdline, unsigned long long system_ram,
> -		unsigned long long *crash_size, unsigned long long *crash_base);
> +		unsigned long long *crash_size, unsigned long long *crash_base,
> +		unsigned long long *low_size, bool *high);
>  int parse_crashkernel_high(char *cmdline, unsigned long long system_ram,
>  		unsigned long long *crash_size, unsigned long long *crash_base);
>  int parse_crashkernel_low(char *cmdline, unsigned long long system_ram,
> diff --git a/kernel/crash_core.c b/kernel/crash_core.c
> index f27b4e45d410..f6a5c219e2e1 100644
> --- a/kernel/crash_core.c
> +++ b/kernel/crash_core.c
> @@ -280,10 +280,19 @@ static int __init __parse_crashkernel(char *cmdline,
>  int __init parse_crashkernel(char *cmdline,
>  			     unsigned long long system_ram,
>  			     unsigned long long *crash_size,
> -			     unsigned long long *crash_base)
> +			     unsigned long long *crash_base,
> +			     unsigned long long *low_size,
> +			     bool *high)
>  {
> -	return __parse_crashkernel(cmdline, system_ram, crash_size, crash_base,
> -				NULL);
> +	int ret;
> +
> +	/* crashkernel=X[@offset] */
> +	ret = __parse_crashkernel(cmdline, system_ram, crash_size,
> +				crash_base, NULL);
> +	if (!high)
> +		return ret;
> +
> +	return 0;
>  }
>  
>  int __init parse_crashkernel_high(char *cmdline,
> 

-- 
Regards,
  Zhen Lei

Re: [PATCH v2 3/8] crash_core: change parse_crashkernel() to support crashkernel=,high|low parsing

[Leizhen (ThunderTown)]

On 2023/8/29 20:16, Baoquan He wrote:
> Now parse_crashkernel() is a real entry point for all kinds of
> crahskernel parsing on any architecture.
> 
> And wrap the crahskernel=,high|low handling inside
> CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION ifdeffery scope.
> 
> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
>  include/linux/crash_core.h |  6 ++++++
>  kernel/crash_core.c        | 28 +++++++++++++++++++++++++++-
>  2 files changed, 33 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
> index 2e76289699ff..85260bf4a734 100644
> --- a/include/linux/crash_core.h
> +++ b/include/linux/crash_core.h
> @@ -77,6 +77,12 @@ Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
>  			  void *data, size_t data_len);
>  void final_note(Elf_Word *buf);
>  
> +#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
> +#ifndef DEFAULT_CRASH_KERNEL_LOW_SIZE
> +#define DEFAULT_CRASH_KERNEL_LOW_SIZE  (128UL << 20)
> +#endif
> +#endif
> +
>  int __init parse_crashkernel(char *cmdline, unsigned long long system_ram,
>  		unsigned long long *crash_size, unsigned long long *crash_base,
>  		unsigned long long *low_size, bool *high);
> diff --git a/kernel/crash_core.c b/kernel/crash_core.c
> index f6a5c219e2e1..355b0ab5189c 100644
> --- a/kernel/crash_core.c
> +++ b/kernel/crash_core.c
> @@ -276,6 +276,9 @@ static int __init __parse_crashkernel(char *cmdline,
>  /*
>   * That function is the entry point for command line parsing and should be
>   * called from the arch-specific code.
> + *
> + * If crashkernel=,high|low is supported on architecture, non-NULL values
> + * should be passed to parameters 'low_size' and 'high'.
>   */
>  int __init parse_crashkernel(char *cmdline,
>  			     unsigned long long system_ram,
> @@ -291,7 +294,30 @@ int __init parse_crashkernel(char *cmdline,
>  				crash_base, NULL);
>  	if (!high)
>  		return ret;
> -
> +#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
> +	else if (ret == -ENOENT) {
> +		ret = __parse_crashkernel(cmdline, 0, crash_size,
> +				crash_base, suffix_tbl[SUFFIX_HIGH]);
> +		if (ret || !*crash_size)
> +			return -1;

Change -1 to -EINVAL?

> +
> +		/*
> +		 * crashkernel=Y,low can be specified or not, but invalid value
> +		 * is not allowed.
> +		 */
> +		ret = __parse_crashkernel(cmdline, 0, low_size,
> +				crash_base, suffix_tbl[SUFFIX_LOW]);
> +		if (ret == -ENOENT)
> +			*low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
> +		else if (ret)
> +			return -1;

return ret;

> +
> +		*high = true;
> +	} else if (ret || !*crash_size) {

This check can be moved outside of #ifdef. Because even '!high', it's completely
applicable. The overall adjustment is as follows:

-  	if (!high)
-  		return ret;

#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
	if (high && ret == -ENOENT) {
		... ...
		if (ret || !*crash_size)	//parse HIGH
		... ...
	}

	//At this point, *crash_size is not 0 and ret is 0.
	//We can also delete if (!*crash_size) above because it will be checked later.
#endif

	if (!*crash_size)
		ret = -EINVAL;

	return ret;

-  	return 0;

> +		/* The specified value is invalid */
> +		return -1;
> +	}
> +#endif
>  	return 0;
>  }
>  
> 

-- 
Regards,
  Zhen Lei

Re: [PATCH v2 4/8] crash_core: add generic function to do reservation

[Leizhen (ThunderTown)]

On 2023/8/29 20:16, Baoquan He wrote:
> In architecture like x86_64, arm64 and riscv, they have vast virtual
> address space and usually have huge physical memory RAM. Their
> crashkernel reservation doesn't have to be limited under 4G RAM,
> but can be extended to the whole physical memory via crashkernel=,high
> support.
> 
> Now add function reserve_crashkernel_generic() to reserve crashkernel
> memory if users specify any case of kernel pamameters, like
> crashkernel=xM[@offset] or crashkernel=,high|low.
> 
> This is preparation to simplify code of crashkernel=,high support
> in architecutures.
> 
> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
>  include/linux/crash_core.h |  34 ++++++++++--
>  kernel/crash_core.c        | 109 ++++++++++++++++++++++++++++++++++++-
>  2 files changed, 136 insertions(+), 7 deletions(-)
> 
> diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
> index 85260bf4a734..2f732493e922 100644
> --- a/include/linux/crash_core.h
> +++ b/include/linux/crash_core.h
> @@ -77,12 +77,6 @@ Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
>  			  void *data, size_t data_len);
>  void final_note(Elf_Word *buf);
>  
> -#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
> -#ifndef DEFAULT_CRASH_KERNEL_LOW_SIZE
> -#define DEFAULT_CRASH_KERNEL_LOW_SIZE  (128UL << 20)
> -#endif
> -#endif
> -
>  int __init parse_crashkernel(char *cmdline, unsigned long long system_ram,
>  		unsigned long long *crash_size, unsigned long long *crash_base,
>  		unsigned long long *low_size, bool *high);
> @@ -91,4 +85,32 @@ int parse_crashkernel_high(char *cmdline, unsigned long long system_ram,
>  int parse_crashkernel_low(char *cmdline, unsigned long long system_ram,
>  		unsigned long long *crash_size, unsigned long long *crash_base);
>  
> +#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
> +#ifndef DEFAULT_CRASH_KERNEL_LOW_SIZE
> +#define DEFAULT_CRASH_KERNEL_LOW_SIZE	(128UL << 20)
> +#endif
> +#ifndef CRASH_ALIGN
> +#define CRASH_ALIGN			SZ_2M
> +#endif
> +#ifndef CRASH_ADDR_LOW_MAX
> +#define CRASH_ADDR_LOW_MAX		SZ_4G
> +#endif
> +#ifndef CRASH_ADDR_HIGH_MAX
> +#define CRASH_ADDR_HIGH_MAX		memblock_end_of_DRAM()
> +#endif
> +
> +void __init reserve_crashkernel_generic(char *cmdline,
> +		unsigned long long crash_size,
> +		unsigned long long crash_base,
> +		unsigned long long crash_low_size,
> +		bool high);
> +#else
> +static inline void __init reserve_crashkernel_generic(char *cmdline,
> +		unsigned long long crash_size,
> +		unsigned long long crash_base,
> +		unsigned long long crash_low_size,
> +		bool high)
> +{}
> +#endif
> +
>  #endif /* LINUX_CRASH_CORE_H */
> diff --git a/kernel/crash_core.c b/kernel/crash_core.c
> index 355b0ab5189c..6bc00cc390b5 100644
> --- a/kernel/crash_core.c
> +++ b/kernel/crash_core.c
> @@ -5,11 +5,13 @@
>   */
>  
>  #include <linux/buildid.h>
> -#include <linux/crash_core.h>
>  #include <linux/init.h>
>  #include <linux/utsname.h>
>  #include <linux/vmalloc.h>
>  #include <linux/sizes.h>
> +#include <linux/memblock.h>
> +#include <linux/kexec.h>
> +#include <linux/kmemleak.h>
>  
>  #include <asm/page.h>
>  #include <asm/sections.h>
> @@ -349,6 +351,111 @@ static int __init parse_crashkernel_dummy(char *arg)
>  }
>  early_param("crashkernel", parse_crashkernel_dummy);
>  
> +#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
> +static int __init reserve_crashkernel_low(unsigned long long low_size)
> +{
> +#ifdef CONFIG_64BIT
> +	unsigned long long low_base;
> +
> +	low_base = memblock_phys_alloc_range(low_size, CRASH_ALIGN, 0, CRASH_ADDR_LOW_MAX);
> +	if (!low_base) {
> +		pr_err("cannot allocate crashkernel low memory (size:0x%llx).\n", low_size);
> +		return -ENOMEM;
> +	}
> +
> +	pr_info("crashkernel low memory reserved: 0x%08llx - 0x%08llx (%lld MB)\n",
> +		low_base, low_base + low_size, low_size >> 20);
> +
> +	crashk_low_res.start = low_base;
> +	crashk_low_res.end   = low_base + low_size - 1;
> +	insert_resource(&iomem_resource, &crashk_low_res);
> +#endif
> +	return 0;
> +}
> +
> +void __init reserve_crashkernel_generic(char *cmdline,
> +			     unsigned long long crash_size,
> +			     unsigned long long crash_base,
> +			     unsigned long long crash_low_size,
> +			     bool high)
> +{
> +	unsigned long long search_end = CRASH_ADDR_LOW_MAX, search_base = 0;
> +	bool fixed_base = false;
> +
> +	/* User specifies base address explicitly. */
> +	if (crash_base) {
> +		fixed_base = true;
> +		search_base = crash_base;
> +		search_end = crash_base + crash_size;
> +	}
> +
> +	if (high) {

It might be a little clearer to use "else if (high) {"

> +		search_base = CRASH_ADDR_LOW_MAX;
> +		search_end = CRASH_ADDR_HIGH_MAX;
> +	}
> +
> +retry:
> +	crash_base = memblock_phys_alloc_range(crash_size, CRASH_ALIGN,
> +					       search_base, search_end);
> +	if (!crash_base) {
> +		/*
> +		 * For crashkernel=size[KMG]@offset[KMG], print out failure
> +		 * message if can't reserve the specified region.
> +		 */
> +		if (fixed_base) {
> +			pr_warn("crashkernel reservation failed - memory is in use.\n");
> +			return;
> +		}
> +
> +		/*
> +		 * For crashkernel=size[KMG], if the first attempt was for
> +		 * low memory, fall back to high memory, the minimum required
> +		 * low memory will be reserved later.
> +		 */
> +		if (!high && search_end == CRASH_ADDR_LOW_MAX) {
> +			search_end = CRASH_ADDR_HIGH_MAX;
> +			search_base = CRASH_ADDR_LOW_MAX;
> +			crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
> +			goto retry;
> +		}
> +
> +		/*
> +		 * For crashkernel=size[KMG],high, if the first attempt was
> +		 * for high memory, fall back to low memory.
> +		 */
> +		if (high && search_end == CRASH_ADDR_HIGH_MAX) {
> +			search_end = CRASH_ADDR_LOW_MAX;
> +			search_base = 0;
> +			goto retry;
> +		}
> +		pr_warn("cannot allocate crashkernel (size:0x%llx)\n",
> +			crash_size);
> +		return;
> +	}
> +
> +	if ((crash_base > CRASH_ADDR_LOW_MAX) &&
> +	     crash_low_size && reserve_crashkernel_low(crash_low_size)) {
> +		memblock_phys_free(crash_base, crash_size);
> +		return;
> +	}
> +
> +	pr_info("crashkernel reserved: 0x%016llx - 0x%016llx (%lld MB)\n",
> +		crash_base, crash_base + crash_size, crash_size >> 20);
> +
> +	/*
> +	 * The crashkernel memory will be removed from the kernel linear
> +	 * map. Inform kmemleak so that it won't try to access it.
> +	 */
> +	kmemleak_ignore_phys(crash_base);
> +	if (crashk_low_res.end)
> +		kmemleak_ignore_phys(crashk_low_res.start);
> +
> +	crashk_res.start = crash_base;
> +	crashk_res.end = crash_base + crash_size - 1;
> +	insert_resource(&iomem_resource, &crashk_res);
> +}
> +#endif
> +
>  Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
>  			  void *data, size_t data_len)
>  {
> 

-- 
Regards,
  Zhen Lei

Re: [PATCH v2 6/8] x86: kdump: use generic interface to simplify crashkernel reservation code

[Leizhen (ThunderTown)]

On 2023/8/29 20:16, Baoquan He wrote:
> With the help of newly changed function parse_crashkernel() and
> generic reserve_crashkernel_generic(), crashkernel reservation can be
> simplified by steps:
> 
> 1) Add a new header file <asm/crash_core.h>, and define CRASH_ALIGN,
>    CRASH_ADDR_LOW_MAX, CRASH_ADDR_HIGH_MAX and
>    DEFAULT_CRASH_KERNEL_LOW_SIZE in <asm/crash_core.h>;
> 
> 2) Add arch_reserve_crashkernel() to call parse_crashkernel() and
>    reserve_crashkernel_generic(), and do the ARCH specific work if
>    needed.
> 
> 3) Add ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION Kconfig in
>    arch/x86/Kconfig.
> 
> When adding DEFAULT_CRASH_KERNEL_LOW_SIZE, add crash_low_size_default()
> to calculate crashkernel low memory because x86_64 has special
> requirement.
> 
> The old reserve_crashkernel_low() and reserve_crashkernel() can be
> removed.
> 
> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
>  arch/x86/Kconfig                  |   3 +
>  arch/x86/include/asm/crash_core.h |  34 +++++++
>  arch/x86/kernel/setup.c           | 144 ++++--------------------------
>  3 files changed, 53 insertions(+), 128 deletions(-)
>  create mode 100644 arch/x86/include/asm/crash_core.h
> 
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 8d9e4b362572..c4539dc35985 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -2037,6 +2037,9 @@ config KEXEC_FILE
>  config ARCH_HAS_KEXEC_PURGATORY
>  	def_bool KEXEC_FILE
>  
> +config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
> +	def_bool CRASH_CORE
> +
>  config KEXEC_SIG
>  	bool "Verify kernel signature during kexec_file_load() syscall"
>  	depends on KEXEC_FILE
> diff --git a/arch/x86/include/asm/crash_core.h b/arch/x86/include/asm/crash_core.h
> new file mode 100644
> index 000000000000..5fc5e4f94521
> --- /dev/null
> +++ b/arch/x86/include/asm/crash_core.h
> @@ -0,0 +1,34 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _X86_CRASH_CORE_H
> +#define _X86_CRASH_CORE_H
> +
> +/* 16M alignment for crash kernel regions */
> +#define CRASH_ALIGN             SZ_16M
> +
> +/*
> + * Keep the crash kernel below this limit.
> + *
> + * Earlier 32-bits kernels would limit the kernel to the low 512 MB range
> + * due to mapping restrictions.
> + *
> + * 64-bit kdump kernels need to be restricted to be under 64 TB, which is
> + * the upper limit of system RAM in 4-level paging mode. Since the kdump
> + * jump could be from 5-level paging to 4-level paging, the jump will fail if
> + * the kernel is put above 64 TB, and during the 1st kernel bootup there's
> + * no good way to detect the paging mode of the target kernel which will be
> + * loaded for dumping.
> + */
> +
> +#ifdef CONFIG_X86_32
> +# define CRASH_ADDR_LOW_MAX     SZ_512M
> +# define CRASH_ADDR_HIGH_MAX    SZ_512M
> +#else
> +# define CRASH_ADDR_LOW_MAX     SZ_4G
> +# define CRASH_ADDR_HIGH_MAX    SZ_64T
> +#endif
> +
> +# define DEFAULT_CRASH_KERNEL_LOW_SIZE crash_low_size_default()
> +
> +extern unsigned long crash_low_size_default(void);
> +
> +#endif /* _X86_CRASH_CORE_H */
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index 382c66d2cf71..559a5c4141db 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -474,152 +474,40 @@ static void __init memblock_x86_reserve_range_setup_data(void)
>  /*
>   * --------- Crashkernel reservation ------------------------------
>   */
> -
> -/* 16M alignment for crash kernel regions */
> -#define CRASH_ALIGN		SZ_16M
> -
> -/*
> - * Keep the crash kernel below this limit.
> - *
> - * Earlier 32-bits kernels would limit the kernel to the low 512 MB range
> - * due to mapping restrictions.
> - *
> - * 64-bit kdump kernels need to be restricted to be under 64 TB, which is
> - * the upper limit of system RAM in 4-level paging mode. Since the kdump
> - * jump could be from 5-level paging to 4-level paging, the jump will fail if
> - * the kernel is put above 64 TB, and during the 1st kernel bootup there's
> - * no good way to detect the paging mode of the target kernel which will be
> - * loaded for dumping.
> - */
> -#ifdef CONFIG_X86_32
> -# define CRASH_ADDR_LOW_MAX	SZ_512M
> -# define CRASH_ADDR_HIGH_MAX	SZ_512M
> -#else
> -# define CRASH_ADDR_LOW_MAX	SZ_4G
> -# define CRASH_ADDR_HIGH_MAX	SZ_64T
> -#endif
> -
> -static int __init reserve_crashkernel_low(void)
> +unsigned long crash_low_size_default(void)
>  {
>  #ifdef CONFIG_X86_64
> -	unsigned long long base, low_base = 0, low_size = 0;
> -	unsigned long low_mem_limit;
> -	int ret;
> -
> -	low_mem_limit = min(memblock_phys_mem_size(), CRASH_ADDR_LOW_MAX);
> -
> -	/* crashkernel=Y,low */
> -	ret = parse_crashkernel_low(boot_command_line, low_mem_limit, &low_size, &base);
> -	if (ret) {
> -		/*
> -		 * two parts from kernel/dma/swiotlb.c:
> -		 * -swiotlb size: user-specified with swiotlb= or default.
> -		 *
> -		 * -swiotlb overflow buffer: now hardcoded to 32k. We round it
> -		 * to 8M for other buffers that may need to stay low too. Also
> -		 * make sure we allocate enough extra low memory so that we
> -		 * don't run out of DMA buffers for 32-bit devices.
> -		 */
> -		low_size = max(swiotlb_size_or_default() + (8UL << 20), 256UL << 20);
> -	} else {
> -		/* passed with crashkernel=0,low ? */
> -		if (!low_size)
> -			return 0;
> -	}
> -
> -	low_base = memblock_phys_alloc_range(low_size, CRASH_ALIGN, 0, CRASH_ADDR_LOW_MAX);
> -	if (!low_base) {
> -		pr_err("Cannot reserve %ldMB crashkernel low memory, please try smaller size.\n",
> -		       (unsigned long)(low_size >> 20));
> -		return -ENOMEM;
> -	}
> -
> -	pr_info("Reserving %ldMB of low memory at %ldMB for crashkernel (low RAM limit: %ldMB)\n",
> -		(unsigned long)(low_size >> 20),
> -		(unsigned long)(low_base >> 20),
> -		(unsigned long)(low_mem_limit >> 20));
> -
> -	crashk_low_res.start = low_base;
> -	crashk_low_res.end   = low_base + low_size - 1;
> -	insert_resource(&iomem_resource, &crashk_low_res);
> -#endif
> +	return max(swiotlb_size_or_default() + (8UL << 20), 256UL << 20);
> +#else
>  	return 0;
> +#endif
>  }
>  
> -static void __init reserve_crashkernel(void)
> +static void __init arch_reserve_crashkernel(void)
>  {
> -	unsigned long long crash_size, crash_base, total_mem;
> +	unsigned long long crash_base, crash_size, low_size = 0;
> +	char *cmdline = boot_command_line;
>  	bool high = false;
>  	int ret;
>  
>  	if (!IS_ENABLED(CONFIG_KEXEC_CORE))
>  		return;
>  
> -	total_mem = memblock_phys_mem_size();
> -
> -	/* crashkernel=XM */
> -	ret = parse_crashkernel(boot_command_line, total_mem,
> -				&crash_size, &crash_base, NULL, NULL);
> -	if (ret != 0 || crash_size <= 0) {
> -		/* crashkernel=X,high */
> -		ret = parse_crashkernel_high(boot_command_line, total_mem,
> -					     &crash_size, &crash_base);
> -		if (ret != 0 || crash_size <= 0)
> -			return;
> -		high = true;
> -	}
> +	ret = parse_crashkernel(cmdline, memblock_phys_mem_size(),
> +				&crash_size, &crash_base,
> +				&low_size, &high);
> +	if (ret)
> +		return;
>  
>  	if (xen_pv_domain()) {
>  		pr_info("Ignoring crashkernel for a Xen PV domain\n");
>  		return;
>  	}
>  
> -	/* 0 means: find the address automatically */
> -	if (!crash_base) {
> -		/*
> -		 * Set CRASH_ADDR_LOW_MAX upper bound for crash memory,
> -		 * crashkernel=x,high reserves memory over 4G, also allocates
> -		 * 256M extra low memory for DMA buffers and swiotlb.
> -		 * But the extra memory is not required for all machines.
> -		 * So try low memory first and fall back to high memory
> -		 * unless "crashkernel=size[KMG],high" is specified.
> -		 */
> -		if (!high)
> -			crash_base = memblock_phys_alloc_range(crash_size,
> -						CRASH_ALIGN, CRASH_ALIGN,
> -						CRASH_ADDR_LOW_MAX);
> -		if (!crash_base)
> -			crash_base = memblock_phys_alloc_range(crash_size,
> -						CRASH_ALIGN, CRASH_ALIGN,
> -						CRASH_ADDR_HIGH_MAX);
> -		if (!crash_base) {
> -			pr_info("crashkernel reservation failed - No suitable area found.\n");
> -			return;
> -		}
> -	} else {
> -		unsigned long long start;
> -
> -		start = memblock_phys_alloc_range(crash_size, SZ_1M, crash_base,
> -						  crash_base + crash_size);
> -		if (start != crash_base) {
> -			pr_info("crashkernel reservation failed - memory is in use.\n");
> -			return;
> -		}
> -	}
> -
> -	if (crash_base >= (1ULL << 32) && reserve_crashkernel_low()) {
> -		memblock_phys_free(crash_base, crash_size);
> -		return;
> -	}
> -
> -	pr_info("Reserving %ldMB of memory at %ldMB for crashkernel (System RAM: %ldMB)\n",
> -		(unsigned long)(crash_size >> 20),
> -		(unsigned long)(crash_base >> 20),
> -		(unsigned long)(total_mem >> 20));
> +	reserve_crashkernel_generic(cmdline, crash_size, crash_base,
> +				    low_size, high);
>  
> -	crashk_res.start = crash_base;
> -	crashk_res.end   = crash_base + crash_size - 1;
> -	insert_resource(&iomem_resource, &crashk_res);
> +	return;

This can be omitted.

>  }
>  
>  static struct resource standard_io_resources[] = {
> @@ -1231,7 +1119,7 @@ void __init setup_arch(char **cmdline_p)
>  	 * Reserve memory for crash kernel after SRAT is parsed so that it
>  	 * won't consume hotpluggable memory.
>  	 */
> -	reserve_crashkernel();
> +	arch_reserve_crashkernel();
>  
>  	memblock_find_dma_reserve();
>  
> 

-- 
Regards,
  Zhen Lei

Re: [PATCH v2 7/8] arm64: kdump: use generic interface to simplify crashkernel reservation

[Leizhen (ThunderTown)]

On 2023/8/29 20:16, Baoquan He wrote:
> With the help of newly changed function parse_crashkernel() and
> generic reserve_crashkernel_generic(), crashkernel reservation can be
> simplified by steps:
> 
> 1) Add a new header file <asm/crash_core.h>, and define CRASH_ALIGN,
>    CRASH_ADDR_LOW_MAX, CRASH_ADDR_HIGH_MAX and
>    DEFAULT_CRASH_KERNEL_LOW_SIZE in <asm/crash_core.h>;
> 
> 2) Add arch_reserve_crashkernel() to call parse_crashkernel() and
>    reserve_crashkernel_generic();
> 
> 3) Add ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION Kconfig in
>    arch/arm64/Kconfig.
> 
> The old reserve_crashkernel_low() and reserve_crashkernel() can be
> removed.

Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com>

> 
> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
>  arch/arm64/Kconfig                  |   3 +
>  arch/arm64/include/asm/crash_core.h |  10 ++
>  arch/arm64/mm/init.c                | 140 ++--------------------------
>  3 files changed, 21 insertions(+), 132 deletions(-)
>  create mode 100644 arch/arm64/include/asm/crash_core.h
> 
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 29db061db9bb..07fb8c71339d 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -1481,6 +1481,9 @@ config KEXEC_FILE
>  	  for kernel and initramfs as opposed to list of segments as
>  	  accepted by previous system call.
>  
> +config ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
> +	def_bool CRASH_CORE
> +
>  config KEXEC_SIG
>  	bool "Verify kernel signature during kexec_file_load() syscall"
>  	depends on KEXEC_FILE
> diff --git a/arch/arm64/include/asm/crash_core.h b/arch/arm64/include/asm/crash_core.h
> new file mode 100644
> index 000000000000..9f5c8d339f44
> --- /dev/null
> +++ b/arch/arm64/include/asm/crash_core.h
> @@ -0,0 +1,10 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +#ifndef _ARM64_CRASH_CORE_H
> +#define _ARM64_CRASH_CORE_H
> +
> +/* Current arm64 boot protocol requires 2MB alignment */
> +#define CRASH_ALIGN                     SZ_2M
> +
> +#define CRASH_ADDR_LOW_MAX              arm64_dma_phys_limit
> +#define CRASH_ADDR_HIGH_MAX             (PHYS_MASK + 1)
> +#endif
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 4ad637508b75..48ab23531bb6 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -64,15 +64,6 @@ EXPORT_SYMBOL(memstart_addr);
>   */
>  phys_addr_t __ro_after_init arm64_dma_phys_limit;
>  
> -/* Current arm64 boot protocol requires 2MB alignment */
> -#define CRASH_ALIGN			SZ_2M
> -
> -#define CRASH_ADDR_LOW_MAX		arm64_dma_phys_limit
> -#define CRASH_ADDR_HIGH_MAX		(PHYS_MASK + 1)
> -#define CRASH_HIGH_SEARCH_BASE		SZ_4G
> -
> -#define DEFAULT_CRASH_KERNEL_LOW_SIZE	(128UL << 20)
> -
>  /*
>   * To make optimal use of block mappings when laying out the linear
>   * mapping, round down the base of physical memory to a size that can
> @@ -100,140 +91,25 @@ phys_addr_t __ro_after_init arm64_dma_phys_limit;
>  #define ARM64_MEMSTART_ALIGN	(1UL << ARM64_MEMSTART_SHIFT)
>  #endif
>  
> -static int __init reserve_crashkernel_low(unsigned long long low_size)
> -{
> -	unsigned long long low_base;
> -
> -	low_base = memblock_phys_alloc_range(low_size, CRASH_ALIGN, 0, CRASH_ADDR_LOW_MAX);
> -	if (!low_base) {
> -		pr_err("cannot allocate crashkernel low memory (size:0x%llx).\n", low_size);
> -		return -ENOMEM;
> -	}
> -
> -	pr_info("crashkernel low memory reserved: 0x%08llx - 0x%08llx (%lld MB)\n",
> -		low_base, low_base + low_size, low_size >> 20);
> -
> -	crashk_low_res.start = low_base;
> -	crashk_low_res.end   = low_base + low_size - 1;
> -	insert_resource(&iomem_resource, &crashk_low_res);
> -
> -	return 0;
> -}
> -
> -/*
> - * reserve_crashkernel() - reserves memory for crash kernel
> - *
> - * This function reserves memory area given in "crashkernel=" kernel command
> - * line parameter. The memory reserved is used by dump capture kernel when
> - * primary kernel is crashing.
> - */
> -static void __init reserve_crashkernel(void)
> +static void __init arch_reserve_crashkernel(void)
>  {
> -	unsigned long long crash_low_size = 0, search_base = 0;
> -	unsigned long long crash_max = CRASH_ADDR_LOW_MAX;
> +	unsigned long long low_size = 0;
>  	unsigned long long crash_base, crash_size;
>  	char *cmdline = boot_command_line;
> -	bool fixed_base = false;
>  	bool high = false;
>  	int ret;
>  
>  	if (!IS_ENABLED(CONFIG_KEXEC_CORE))
>  		return;
>  
> -	/* crashkernel=X[@offset] */
>  	ret = parse_crashkernel(cmdline, memblock_phys_mem_size(),
> -				&crash_size, &crash_base, NULL, NULL);
> -	if (ret == -ENOENT) {
> -		ret = parse_crashkernel_high(cmdline, 0, &crash_size, &crash_base);
> -		if (ret || !crash_size)
> -			return;
> -
> -		/*
> -		 * crashkernel=Y,low can be specified or not, but invalid value
> -		 * is not allowed.
> -		 */
> -		ret = parse_crashkernel_low(cmdline, 0, &crash_low_size, &crash_base);
> -		if (ret == -ENOENT)
> -			crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
> -		else if (ret)
> -			return;
> -
> -		search_base = CRASH_HIGH_SEARCH_BASE;
> -		crash_max = CRASH_ADDR_HIGH_MAX;
> -		high = true;
> -	} else if (ret || !crash_size) {
> -		/* The specified value is invalid */
> +				&crash_size, &crash_base,
> +				&low_size, &high);
> +	if (ret)
>  		return;
> -	}
> -
> -	crash_size = PAGE_ALIGN(crash_size);
> -
> -	/* User specifies base address explicitly. */
> -	if (crash_base) {
> -		fixed_base = true;
> -		search_base = crash_base;
> -		crash_max = crash_base + crash_size;
> -	}
> -
> -retry:
> -	crash_base = memblock_phys_alloc_range(crash_size, CRASH_ALIGN,
> -					       search_base, crash_max);
> -	if (!crash_base) {
> -		/*
> -		 * For crashkernel=size[KMG]@offset[KMG], print out failure
> -		 * message if can't reserve the specified region.
> -		 */
> -		if (fixed_base) {
> -			pr_warn("crashkernel reservation failed - memory is in use.\n");
> -			return;
> -		}
> -
> -		/*
> -		 * For crashkernel=size[KMG], if the first attempt was for
> -		 * low memory, fall back to high memory, the minimum required
> -		 * low memory will be reserved later.
> -		 */
> -		if (!high && crash_max == CRASH_ADDR_LOW_MAX) {
> -			crash_max = CRASH_ADDR_HIGH_MAX;
> -			search_base = CRASH_ADDR_LOW_MAX;
> -			crash_low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
> -			goto retry;
> -		}
> -
> -		/*
> -		 * For crashkernel=size[KMG],high, if the first attempt was
> -		 * for high memory, fall back to low memory.
> -		 */
> -		if (high && crash_max == CRASH_ADDR_HIGH_MAX) {
> -			crash_max = CRASH_ADDR_LOW_MAX;
> -			search_base = 0;
> -			goto retry;
> -		}
> -		pr_warn("cannot allocate crashkernel (size:0x%llx)\n",
> -			crash_size);
> -		return;
> -	}
> -
> -	if ((crash_base >= CRASH_ADDR_LOW_MAX) && crash_low_size &&
> -	     reserve_crashkernel_low(crash_low_size)) {
> -		memblock_phys_free(crash_base, crash_size);
> -		return;
> -	}
> -
> -	pr_info("crashkernel reserved: 0x%016llx - 0x%016llx (%lld MB)\n",
> -		crash_base, crash_base + crash_size, crash_size >> 20);
> -
> -	/*
> -	 * The crashkernel memory will be removed from the kernel linear
> -	 * map. Inform kmemleak so that it won't try to access it.
> -	 */
> -	kmemleak_ignore_phys(crash_base);
> -	if (crashk_low_res.end)
> -		kmemleak_ignore_phys(crashk_low_res.start);
>  
> -	crashk_res.start = crash_base;
> -	crashk_res.end = crash_base + crash_size - 1;
> -	insert_resource(&iomem_resource, &crashk_res);
> +	reserve_crashkernel_generic(cmdline, crash_size, crash_base,
> +				    low_size, high);
>  }
>  
>  /*
> @@ -481,7 +357,7 @@ void __init bootmem_init(void)
>  	 * request_standard_resources() depends on crashkernel's memory being
>  	 * reserved, so do it here.
>  	 */
> -	reserve_crashkernel();
> +	arch_reserve_crashkernel();
>  
>  	memblock_dump_all();
>  }
> 

-- 
Regards,
  Zhen Lei

Re: [PATCH v2 8/8] crash_core.c: remove unneeded functions

[Leizhen (ThunderTown)]

On 2023/8/29 20:16, Baoquan He wrote:
> So far, nobody calls functions parse_crashkernel_high() and
> parse_crashkernel_low(), remove both of them.

Reviewed-by: Zhen Lei <thunder.leizhen@huawei.com>

> 
> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
>  include/linux/crash_core.h |  4 ----
>  kernel/crash_core.c        | 18 ------------------
>  2 files changed, 22 deletions(-)
> 
> diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
> index 86e22e6a039f..d64006c4bd43 100644
> --- a/include/linux/crash_core.h
> +++ b/include/linux/crash_core.h
> @@ -83,10 +83,6 @@ void final_note(Elf_Word *buf);
>  int __init parse_crashkernel(char *cmdline, unsigned long long system_ram,
>  		unsigned long long *crash_size, unsigned long long *crash_base,
>  		unsigned long long *low_size, bool *high);
> -int parse_crashkernel_high(char *cmdline, unsigned long long system_ram,
> -		unsigned long long *crash_size, unsigned long long *crash_base);
> -int parse_crashkernel_low(char *cmdline, unsigned long long system_ram,
> -		unsigned long long *crash_size, unsigned long long *crash_base);
>  
>  #ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
>  #ifndef DEFAULT_CRASH_KERNEL_LOW_SIZE
> diff --git a/kernel/crash_core.c b/kernel/crash_core.c
> index 6bc00cc390b5..61a8ea3b23a2 100644
> --- a/kernel/crash_core.c
> +++ b/kernel/crash_core.c
> @@ -323,24 +323,6 @@ int __init parse_crashkernel(char *cmdline,
>  	return 0;
>  }
>  
> -int __init parse_crashkernel_high(char *cmdline,
> -			     unsigned long long system_ram,
> -			     unsigned long long *crash_size,
> -			     unsigned long long *crash_base)
> -{
> -	return __parse_crashkernel(cmdline, system_ram, crash_size, crash_base,
> -				suffix_tbl[SUFFIX_HIGH]);
> -}
> -
> -int __init parse_crashkernel_low(char *cmdline,
> -			     unsigned long long system_ram,
> -			     unsigned long long *crash_size,
> -			     unsigned long long *crash_base)
> -{
> -	return __parse_crashkernel(cmdline, system_ram, crash_size, crash_base,
> -				suffix_tbl[SUFFIX_LOW]);
> -}
> -
>  /*
>   * Add a dummy early_param handler to mark crashkernel= as a known command line
>   * parameter and suppress incorrect warnings in init/main.c.
> 

-- 
Regards,
  Zhen Lei

Re: [PATCH v2 3/8] crash_core: change parse_crashkernel() to support crashkernel=,high|low parsing

[Baoquan He]

On 08/31/23 at 10:56am, Leizhen (ThunderTown) wrote:
> 
> 
> On 2023/8/29 20:16, Baoquan He wrote:
> > Now parse_crashkernel() is a real entry point for all kinds of
> > crahskernel parsing on any architecture.
> > 
> > And wrap the crahskernel=,high|low handling inside
> > CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION ifdeffery scope.
> > 
> > Signed-off-by: Baoquan He <bhe@redhat.com>
> > ---
> >  include/linux/crash_core.h |  6 ++++++
> >  kernel/crash_core.c        | 28 +++++++++++++++++++++++++++-
> >  2 files changed, 33 insertions(+), 1 deletion(-)
> > 
> > diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
> > index 2e76289699ff..85260bf4a734 100644
> > --- a/include/linux/crash_core.h
> > +++ b/include/linux/crash_core.h
> > @@ -77,6 +77,12 @@ Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
> >  			  void *data, size_t data_len);
> >  void final_note(Elf_Word *buf);
> >  
> > +#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
> > +#ifndef DEFAULT_CRASH_KERNEL_LOW_SIZE
> > +#define DEFAULT_CRASH_KERNEL_LOW_SIZE  (128UL << 20)
> > +#endif
> > +#endif
> > +
> >  int __init parse_crashkernel(char *cmdline, unsigned long long system_ram,
> >  		unsigned long long *crash_size, unsigned long long *crash_base,
> >  		unsigned long long *low_size, bool *high);
> > diff --git a/kernel/crash_core.c b/kernel/crash_core.c
> > index f6a5c219e2e1..355b0ab5189c 100644
> > --- a/kernel/crash_core.c
> > +++ b/kernel/crash_core.c
> > @@ -276,6 +276,9 @@ static int __init __parse_crashkernel(char *cmdline,
> >  /*
> >   * That function is the entry point for command line parsing and should be
> >   * called from the arch-specific code.
> > + *
> > + * If crashkernel=,high|low is supported on architecture, non-NULL values
> > + * should be passed to parameters 'low_size' and 'high'.
> >   */
> >  int __init parse_crashkernel(char *cmdline,
> >  			     unsigned long long system_ram,
> > @@ -291,7 +294,30 @@ int __init parse_crashkernel(char *cmdline,
> >  				crash_base, NULL);
> >  	if (!high)
> >  		return ret;
> > -
> > +#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
> > +	else if (ret == -ENOENT) {
> > +		ret = __parse_crashkernel(cmdline, 0, crash_size,
> > +				crash_base, suffix_tbl[SUFFIX_HIGH]);
> > +		if (ret || !*crash_size)
> > +			return -1;
> 
> Change -1 to -EINVAL?

Thanks a lot for careful reviewing, Zhen Lei.

Here, it's fine to me, parse_crashkernel() returns 0 on success, other value
on failure. '-1' or '-EINVAL' is not different to me in this case. I can
update if you think '-EINVAL' is better.

> 
> > +
> > +		/*
> > +		 * crashkernel=Y,low can be specified or not, but invalid value
> > +		 * is not allowed.
> > +		 */
> > +		ret = __parse_crashkernel(cmdline, 0, low_size,
> > +				crash_base, suffix_tbl[SUFFIX_LOW]);
> > +		if (ret == -ENOENT)
> > +			*low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
> > +		else if (ret)
> > +			return -1;
> 
> return ret;

Ditto.

> 
> > +
> > +		*high = true;
> > +	} else if (ret || !*crash_size) {
> 
> This check can be moved outside of #ifdef. Because even '!high', it's completely
> applicable. The overall adjustment is as follows:

Hmm, the current logic is much easier to understand. However, I may not
100% get your suggestion. Can you paste the complete code in your
suggested way? Do not need 100% correct code, just the skeleton of code logic
so that I can better understand it and add inline comment.

> 
> -  	if (!high)
> -  		return ret;
> 
> #ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
> 	if (high && ret == -ENOENT) {
> 		... ...
> 		if (ret || !*crash_size)	//parse HIGH
> 		... ...
> 	}
> 
> 	//At this point, *crash_size is not 0 and ret is 0.
> 	//We can also delete if (!*crash_size) above because it will be checked later.
> #endif
> 
> 	if (!*crash_size)
> 		ret = -EINVAL;
> 
> 	return ret;

When crashkernel=,high is specified while crashkernel=,low is omitted,
the ret==-ENOENT, but we can't return ret directly. That is still an
acceptable way.

> 
> -  	return 0;
> 
> > +		/* The specified value is invalid */
> > +		return -1;
> > +	}
> > +#endif
> >  	return 0;
> >  }
> >  
> > 
> 
> -- 
> Regards,
>   Zhen Lei
> 

Re: [PATCH v2 4/8] crash_core: add generic function to do reservation

[Baoquan He]

On 08/31/23 at 11:23am, Leizhen (ThunderTown) wrote:
......
> > +void __init reserve_crashkernel_generic(char *cmdline,
> > +			     unsigned long long crash_size,
> > +			     unsigned long long crash_base,
> > +			     unsigned long long crash_low_size,
> > +			     bool high)
> > +{
> > +	unsigned long long search_end = CRASH_ADDR_LOW_MAX, search_base = 0;
> > +	bool fixed_base = false;
> > +
> > +	/* User specifies base address explicitly. */
> > +	if (crash_base) {
> > +		fixed_base = true;
> > +		search_base = crash_base;
> > +		search_end = crash_base + crash_size;
> > +	}
> > +
> > +	if (high) {
> 
> It might be a little clearer to use "else if (high) {"

Makes sense, will update.

> 
> > +		search_base = CRASH_ADDR_LOW_MAX;
> > +		search_end = CRASH_ADDR_HIGH_MAX;
> > +	}
> > +
> > +retry:
> > +	crash_base = memblock_phys_alloc_range(crash_size, CRASH_ALIGN,
> > +					       search_base, search_end);
......

Re: [PATCH v2 6/8] x86: kdump: use generic interface to simplify crashkernel reservation code

[Baoquan He]

On 08/31/23 at 11:43am, Leizhen (ThunderTown) wrote:
......  
> > -static void __init reserve_crashkernel(void)
> > +static void __init arch_reserve_crashkernel(void)
> >  {
> > -	unsigned long long crash_size, crash_base, total_mem;
> > +	unsigned long long crash_base, crash_size, low_size = 0;
> > +	char *cmdline = boot_command_line;
> >  	bool high = false;
> >  	int ret;
> >  
> >  	if (!IS_ENABLED(CONFIG_KEXEC_CORE))
> >  		return;
> >  
> > -	total_mem = memblock_phys_mem_size();
> > -
> > -	/* crashkernel=XM */
> > -	ret = parse_crashkernel(boot_command_line, total_mem,
> > -				&crash_size, &crash_base, NULL, NULL);
> > -	if (ret != 0 || crash_size <= 0) {
> > -		/* crashkernel=X,high */
> > -		ret = parse_crashkernel_high(boot_command_line, total_mem,
> > -					     &crash_size, &crash_base);
> > -		if (ret != 0 || crash_size <= 0)
> > -			return;
> > -		high = true;
> > -	}
> > +	ret = parse_crashkernel(cmdline, memblock_phys_mem_size(),
> > +				&crash_size, &crash_base,
> > +				&low_size, &high);
> > +	if (ret)
> > +		return;
> >  
> >  	if (xen_pv_domain()) {
> >  		pr_info("Ignoring crashkernel for a Xen PV domain\n");
> >  		return;
> >  	}
> >  
> > -	/* 0 means: find the address automatically */
> > -	if (!crash_base) {
> > -		/*
> > -		 * Set CRASH_ADDR_LOW_MAX upper bound for crash memory,
> > -		 * crashkernel=x,high reserves memory over 4G, also allocates
> > -		 * 256M extra low memory for DMA buffers and swiotlb.
> > -		 * But the extra memory is not required for all machines.
> > -		 * So try low memory first and fall back to high memory
> > -		 * unless "crashkernel=size[KMG],high" is specified.
> > -		 */
> > -		if (!high)
> > -			crash_base = memblock_phys_alloc_range(crash_size,
> > -						CRASH_ALIGN, CRASH_ALIGN,
> > -						CRASH_ADDR_LOW_MAX);
> > -		if (!crash_base)
> > -			crash_base = memblock_phys_alloc_range(crash_size,
> > -						CRASH_ALIGN, CRASH_ALIGN,
> > -						CRASH_ADDR_HIGH_MAX);
> > -		if (!crash_base) {
> > -			pr_info("crashkernel reservation failed - No suitable area found.\n");
> > -			return;
> > -		}
> > -	} else {
> > -		unsigned long long start;
> > -
> > -		start = memblock_phys_alloc_range(crash_size, SZ_1M, crash_base,
> > -						  crash_base + crash_size);
> > -		if (start != crash_base) {
> > -			pr_info("crashkernel reservation failed - memory is in use.\n");
> > -			return;
> > -		}
> > -	}
> > -
> > -	if (crash_base >= (1ULL << 32) && reserve_crashkernel_low()) {
> > -		memblock_phys_free(crash_base, crash_size);
> > -		return;
> > -	}
> > -
> > -	pr_info("Reserving %ldMB of memory at %ldMB for crashkernel (System RAM: %ldMB)\n",
> > -		(unsigned long)(crash_size >> 20),
> > -		(unsigned long)(crash_base >> 20),
> > -		(unsigned long)(total_mem >> 20));
> > +	reserve_crashkernel_generic(cmdline, crash_size, crash_base,
> > +				    low_size, high);
> >  
> > -	crashk_res.start = crash_base;
> > -	crashk_res.end   = crash_base + crash_size - 1;
> > -	insert_resource(&iomem_resource, &crashk_res);
> > +	return;
> 
> This can be omitted.

Will update, thx.

> 
> >  }
......

Re: [PATCH v2 3/8] crash_core: change parse_crashkernel() to support crashkernel=,high|low parsing

[Leizhen (ThunderTown)]

On 2023/9/1 17:49, Baoquan He wrote:
>>> +
>>> +		*high = true;
>>> +	} else if (ret || !*crash_size) {
>> This check can be moved outside of #ifdef. Because even '!high', it's completely
>> applicable. The overall adjustment is as follows:
> Hmm, the current logic is much easier to understand. However, I may not
> 100% get your suggestion. Can you paste the complete code in your
> suggested way? Do not need 100% correct code, just the skeleton of code logic
> so that I can better understand it and add inline comment.

int __init parse_crashkernel(...)
{
	int ret;

	/* crashkernel=X[@offset] */
	ret = __parse_crashkernel(cmdline, system_ram, crash_size,
				crash_base, NULL);

#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
	if (high && ret == -ENOENT) {
		... ...		//The code for your original branch "else if (ret == -ENOENT) {"
		ret = 0;	//Added based on the next discussion
	}
+#endif

 	if (!*crash_size)
		ret = -EINVAL;

	return ret;
}

> 
>> -  	if (!high)
>> -  		return ret;
>>
>> #ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
>> 	if (high && ret == -ENOENT) {
>> 		... ...
>> 		if (ret || !*crash_size)	//parse HIGH
>> 		... ...
>> 	}
>>
>> 	//At this point, *crash_size is not 0 and ret is 0.
>> 	//We can also delete if (!*crash_size) above because it will be checked later.
>> #endif
>>
>> 	if (!*crash_size)
>> 		ret = -EINVAL;
>>
>> 	return ret;
> When crashkernel=,high is specified while crashkernel=,low is omitted,
> the ret==-ENOENT, but we can't return ret directly. That is still an
> acceptable way.

Oh, yes. Sorry, I didn't notice branch "ret==-ENOENT" didn't return. So "ret = 0;"
needs to be added.

	if (high && ret == -ENOENT) {
		... ...
		*high = true;
+		ret = 0;
	}

> 
>> -  	return 0;
>>
>>> +		/* The specified value is invalid */
>>> +		return -1;
>>> +	}
>>> +#endif
>>>  	return 0;
>>>  }
>>>  
>>>

-- 
Regards,
  Zhen Lei

Re: [PATCH v2 3/8] crash_core: change parse_crashkernel() to support crashkernel=,high|low parsing

[Baoquan He]

On 09/04/23 at 10:47am, Leizhen (ThunderTown) wrote:
> 
> 
> On 2023/9/1 17:49, Baoquan He wrote:
> >>> +
> >>> +		*high = true;
> >>> +	} else if (ret || !*crash_size) {
> >> This check can be moved outside of #ifdef. Because even '!high', it's completely
> >> applicable. The overall adjustment is as follows:
> > Hmm, the current logic is much easier to understand. However, I may not
> > 100% get your suggestion. Can you paste the complete code in your
> > suggested way? Do not need 100% correct code, just the skeleton of code logic
> > so that I can better understand it and add inline comment.
> 
> int __init parse_crashkernel(...)
> {
> 	int ret;
> 
> 	/* crashkernel=X[@offset] */
> 	ret = __parse_crashkernel(cmdline, system_ram, crash_size,
> 				crash_base, NULL);
> 
> #ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
> 	if (high && ret == -ENOENT) {
> 		... ...		//The code for your original branch "else if (ret == -ENOENT) {"
> 		ret = 0;	//Added based on the next discussion
> 	}
> +#endif
> 
>  	if (!*crash_size)
> 		ret = -EINVAL;
> 
> 	return ret;
> }
> 
Thanks, Zhen Lei.

I paste the whole parse_crashkernel() as you suggested at bottom. Please
check if it's what you want. To me, both is fine to me. I have two minor
concerns to your suggested way.

1)
I took the "if (!high) return" way because except of x86/arm64, all
other architectures will call parse_crashkerne() and check
if *crash_size ==0. Please try 'git grep "parse_crashkernel(" arch'
and check those call sites. With that, we will have duplicated checking.

        ret = __parse_crashkernel(cmdline, system_ram, crash_size,
                                crash_base, NULL);
        if (!high)
                return ret;
2)
I actually like below branch and the code comment. It can give people
hint about what's going on in that case. Discarding it is a little pity.

        } else if (ret || !*crash_size) {
                /* The specified value is invalid */
                return -1;
        }

int __init parse_crashkernel(...)
{
	int ret;

	/* crashkernel=X[@offset] */
	ret = __parse_crashkernel(cmdline, system_ram, crash_size,
				crash_base, NULL);
#ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
	if (high && ret == -ENOENT) {
		ret = __parse_crashkernel(cmdline, 0, crash_size,
				crash_base, suffix_tbl[SUFFIX_HIGH]);
		if (ret || !*crash_size)
			return -EINVAL;

		/*
		 * crashkernel=Y,low can be specified or not, but invalid value
		 * is not allowed.
		 */
		ret = __parse_crashkernel(cmdline, 0, low_size,
				crash_base, suffix_tbl[SUFFIX_LOW]);
		if (ret == -ENOENT) {
			*low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
			ret = 0;
		} else if (ret) {
			return ret;
		}

		*high = true;
	}
#endif

	if (!*crash_size)
		ret = -EINVAL;

	return ret;
}

Re: [PATCH v2 3/8] crash_core: change parse_crashkernel() to support crashkernel=,high|low parsing

[Leizhen (ThunderTown)]

On 2023/9/5 16:29, Baoquan He wrote:
> On 09/04/23 at 10:47am, Leizhen (ThunderTown) wrote:
>>
>>
>> On 2023/9/1 17:49, Baoquan He wrote:
>>>>> +
>>>>> +		*high = true;
>>>>> +	} else if (ret || !*crash_size) {
>>>> This check can be moved outside of #ifdef. Because even '!high', it's completely
>>>> applicable. The overall adjustment is as follows:
>>> Hmm, the current logic is much easier to understand. However, I may not
>>> 100% get your suggestion. Can you paste the complete code in your
>>> suggested way? Do not need 100% correct code, just the skeleton of code logic
>>> so that I can better understand it and add inline comment.
>>
>> int __init parse_crashkernel(...)
>> {
>> 	int ret;
>>
>> 	/* crashkernel=X[@offset] */
>> 	ret = __parse_crashkernel(cmdline, system_ram, crash_size,
>> 				crash_base, NULL);
>>
>> #ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
>> 	if (high && ret == -ENOENT) {
>> 		... ...		//The code for your original branch "else if (ret == -ENOENT) {"
>> 		ret = 0;	//Added based on the next discussion
>> 	}
>> +#endif
>>
>>  	if (!*crash_size)
>> 		ret = -EINVAL;
>>
>> 	return ret;
>> }
>>
> Thanks, Zhen Lei.
> 
> I paste the whole parse_crashkernel() as you suggested at bottom. Please
> check if it's what you want. 

Yes.

> To me, both is fine to me. I have two minor
> concerns to your suggested way.
> 
> 1)
> I took the "if (!high) return" way because except of x86/arm64, all
> other architectures will call parse_crashkerne() and check
> if *crash_size ==0. Please try 'git grep "parse_crashkernel(" arch'
> and check those call sites. With that, we will have duplicated checking.

Add some patches to remove the duplicated checking of other ARCHs? After this
patch series upstreamed.

> 
>         ret = __parse_crashkernel(cmdline, system_ram, crash_size,
>                                 crash_base, NULL);
>         if (!high)
>                 return ret;
> 2)
> I actually like below branch and the code comment. It can give people
> hint about what's going on in that case. Discarding it is a little pity.

Except that "!*crash_size" and "(high && ret == -ENOENT)" needs special comments,
other common errors do not need to be described, I think. Even if some is required,
it should be placed in function __parse_crashkernel().

> 
>         } else if (ret || !*crash_size) {
>                 /* The specified value is invalid */
>                 return -1;
>         }
> 
> int __init parse_crashkernel(...)
> {
> 	int ret;
> 
> 	/* crashkernel=X[@offset] */
> 	ret = __parse_crashkernel(cmdline, system_ram, crash_size,
> 				crash_base, NULL);
> #ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
> 	if (high && ret == -ENOENT) {
> 		ret = __parse_crashkernel(cmdline, 0, crash_size,
> 				crash_base, suffix_tbl[SUFFIX_HIGH]);
> 		if (ret || !*crash_size)
> 			return -EINVAL;
> 
> 		/*
> 		 * crashkernel=Y,low can be specified or not, but invalid value
> 		 * is not allowed.
> 		 */
> 		ret = __parse_crashkernel(cmdline, 0, low_size,
> 				crash_base, suffix_tbl[SUFFIX_LOW]);
> 		if (ret == -ENOENT) {
> 			*low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
> 			ret = 0;
> 		} else if (ret) {
> 			return ret;
> 		}
> 
> 		*high = true;
> 	}
> #endif
> 
> 	if (!*crash_size)
> 		ret = -EINVAL;
> 
> 	return ret;
> }
> 
> .
> 

-- 
Regards,
  Zhen Lei

Re: [PATCH v2 3/8] crash_core: change parse_crashkernel() to support crashkernel=,high|low parsing

[Baoquan He]

On 09/06/23 at 05:07pm, Leizhen (ThunderTown) wrote:
> 
> 
> On 2023/9/5 16:29, Baoquan He wrote:
> > On 09/04/23 at 10:47am, Leizhen (ThunderTown) wrote:
> >>
> >>
> >> On 2023/9/1 17:49, Baoquan He wrote:
> >>>>> +
> >>>>> +		*high = true;
> >>>>> +	} else if (ret || !*crash_size) {
> >>>> This check can be moved outside of #ifdef. Because even '!high', it's completely
> >>>> applicable. The overall adjustment is as follows:
> >>> Hmm, the current logic is much easier to understand. However, I may not
> >>> 100% get your suggestion. Can you paste the complete code in your
> >>> suggested way? Do not need 100% correct code, just the skeleton of code logic
> >>> so that I can better understand it and add inline comment.
> >>
> >> int __init parse_crashkernel(...)
> >> {
> >> 	int ret;
> >>
> >> 	/* crashkernel=X[@offset] */
> >> 	ret = __parse_crashkernel(cmdline, system_ram, crash_size,
> >> 				crash_base, NULL);
> >>
> >> #ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
> >> 	if (high && ret == -ENOENT) {
> >> 		... ...		//The code for your original branch "else if (ret == -ENOENT) {"
> >> 		ret = 0;	//Added based on the next discussion
> >> 	}
> >> +#endif
> >>
> >>  	if (!*crash_size)
> >> 		ret = -EINVAL;
> >>
> >> 	return ret;
> >> }
> >>
> > Thanks, Zhen Lei.
> > 
> > I paste the whole parse_crashkernel() as you suggested at bottom. Please
> > check if it's what you want. 
> 
> Yes.
> 
> > To me, both is fine to me. I have two minor
> > concerns to your suggested way.
> > 
> > 1)
> > I took the "if (!high) return" way because except of x86/arm64, all
> > other architectures will call parse_crashkerne() and check
> > if *crash_size ==0. Please try 'git grep "parse_crashkernel(" arch'
> > and check those call sites. With that, we will have duplicated checking.
> 
> Add some patches to remove the duplicated checking of other ARCHs? After this
> patch series upstreamed.

I resisted this in the first place, after rethinking, it makes sense.
parse_crashkernel() returning 0 indicates a meaningful crashkernel vlaue
parsed, otherwise non-zero. I will go with this.

> 
> > 
> >         ret = __parse_crashkernel(cmdline, system_ram, crash_size,
> >                                 crash_base, NULL);
> >         if (!high)
> >                 return ret;
> > 2)
> > I actually like below branch and the code comment. It can give people
> > hint about what's going on in that case. Discarding it is a little pity.
> 
> Except that "!*crash_size" and "(high && ret == -ENOENT)" needs special comments,
> other common errors do not need to be described, I think. Even if some is required,
> it should be placed in function __parse_crashkernel().

Hmm, I will consider how to comment these better, will update and post
v3.

Thanks, Lei.

> 
> > 
> >         } else if (ret || !*crash_size) {
> >                 /* The specified value is invalid */
> >                 return -1;
> >         }
> > 
> > int __init parse_crashkernel(...)
> > {
> > 	int ret;
> > 
> > 	/* crashkernel=X[@offset] */
> > 	ret = __parse_crashkernel(cmdline, system_ram, crash_size,
> > 				crash_base, NULL);
> > #ifdef CONFIG_ARCH_HAS_GENERIC_CRASHKERNEL_RESERVATION
> > 	if (high && ret == -ENOENT) {
> > 		ret = __parse_crashkernel(cmdline, 0, crash_size,
> > 				crash_base, suffix_tbl[SUFFIX_HIGH]);
> > 		if (ret || !*crash_size)
> > 			return -EINVAL;
> > 
> > 		/*
> > 		 * crashkernel=Y,low can be specified or not, but invalid value
> > 		 * is not allowed.
> > 		 */
> > 		ret = __parse_crashkernel(cmdline, 0, low_size,
> > 				crash_base, suffix_tbl[SUFFIX_LOW]);
> > 		if (ret == -ENOENT) {
> > 			*low_size = DEFAULT_CRASH_KERNEL_LOW_SIZE;
> > 			ret = 0;
> > 		} else if (ret) {
> > 			return ret;
> > 		}
> > 
> > 		*high = true;
> > 	}
> > #endif
> > 
> > 	if (!*crash_size)
> > 		ret = -EINVAL;
> > 
> > 	return ret;
> > }
> > 
> > .
> > 
> 
> -- 
> Regards,
>   Zhen Lei
>