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Subject[PATCH v6 1/4] x86: kdump: move reserve_crashkernel_low() into crash_core.c
Date
In preparation for supporting reserve_crashkernel_low in arm64 as
x86_64 does, move reserve_crashkernel_low() into kernel/crash_core.c.

Note, in arm64, we reserve low memory if and only if crashkernel=X,low
is specified. Different with x86_64, don't set low memory automatically.

Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
---
arch/x86/include/asm/kexec.h | 3 ++
arch/x86/kernel/setup.c | 65 ++++----------------------------------------
include/linux/crash_core.h | 4 +++
include/linux/kexec.h | 1 -
kernel/crash_core.c | 65 ++++++++++++++++++++++++++++++++++++++++++++
5 files changed, 78 insertions(+), 60 deletions(-)

diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h
index 5e7d6b4..bf21d6c 100644
--- a/arch/x86/include/asm/kexec.h
+++ b/arch/x86/include/asm/kexec.h
@@ -18,6 +18,9 @@

# define KEXEC_CONTROL_CODE_MAX_SIZE 2048

+/* 16M alignment for crash kernel regions */
+#define CRASH_ALIGN SZ_16M
+
#ifndef __ASSEMBLY__

#include <linux/string.h>
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index bbe35bf..2b437c4 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -449,9 +449,6 @@ static void __init memblock_x86_reserve_range_setup_data(void)

#ifdef CONFIG_KEXEC_CORE

-/* 16M alignment for crash kernel regions */
-#define CRASH_ALIGN SZ_16M
-
/*
* Keep the crash kernel below this limit.
*
@@ -473,59 +470,6 @@ static void __init memblock_x86_reserve_range_setup_data(void)
# define CRASH_ADDR_HIGH_MAX SZ_64T
#endif

-static int __init reserve_crashkernel_low(void)
-{
-#ifdef CONFIG_X86_64
- unsigned long long base, low_base = 0, low_size = 0;
- unsigned long total_low_mem;
- int ret;
-
- total_low_mem = memblock_mem_size(1UL << (32 - PAGE_SHIFT));
-
- /* crashkernel=Y,low */
- ret = parse_crashkernel_low(boot_command_line, total_low_mem, &low_size, &base);
- if (ret) {
- /*
- * two parts from lib/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_find_in_range(0, 1ULL << 32, low_size, CRASH_ALIGN);
- if (!low_base) {
- pr_err("Cannot reserve %ldMB crashkernel low memory, please try smaller size.\n",
- (unsigned long)(low_size >> 20));
- return -ENOMEM;
- }
-
- ret = memblock_reserve(low_base, low_size);
- if (ret) {
- pr_err("%s: Error reserving crashkernel low memblock.\n", __func__);
- return ret;
- }
-
- pr_info("Reserving %ldMB of low memory at %ldMB for crashkernel (System low RAM: %ldMB)\n",
- (unsigned long)(low_size >> 20),
- (unsigned long)(low_base >> 20),
- (unsigned long)(total_low_mem >> 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;
-}
-
static void __init reserve_crashkernel(void)
{
unsigned long long crash_size, crash_base, total_mem;
@@ -589,9 +533,12 @@ static void __init reserve_crashkernel(void)
return;
}

- if (crash_base >= (1ULL << 32) && reserve_crashkernel_low()) {
- memblock_free(crash_base, crash_size);
- return;
+ if (crash_base >= (1ULL << 32)) {
+ if (reserve_crashkernel_low()) {
+ memblock_free(crash_base, crash_size);
+ return;
+ }
+ insert_resource(&iomem_resource, &crashk_low_res);
}

pr_info("Reserving %ldMB of memory at %ldMB for crashkernel (System RAM: %ldMB)\n",
diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
index 525510a..9192e43 100644
--- a/include/linux/crash_core.h
+++ b/include/linux/crash_core.h
@@ -6,6 +6,8 @@
#include <linux/elfcore.h>
#include <linux/elf.h>

+#include <asm/kexec.h>
+
#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)
@@ -63,6 +65,7 @@ phys_addr_t paddr_vmcoreinfo_note(void);
extern unsigned char *vmcoreinfo_data;
extern size_t vmcoreinfo_size;
extern u32 *vmcoreinfo_note;
+extern struct resource crashk_low_res;

Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
void *data, size_t data_len);
@@ -74,5 +77,6 @@ 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);
+int __init reserve_crashkernel_low(void);

#endif /* LINUX_CRASH_CORE_H */
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index b9b1bc5..62330aa 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -306,7 +306,6 @@ extern int kexec_load_disabled;
/* 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;

/* flag to track if kexec reboot is in progress */
diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index 9f1557b..13cdf35 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -7,6 +7,8 @@
#include <linux/crash_core.h>
#include <linux/utsname.h>
#include <linux/vmalloc.h>
+#include <linux/memblock.h>
+#include <linux/swiotlb.h>

#include <asm/page.h>
#include <asm/sections.h>
@@ -292,6 +294,69 @@ int __init parse_crashkernel_low(char *cmdline,
"crashkernel=", suffix_tbl[SUFFIX_LOW]);
}

+int __init reserve_crashkernel_low(void)
+{
+#if defined(CONFIG_X86_64) || defined(CONFIG_ARM64)
+ unsigned long long base, low_base = 0, low_size = 0;
+ unsigned long total_low_mem;
+ int ret;
+
+ total_low_mem = memblock_mem_size(1UL << (32 - PAGE_SHIFT));
+
+ /* crashkernel=Y,low */
+ ret = parse_crashkernel_low(boot_command_line, total_low_mem, &low_size,
+ &base);
+ if (ret) {
+#ifdef CONFIG_X86_64
+ /*
+ * two parts from lib/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
+ /*
+ * in arm64, reserve low memory if and only if crashkernel=X,low
+ * specified.
+ */
+ return -EINVAL;
+#endif
+ } else {
+ /* passed with crashkernel=0,low ? */
+ if (!low_size)
+ return 0;
+ }
+
+ low_base = memblock_find_in_range(0, 1ULL << 32, low_size, CRASH_ALIGN);
+ if (!low_base) {
+ pr_err("Cannot reserve %ldMB crashkernel low memory, please try smaller size.\n",
+ (unsigned long)(low_size >> 20));
+ return -ENOMEM;
+ }
+
+ ret = memblock_reserve(low_base, low_size);
+ if (ret) {
+ pr_err("%s: Error reserving crashkernel low memblock.\n",
+ __func__);
+ return ret;
+ }
+
+ pr_info("Reserving %ldMB of low memory at %ldMB for crashkernel (System low RAM: %ldMB)\n",
+ (unsigned long)(low_size >> 20),
+ (unsigned long)(low_base >> 20),
+ (unsigned long)(total_low_mem >> 20));
+
+ crashk_low_res.start = low_base;
+ crashk_low_res.end = low_base + low_size - 1;
+#endif
+ return 0;
+}
+
Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
void *data, size_t data_len)
{
--
2.7.4
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