[PATCH v6 9/9] x86: Pass memory range via E820 for kdump

WANG Chao
2014-04-14T14:56:32Z

command line size is restricted by kernel, sometimes memmap=exactmap has
too many memory ranges to pass to cmdline. And also memmap=exactmap and
kASLR doesn't work together.

A better approach, to pass the memory ranges for crash kernel to boot
into, is filling the memory ranges into E820.

boot_params only got 128 slots for E820 map to fit in, when the number of
memory map exceeds 128, use setup_data to pass the rest as extended E820
memory map.

kexec boot could also benefit from setup_data in case E820 memory map
exceeds 128.

Now this new approach becomes default instead of memmap=exactmap.
saved_max_pfn users can specify --pass-memmap-cmdline to use the
exactmap approach.

Signed-off-by: WANG Chao <chaowang@redhat.com>
Tested-by: Linn Crosetto <linn@hp.com>
Reviewed-by: Linn Crosetto <linn@hp.com>
---
kexec/arch/i386/crashdump-x86.c | 6 +-
kexec/arch/i386/x86-linux-setup.c | 149 +++++++++++++++++++++++++-------------
kexec/arch/i386/x86-linux-setup.h | 1 +
3 files changed, 103 insertions(+), 53 deletions(-)

diff --git a/kexec/arch/i386/crashdump-x86.c b/kexec/arch/i386/crashdump-x86.c
index 7b618a6..4a1491b 100644
--- a/kexec/arch/i386/crashdump-x86.c
+++ b/kexec/arch/i386/crashdump-x86.c
@@ -979,7 +979,8 @@ int load_crashdump_segments(struct kexec_info *info, char* mod_cmdline,
dbgprintf("Created elf header segment at 0x%lx\n", elfcorehdr);
if (delete_memmap(memmap_p, &nr_memmap, elfcorehdr, memsz) < 0)
return -1;
- cmdline_add_memmap(mod_cmdline, memmap_p);
+ if (arch_options.pass_memmap_cmdline)
+ cmdline_add_memmap(mod_cmdline, memmap_p);
if (!bzImage_support_efi_boot)
cmdline_add_efi(mod_cmdline);
cmdline_add_elfcorehdr(mod_cmdline, elfcorehdr);
@@ -995,7 +996,8 @@ int load_crashdump_segments(struct kexec_info *info, char* mod_cmdline,
type = mem_range[i].type;
size = end - start + 1;
add_memmap(memmap_p, &nr_memmap, start, size, type);
- cmdline_add_memmap_acpi(mod_cmdline, start, end);
+ if (arch_options.pass_memmap_cmdline)
+ cmdline_add_memmap_acpi(mod_cmdline, start, end);
}

/* Store 2nd kernel boot memory ranges for later reference in
diff --git a/kexec/arch/i386/x86-linux-setup.c b/kexec/arch/i386/x86-linux-setup.c
index 9f8355f..4437ed7 100644
--- a/kexec/arch/i386/x86-linux-setup.c
+++ b/kexec/arch/i386/x86-linux-setup.c
@@ -36,8 +36,6 @@
#include "x86-linux-setup.h"
#include "../../kexec/kexec-syscall.h"

-#define SETUP_EFI 4
-
void init_linux_parameters(struct x86_linux_param_header *real_mode)
{
/* Fill in the values that are usually provided by the kernel. */
@@ -502,6 +500,11 @@ struct efi_setup_data {
struct setup_data {
uint64_t next;
uint32_t type;
+#define SETUP_NONE 0
+#define SETUP_E820_EXT 1
+#define SETUP_DTB 2
+#define SETUP_PCI 3
+#define SETUP_EFI 4
uint32_t len;
uint8_t data[0];
} __attribute__((packed));
@@ -684,6 +687,98 @@ out:
return ret;
}

+static void add_e820_map_from_mr(struct x86_linux_param_header *real_mode,
+ struct e820entry *e820, struct memory_range *range, int nr_range)
+{
+ int i;
+
+ for (i = 0; i < nr_range; i++) {
+ e820[i].addr = range[i].start;
+ e820[i].size = range[i].end - range[i].start + 1;
+ switch (range[i].type) {
+ case RANGE_RAM:
+ e820[i].type = E820_RAM;
+ break;
+ case RANGE_ACPI:
+ e820[i].type = E820_ACPI;
+ break;
+ case RANGE_ACPI_NVS:
+ e820[i].type = E820_NVS;
+ break;
+ default:
+ case RANGE_RESERVED:
+ e820[i].type = E820_RESERVED;
+ break;
+ }
+ dbgprintf("%016lx-%016lx (%d)\n",
+ e820[i].addr,
+ e820[i].addr + e820[i].size - 1,
+ e820[i].type);
+
+ if (range[i].type != RANGE_RAM)
+ continue;
+ if ((range[i].start <= 0x100000) && range[i].end > 0x100000) {
+ unsigned long long mem_k = (range[i].end >> 10) - (0x100000 >> 10);
+ real_mode->ext_mem_k = mem_k;
+ real_mode->alt_mem_k = mem_k;
+ if (mem_k > 0xfc00) {
+ real_mode->ext_mem_k = 0xfc00; /* 64M */
+ }
+ if (mem_k > 0xffffffff) {
+ real_mode->alt_mem_k = 0xffffffff;
+ }
+ }
+ }
+}
+
+static void setup_e820_ext(struct kexec_info *info, struct x86_linux_param_header *real_mode,
+ struct memory_range *range, int nr_range)
+{
+ struct setup_data *sd;
+ struct e820entry *e820;
+ int nr_range_ext;
+
+ nr_range_ext = nr_range - E820MAX;
+ sd = xmalloc(sizeof(struct setup_data) + nr_range_ext * sizeof(struct e820entry));
+ sd->next = 0;
+ sd->len = nr_range_ext * sizeof(struct e820entry);
+ sd->type = SETUP_E820_EXT;
+
+ e820 = (struct e820entry *) sd->data;
+ dbgprintf("Extended E820 via setup_data:\n");
+ add_e820_map_from_mr(real_mode, e820, range + E820MAX, nr_range_ext);
+ add_setup_data(info, real_mode, sd);
+}
+
+static void setup_e820(struct kexec_info *info, struct x86_linux_param_header *real_mode)
+{
+ struct memory_range *range;
+ int nr_range, nr_range_saved;
+
+
+ if (info->kexec_flags & KEXEC_ON_CRASH && !arch_options.pass_memmap_cmdline) {
+ range = info->crash_range;
+ nr_range = info->nr_crash_ranges;
+ } else {
+ range = info->memory_range;
+ nr_range = info->memory_ranges;
+ }
+
+ nr_range_saved = nr_range;
+ if (nr_range > E820MAX) {
+ nr_range = E820MAX;
+ }
+
+ real_mode->e820_map_nr = nr_range;
+ dbgprintf("E820 memmap:\n");
+ add_e820_map_from_mr(real_mode, real_mode->e820_map, range, nr_range);
+
+ if (nr_range_saved > E820MAX) {
+ dbgprintf("extra E820 memmap are passed via setup_data\n");
+ setup_e820_ext(info, real_mode, range, nr_range_saved);
+ }
+}
+
static int
get_efi_mem_desc_version(struct x86_linux_param_header *real_mode)
{
@@ -725,10 +820,6 @@ out:
void setup_linux_system_parameters(struct kexec_info *info,
struct x86_linux_param_header *real_mode)
{
- /* Fill in information the BIOS would usually provide */
- struct memory_range *range;
- int i, ranges;
-
/* get subarch from running kernel */
setup_subarch(real_mode);
if (bzImage_support_efi_boot)
@@ -769,51 +860,7 @@ void setup_linux_system_parameters(struct kexec_info *info,
/* another safe default */
real_mode->aux_device_info = 0;

- range = info->memory_range;
- ranges = info->memory_ranges;
- if (ranges > E820MAX) {
- if (!(info->kexec_flags & KEXEC_ON_CRASH))
- /*
- * this e820 not used for capture kernel, see
- * do_bzImage_load()
- */
- fprintf(stderr,
- "Too many memory ranges, truncating...\n");
- ranges = E820MAX;
- }
- real_mode->e820_map_nr = ranges;
- for(i = 0; i < ranges; i++) {
- real_mode->e820_map[i].addr = range[i].start;
- real_mode->e820_map[i].size = range[i].end - range[i].start + 1;
- switch (range[i].type) {
- case RANGE_RAM:
- real_mode->e820_map[i].type = E820_RAM;
- break;
- case RANGE_ACPI:
- real_mode->e820_map[i].type = E820_ACPI;
- break;
- case RANGE_ACPI_NVS:
- real_mode->e820_map[i].type = E820_NVS;
- break;
- default:
- case RANGE_RESERVED:
- real_mode->e820_map[i].type = E820_RESERVED;
- break;
- }
- if (range[i].type != RANGE_RAM)
- continue;
- if ((range[i].start <= 0x100000) && range[i].end > 0x100000) {
- unsigned long long mem_k = (range[i].end >> 10) - (0x100000 >> 10);
- real_mode->ext_mem_k = mem_k;
- real_mode->alt_mem_k = mem_k;
- if (mem_k > 0xfc00) {
- real_mode->ext_mem_k = 0xfc00; /* 64M */
- }
- if (mem_k > 0xffffffff) {
- real_mode->alt_mem_k = 0xffffffff;
- }
- }
- }
+ setup_e820(info, real_mode);

/* fill the EDD information */
setup_edd_info(real_mode);
diff --git a/kexec/arch/i386/x86-linux-setup.h b/kexec/arch/i386/x86-linux-setup.h
index 6fb84b4..f5d23d3 100644
--- a/kexec/arch/i386/x86-linux-setup.h
+++ b/kexec/arch/i386/x86-linux-setup.h
@@ -30,5 +30,6 @@ void setup_linux_system_parameters(struct kexec_info *info,
/* command line parameter may be appended by purgatory */
#define PURGATORY_CMDLINE_SIZE 64
extern int bzImage_support_efi_boot;
+extern struct arch_options_t arch_options;

#endif /* X86_LINUX_SETUP_H */
--
1.9.0