[PATCH] Enable kdump with EFI boot
Neil Horman
nhorman at tuxdriver.com
Tue Jul 27 07:10:29 EDT 2010
On Mon, Jul 26, 2010 at 06:09:18PM -0400, Takao Indoh wrote:
> Hi all,
>
> The attached patch enables kdump on EFI-boot machine.
>
> [Background]
> Current kdump does not work on EFI-boot system because 2nd kernel cannot
> find ACPI Table(RSDP). The URL below explains this problem.
> http://lists.infradead.org/pipermail/kexec/2010-March/003889.html
>
> This problem can be solved by fixing kexec-tools so that it can set up
> struct efi_info correctly in the boot_params for 2nd kernel. However
> there is another problem.
>
> When the 1st kernel boots, EFI system table(efi_system_table_t) is
> modified by SetVirtualAddressMap, which is one of EFI runtime service.
> This runtime changes physical address in EFI system table to virtual
> address.
>
> When the 2nd kernel boots, it also receives the same EFI system table,
> and the address included in it is already virtual address(1st kernel
> rewrote it). But 2nd kernel does not know that, 2nd kernel thinks it is
> a physical address. This causes problems.
>
> For example, the following is a part of efi_init().
>
> c16 = tmp = early_ioremap(efi.systab->fw_vendor, 2);
> if (c16) {
> for (i = 0; i < sizeof(vendor) - 1 && *c16; ++i)
> vendor[i] = *c16++;
> vendor[i] = '\0';
> } else
> printk(KERN_ERR PFX "Could not map the firmware vendor!\n");
>
> 2nd kernel thinks efi.systab->fw_vendor has a physical address and tries
> to change it to virtual address, but it is already virtual address, so
> this code fails and 2nd kernel hangs up.
>
> [How to fix]
> My solution is as follows.
> 1) Export physical address of each EFI system table entry via debugfs
> /sys/kernel/debug/efi/systab/fw_vendor
> /sys/kernel/debug/efi/systab/tables
> /sys/kernel/debug/efi/systab/runtime
>
> Kexec-tools can get physical address of each entry in EFI system table
> via these entries. Kexec tools adds these physical addresses to boot
> parameters
> ex.)
> efi_systab_fw_vendor=0x7a6a1398 efi_systab_tables=0x7a6a2e18 \
> efi_systab_runtime=0x7a6a3e18
>
> 2) Kernel parses these parameters and use them in efi_init()
>
>
> So, what this patch is doing is:
> - Add debugfs interface for each EFI system table entry
> - eif_init() gets physical address of each EFI system table entry from
> boot paramteter instead of the table
> - Don't call SetVirtualAddressMap in 2nd kernel because panic occurred
> when SetVirtualAddressMap is called in 2nd kernel. This is called in
> 1st kernel, and doesn't need to be called again.
>
> Any comments would be appreciated!
>
> Signed-off-by: Takao Indoh <indou.takao at jp.fujitsu.com>
CC-ing the maintainers for x86. nd kexec
Acked-by: Neil Horman <nhorman at tuxdriver.com>
> ---
> arch/x86/kernel/efi.c | 132 +++++++++++++++++++++++++++++++++++++---
> 1 file changed, 123 insertions(+), 9 deletions(-)
>
> diff -Nurp linux-2.6.35-rc6.org/arch/x86/kernel/efi.c linux-2.6.35-rc6/arch/x86/kernel/efi.c
> --- linux-2.6.35-rc6.org/arch/x86/kernel/efi.c 2010-07-26 12:02:31.216675044 -0400
> +++ linux-2.6.35-rc6/arch/x86/kernel/efi.c 2010-07-26 12:17:24.486677191 -0400
> @@ -36,6 +36,8 @@
> #include <linux/io.h>
> #include <linux/reboot.h>
> #include <linux/bcd.h>
> +#include <linux/crash_dump.h>
> +#include <linux/debugfs.h>
>
> #include <asm/setup.h>
> #include <asm/efi.h>
> @@ -314,6 +316,97 @@ static void __init print_efi_memmap(void
> }
> #endif /* EFI_DEBUG */
>
> +unsigned long systab_fw_vendor_paddr;
> +unsigned long systab_runtime_paddr;
> +unsigned long systab_tables_paddr;
> +
> +static struct debugfs_blob_wrapper fw_vendor_blob = {
> + .data = &systab_fw_vendor_paddr,
> + .size = sizeof(systab_fw_vendor_paddr),
> +};
> +
> +static struct debugfs_blob_wrapper runtime_blob = {
> + .data = &systab_runtime_paddr,
> + .size = sizeof(systab_runtime_paddr),
> +};
> +
> +static struct debugfs_blob_wrapper tables_blob = {
> + .data = &systab_tables_paddr,
> + .size = sizeof(systab_tables_paddr),
> +};
> +
> +static int __init setup_systab_fw_vendor_paddr(char *arg)
> +{
> + systab_fw_vendor_paddr = simple_strtoul(arg, NULL, 16);
> + return 0;
> +}
> +early_param("efi_systab_fw_vendor", setup_systab_fw_vendor_paddr);
> +
> +static int __init setup_systab_runtime_paddr(char *arg)
> +{
> + systab_runtime_paddr = simple_strtoul(arg, NULL, 16);
> + return 0;
> +}
> +early_param("efi_systab_runtime", setup_systab_runtime_paddr);
> +
> +static int __init setup_systab_tables_paddr(char *arg)
> +{
> + systab_tables_paddr = simple_strtoul(arg, NULL, 16);
> + return 0;
> +}
> +early_param("efi_systab_tables", setup_systab_tables_paddr);
> +
> +static int create_debug_files_systab (struct dentry *root)
> +{
> + struct dentry *systab_dir, *fw_vendor, *runtime, *tables;
> +
> + systab_dir = debugfs_create_dir("systab", root);
> + if (!systab_dir)
> + return -1;
> +
> + fw_vendor = debugfs_create_blob("fw_vendor", S_IRUGO, systab_dir,
> + &fw_vendor_blob);
> + if (!fw_vendor)
> + goto err_fw;
> +
> + runtime = debugfs_create_blob("runtime", S_IRUGO, systab_dir,
> + &runtime_blob);
> + if (!runtime)
> + goto err_runtime;
> +
> + tables = debugfs_create_blob("tables", S_IRUGO, systab_dir,
> + &tables_blob);
> + if (tables)
> + return 0;
> +
> + debugfs_remove(runtime);
> +err_runtime:
> + debugfs_remove(fw_vendor);
> +err_fw:
> + debugfs_remove(systab_dir);
> + return -1;
> +}
> +
> +static int crate_debug_files (void)
> +{
> + int error;
> + struct dentry *efi_dir;
> +
> + efi_dir = debugfs_create_dir("efi", NULL);
> + if (!efi_dir)
> + return -1;
> +
> + error = create_debug_files_systab(efi_dir);
> + if (error) {
> + debugfs_remove(efi_dir);
> + return -1;
> + }
> +
> + return 0;
> +}
> +
> +late_initcall(crate_debug_files);
> +
> void __init efi_init(void)
> {
> efi_config_table_t *config_tables;
> @@ -322,6 +415,7 @@ void __init efi_init(void)
> char vendor[100] = "unknown";
> int i = 0;
> void *tmp;
> + resource_size_t phys_addr;
>
> #ifdef CONFIG_X86_32
> efi_phys.systab = (efi_system_table_t *)boot_params.efi_info.efi_systab;
> @@ -353,7 +447,11 @@ void __init efi_init(void)
> /*
> * Show what we know for posterity
> */
> - c16 = tmp = early_ioremap(efi.systab->fw_vendor, 2);
> + if (is_kdump_kernel() && systab_fw_vendor_paddr != 0)
> + phys_addr = systab_fw_vendor_paddr;
> + else
> + phys_addr = efi.systab->fw_vendor;
> + c16 = tmp = early_ioremap(phys_addr, 2);
> if (c16) {
> for (i = 0; i < sizeof(vendor) - 1 && *c16; ++i)
> vendor[i] = *c16++;
> @@ -369,8 +467,12 @@ void __init efi_init(void)
> /*
> * Let's see what config tables the firmware passed to us.
> */
> + if (is_kdump_kernel() && systab_tables_paddr != 0)
> + phys_addr = systab_tables_paddr;
> + else
> + phys_addr = efi.systab->tables;
> config_tables = early_ioremap(
> - efi.systab->tables,
> + phys_addr,
> efi.systab->nr_tables * sizeof(efi_config_table_t));
> if (config_tables == NULL)
> printk(KERN_ERR "Could not map EFI Configuration Table!\n");
> @@ -418,8 +520,11 @@ void __init efi_init(void)
> * address of several of the EFI runtime functions, needed to
> * set the firmware into virtual mode.
> */
> - runtime = early_ioremap((unsigned long)efi.systab->runtime,
> - sizeof(efi_runtime_services_t));
> + if (is_kdump_kernel() && systab_runtime_paddr != 0)
> + phys_addr = systab_runtime_paddr;
> + else
> + phys_addr = (unsigned long)efi.systab->runtime;
> + runtime = early_ioremap(phys_addr, sizeof(efi_runtime_services_t));
> if (runtime != NULL) {
> /*
> * We will only need *early* access to the following
> @@ -465,6 +570,12 @@ void __init efi_init(void)
> #if EFI_DEBUG
> print_efi_memmap();
> #endif
> + /* Save original physical address */
> + if (!is_kdump_kernel()) {
> + systab_fw_vendor_paddr = efi.systab->fw_vendor;
> + systab_tables_paddr = efi.systab->tables;
> + systab_runtime_paddr = (unsigned long)efi.systab->runtime;
> + }
> }
>
> static void __init runtime_code_page_mkexec(void)
> @@ -544,11 +655,14 @@ void __init efi_enter_virtual_mode(void)
>
> BUG_ON(!efi.systab);
>
> - status = phys_efi_set_virtual_address_map(
> - memmap.desc_size * memmap.nr_map,
> - memmap.desc_size,
> - memmap.desc_version,
> - memmap.phys_map);
> + if (!is_kdump_kernel())
> + status = phys_efi_set_virtual_address_map(
> + memmap.desc_size * memmap.nr_map,
> + memmap.desc_size,
> + memmap.desc_version,
> + memmap.phys_map);
> + else
> + status = EFI_SUCCESS;
>
> if (status != EFI_SUCCESS) {
> printk(KERN_ALERT "Unable to switch EFI into virtual mode "
>
> --
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