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Subject[PATCH 12/13] x86/efi: Add EFI_PGT_DUMP support for x86_32 and kexec
Date
From: Sai Praneeth <sai.praneeth.prakhya@intel.com>

EFI_PGT_DUMP, as the name suggests dumps efi page tables to dmesg during
kernel boot. This feature is very useful while debugging page
faults/null pointer dereferences to efi related addresses. Presently,
this feature is limited only to x86_64, so let's extend it to other efi
configurations like kexec kernel, efi=old_map and to x86_32 as well.
This doesn't effect normal boot path because this config option should
be used only for debug purposes.

Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Ricardo Neri <ricardo.neri@intel.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Ravi Shankar <ravi.v.shankar@intel.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
---
arch/x86/platform/efi/efi.c | 3 ++-
arch/x86/platform/efi/efi_32.c | 9 ++++++++-
arch/x86/platform/efi/efi_64.c | 5 ++++-
3 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index dc2da5e2c7e4..3cf8536e803b 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -1012,7 +1012,6 @@ static void __init __efi_enter_virtual_mode(void)
* necessary relocation fixups for the new virtual addresses.
*/
efi_runtime_update_mappings();
- efi_dump_pagetable();

/* clean DUMMY object */
efi_delete_dummy_variable();
@@ -1027,6 +1026,8 @@ void __init efi_enter_virtual_mode(void)
kexec_enter_virtual_mode();
else
__efi_enter_virtual_mode();
+
+ efi_dump_pagetable();
}

/*
diff --git a/arch/x86/platform/efi/efi_32.c b/arch/x86/platform/efi/efi_32.c
index 403a987d06c7..fe18c5d32bf0 100644
--- a/arch/x86/platform/efi/efi_32.c
+++ b/arch/x86/platform/efi/efi_32.c
@@ -44,7 +44,14 @@ int __init efi_alloc_page_tables(void)
}

void efi_sync_low_kernel_mappings(void) {}
-void __init efi_dump_pagetable(void) {}
+
+void __init efi_dump_pagetable(void)
+{
+#ifdef CONFIG_EFI_PGT_DUMP
+ ptdump_walk_pgd_level(NULL, swapper_pg_dir);
+#endif
+}
+
int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
{
return 0;
diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 6fbf6c47e603..0d8180811445 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -528,7 +528,10 @@ void __init efi_runtime_update_mappings(void)
void __init efi_dump_pagetable(void)
{
#ifdef CONFIG_EFI_PGT_DUMP
- ptdump_walk_pgd_level(NULL, efi_pgd);
+ if (efi_enabled(EFI_OLD_MEMMAP))
+ ptdump_walk_pgd_level(NULL, swapper_pg_dir);
+ else
+ ptdump_walk_pgd_level(NULL, efi_pgd);
#endif
}

--
2.9.3
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