linux-kernel - [tip:efi/core] x86/efi: Extend CONFIG_EFI_PGT_DUMP support to x86

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Message-ID: <tip-ac81d3de03f7d8593a94240d057c8e2e8e869897@git.kernel.org>
Date:   Mon, 5 Jun 2017 10:16:02 -0700
From:   tip-bot for Sai Praneeth <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     ricardo.neri@...el.com, ard.biesheuvel@...aro.org,
        mingo@...nel.org, tglx@...utronix.de,
        sai.praneeth.prakhya@...el.com, hpa@...or.com,
        linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org,
        matt@...eblueprint.co.uk, bp@...en8.de, ravi.v.shankar@...el.com,
        peterz@...radead.org
Subject: [tip:efi/core] x86/efi: Extend CONFIG_EFI_PGT_DUMP support to
 x86_32 and kexec as well

Commit-ID:  ac81d3de03f7d8593a94240d057c8e2e8e869897
Gitweb:     http://git.kernel.org/tip/ac81d3de03f7d8593a94240d057c8e2e8e869897
Author:     Sai Praneeth <sai.praneeth.prakhya@...el.com>
AuthorDate: Fri, 2 Jun 2017 13:52:06 +0000
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Mon, 5 Jun 2017 17:50:43 +0200

x86/efi: Extend CONFIG_EFI_PGT_DUMP support to x86_32 and kexec as well

CONFIG_EFI_PGT_DUMP=y, as the name suggests, dumps EFI page tables to the
kernel log 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@...el.com>
Signed-off-by: Matt Fleming <matt@...eblueprint.co.uk>
Cc: Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Ravi Shankar <ravi.v.shankar@...el.com>
Cc: Ricardo Neri <ricardo.neri@...el.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: linux-efi@...r.kernel.org
Link: http://lkml.kernel.org/r/20170602135207.21708-13-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 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 43b96f5..f084d87 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -1014,7 +1014,6 @@ 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();
@@ -1029,6 +1028,8 @@ 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 3481268..52f7faa 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 eb8dff1..8ff1f95 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -589,7 +589,10 @@ 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
 }