linux-kernel - [tip:x86/mm] kdump, vmcoreinfo: Export pgtable_l5

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Message-ID: <tip-c100a583601d357f923c41af5434dc1f8d07890f@git.kernel.org>
Date:   Mon, 12 Mar 2018 02:30:32 -0700
From:   tip-bot for Baoquan He <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     kirill.shutemov@...ux.intel.com, peterz@...radead.org,
        torvalds@...ux-foundation.org, bhe@...hat.com, tglx@...utronix.de,
        linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org
Subject: [tip:x86/mm] kdump, vmcoreinfo: Export pgtable_l5_enabled value

Commit-ID:  c100a583601d357f923c41af5434dc1f8d07890f
Gitweb:     https://git.kernel.org/tip/c100a583601d357f923c41af5434dc1f8d07890f
Author:     Baoquan He <bhe@...hat.com>
AuthorDate: Fri, 2 Mar 2018 13:18:01 +0800
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Mon, 12 Mar 2018 09:43:56 +0100

kdump, vmcoreinfo: Export pgtable_l5_enabled value

User-space utilities examining crash-kernels need to know if the
crashed kernel was in 5-level paging mode or not.

So write 'pgtable_l5_enabled' to vmcoreinfo, which covers these
three cases:

  pgtable_l5_enabled == 0 when:
   - Compiled with !CONFIG_X86_5LEVEL
   - Compiled with CONFIG_X86_5LEVEL=y while CPU has no 'la57' flag

  pgtable_l5_enabled != 0 when:
   - Compiled with CONFIG_X86_5LEVEL=y and CPU has 'la57' flag

Signed-off-by: Baoquan He <bhe@...hat.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: douly.fnst@...fujitsu.com
Cc: dyoung@...hat.com
Cc: ebiederm@...ssion.com
Cc: kirill.shutemov@...ux.intel.com
Cc: vgoyal@...hat.com
Link: http://lkml.kernel.org/r/20180302051801.19594-1-bhe@redhat.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/kernel/machine_kexec_64.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
index 3b7427aa7d85..02f913cb27b5 100644
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -350,6 +350,7 @@ void arch_crash_save_vmcoreinfo(void)
 {
 	VMCOREINFO_NUMBER(phys_base);
 	VMCOREINFO_SYMBOL(init_top_pgt);
+	VMCOREINFO_NUMBER(pgtable_l5_enabled);
 
 #ifdef CONFIG_NUMA
 	VMCOREINFO_SYMBOL(node_data);