linux-kernel - [PATCH 9/9] x86: Save FS/GS base in core dump

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Date:	Mon, 21 Mar 2016 09:16:09 -0700
From:	Andi Kleen <andi@...stfloor.org>
To:	x86@...nel.org
Cc:	luto@...capital.net, linux-kernel@...r.kernel.org,
	Andi Kleen <ak@...ux.intel.com>
Subject: [PATCH 9/9] x86: Save FS/GS base in core dump

From: Andi Kleen <ak@...ux.intel.com>

Add FS/GS base dumping to the standard ELF_CORE_COPY_REGS macro

I think this is only used in some special cases, the majority
of core dumps seem to go through the getregs interface also
used by ptrace.

Signed-off-by: Andi Kleen <ak@...ux.intel.com>
---
 arch/x86/include/asm/elf.h | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/elf.h b/arch/x86/include/asm/elf.h
index 0df9c95..f57cc17 100644
--- a/arch/x86/include/asm/elf.h
+++ b/arch/x86/include/asm/elf.h
@@ -9,6 +9,8 @@
 #include <asm/ptrace.h>
 #include <asm/user.h>
 #include <asm/auxvec.h>
+#include <asm/proto.h>
+#include <asm/fsgs.h>
 
 typedef unsigned long elf_greg_t;
 
@@ -226,8 +228,13 @@ do {								\
 	(pr_reg)[18] = (regs)->flags;				\
 	(pr_reg)[19] = (regs)->sp;				\
 	(pr_reg)[20] = (regs)->ss;				\
-	(pr_reg)[21] = current->thread.fs;			\
-	(pr_reg)[22] = current->thread.gs;			\
+	if (boot_cpu_has(X86_FEATURE_FSGSBASE)) {		\
+		(pr_reg)[21] = rdfsbase();			\
+		(pr_reg)[22] = read_user_gsbase();		\
+	} else {						\
+		(pr_reg)[21] = current->thread.fs;		\
+		(pr_reg)[22] = current->thread.gs;		\
+	}							\
 	asm("movl %%ds,%0" : "=r" (v)); (pr_reg)[23] = v;	\
 	asm("movl %%es,%0" : "=r" (v)); (pr_reg)[24] = v;	\
 	asm("movl %%fs,%0" : "=r" (v)); (pr_reg)[25] = v;	\
-- 
2.5.5