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From: "Chang S. Bae" <chang.seok.bae@intel.com>
To: Andy Lutomirski <luto@kernel.org>,
	"H . Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Markus T Metzger <markus.t.metzger@intel.com>,
	"Ravi V . Shankar" <ravi.v.shankar@intel.com>,
	"Chang S . Bae" <chang.seok.bae@intel.com>,
	linux-kernel@vger.kernel.org
Subject: [PATCH V2 08/15] x86/fsgsbase/64: Add intrinsics/macros for FSGSBASE instructions
Date: Thu, 31 May 2018 10:58:38 -0700	[thread overview]
Message-ID: <1527789525-8857-9-git-send-email-chang.seok.bae@intel.com> (raw)
In-Reply-To: <1527789525-8857-1-git-send-email-chang.seok.bae@intel.com>

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

Add C intrinsics and assembler macros for the new RD/WR FS/GS BASE
instructions.

Very straight forward. Used in followon patch.

[luto: rename the variables from fs and gs to fsbase and gsbase and
 make fsgs.h safe to include on 32-bit kernels.]

v2: Use __always_inline

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
[chang: Replace new instruction macros with GAS-compatible and
renaming. Note: if GCC supports it, we can add -mfsgsbase to
CFLAGS and use the builtins here for extra performance.]
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/include/asm/fsgsbase.h | 70 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)

diff --git a/arch/x86/include/asm/fsgsbase.h b/arch/x86/include/asm/fsgsbase.h
index 0d4fbef..ed42015 100644
--- a/arch/x86/include/asm/fsgsbase.h
+++ b/arch/x86/include/asm/fsgsbase.h
@@ -18,6 +18,42 @@ unsigned long read_task_gsbase(struct task_struct *task);
 int write_task_fsbase(struct task_struct *task, unsigned long fsbase);
 int write_task_gsbase(struct task_struct *task, unsigned long gsbase);
 
+/* Must be protected by X86_FEATURE_FSGSBASE check. */
+
+static __always_inline unsigned long rdfsbase(void)
+{
+	unsigned long fsbase;
+
+	asm volatile(".byte 0xf3, 0x48, 0x0f, 0xae, 0xc0 # rdfsbaseq %%rax"
+			: "=a" (fsbase)
+			:: "memory");
+	return fsbase;
+}
+
+static __always_inline unsigned long rdgsbase(void)
+{
+	unsigned long gsbase;
+
+	asm volatile(".byte 0xf3, 0x48, 0x0f, 0xae, 0xc8 # rdgsbaseq %%rax;"
+			: "=a" (gsbase)
+			:: "memory");
+	return gsbase;
+}
+
+static __always_inline void wrfsbase(unsigned long fsbase)
+{
+	asm volatile(".byte 0xf3, 0x48, 0x0f, 0xae, 0xd0 # wrfsbaseq %%rax"
+			:: "a" (fsbase)
+			: "memory");
+}
+
+static __always_inline void wrgsbase(unsigned long gsbase)
+{
+	asm volatile(".byte 0xf3, 0x48, 0x0f, 0xae, 0xd8 # wrgsbaseq %%rax;"
+			:: "a" (gsbase)
+			: "memory");
+}
+
 /* Helper functions for reading/writing FS/GS base */
 
 static inline unsigned long read_fsbase(void)
@@ -42,6 +78,40 @@ void  write_inactive_gsbase(unsigned long gsbase);
 
 #endif /* CONFIG_X86_64 */
 
+#else /* __ASSEMBLY__ */
+
+#ifdef CONFIG_X86_64
+
+#include <asm/inst.h>
+
+.macro RDGSBASE opd
+	REG_TYPE rdgsbase_opd_type \opd
+	.if rdgsbase_opd_type == REG_TYPE_R64
+	R64_NUM rdgsbase_opd \opd
+	.byte 0xf3
+	PFX_REX rdgsbase_opd 0 W = 1
+	.else
+	.error "RDGSBASE: only for 64-bit value"
+	.endif
+	.byte 0xf, 0xae
+	MODRM 0xc0 rdgsbase_opd 1
+.endm
+
+.macro WRGSBASE opd
+	REG_TYPE wrgsbase_opd_type \opd
+	.if wrgsbase_opd_type == REG_TYPE_R64
+	R64_NUM wrgsbase_opd \opd
+	.byte 0xf3
+	PFX_REX wrgsbase_opd 0 W = 1
+	.else
+	.error "WRGSBASE: only for 64-bit value"
+	.endif
+	.byte 0xf, 0xae
+	MODRM 0xd0 wrgsbase_opd 1
+.endm
+
+#endif /* CONFIG_X86_64 */
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* _ASM_FSGSBASE_H */
-- 
2.7.4

  parent reply	other threads:[~2018-05-31 18:01 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-31 17:58 [PATCH V2 00/15] x86: Enable " Chang S. Bae
2018-05-31 17:58 ` [PATCH V2 01/15] x86/fsgsbase/64: Introduce FS/GS base helper functions Chang S. Bae
2018-05-31 20:14   ` Andy Lutomirski
2018-05-31 21:03     ` Bae, Chang Seok
2018-05-31 17:58 ` [PATCH V2 02/15] x86/fsgsbase/64: Make ptrace read FS/GS base accurately Chang S. Bae
2018-05-31 20:14   ` Andy Lutomirski
2018-05-31 20:31     ` hpa
2018-05-31 20:38       ` Andy Lutomirski
2018-05-31 17:58 ` [PATCH V2 03/15] x86/fsgsbase/64: Use FS/GS base helpers in core dump Chang S. Bae
2018-05-31 20:15   ` Andy Lutomirski
2018-05-31 21:03     ` Bae, Chang Seok
2018-05-31 17:58 ` [PATCH V2 04/15] x86/fsgsbase/64: Factor out load FS/GS segments from __switch_to Chang S. Bae
2018-05-31 20:16   ` Andy Lutomirski
2018-05-31 17:58 ` [PATCH V2 05/15] x86/vdso: Move out the CPU number store Chang S. Bae
2018-05-31 20:25   ` Andy Lutomirski
2018-05-31 21:06     ` Bae, Chang Seok
2018-06-05  7:02   ` [lkp-robot] [x86/vdso] f52001961d: BUG:kernel_hang_in_early-boot_stage,last_printk:Probing_EDD(edd=off_to_disable)...ok kernel test robot
2018-05-31 17:58 ` [PATCH V2 06/15] taint: Add taint for insecure Chang S. Bae
2018-05-31 20:25   ` Andy Lutomirski
2018-05-31 20:50     ` hpa
2018-05-31 17:58 ` [PATCH V2 07/15] x86/fsgsbase/64: Add 'unsafe_fsgsbase' to enable CR4.FSGSBASE Chang S. Bae
2018-05-31 17:58 ` Chang S. Bae [this message]
2018-05-31 17:58 ` [PATCH V2 09/15] x86/fsgsbase/64: Enable FSGSBASE instructions in helper functions Chang S. Bae
2018-05-31 17:58 ` [PATCH V2 10/15] x86/fsgsbase/64: Preserve FS/GS state in __switch_to if FSGSBASE is on Chang S. Bae
2018-05-31 17:58 ` [PATCH V2 11/15] x86/fsgsbase/64: When copying a thread, use FSGSBASE if enabled Chang S. Bae
2018-05-31 17:58 ` [PATCH V2 12/15] x86/fsgsbase/64: Use per-CPU base as GS base on paranoid_entry Chang S. Bae
2018-05-31 17:58 ` [PATCH V2 13/15] x86/fsgsbase/64: Enable FSGSBASE by default and add a chicken bit Chang S. Bae
2018-05-31 17:58 ` [PATCH V2 14/15] x86/elf: Enumerate kernel FSGSBASE capability in AT_HWCAP2 Chang S. Bae
2018-05-31 17:58 ` [PATCH V2 15/15] x86/fsgsbase/64: Add documentation for FSGSBASE Chang S. Bae
2018-05-31 20:37 ` [PATCH V2 00/15] x86: Enable FSGSBASE instructions Andy Lutomirski
2018-05-31 21:11   ` Bae, Chang Seok

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