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From: Andy Lutomirski <luto@kernel.org>
To: x86@kernel.org
Cc: linux-kernel@vger.kernel.org, Borislav Petkov <bp@alien8.de>,
	Brian Gerst <brgerst@gmail.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Juergen Gross <jgross@suse.com>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	Kees Cook <keescook@chromium.org>,
	Andy Lutomirski <luto@kernel.org>
Subject: [RFC 02/17] x86/asm/64: Split the iret-to-user and iret-to-kernel paths
Date: Wed,  6 Sep 2017 14:36:47 -0700	[thread overview]
Message-ID: <7dfe73f228cc904460715552fa2ab5707f4b49fd.1504733277.git.luto@kernel.org> (raw)
In-Reply-To: <cover.1504733277.git.luto@kernel.org>
In-Reply-To: <cover.1504733277.git.luto@kernel.org>

These code paths will diverge soon.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
---
 arch/x86/entry/entry_64.S        | 20 +++++++++++---------
 arch/x86/entry/entry_64_compat.S |  2 +-
 arch/x86/kernel/head_64.S        |  2 +-
 3 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index a0ebeeb9d12f..34156d50c3d6 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -315,7 +315,7 @@ syscall_return_via_sysret:
 
 opportunistic_sysret_failed:
 	SWAPGS
-	jmp	restore_regs_and_iret
+	jmp	restore_regs_and_return_to_usermode
 END(entry_SYSCALL_64)
 
 ENTRY(stub_ptregs_64)
@@ -412,7 +412,7 @@ ENTRY(ret_from_fork)
 	call	syscall_return_slowpath	/* returns with IRQs disabled */
 	TRACE_IRQS_ON			/* user mode is traced as IRQS on */
 	SWAPGS
-	jmp	restore_regs_and_iret
+	jmp	restore_regs_and_return_to_usermode
 
 1:
 	/* kernel thread */
@@ -524,7 +524,13 @@ GLOBAL(retint_user)
 	call	prepare_exit_to_usermode
 	TRACE_IRQS_IRETQ
 	SWAPGS
-	jmp	restore_regs_and_iret
+
+GLOBAL(restore_regs_and_return_to_usermode)
+	RESTORE_EXTRA_REGS
+	RESTORE_C_REGS
+	REMOVE_PT_GPREGS_FROM_STACK 8
+	INTERRUPT_RETURN
+
 
 /* Returning to kernel space */
 retint_kernel:
@@ -544,11 +550,7 @@ retint_kernel:
 	 */
 	TRACE_IRQS_IRETQ
 
-/*
- * At this label, code paths which return to kernel and to user,
- * which come from interrupts/exception and from syscalls, merge.
- */
-GLOBAL(restore_regs_and_iret)
+GLOBAL(restore_regs_and_return_to_kernel)
 	RESTORE_EXTRA_REGS
 	RESTORE_C_REGS
 	REMOVE_PT_GPREGS_FROM_STACK 8
@@ -1264,7 +1266,7 @@ ENTRY(nmi)
 	 * work, because we don't want to enable interrupts.
 	 */
 	SWAPGS
-	jmp	restore_regs_and_iret
+	jmp	restore_regs_and_return_to_usermode
 
 .Lnmi_from_kernel:
 	/*
diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index 5314d7b8e5ad..e4ab8ffa94b1 100644
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -338,7 +338,7 @@ ENTRY(entry_INT80_compat)
 	/* Go back to user mode. */
 	TRACE_IRQS_ON
 	SWAPGS
-	jmp	restore_regs_and_iret
+	jmp	restore_regs_and_return_to_usermode
 END(entry_INT80_compat)
 
 	ALIGN
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 6225550883df..63fa56ead56e 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -310,7 +310,7 @@ early_idt_handler_common:
 
 20:
 	decl early_recursion_flag(%rip)
-	jmp restore_regs_and_iret
+	jmp restore_regs_and_return_to_kernel
 ENDPROC(early_idt_handler_common)
 
 	__INITDATA
-- 
2.13.5

  parent reply	other threads:[~2017-09-06 21:37 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-09-06 21:36 [RFC 00/17] Pile o' entry stack changes Andy Lutomirski
2017-09-06 21:36 ` [RFC 01/17] x86/asm/64: Remove the restore_c_regs_and_iret label Andy Lutomirski
2017-09-07  9:40   ` Borislav Petkov
2017-09-07  9:46     ` Ingo Molnar
2017-09-07  9:49       ` Ingo Molnar
2017-09-07  9:57         ` Borislav Petkov
2017-09-07 10:29           ` Ingo Molnar
2017-09-06 21:36 ` Andy Lutomirski [this message]
2017-09-06 21:36 ` [RFC 03/17] x86/asm/64: Move SWAPGS into the common iret-to-usermode path Andy Lutomirski
2017-09-06 21:36 ` [RFC 04/17] x86/asm/64: Simplify reg restore code in the standard IRET paths Andy Lutomirski
2017-09-12 20:05   ` Josh Poimboeuf
2017-09-06 21:36 ` [RFC 05/17] x86/asm/64: Shrink paranoid_exit_restore and make labels local Andy Lutomirski
2017-09-06 21:36 ` [RFC 06/17] x86/asm/64: Use pop instead of movq in syscall_return_via_sysret Andy Lutomirski
2017-09-06 21:36 ` [RFC 07/17] x86/asm/64: Merge the fast and slow SYSRET paths Andy Lutomirski
2017-09-06 21:36 ` [RFC 08/17] x86/asm/64: De-Xen-ify our NMI code Andy Lutomirski
2017-09-07  9:34   ` Juergen Gross
2017-09-07 18:38     ` Andy Lutomirski
2017-09-08  4:26       ` Juergen Gross
2017-09-06 21:36 ` [RFC 09/17] x86/asm/32: Pull MSR_IA32_SYSENTER_CS update code out of native_load_sp0() Andy Lutomirski
2017-09-12 20:06   ` Josh Poimboeuf
2017-09-06 21:36 ` [RFC 10/17] x86/asm/64: Pass sp0 directly to load_sp0() Andy Lutomirski
2017-09-06 21:36 ` [RFC 11/17] x86/asm: Add task_top_of_stack() to find the top of a task's stack Andy Lutomirski
2017-09-06 21:36 ` [RFC 12/17] x86/xen/64: Clean up SP code in cpu_initialize_context() Andy Lutomirski
2017-09-12 20:09   ` Josh Poimboeuf
2017-09-06 21:36 ` [RFC 13/17] x86/boot/64: Stop initializing TSS.sp0 at boot Andy Lutomirski
2017-09-06 21:36 ` [RFC 14/17] x86/asm/64: Remove all remaining direct thread_struct::sp0 reads Andy Lutomirski
2017-09-06 21:37 ` [RFC 15/17] x86/boot/32: Fix cpu_current_top_of_stack initialization at boot Andy Lutomirski
2017-09-06 21:37 ` [RFC 16/17] x86/asm/64: Remove thread_struct::sp0 Andy Lutomirski
2017-09-06 21:37 ` [RFC 17/17] x86/traps: Use a new on_thread_stack() helper to clean up an assertion Andy Lutomirski
2017-09-12 20:11   ` Josh Poimboeuf
2017-09-12 20:25     ` Andrew Cooper
2017-09-06 22:16 ` [RFC 00/17] Pile o' entry stack changes Andi Kleen
2017-09-07  0:01   ` Andy Lutomirski
2017-09-07  7:04     ` Ingo Molnar

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