linux-kernel - [PATCH v5 03/10] x86/asm/entry: Fix asmvalidate warnings for entry_64

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Date:	Wed, 10 Jun 2015 07:06:11 -0500
From:	Josh Poimboeuf <jpoimboe@...hat.com>
To:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>
Cc:	Michal Marek <mmarek@...e.cz>,
	Peter Zijlstra <peterz@...radead.org>,
	Andy Lutomirski <luto@...nel.org>,
	Borislav Petkov <bp@...en8.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andi Kleen <andi@...stfloor.org>, x86@...nel.org,
	live-patching@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v5 03/10] x86/asm/entry: Fix asmvalidate warnings for entry_64_compat.S

Fix the following asmvalidate warnings:

   asmvalidate: arch/x86/entry/entry_64_compat.o: native_usergs_sysret32(): unsupported fallthrough at end of function
   asmvalidate: arch/x86/entry/entry_64_compat.o: entry_SYSENTER_compat()+0xcf: unsupported jump to outside of function
   asmvalidate: arch/x86/entry/entry_64_compat.o: entry_SYSENTER_compat()+0x113: unsupported jump to outside of function
   asmvalidate: arch/x86/entry/entry_64_compat.o: entry_SYSENTER_compat()+0x16d: unsupported jump to outside of function
   asmvalidate: arch/x86/entry/entry_64_compat.o: entry_SYSENTER_compat(): missing FP_SAVE/RESTORE macros
   asmvalidate: arch/x86/entry/entry_64_compat.o: .entry.text+0x56e: return instruction outside of a function

1. native_usergs_sysret32 is redirected to from a jump rather than a
   call, so it shouldn't be annotated as a function.  Change ENDPROC ->
   END accordingly.

2. Ditto for entry_SYSENTER_compat.

3. The stub functions can be called, so annotate them as functions with
   ENTRY/ENDPROC.

4. The stub functions aren't leaf functions, so save/restore the frame
   pointer with FP_SAVE/RESTORE.

5. The stub functions all jump outside of their respective functions'
   boundaries to the ia32_ptregs_common label.  Change them to be
   self-contained so they stay within their boundaries.

Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
---
 arch/x86/entry/entry_64_compat.S | 35 +++++++++++++++++++----------------
 arch/x86/include/asm/func.h      |  6 ++++++
 2 files changed, 25 insertions(+), 16 deletions(-)

diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index bb187a6..07f5ae8 100644
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -13,6 +13,7 @@
 #include <asm/irqflags.h>
 #include <asm/asm.h>
 #include <asm/smap.h>
+#include <asm/func.h>
 #include <linux/linkage.h>
 #include <linux/err.h>
 
@@ -32,7 +33,7 @@
 ENTRY(native_usergs_sysret32)
 	swapgs
 	sysretl
-ENDPROC(native_usergs_sysret32)
+END(native_usergs_sysret32)
 #endif
 
 /*
@@ -270,7 +271,7 @@ sysenter_tracesys:
 
 	RESTORE_EXTRA_REGS
 	jmp	sysenter_do_call
-ENDPROC(entry_SYSENTER_compat)
+END(entry_SYSENTER_compat)
 
 /*
  * 32-bit SYSCALL instruction entry.
@@ -523,10 +524,15 @@ ia32_tracesys:
 END(entry_INT80_compat)
 
 	.macro PTREGSCALL label, func
-	ALIGN
-GLOBAL(\label)
-	leaq	\func(%rip), %rax
-	jmp	ia32_ptregs_common
+ENTRY(\label)
+	FP_SAVE
+	leaq	\func(%rip),%rax
+	SAVE_EXTRA_REGS(8+FP_SIZE)
+	call	*%rax
+	RESTORE_EXTRA_REGS(8+FP_SIZE)
+	FP_RESTORE
+	ret
+ENDPROC(\label)
 	.endm
 
 	PTREGSCALL stub32_rt_sigreturn,	sys32_rt_sigreturn
@@ -534,9 +540,9 @@ GLOBAL(\label)
 	PTREGSCALL stub32_fork,		sys_fork
 	PTREGSCALL stub32_vfork,	sys_vfork
 
-	ALIGN
-GLOBAL(stub32_clone)
-	leaq	sys_clone(%rip), %rax
+ENTRY(stub32_clone)
+	FP_SAVE
+	leaq	sys_clone(%rip),%rax
 	/*
 	 * The 32-bit clone ABI is: clone(..., int tls_val, int *child_tidptr).
 	 * The 64-bit clone ABI is: clone(..., int *child_tidptr, int tls_val).
@@ -545,12 +551,9 @@ GLOBAL(stub32_clone)
 	 * so we need to swap arguments here before calling it:
 	 */
 	xchg	%r8, %rcx
-	jmp	ia32_ptregs_common
-
-	ALIGN
-ia32_ptregs_common:
-	SAVE_EXTRA_REGS 8
+	SAVE_EXTRA_REGS(8+FP_SIZE)
 	call	*%rax
-	RESTORE_EXTRA_REGS 8
+	RESTORE_EXTRA_REGS(8+FP_SIZE)
+	FP_RESTORE
 	ret
-END(ia32_ptregs_common)
+ENDPROC(stub32_clone)
diff --git a/arch/x86/include/asm/func.h b/arch/x86/include/asm/func.h
index 52b3225..1d923bd 100644
--- a/arch/x86/include/asm/func.h
+++ b/arch/x86/include/asm/func.h
@@ -37,6 +37,12 @@
 	.endif
 .endm
 
+#ifdef CONFIG_FRAME_POINTER
+#define FP_SIZE __ASM_SEL(4, 8)
+#else
+#define FP_SIZE 0
+#endif
+
 /*
  * This macro tells the asm validation script to ignore the instruction
  * immediately after the macro.  It should only be used in special cases where
-- 
2.1.0

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