linux-kernel - [PATCH 1/5] x86-32: Split cache flush handler from simd handler

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Message-Id: <1268936453-3727-2-git-send-email-brgerst@gmail.com>
Date:	Thu, 18 Mar 2010 14:20:49 -0400
From:	Brian Gerst <brgerst@...il.com>
To:	hpa@...or.com
Cc:	x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/5] x86-32: Split cache flush handler from simd handler

Make the cache flush handler a seperate function, and use
an alternative to call the appropriate handler.

Signed-off-by: Brian Gerst <brgerst@...il.com>
---
 arch/x86/kernel/entry_32.S |   16 +++++++++++++++-
 arch/x86/kernel/traps.c    |   43 ++++++++++++++++++++++++-------------------
 2 files changed, 39 insertions(+), 20 deletions(-)

diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index 44a8e0d..c3769fa 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -53,6 +53,7 @@
 #include <asm/processor-flags.h>
 #include <asm/ftrace.h>
 #include <asm/irq_vectors.h>
+#include <asm/cpufeature.h>
 
 /* Avoid __ASSEMBLER__'ifying <linux/audit.h> just for this.  */
 #include <linux/elf-em.h>
@@ -905,7 +906,20 @@ ENTRY(simd_coprocessor_error)
 	RING0_INT_FRAME
 	pushl $0
 	CFI_ADJUST_CFA_OFFSET 4
-	pushl $do_simd_coprocessor_error
+661:	pushl $do_cache_flush_error
+662:
+.section .altinstructions,"a"
+	ALIGN
+	.long 661b
+	.long 663f
+	.byte X86_FEATURE_XMM
+	.byte 662b-661b
+	.byte 664f-663f
+.previous
+.section .altinstr_replacement,"ax"	
+663:	pushl $do_simd_coprocessor_error
+664:
+.previous
 	CFI_ADJUST_CFA_OFFSET 4
 	jmp error_code
 	CFI_ENDPROC
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 1168e44..45b9cb0 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -257,6 +257,27 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code)
 }
 #endif
 
+#ifdef CONFIG_X86_32
+dotraplinkage void
+do_cache_flush_error(struct pt_regs *regs, long error_code)
+{
+	conditional_sti(regs);
+
+	/*
+	 * Handle strange cache flush from user space exception.
+	 * This is undocumented behaviour.
+	 */
+	if (regs->flags & X86_VM_MASK) {
+		handle_vm86_fault((struct kernel_vm86_regs *)regs, error_code);
+		return;
+	}
+	current->thread.trap_no = 19;
+	current->thread.error_code = error_code;
+	die_if_kernel("cache flush denied", regs, error_code);
+	force_sig(SIGSEGV, current);
+}
+#endif
+
 dotraplinkage void __kprobes
 do_general_protection(struct pt_regs *regs, long error_code)
 {
@@ -729,30 +750,14 @@ do_simd_coprocessor_error(struct pt_regs *regs, long error_code)
 	conditional_sti(regs);
 
 #ifdef CONFIG_X86_32
-	if (cpu_has_xmm) {
-		/* Handle SIMD FPU exceptions on PIII+ processors. */
-		ignore_fpu_irq = 1;
-		simd_math_error((void __user *)regs->ip);
-		return;
-	}
-	/*
-	 * Handle strange cache flush from user space exception
-	 * in all other cases.  This is undocumented behaviour.
-	 */
-	if (regs->flags & X86_VM_MASK) {
-		handle_vm86_fault((struct kernel_vm86_regs *)regs, error_code);
-		return;
-	}
-	current->thread.trap_no = 19;
-	current->thread.error_code = error_code;
-	die_if_kernel("cache flush denied", regs, error_code);
-	force_sig(SIGSEGV, current);
+	ignore_fpu_irq = 1;
 #else
 	if (!user_mode(regs) &&
 			kernel_math_error(regs, "kernel simd math error", 19))
 		return;
-	simd_math_error((void __user *)regs->ip);
 #endif
+
+	simd_math_error((void __user *)regs->ip);
 }
 
 dotraplinkage void
-- 
1.6.6.1

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