fix VFP handling on feroceon cores

SVN-Revision: 16246
2009-06-01 12:45:50 +00:00 · 2009-06-01 12:45:50 +00:00 · 09a6262b3c
commit 09a6262b3c
parent 690cb12f3c
1 changed files with 70 additions and 0 deletions
--- a/target/linux/generic-2.6/patches-2.6.30/990-fix_feroceon_vfp_handling.patch
+++ b/target/linux/generic-2.6/patches-2.6.30/990-fix_feroceon_vfp_handling.patch
@ -0,0 +1,70 @@
+From: Catalin Marinas <catalin.marinas@arm.com>
+Date: Sat, 30 May 2009 13:00:18 +0000 (+0100)
+Subject: Fix the VFP handling on the Feroceon CPU
+X-Git-Url: http://www.linux-arm.org/git?p=linux-2.6.git;a=commitdiff_plain;h=85d6943af50537d3aec58b967ffbd3fec88453e9;hp=26584853a44c58f3d6ac7360d697a2ddcd1a3efa
+
+Fix the VFP handling on the Feroceon CPU
+
+This CPU generates synchronous VFP exceptions in a non-standard way -
+the FPEXC.EX bit set but without the FPSCR.IXE bit being set like in the
+VFP subarchitecture 1 or just the FPEXC.DEX bit like in VFP
+subarchitecture 2. The main problem is that the faulty instruction
+(which needs to be emulated in software) will be restarted several times
+(normally until a context switch disables the VFP). This patch ensures
+that the VFP exception is treated as synchronous.
+
+Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
+Cc: Nicolas Pitre <nico@cam.org>
+---
+
+--- a/arch/arm/vfp/vfphw.S
+++ b/arch/arm/vfp/vfphw.S
+@@ -100,6 +100,7 @@ ENTRY(vfp_support_entry)
+ 	beq	no_old_VFP_process
+ 	VFPFSTMIA r4, r5		@ save the working registers
+ 	VFPFMRX	r5, FPSCR		@ current status
+#ifndef CONFIG_CPU_FEROCEON
+ 	tst	r1, #FPEXC_EX		@ is there additional state to save?
+ 	beq	1f
+ 	VFPFMRX	r6, FPINST		@ FPINST (only if FPEXC.EX is set)
+@@ -107,6 +108,7 @@ ENTRY(vfp_support_entry)
+ 	beq	1f
+ 	VFPFMRX	r8, FPINST2		@ FPINST2 if needed (and present)
+ 1:
+#endif
+ 	stmia	r4, {r1, r5, r6, r8}	@ save FPEXC, FPSCR, FPINST, FPINST2
+ 					@ and point r4 at the word at the
+ 					@ start of the register dump
+@@ -119,6 +121,7 @@ no_old_VFP_process:
+ 	VFPFLDMIA r10, r5		@ reload the working registers while
+ 					@ FPEXC is in a safe state
+ 	ldmia	r10, {r1, r5, r6, r8}	@ load FPEXC, FPSCR, FPINST, FPINST2
+#ifndef CONFIG_CPU_FEROCEON
+ 	tst	r1, #FPEXC_EX		@ is there additional state to restore?
+ 	beq	1f
+ 	VFPFMXR	FPINST, r6		@ restore FPINST (only if FPEXC.EX is set)
+@@ -126,6 +129,7 @@ no_old_VFP_process:
+ 	beq	1f
+ 	VFPFMXR	FPINST2, r8		@ FPINST2 if needed (and present)
+ 1:
+#endif
+ 	VFPFMXR	FPSCR, r5		@ restore status
+ 
+ check_for_exception:
+--- a/arch/arm/vfp/vfpmodule.c
+++ b/arch/arm/vfp/vfpmodule.c
+@@ -253,12 +253,14 @@ void VFP_bounce(u32 trigger, u32 fpexc, 
+ 	}
+ 
+ 	if (fpexc & FPEXC_EX) {
+#ifndef CONFIG_CPU_FEROCEON
+ 		/*
+ 		 * Asynchronous exception. The instruction is read from FPINST
+ 		 * and the interrupted instruction has to be restarted.
+ 		 */
+ 		trigger = fmrx(FPINST);
+ 		regs->ARM_pc -= 4;
+#endif
+ 	} else if (!(fpexc & FPEXC_DEX)) {
+ 		/*
+ 		 * Illegal combination of bits. It can be caused by an