fix VFP handling on feroceon cores

SVN-Revision: 16246

diff --git 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
new file mode 100644 (file)
index 0000000..0ee18f0
--- /dev/null
+++ 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