target/linux/generic-2.6/patches-2.6.30/990-fix_feroceon_vfp_handling.patch

   1 From: Catalin Marinas <catalin.marinas@arm.com>
   2 Date: Sat, 30 May 2009 13:00:18 +0000 (+0100)
   3 Subject: Fix the VFP handling on the Feroceon CPU
   4 X-Git-Url: http://www.linux-arm.org/git?p=linux-2.6.git;a=commitdiff_plain;h=85d6943af50537d3aec58b967ffbd3fec88453e9;hp=26584853a44c58f3d6ac7360d697a2ddcd1a3efa
   5
   6 Fix the VFP handling on the Feroceon CPU
   7
   8 This CPU generates synchronous VFP exceptions in a non-standard way -
   9 the FPEXC.EX bit set but without the FPSCR.IXE bit being set like in the
  10 VFP subarchitecture 1 or just the FPEXC.DEX bit like in VFP
  11 subarchitecture 2. The main problem is that the faulty instruction
  12 (which needs to be emulated in software) will be restarted several times
  13 (normally until a context switch disables the VFP). This patch ensures
  14 that the VFP exception is treated as synchronous.
  15
  16 Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
  17 Cc: Nicolas Pitre <nico@cam.org>
  18 ---
  19
  20 --- a/arch/arm/vfp/vfphw.S
  21 +++ b/arch/arm/vfp/vfphw.S
  22 @@ -100,6 +100,7 @@ ENTRY(vfp_support_entry)
  23         beq     no_old_VFP_process
  24         VFPFSTMIA r4, r5                @ save the working registers
  25         VFPFMRX r5, FPSCR               @ current status
  26 +#ifndef CONFIG_CPU_FEROCEON
  27         tst     r1, #FPEXC_EX           @ is there additional state to save?
  28         beq     1f
  29         VFPFMRX r6, FPINST              @ FPINST (only if FPEXC.EX is set)
  30 @@ -107,6 +108,7 @@ ENTRY(vfp_support_entry)
  31         beq     1f
  32         VFPFMRX r8, FPINST2             @ FPINST2 if needed (and present)
  33  1:
  34 +#endif
  35         stmia   r4, {r1, r5, r6, r8}    @ save FPEXC, FPSCR, FPINST, FPINST2
  36                                         @ and point r4 at the word at the
  37                                         @ start of the register dump
  38 @@ -119,6 +121,7 @@ no_old_VFP_process:
  39         VFPFLDMIA r10, r5               @ reload the working registers while
  40                                         @ FPEXC is in a safe state
  41         ldmia   r10, {r1, r5, r6, r8}   @ load FPEXC, FPSCR, FPINST, FPINST2
  42 +#ifndef CONFIG_CPU_FEROCEON
  43         tst     r1, #FPEXC_EX           @ is there additional state to restore?
  44         beq     1f
  45         VFPFMXR FPINST, r6              @ restore FPINST (only if FPEXC.EX is set)
  46 @@ -126,6 +129,7 @@ no_old_VFP_process:
  47         beq     1f
  48         VFPFMXR FPINST2, r8             @ FPINST2 if needed (and present)
  49  1:
  50 +#endif
  51         VFPFMXR FPSCR, r5               @ restore status
  52
  53  check_for_exception:
  54 --- a/arch/arm/vfp/vfpmodule.c
  55 +++ b/arch/arm/vfp/vfpmodule.c
  56 @@ -253,12 +253,14 @@ void VFP_bounce(u32 trigger, u32 fpexc,
  57         }
  58
  59         if (fpexc & FPEXC_EX) {
  60 +#ifndef CONFIG_CPU_FEROCEON
  61                 /*
  62                  * Asynchronous exception. The instruction is read from FPINST
  63                  * and the interrupted instruction has to be restarted.
  64                  */
  65                 trigger = fmrx(FPINST);
  66                 regs->ARM_pc -= 4;
  67 +#endif
  68         } else if (!(fpexc & FPEXC_DEX)) {
  69                 /*
  70                  * Illegal combination of bits. It can be caused by an