diff options
| author | Kim Phillips <kim.phillips@freescale.com> | 2006-12-08 02:43:30 -0600 |
|---|---|---|
| committer | Kumar Gala <galak@kernel.crashing.org> | 2006-12-08 02:43:30 -0600 |
| commit | aa42c69c67f82e88f0726258efe7306708e1cf14 (patch) | |
| tree | d5305de3285d504e1bd1e955155e5e06b5b9ef76 /arch/powerpc/kernel | |
| parent | c99767974ebd2a719d849fdeaaa1674456f5283f (diff) | |
[POWERPC] Add support for FP emulation for the e300c2 core
The e300c2 has no FPU. Its MSR[FP] is grounded to zero. If an attempt
is made to execute a floating point instruction (including floating-point
load, store, or move instructions), the e300c2 takes a floating-point
unavailable interrupt.
This patch adds support for FP emulation on the e300c2 by declaring a
new CPU_FTR_FP_TAKES_FPUNAVAIL, where FP unavail interrupts are
intercepted and redirected to the ProgramCheck exception path for
correct emulation handling.
(If we run out of CPU_FTR bits we could look to reclaim this bit by adding
support to test the cpu_user_features for PPC_FEATURE_HAS_FPU instead)
It adds a nop to the exception path for 32-bit processors with a FPU.
Signed-off-by: Kim Phillips <kim.phillips@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/kernel')
| -rw-r--r-- | arch/powerpc/kernel/cputable.c | 2 | ||||
| -rw-r--r-- | arch/powerpc/kernel/head_32.S | 7 | ||||
| -rw-r--r-- | arch/powerpc/kernel/traps.c | 2 |
3 files changed, 10 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/cputable.c b/arch/powerpc/kernel/cputable.c index 9d1614c3ce6..11bfbaf655b 100644 --- a/arch/powerpc/kernel/cputable.c +++ b/arch/powerpc/kernel/cputable.c @@ -833,7 +833,7 @@ static struct cpu_spec cpu_specs[] = { .pvr_mask = 0x7fff0000, .pvr_value = 0x00840000, .cpu_name = "e300c2", - .cpu_features = CPU_FTRS_E300, + .cpu_features = CPU_FTRS_E300C2, .cpu_user_features = PPC_FEATURE_32 | PPC_FEATURE_HAS_MMU, .icache_bsize = 32, .dcache_bsize = 32, diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S index d88e182e40b..9417cf5b4b7 100644 --- a/arch/powerpc/kernel/head_32.S +++ b/arch/powerpc/kernel/head_32.S @@ -437,6 +437,13 @@ Alignment: /* Floating-point unavailable */ . = 0x800 FPUnavailable: +BEGIN_FTR_SECTION +/* + * Certain Freescale cores don't have a FPU and treat fp instructions + * as a FP Unavailable exception. Redirect to illegal/emulation handling. + */ + b ProgramCheck +END_FTR_SECTION_IFSET(CPU_FTR_FPU_UNAVAILABLE) EXCEPTION_PROLOG bne load_up_fpu /* if from user, just load it up */ addi r3,r1,STACK_FRAME_OVERHEAD diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c index 0d4e203fa7a..fde820e52d0 100644 --- a/arch/powerpc/kernel/traps.c +++ b/arch/powerpc/kernel/traps.c @@ -782,6 +782,8 @@ void __kprobes program_check_exception(struct pt_regs *regs) unsigned int reason = get_reason(regs); extern int do_mathemu(struct pt_regs *regs); + /* We can now get here via a FP Unavailable exception if the core + * has no FPU, in that case no reason flags will be set */ #ifdef CONFIG_MATH_EMULATION /* (reason & REASON_ILLEGAL) would be the obvious thing here, * but there seems to be a hardware bug on the 405GP (RevD) |