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| author | Ralf Baechle <ralf@linux-mips.org> | 2012-08-15 19:42:19 +0200 |
|---|---|---|
| committer | Ralf Baechle <ralf@linux-mips.org> | 2012-12-13 18:15:27 +0100 |
| commit | 51d943f07d3015998d448f9d8353f618e3fe5873 (patch) | |
| tree | 7765f573133f87148a594d2e49b3b8543c7a77cf /arch/mips | |
| parent | MIPS: Handle COP3 Unusable exception as COP1X for FP emulation (diff) | |
| download | linux-51d943f07d3015998d448f9d8353f618e3fe5873.tar.xz linux-51d943f07d3015998d448f9d8353f618e3fe5873.zip | |
MIPS: Fix for warning from FPU emulation code
The default implementation of 'cpu_has_fpu' macro calls
smp_processor_id() which causes this warning to be printed when
preemption is enabled:
[ 4.664000] Algorithmics/MIPS FPU Emulator v1.5
[ 4.676000] BUG: using smp_processor_id() in preemptible [00000000] code: ini
[ 4.700000] caller is fpu_emulator_cop1Handler+0x434/0x27b8
This problem got introduced in November 2009 by
af1d2af877ef6c36990671bc86a5b9c5bb50b1da (lmo) [MIPS: Fix emulation of
64-bit FPU on 64-bit CPUs.] rsp. da0bac33413b2888d3623dad3ad19ce76b688f07
(kernel.org) [MIPS: Fix emulation of 64-bit FPU on FPU-less 64-bit CPUs.]
in 2.6.32.
Fixed by rewriting cop1_64bit() to return a constant whenever possible
but most importantly avoid the use pf cpu_has_fpu entirely.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Reported-by: Jayachandran C <jchandra@broadcom.com>
Initial-patch-by: Jayachandran C <jchandra@broadcom.com>
Patchwork: https://patchwork.linux-mips.org/patch/4225/
Diffstat (limited to 'arch/mips')
| -rw-r--r-- | arch/mips/math-emu/cp1emu.c | 15 |
1 files changed, 8 insertions, 7 deletions
diff --git a/arch/mips/math-emu/cp1emu.c b/arch/mips/math-emu/cp1emu.c index a03bf00a1a9c..47c77e7ffbf8 100644 --- a/arch/mips/math-emu/cp1emu.c +++ b/arch/mips/math-emu/cp1emu.c @@ -171,16 +171,17 @@ static int isBranchInstr(mips_instruction * i) * In the Linux kernel, we support selection of FPR format on the * basis of the Status.FR bit. If an FPU is not present, the FR bit * is hardwired to zero, which would imply a 32-bit FPU even for - * 64-bit CPUs. For 64-bit kernels with no FPU we use TIF_32BIT_REGS - * as a proxy for the FR bit so that a 64-bit FPU is emulated. In any - * case, for a 32-bit kernel which uses the O32 MIPS ABI, only the - * even FPRs are used (Status.FR = 0). + * 64-bit CPUs so we rather look at TIF_32BIT_REGS. + * FPU emu is slow and bulky and optimizing this function offers fairly + * sizeable benefits so we try to be clever and make this function return + * a constant whenever possible, that is on 64-bit kernels without O32 + * compatibility enabled and on 32-bit kernels. */ static inline int cop1_64bit(struct pt_regs *xcp) { - if (cpu_has_fpu) - return xcp->cp0_status & ST0_FR; -#ifdef CONFIG_64BIT +#if defined(CONFIG_64BIT) && !defined(CONFIG_MIPS32_O32) + return 1; +#elif defined(CONFIG_64BIT) && defined(CONFIG_MIPS32_O32) return !test_thread_flag(TIF_32BIT_REGS); #else return 0; |