From 51d943f07d3015998d448f9d8353f618e3fe5873 Mon Sep 17 00:00:00 2001 From: Ralf Baechle Date: Wed, 15 Aug 2012 19:42:19 +0200 Subject: 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 Reported-by: Jayachandran C Initial-patch-by: Jayachandran C Patchwork: https://patchwork.linux-mips.org/patch/4225/ --- arch/mips/math-emu/cp1emu.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) (limited to 'arch/mips/math-emu') diff --git a/arch/mips/math-emu/cp1emu.c b/arch/mips/math-emu/cp1emu.c index a03bf00a1a9..47c77e7ffbf 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; -- cgit v1.2.3