From 9b26616c8d9dae53fbac7f7cb2c6dd1308102976 Mon Sep 17 00:00:00 2001 From: "Maciej W. Rozycki" Date: Fri, 3 Apr 2015 23:27:48 +0100 Subject: MIPS: Respect the ISA level in FCSR handling Define the central place the default FCSR value is set from, initialised in `cpu_probe'. Determine the FCSR mask applied to values written to the register with CTC1 in the full emulation mode and via ptrace(2), according to the ISA level of processor hardware or the writability of bits 31:18 if actual FPU hardware is used. Software may rely on FCSR bits whose functions our emulator does not implement, so it should not allow them to be set or software may get confused. For ptrace(2) it's just sanity. [ralf@linux-mips.org: Fixed double inclusion of .] Signed-off-by: Maciej W. Rozycki Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/9711/ Signed-off-by: Ralf Baechle --- arch/mips/kernel/cpu-probe.c | 53 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 53 insertions(+) (limited to 'arch/mips/kernel/cpu-probe.c') diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c index ca9b9c62c6ea..2911ad5977d7 100644 --- a/arch/mips/kernel/cpu-probe.c +++ b/arch/mips/kernel/cpu-probe.c @@ -32,6 +32,35 @@ #include #include +/* + * Determine the FCSR mask for FPU hardware. + */ +static inline void cpu_set_fpu_fcsr_mask(struct cpuinfo_mips *c) +{ + unsigned long sr, mask, fcsr, fcsr0, fcsr1; + + mask = FPU_CSR_ALL_X | FPU_CSR_ALL_E | FPU_CSR_ALL_S | FPU_CSR_RM; + + sr = read_c0_status(); + __enable_fpu(FPU_AS_IS); + + fcsr = read_32bit_cp1_register(CP1_STATUS); + + fcsr0 = fcsr & mask; + write_32bit_cp1_register(CP1_STATUS, fcsr0); + fcsr0 = read_32bit_cp1_register(CP1_STATUS); + + fcsr1 = fcsr | ~mask; + write_32bit_cp1_register(CP1_STATUS, fcsr1); + fcsr1 = read_32bit_cp1_register(CP1_STATUS); + + write_32bit_cp1_register(CP1_STATUS, fcsr); + + write_c0_status(sr); + + c->fpu_msk31 = ~(fcsr0 ^ fcsr1) & ~mask; +} + /* * Set the FIR feature flags for the FPU emulator. */ @@ -50,11 +79,15 @@ static void cpu_set_nofpu_id(struct cpuinfo_mips *c) c->fpu_id = value; } +/* Determined FPU emulator mask to use for the boot CPU with "nofpu". */ +static unsigned int mips_nofpu_msk31; + static int mips_fpu_disabled; static int __init fpu_disable(char *s) { boot_cpu_data.options &= ~MIPS_CPU_FPU; + boot_cpu_data.fpu_msk31 = mips_nofpu_msk31; cpu_set_nofpu_id(&boot_cpu_data); mips_fpu_disabled = 1; @@ -597,6 +630,7 @@ static inline void cpu_probe_legacy(struct cpuinfo_mips *c, unsigned int cpu) case PRID_IMP_R2000: c->cputype = CPU_R2000; __cpu_name[cpu] = "R2000"; + c->fpu_msk31 |= FPU_CSR_CONDX | FPU_CSR_FS; c->options = MIPS_CPU_TLB | MIPS_CPU_3K_CACHE | MIPS_CPU_NOFPUEX; if (__cpu_has_fpu()) @@ -616,6 +650,7 @@ static inline void cpu_probe_legacy(struct cpuinfo_mips *c, unsigned int cpu) c->cputype = CPU_R3000; __cpu_name[cpu] = "R3000"; } + c->fpu_msk31 |= FPU_CSR_CONDX | FPU_CSR_FS; c->options = MIPS_CPU_TLB | MIPS_CPU_3K_CACHE | MIPS_CPU_NOFPUEX; if (__cpu_has_fpu()) @@ -664,6 +699,7 @@ static inline void cpu_probe_legacy(struct cpuinfo_mips *c, unsigned int cpu) } set_isa(c, MIPS_CPU_ISA_III); + c->fpu_msk31 |= FPU_CSR_CONDX; c->options = R4K_OPTS | MIPS_CPU_FPU | MIPS_CPU_32FPR | MIPS_CPU_WATCH | MIPS_CPU_VCE | MIPS_CPU_LLSC; @@ -671,6 +707,7 @@ static inline void cpu_probe_legacy(struct cpuinfo_mips *c, unsigned int cpu) break; case PRID_IMP_VR41XX: set_isa(c, MIPS_CPU_ISA_III); + c->fpu_msk31 |= FPU_CSR_CONDX; c->options = R4K_OPTS; c->tlbsize = 32; switch (c->processor_id & 0xf0) { @@ -712,6 +749,7 @@ static inline void cpu_probe_legacy(struct cpuinfo_mips *c, unsigned int cpu) c->cputype = CPU_R4300; __cpu_name[cpu] = "R4300"; set_isa(c, MIPS_CPU_ISA_III); + c->fpu_msk31 |= FPU_CSR_CONDX; c->options = R4K_OPTS | MIPS_CPU_FPU | MIPS_CPU_32FPR | MIPS_CPU_LLSC; c->tlbsize = 32; @@ -720,6 +758,7 @@ static inline void cpu_probe_legacy(struct cpuinfo_mips *c, unsigned int cpu) c->cputype = CPU_R4600; __cpu_name[cpu] = "R4600"; set_isa(c, MIPS_CPU_ISA_III); + c->fpu_msk31 |= FPU_CSR_CONDX; c->options = R4K_OPTS | MIPS_CPU_FPU | MIPS_CPU_32FPR | MIPS_CPU_LLSC; c->tlbsize = 48; @@ -735,11 +774,13 @@ static inline void cpu_probe_legacy(struct cpuinfo_mips *c, unsigned int cpu) c->cputype = CPU_R4650; __cpu_name[cpu] = "R4650"; set_isa(c, MIPS_CPU_ISA_III); + c->fpu_msk31 |= FPU_CSR_CONDX; c->options = R4K_OPTS | MIPS_CPU_FPU | MIPS_CPU_LLSC; c->tlbsize = 48; break; #endif case PRID_IMP_TX39: + c->fpu_msk31 |= FPU_CSR_CONDX | FPU_CSR_FS; c->options = MIPS_CPU_TLB | MIPS_CPU_TX39_CACHE; if ((c->processor_id & 0xf0) == (PRID_REV_TX3927 & 0xf0)) { @@ -765,6 +806,7 @@ static inline void cpu_probe_legacy(struct cpuinfo_mips *c, unsigned int cpu) c->cputype = CPU_R4700; __cpu_name[cpu] = "R4700"; set_isa(c, MIPS_CPU_ISA_III); + c->fpu_msk31 |= FPU_CSR_CONDX; c->options = R4K_OPTS | MIPS_CPU_FPU | MIPS_CPU_32FPR | MIPS_CPU_LLSC; c->tlbsize = 48; @@ -773,6 +815,7 @@ static inline void cpu_probe_legacy(struct cpuinfo_mips *c, unsigned int cpu) c->cputype = CPU_TX49XX; __cpu_name[cpu] = "R49XX"; set_isa(c, MIPS_CPU_ISA_III); + c->fpu_msk31 |= FPU_CSR_CONDX; c->options = R4K_OPTS | MIPS_CPU_LLSC; if (!(c->processor_id & 0x08)) c->options |= MIPS_CPU_FPU | MIPS_CPU_32FPR; @@ -814,6 +857,7 @@ static inline void cpu_probe_legacy(struct cpuinfo_mips *c, unsigned int cpu) c->cputype = CPU_R6000; __cpu_name[cpu] = "R6000"; set_isa(c, MIPS_CPU_ISA_II); + c->fpu_msk31 |= FPU_CSR_CONDX | FPU_CSR_FS; c->options = MIPS_CPU_TLB | MIPS_CPU_FPU | MIPS_CPU_LLSC; c->tlbsize = 32; @@ -822,6 +866,7 @@ static inline void cpu_probe_legacy(struct cpuinfo_mips *c, unsigned int cpu) c->cputype = CPU_R6000A; __cpu_name[cpu] = "R6000A"; set_isa(c, MIPS_CPU_ISA_II); + c->fpu_msk31 |= FPU_CSR_CONDX | FPU_CSR_FS; c->options = MIPS_CPU_TLB | MIPS_CPU_FPU | MIPS_CPU_LLSC; c->tlbsize = 32; @@ -893,12 +938,14 @@ static inline void cpu_probe_legacy(struct cpuinfo_mips *c, unsigned int cpu) __cpu_name[cpu] = "ICT Loongson-2"; set_elf_platform(cpu, "loongson2e"); set_isa(c, MIPS_CPU_ISA_III); + c->fpu_msk31 |= FPU_CSR_CONDX; break; case PRID_REV_LOONGSON2F: c->cputype = CPU_LOONGSON2; __cpu_name[cpu] = "ICT Loongson-2"; set_elf_platform(cpu, "loongson2f"); set_isa(c, MIPS_CPU_ISA_III); + c->fpu_msk31 |= FPU_CSR_CONDX; break; case PRID_REV_LOONGSON3A: c->cputype = CPU_LOONGSON3; @@ -1335,6 +1382,9 @@ void cpu_probe(void) c->cputype = CPU_UNKNOWN; c->writecombine = _CACHE_UNCACHED; + c->fpu_csr31 = FPU_CSR_RN; + c->fpu_msk31 = FPU_CSR_RSVD | FPU_CSR_ABS2008 | FPU_CSR_NAN2008; + c->processor_id = read_c0_prid(); switch (c->processor_id & PRID_COMP_MASK) { case PRID_COMP_LEGACY: @@ -1393,6 +1443,7 @@ void cpu_probe(void) if (c->options & MIPS_CPU_FPU) { c->fpu_id = cpu_get_fpu_id(); + mips_nofpu_msk31 = c->fpu_msk31; if (c->isa_level & (MIPS_CPU_ISA_M32R1 | MIPS_CPU_ISA_M64R1 | MIPS_CPU_ISA_M32R2 | MIPS_CPU_ISA_M64R2 | @@ -1402,6 +1453,8 @@ void cpu_probe(void) if (c->fpu_id & MIPS_FPIR_FREP) c->options |= MIPS_CPU_FRE; } + + cpu_set_fpu_fcsr_mask(c); } else cpu_set_nofpu_id(c); 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