Implement FIR feature flags in the FPU emulator according to features
supported and architecture level requirements. The W, L and F64 bits
have only been added at level #2 even though the features they refer to
were also included with the MIPS64r1 ISA and the W fixed-point format
also with the MIPS32r1 ISA.
This is only relevant for the full emulation mode and the emulated CFC1
instruction as well as ptrace(2) accesses.
Signed-off-by: Maciej W. Rozycki <macro@xxxxxxxxxxxxxx>
---
linux-mips-emu-fir.diff
Index: linux/arch/mips/kernel/cpu-probe.c
===================================================================
--- linux.orig/arch/mips/kernel/cpu-probe.c 2015-04-02 20:27:58.700229000 +0100
+++ linux/arch/mips/kernel/cpu-probe.c 2015-04-02 20:27:58.890231000 +0100
@@ -20,6 +20,7 @@
#include <asm/bugs.h>
#include <asm/cpu.h>
+#include <asm/cpu-features.h>
#include <asm/cpu-type.h>
#include <asm/fpu.h>
#include <asm/mipsregs.h>
@@ -31,11 +32,30 @@
#include <asm/spram.h>
#include <asm/uaccess.h>
+/*
+ * Set the FIR feature flags for the FPU emulator.
+ */
+static void cpu_set_nofpu_id(struct cpuinfo_mips *c)
+{
+ u32 value;
+
+ value = 0;
+ if (c->isa_level & (MIPS_CPU_ISA_M32R1 | MIPS_CPU_ISA_M64R1 |
+ MIPS_CPU_ISA_M32R2 | MIPS_CPU_ISA_M64R2 |
+ MIPS_CPU_ISA_M32R6 | MIPS_CPU_ISA_M64R6))
+ value |= MIPS_FPIR_D | MIPS_FPIR_S;
+ if (c->isa_level & (MIPS_CPU_ISA_M32R2 | MIPS_CPU_ISA_M64R2 |
+ MIPS_CPU_ISA_M32R6 | MIPS_CPU_ISA_M64R6))
+ value |= MIPS_FPIR_F64 | MIPS_FPIR_L | MIPS_FPIR_W;
+ c->fpu_id = value;
+}
+
static int mips_fpu_disabled;
static int __init fpu_disable(char *s)
{
- cpu_data[0].options &= ~MIPS_CPU_FPU;
+ boot_cpu_data.options &= ~MIPS_CPU_FPU;
+ cpu_set_nofpu_id(&boot_cpu_data);
mips_fpu_disabled = 1;
return 1;
@@ -1375,7 +1395,8 @@ void cpu_probe(void)
if (c->fpu_id & MIPS_FPIR_FREP)
c->options |= MIPS_CPU_FRE;
}
- }
+ } else
+ cpu_set_nofpu_id(c);
if (cpu_has_mips_r2_r6) {
c->srsets = ((read_c0_srsctl() >> 26) & 0x0f) + 1;
Index: linux/arch/mips/math-emu/cp1emu.c
===================================================================
--- linux.orig/arch/mips/math-emu/cp1emu.c 2015-04-02 20:27:57.710224000 +0100
+++ linux/arch/mips/math-emu/cp1emu.c 2015-04-02 20:27:58.894230000 +0100
@@ -45,6 +45,7 @@
#include <asm/signal.h>
#include <asm/uaccess.h>
+#include <asm/cpu-info.h>
#include <asm/processor.h>
#include <asm/fpu_emulator.h>
#include <asm/fpu.h>
@@ -853,7 +854,7 @@ static inline void cop1_cfc(struct pt_re
(void *)xcp->cp0_epc,
MIPSInst_RT(ir), value);
} else if (MIPSInst_RD(ir) == FPCREG_RID)
- value = 0;
+ value = current_cpu_data.fpu_id;
else
value = 0;
if (MIPSInst_RT(ir))
