diff options
| author | Paul Burton <paul.burton@imgtec.com> | 2013-11-22 13:12:07 +0000 |
|---|---|---|
| committer | Ralf Baechle <ralf@linux-mips.org> | 2014-01-13 23:40:56 +0100 |
| commit | 597ce1723e0fa0bdbe2ae4c94f18da6e29b92635 (patch) | |
| tree | 21f67268915b8457dd305c6bcf7ac905772fd0ee /arch/mips/kernel/traps.c | |
| parent | 56a22d21bf9744315f56b2bbd6416170f27b7765 (diff) | |
MIPS: Support for 64-bit FP with O32 binaries
CPUs implementing MIPS32 R2 may include a 64-bit FPU, just as MIPS64 CPUs
do. In order to preserve backwards compatibility a 64-bit FPU will act
like a 32-bit FPU (by accessing doubles from the least significant 32
bits of an even-odd pair of FP registers) when the Status.FR bit is
zero, again just like a mips64 CPU. The standard O32 ABI is defined
expecting a 32-bit FPU, however recent toolchains support use of a
64-bit FPU from an O32 MIPS32 executable. When an ELF executable is
built to use a 64-bit FPU a new flag (EF_MIPS_FP64) is set in the ELF
header.
With this patch the kernel will check the EF_MIPS_FP64 flag when
executing an O32 binary, and set Status.FR accordingly. The addition
of O32 64-bit FP support lessens the opportunity for optimisation in
the FPU emulator, so a CONFIG_MIPS_O32_FP64_SUPPORT Kconfig option is
introduced to allow this support to be disabled for those that don't
require it.
Inspired by an earlier patch by Leonid Yegoshin, but implemented more
cleanly & correctly.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Paul Burton <paul.burton@imgtec.com>
Patchwork: https://patchwork.linux-mips.org/patch/6154/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/kernel/traps.c')
| -rw-r--r-- | arch/mips/kernel/traps.c | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c index f9c8746be8d6..f40f688276c2 100644 --- a/arch/mips/kernel/traps.c +++ b/arch/mips/kernel/traps.c @@ -1080,7 +1080,7 @@ asmlinkage void do_cpu(struct pt_regs *regs) unsigned long old_epc, old31; unsigned int opcode; unsigned int cpid; - int status; + int status, err; unsigned long __maybe_unused flags; prev_state = exception_enter(); @@ -1153,19 +1153,19 @@ asmlinkage void do_cpu(struct pt_regs *regs) case 1: if (used_math()) /* Using the FPU again. */ - own_fpu(1); + err = own_fpu(1); else { /* First time FPU user. */ - init_fpu(); + err = init_fpu(); set_used_math(); } - if (!raw_cpu_has_fpu) { + if (!raw_cpu_has_fpu || err) { int sig; void __user *fault_addr = NULL; sig = fpu_emulator_cop1Handler(regs, ¤t->thread.fpu, 0, &fault_addr); - if (!process_fpemu_return(sig, fault_addr)) + if (!process_fpemu_return(sig, fault_addr) && !err) mt_ase_fp_affinity(); } |