Add a config option to disable the FPU emulator.
Saves around 56kB on 32bit, and kills FPU users with SIGILL.
Signed-off-by: Manuel Lauss <manuel.lauss@xxxxxxxxx>
---
arch/mips/Kbuild | 2 ++
arch/mips/Kconfig | 14 ++++++++++++++
arch/mips/include/asm/fpu.h | 2 ++
arch/mips/include/asm/fpu_emulator.h | 24 +++++++++++++++++++++++-
4 files changed, 41 insertions(+), 1 deletion(-)
diff --git a/arch/mips/Kbuild b/arch/mips/Kbuild
index d2cfe45..da76dc0 100644
--- a/arch/mips/Kbuild
+++ b/arch/mips/Kbuild
@@ -16,7 +16,9 @@ obj- := $(platform-)
obj-y += kernel/
obj-y += mm/
+ifdef CONFIG_MIPS_FPU_EMULATOR
obj-y += math-emu/
+endif
ifdef CONFIG_KVM
obj-y += kvm/
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 9b53358..9a8d7ed 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -2482,6 +2482,20 @@ config MIPS_O32_FP64_SUPPORT
If unsure, say N.
+config MIPS_FPU_EMULATOR
+ bool "Support for MIPS FPU Emulator"
+ default y
+ help
+ This option lets you disable the built-in MIPS FPU (Cop1)
+ Emulator. This emulator executes floating-point instructions on
+ processors which don't have a built-in floating point unit.
+ It is generally a very good idea to keep this support built in,
+ only disable it if you have a complete soft-float userland.
+ Any use of floating point operations in userspace will result in
+ the process being killed with an illegal instruction exception.
+
+ Say Y, please.
+
config USE_OF
bool
select OF
diff --git a/arch/mips/include/asm/fpu.h b/arch/mips/include/asm/fpu.h
index 4d86b72..d6c3d97 100644
--- a/arch/mips/include/asm/fpu.h
+++ b/arch/mips/include/asm/fpu.h
@@ -161,7 +161,9 @@ static inline int init_fpu(void)
if (!ret)
_init_fpu();
} else {
+#ifdef CONFIG_MIPS_FPU_EMULATOR
fpu_emulator_init_fpu();
+#endif
}
preempt_enable();
diff --git a/arch/mips/include/asm/fpu_emulator.h b/arch/mips/include/asm/fpu_emulator.h
index 2abb587..b2c1524 100644
--- a/arch/mips/include/asm/fpu_emulator.h
+++ b/arch/mips/include/asm/fpu_emulator.h
@@ -53,13 +53,35 @@ do { \
extern int mips_dsemul(struct pt_regs *regs, mips_instruction ir,
unsigned long cpc);
+int process_fpemu_return(int sig, void __user *fault_addr);
+
+#ifdef CONFIG_MIPS_FPU_EMULATOR
extern int do_dsemulret(struct pt_regs *xcp);
extern int fpu_emulator_cop1Handler(struct pt_regs *xcp,
struct mips_fpu_struct *ctx, int has_fpu,
void *__user *fault_addr);
-int process_fpemu_return(int sig, void __user *fault_addr);
int mm_isBranchInstr(struct pt_regs *regs, struct mm_decoded_insn dec_insn,
unsigned long *contpc);
+#else /* no CONFIG_MIPS_FPU_EMULATOR */
+static inline int do_dsemulret(struct pt_regs *xcp)
+{
+ return 0; /* 0 means error, should never get here anyway */
+}
+
+static inline int fpu_emulator_cop1Handler(struct pt_regs *xcp,
+ struct mips_fpu_struct *ctx, int has_fpu,
+ void *__user *fault_addr)
+{
+ return SIGILL; /* we don't speak MIPS FPU */
+}
+
+static inline int mm_isBranchInstr(struct pt_regs *regs,
+ struct mm_decoded_insn dec_insn,
+ unsigned long *contpc)
+{
+ return 0;
+}
+#endif /* CONFIG_MIPS_FPU_EMULATOR */
/*
* Instruction inserted following the badinst to further tag the sequence
--
1.9.1
