openwrt/target/linux/generic/patches-3.18/304-mips_disable_fpu.patch
Hauke Mehrtens 5e3d188e89 kernel: add patch header and missing part in 132-mips_inline_dma_ops.patch again
The select SYS_HAS_DMA_OPS in CPU_CAVIUM_OCTEON was from the kernel
patch in 3.13, but it is only included in kernel 3.14 and not in 3.13
and 3.18, add it again.

Thank you swalker for spotting this.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>

SVN-Revision: 43134
2014-10-31 23:32:22 +00:00

106 lines
3.4 KiB
Diff

From: Manuel Lauss <manuel.lauss@gmail.com>
Subject: [RFC PATCH v4 2/2] MIPS: make FPU emulator optional
Date: Mon, 7 Apr 2014 12:57:04 +0200
Message-Id: <1396868224-252888-2-git-send-email-manuel.lauss@gmail.com>
This small patch makes the MIPS FPU emulator optional. The kernel
kills float-users on systems without a hardware FPU by sending a SIGILL.
Disabling the emulator shrinks vmlinux by about 54kBytes (32bit,
optimizing for size).
Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
---
v4: rediffed because of patch 1/2, should now work with micromips as well
v3: updated patch description with size savings.
v2: incorporated changes suggested by Jonas Gorski
force the fpu emulator on for micromips: relocating the parts
of the mmips code in the emulator to other areas would be a
much larger change; I went the cheap route instead with this.
arch/mips/Kbuild | 2 +-
arch/mips/Kconfig | 14 ++++++++++++++
arch/mips/include/asm/fpu.h | 5 +++--
arch/mips/include/asm/fpu_emulator.h | 15 +++++++++++++++
4 files changed, 33 insertions(+), 3 deletions(-)
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -2485,6 +2485,20 @@ config MIPS_O32_FP64_SUPPORT
If unsure, say N.
+config MIPS_FPU_EMULATOR
+ bool "MIPS FPU Emulator"
+ default y
+ help
+ This option lets you disable the built-in MIPS FPU (Coprocessor 1)
+ emulator, which handles floating-point instructions on processors
+ without a hardware FPU. It is generally a good idea to keep the
+ emulator built-in, unless you are perfectly sure you have a
+ complete soft-float environment. With the emulator disabled, all
+ users of float operations will be killed with an illegal instr-
+ uction exception.
+
+ Say Y, please.
+
config USE_OF
bool
select OF
--- a/arch/mips/Makefile
+++ b/arch/mips/Makefile
@@ -266,7 +266,7 @@ OBJCOPYFLAGS += --remove-section=.regin
head-y := arch/mips/kernel/head.o
libs-y += arch/mips/lib/
-libs-y += arch/mips/math-emu/
+libs-$(CONFIG_MIPS_FPU_EMULATOR) += arch/mips/math-emu/
# See arch/mips/Kbuild for content of core part of the kernel
core-y += arch/mips/
--- a/arch/mips/include/asm/fpu.h
+++ b/arch/mips/include/asm/fpu.h
@@ -168,8 +168,10 @@ static inline int init_fpu(void)
ret = __own_fpu();
if (!ret)
_init_fpu();
- } else
+ } else if (IS_ENABLED(CONFIG_MIPS_FPU_EMULATOR))
fpu_emulator_init_fpu();
+ else
+ ret = SIGILL;
return ret;
}
--- a/arch/mips/include/asm/fpu_emulator.h
+++ b/arch/mips/include/asm/fpu_emulator.h
@@ -30,6 +30,7 @@
#include <asm/local.h>
#include <asm/processor.h>
+#ifdef CONFIG_MIPS_FPU_EMULATOR
#ifdef CONFIG_DEBUG_FS
struct mips_fpu_emulator_stats {
@@ -65,6 +66,20 @@ extern int do_dsemulret(struct pt_regs *
extern int fpu_emulator_cop1Handler(struct pt_regs *xcp,
struct mips_fpu_struct *ctx, int has_fpu,
void *__user *fault_addr);
+#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 */
+}
+#endif /* CONFIG_MIPS_FPU_EMULATOR */
+
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);