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| 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/signal32.c | |
| parent | MIPS: Remove unused {en,dis}able_fpu macros (diff) | |
| download | linux-dev-597ce1723e0fa0bdbe2ae4c94f18da6e29b92635.tar.xz linux-dev-597ce1723e0fa0bdbe2ae4c94f18da6e29b92635.zip | |
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/signal32.c')
| -rw-r--r-- | arch/mips/kernel/signal32.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/arch/mips/kernel/signal32.c b/arch/mips/kernel/signal32.c index 1905a419aa46..3d60f7750fa8 100644 --- a/arch/mips/kernel/signal32.c +++ b/arch/mips/kernel/signal32.c @@ -85,8 +85,9 @@ static int protected_save_fp_context32(struct sigcontext32 __user *sc) int err; while (1) { lock_fpu_owner(); - own_fpu_inatomic(1); - err = save_fp_context32(sc); /* this might fail */ + err = own_fpu_inatomic(1); + if (!err) + err = save_fp_context32(sc); /* this might fail */ unlock_fpu_owner(); if (likely(!err)) break; @@ -105,8 +106,9 @@ static int protected_restore_fp_context32(struct sigcontext32 __user *sc) int err, tmp __maybe_unused; while (1) { lock_fpu_owner(); - own_fpu_inatomic(0); - err = restore_fp_context32(sc); /* this might fail */ + err = own_fpu_inatomic(0); + if (!err) + err = restore_fp_context32(sc); /* this might fail */ unlock_fpu_owner(); if (likely(!err)) break; |