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| author |   Paul Burton <paul.burton@imgtec.com> | 2014-01-27 15:23:11 +0000 |
|---|---|---|
| committer |   Ralf Baechle <ralf@linux-mips.org> | 2014-03-26 23:09:10 +0100 |
| commit | 1db1af84d6df99a8e5d6ddea8c7b5c1327c9a620 (patch) | |
| tree | 72865fad6fa4bcfabe94ae3642a58bf28a533181 /arch/mips/include/asm/thread_info.h | |
| parent | MIPS: Detect the MSA ASE (diff) | |
| download | linux-dev-1db1af84d6df99a8e5d6ddea8c7b5c1327c9a620.tar.xz linux-dev-1db1af84d6df99a8e5d6ddea8c7b5c1327c9a620.zip | |
MIPS: Basic MSA context switching support
This patch adds support for context switching the MSA vector registers.
These 128 bit vector registers are aliased with the FP registers - an
FP register accesses the least significant bits of the vector register
with which it is aliased (ie. the register with the same index). Due to
both this & the requirement that the scalar FPU must be 64-bit (FR=1) if
enabled at the same time as MSA the kernel will enable MSA & scalar FP
at the same time for tasks which use MSA. If we restore the MSA vector
context then we might as well enable the scalar FPU since the reason it
was left disabled was to allow for lazy FP context restoring - but we
just restored the FP context as it's a subset of the vector context. If
we restore the FP context and have previously used MSA then we have to
restore the whole vector context anyway (see comment in
enable_restore_fp_context for details) so similarly we might as well
enable MSA.
Thus if a task does not use MSA then it will continue to behave as
without this patch - the scalar FP context will be saved & restored as
usual. But if a task executes an MSA instruction then it will save &
restore the vector context forever more.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6431/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/include/asm/thread_info.h')
| -rw-r--r-- | arch/mips/include/asm/thread_info.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/mips/include/asm/thread_info.h b/arch/mips/include/asm/thread_info.h index e80ae50cae80..d2d961d6cb86 100644 --- a/arch/mips/include/asm/thread_info.h +++ b/arch/mips/include/asm/thread_info.h @@ -116,6 +116,8 @@ static inline struct thread_info *current_thread_info(void) #define TIF_LOAD_WATCH 25 /* If set, load watch registers */ #define TIF_SYSCALL_TRACEPOINT 26 /* syscall tracepoint instrumentation */ #define TIF_32BIT_FPREGS 27 /* 32-bit floating point registers */ +#define TIF_USEDMSA 29 /* MSA has been used this quantum */ +#define TIF_MSA_CTX_LIVE 30 /* MSA context must be preserved */ #define TIF_SYSCALL_TRACE 31 /* syscall trace active */ #define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE) @@ -133,6 +135,8 @@ static inline struct thread_info *current_thread_info(void) #define _TIF_FPUBOUND (1<<TIF_FPUBOUND) #define _TIF_LOAD_WATCH (1<<TIF_LOAD_WATCH) #define _TIF_32BIT_FPREGS (1<<TIF_32BIT_FPREGS) +#define _TIF_USEDMSA (1<<TIF_USEDMSA) +#define _TIF_MSA_CTX_LIVE (1<<TIF_MSA_CTX_LIVE) #define _TIF_SYSCALL_TRACEPOINT (1<<TIF_SYSCALL_TRACEPOINT) #define _TIF_WORK_SYSCALL_ENTRY (_TIF_NOHZ | _TIF_SYSCALL_TRACE | \ |