diff options
| author | Chris Metcalf <cmetcalf@tilera.com> | 2013-08-06 16:04:13 -0400 |
|---|---|---|
| committer | Chris Metcalf <cmetcalf@tilera.com> | 2013-08-13 16:04:10 -0400 |
| commit | 2f9ac29eec71a696cb0dcc5fb82c0f8d4dac28c9 (patch) | |
| tree | ee33ba7e452e8614130a811211eb2383a3133194 /arch/tile/include/asm/processor.h | |
| parent | f10da5472c6907a3fbd6886224b36d21925ce47b (diff) | |
tile: fast-path unaligned memory access for tilegx
This change enables unaligned userspace memory access via a kernel
fast path on tilegx. The kernel tracks user PC/instruction pairs
per-thread using a direct-mapped cache in userspace. The cache
maps those PC/instruction pairs to JIT'ed instruction sequences that
load or store using byte-wide load store intructions and then
synthesize 2-, 4- or 8-byte load or store results. Once an
instruction has been seen to generate an unaligned access once,
subsequent hits on that instruction typically require overhead
of only around 50 cycles if cache and TLB is hot.
We support the prctl() PR_GET_UNALIGN / PR_SET_UNALIGN sys call to
enable or disable unaligned fixups on a per-process basis.
To do this we pull some of the tilepro unaligned support out of the
single_step.c file; tilepro uses instruction disassembly for both
single-step and unaligned access support. Since tilegx actually has
hardware singlestep support, though, it's cleaner to keep the tilegx
unaligned access code in a separate file. While we're at it,
properly rename the tilepro-specific types, etc., to have tilepro
suffixes instead of generic tile suffixes.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Diffstat (limited to 'arch/tile/include/asm/processor.h')
| -rw-r--r-- | arch/tile/include/asm/processor.h | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/tile/include/asm/processor.h b/arch/tile/include/asm/processor.h index b3f104953da2..cda27243fb09 100644 --- a/arch/tile/include/asm/processor.h +++ b/arch/tile/include/asm/processor.h @@ -247,6 +247,13 @@ unsigned long get_wchan(struct task_struct *p); #define KSTK_EIP(task) task_pc(task) #define KSTK_ESP(task) task_sp(task) +/* Fine-grained unaligned JIT support */ +#define GET_UNALIGN_CTL(tsk, adr) get_unalign_ctl((tsk), (adr)) +#define SET_UNALIGN_CTL(tsk, val) set_unalign_ctl((tsk), (val)) + +extern int get_unalign_ctl(struct task_struct *tsk, unsigned long adr); +extern int set_unalign_ctl(struct task_struct *tsk, unsigned int val); + /* Standard format for printing registers and other word-size data. */ #ifdef __tilegx__ # define REGFMT "0x%016lx" |