diff options
| author | Vineet Gupta <vgupta@kernel.org> | 2020-05-12 22:18:08 -0700 |
|---|---|---|
| committer | Vineet Gupta <vgupta@kernel.org> | 2023-08-17 20:31:59 -0700 |
| commit | cfca4b5abe0cc13f9d9f45f760efd8260e31200f (patch) | |
| tree | bac7d51b9a322dbb17a9428c87aeae26aa5678ef /arch/arc/include/asm/current.h | |
| parent | fad84e39f116035ae8d550c6020107b8ac113b45 (diff) | |
ARC: entry: use gp to cache task pointer (vs. r25)
The motivation is eventual ABI considerations for ARCv3 but even without
it this change us worthwhile as diffstat reduces 100 net lines
r25 is a callee saved register, normally not saved by entry code in
pt_regs. However because of its usage in CONFIG_ARC_CURR_IN_REG it needs
to be. This in turn requires a whole bunch of special casing when we
need to access r25. Then there is distinction between user mode r25 vs.
kernel mode r25 - hence distinct SAVE_CALLEE_SAVED_{USER,KERNEL}
Instead use gp which is a scratch register and thus saved already in entry
code. This cleans things up significantly and much nocer on eyes:
- SAVE_CALLEE_SAVED_{USER,KERNEL} are now exactly same
- no special user_r25 slot in pt_reggs
Note that typical global asm registers are callee-saved (r25), but gp is
not callee-saved thus needs additional -ffixed-<reg> toggle
Signed-off-by: Vineet Gupta <vgupta@kernel.org>
Diffstat (limited to 'arch/arc/include/asm/current.h')
| -rw-r--r-- | arch/arc/include/asm/current.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/arc/include/asm/current.h b/arch/arc/include/asm/current.h index 9b9bdd3e6538..06be89f6f2f0 100644 --- a/arch/arc/include/asm/current.h +++ b/arch/arc/include/asm/current.h @@ -13,7 +13,7 @@ #ifdef CONFIG_ARC_CURR_IN_REG -register struct task_struct *curr_arc asm("r25"); +register struct task_struct *curr_arc asm("gp"); #define current (curr_arc) #else |