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/entry-arcv2.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/entry-arcv2.h')
| -rw-r--r-- | arch/arc/include/asm/entry-arcv2.h | 17 |
1 files changed, 6 insertions, 11 deletions
diff --git a/arch/arc/include/asm/entry-arcv2.h b/arch/arc/include/asm/entry-arcv2.h index 0ff4c0610561..858742feab71 100644 --- a/arch/arc/include/asm/entry-arcv2.h +++ b/arch/arc/include/asm/entry-arcv2.h @@ -18,7 +18,6 @@ * | orig_r0 | * | event/ECR | * | bta | - * | user_r25 | * | gp | * | fp | * | sp | @@ -56,7 +55,7 @@ ; hardware does even if CONFIG_ARC_IRQ_NO_AUTOSAVE ; 4. Auto save: (optional) r0-r11, blink, LPE,LPS,LPC, JLI,LDI,EI ; - ; (B) Manually saved some regs: r12,r25,r30, sp,fp,gp, ACCL pair + ; (B) Manually saved some regs: r12,r30, sp,fp,gp, ACCL pair #ifdef CONFIG_ARC_IRQ_NO_AUTOSAVE ; carve pt_regs on stack (case #3), PC/STAT32 already on stack @@ -157,17 +156,17 @@ st r10, [sp, PT_sp] ; SP (pt_regs->sp) -#ifdef CONFIG_ARC_CURR_IN_REG - st r25, [sp, PT_user_r25] - GET_CURR_TASK_ON_CPU r25 -#endif - #ifdef CONFIG_ARC_HAS_ACCL_REGS ST2 r58, r59, PT_r58 #endif /* clobbers r10, r11 registers pair */ DSP_SAVE_REGFILE_IRQ + +#ifdef CONFIG_ARC_CURR_IN_REG + GET_CURR_TASK_ON_CPU gp +#endif + .endm /*------------------------------------------------------------------------*/ @@ -188,10 +187,6 @@ sr r10, [AUX_USER_SP] 1: -#ifdef CONFIG_ARC_CURR_IN_REG - ld r25, [sp, PT_user_r25] -#endif - /* clobbers r10, r11 registers pair */ DSP_RESTORE_REGFILE_IRQ |