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arch: riscv: remove unneeded context switch to gp register

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RISC-V global pointer (GP) register is neither caller nor callee
register, and it's a constant value in the single ELF file. Thus, we
don't need to save/restore GP at ISR enter/exit. Remove it to optimize
context switch performance.

Signed-off-by: Jim Shu <cwshu@andestech.com>
This commit is contained in:
Jim Shu 2021-06-14 23:47:04 +08:00 • committed by Christopher Friedt
commit e3fe63a221
4 changed files with 1 additions and 6 deletions
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2
arch/riscv/core/fatal.c
View file

@ -40,7 +40,7 @@ FUNC_NORETURN void z_riscv_fatal_error(unsigned int reason,
LOG_ERR(" a6: " PR_REG " t6: " PR_REG, esf->a6, esf->t6);
LOG_ERR(" a7: " PR_REG, esf->a7);
LOG_ERR(" " NO_REG " tp: " PR_REG, esf->tp);
LOG_ERR(" ra: " PR_REG " gp: " PR_REG, esf->ra, esf->gp);
LOG_ERR(" ra: " PR_REG, esf->ra);
LOG_ERR(" mepc: " PR_REG, esf->mepc);
LOG_ERR("mstatus: " PR_REG, esf->mstatus);
LOG_ERR("");

3
arch/riscv/core/isr.S
View file

@ -122,8 +122,6 @@
RV_OP_STOREREG temp, __z_arch_esf_t_mstatus_OFFSET(to_reg) ;\
RV_OP_LOADREG temp, __z_arch_esf_t_ra_OFFSET(from_reg) ;\
RV_OP_STOREREG temp, __z_arch_esf_t_ra_OFFSET(to_reg) ;\
RV_OP_LOADREG temp, __z_arch_esf_t_gp_OFFSET(from_reg) ;\
RV_OP_STOREREG temp, __z_arch_esf_t_gp_OFFSET(to_reg) ;\
RV_OP_LOADREG temp, __z_arch_esf_t_tp_OFFSET(from_reg) ;\
RV_OP_STOREREG temp, __z_arch_esf_t_tp_OFFSET(to_reg) ;\
RV_OP_LOADREG temp, __z_arch_esf_t_t0_OFFSET(from_reg) ;\
@ -179,7 +177,6 @@
#define DO_CALLER_SAVED(op) \
op ra, __z_arch_esf_t_ra_OFFSET(sp) ;\
op gp, __z_arch_esf_t_gp_OFFSET(sp) ;\
op tp, __z_arch_esf_t_tp_OFFSET(sp) ;\
op t0, __z_arch_esf_t_t0_OFFSET(sp) ;\
op t1, __z_arch_esf_t_t1_OFFSET(sp) ;\

1
arch/riscv/core/offsets/offsets.c
View file

@ -65,7 +65,6 @@ GEN_OFFSET_SYM(_callee_saved_t, fs11);
/* esf member offsets */
GEN_OFFSET_SYM(z_arch_esf_t, ra);
GEN_OFFSET_SYM(z_arch_esf_t, gp);
GEN_OFFSET_SYM(z_arch_esf_t, tp);
GEN_OFFSET_SYM(z_arch_esf_t, t0);
GEN_OFFSET_SYM(z_arch_esf_t, t1);

1
include/arch/riscv/exp.h
View file

@ -51,7 +51,6 @@ struct soc_esf {
struct __esf {
ulong_t ra; /* return address */
ulong_t gp; /* global pointer */
ulong_t tp; /* thread pointer */
ulong_t t0; /* Caller-saved temporary register */