diff options
| author | Nicholas Piggin <npiggin@gmail.com> | 2021-06-18 01:51:03 +1000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2021-06-25 00:06:55 +1000 |
| commit | 59dc5bfca0cb6a29db1a50847684eb5c19f8f400 (patch) | |
| tree | e59ddd65cf780da3df22074afee961dc8503cdc2 /arch/powerpc/kernel/rtas.c | |
| parent | 1df7d5e4baeac74d14c1bee18b2dff9302b3efbc (diff) | |
powerpc/64s: avoid reloading (H)SRR registers if they are still valid
When an interrupt is taken, the SRR registers are set to return to where
it left off. Unless they are modified in the meantime, or the return
address or MSR are modified, there is no need to reload these registers
when returning from interrupt.
Introduce per-CPU flags that track the validity of SRR and HSRR
registers. These are cleared when returning from interrupt, when
using the registers for something else (e.g., OPAL calls), when
adjusting the return address or MSR of a context, and when context
switching (which changes the return address and MSR).
This improves the performance of interrupt returns.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Fold in fixup patch from Nick]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210617155116.2167984-5-npiggin@gmail.com
Diffstat (limited to 'arch/powerpc/kernel/rtas.c')
| -rw-r--r-- | arch/powerpc/kernel/rtas.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c index 6bada744402b..99f2cce635fb 100644 --- a/arch/powerpc/kernel/rtas.c +++ b/arch/powerpc/kernel/rtas.c @@ -25,6 +25,7 @@ #include <linux/reboot.h> #include <linux/syscalls.h> +#include <asm/interrupt.h> #include <asm/prom.h> #include <asm/rtas.h> #include <asm/hvcall.h> @@ -46,6 +47,13 @@ /* This is here deliberately so it's only used in this file */ void enter_rtas(unsigned long); +static inline void do_enter_rtas(unsigned long args) +{ + enter_rtas(args); + + srr_regs_clobbered(); /* rtas uses SRRs, invalidate */ +} + struct rtas_t rtas = { .lock = __ARCH_SPIN_LOCK_UNLOCKED }; @@ -384,7 +392,7 @@ static char *__fetch_rtas_last_error(char *altbuf) save_args = rtas.args; rtas.args = err_args; - enter_rtas(__pa(&rtas.args)); + do_enter_rtas(__pa(&rtas.args)); err_args = rtas.args; rtas.args = save_args; @@ -430,7 +438,7 @@ va_rtas_call_unlocked(struct rtas_args *args, int token, int nargs, int nret, for (i = 0; i < nret; ++i) args->rets[i] = 0; - enter_rtas(__pa(args)); + do_enter_rtas(__pa(args)); } void rtas_call_unlocked(struct rtas_args *args, int token, int nargs, int nret, ...) @@ -1138,7 +1146,7 @@ SYSCALL_DEFINE1(rtas, struct rtas_args __user *, uargs) flags = lock_rtas(); rtas.args = args; - enter_rtas(__pa(&rtas.args)); + do_enter_rtas(__pa(&rtas.args)); args = rtas.args; /* A -1 return code indicates that the last command couldn't |