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authorNicholas Piggin <npiggin@gmail.com>2021-06-18 01:51:03 +1000
committerMichael Ellerman <mpe@ellerman.id.au>2021-06-25 00:06:55 +1000
commit59dc5bfca0cb6a29db1a50847684eb5c19f8f400 (patch)
treee59ddd65cf780da3df22074afee961dc8503cdc2 /arch/powerpc/kernel/rtas.c
parent1df7d5e4baeac74d14c1bee18b2dff9302b3efbc (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.c14
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