On 20/03/2023 08.03, Nicholas Piggin wrote:
This consolidates several implementations, and it no longer leaves
MSR[EE] enabled after the decrementer interrupt is handled, but
rather disables it on return.
The handler no longer allows a continuous ticking, but rather dec
has to be re-armed and EE re-enabled (e.g., via H_CEDE hcall) each
time.
Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx>
---
lib/powerpc/asm/handlers.h | 2 +-
lib/powerpc/asm/ppc_asm.h | 1 +
lib/powerpc/asm/processor.h | 7 +++++++
lib/powerpc/handlers.c | 10 ++++-----
lib/powerpc/processor.c | 42 +++++++++++++++++++++++++++++++++++++
powerpc/sprs.c | 6 +-----
powerpc/tm.c | 20 +-----------------
7 files changed, 57 insertions(+), 31 deletions(-)
diff --git a/lib/powerpc/asm/handlers.h b/lib/powerpc/asm/handlers.h
index 64ba727..e4a0cd4 100644
--- a/lib/powerpc/asm/handlers.h
+++ b/lib/powerpc/asm/handlers.h
@@ -3,6 +3,6 @@
#include <asm/ptrace.h>
-void dec_except_handler(struct pt_regs *regs, void *data);
+void dec_handler_oneshot(struct pt_regs *regs, void *data);
#endif /* _ASMPOWERPC_HANDLERS_H_ */
diff --git a/lib/powerpc/asm/ppc_asm.h b/lib/powerpc/asm/ppc_asm.h
index 1b85f6b..6299ff5 100644
--- a/lib/powerpc/asm/ppc_asm.h
+++ b/lib/powerpc/asm/ppc_asm.h
@@ -36,6 +36,7 @@
#endif /* __BYTE_ORDER__ */
/* Machine State Register definitions: */
+#define MSR_EE_BIT 15 /* External Interrupts Enable */
#define MSR_SF_BIT 63 /* 64-bit mode */
#endif /* _ASMPOWERPC_PPC_ASM_H */
diff --git a/lib/powerpc/asm/processor.h b/lib/powerpc/asm/processor.h
index ac001e1..ebfeff2 100644
--- a/lib/powerpc/asm/processor.h
+++ b/lib/powerpc/asm/processor.h
@@ -20,6 +20,8 @@ static inline uint64_t get_tb(void)
extern void delay(uint64_t cycles);
extern void udelay(uint64_t us);
+extern void sleep_tb(uint64_t cycles);
+extern void usleep(uint64_t us);
static inline void mdelay(uint64_t ms)
{
@@ -27,4 +29,9 @@ static inline void mdelay(uint64_t ms)
udelay(1000);
}
+static inline void msleep(uint64_t ms)
+{
+ usleep(ms * 1000);
+}
+
#endif /* _ASMPOWERPC_PROCESSOR_H_ */
diff --git a/lib/powerpc/handlers.c b/lib/powerpc/handlers.c
index c8721e0..296f14f 100644
--- a/lib/powerpc/handlers.c
+++ b/lib/powerpc/handlers.c
@@ -9,15 +9,13 @@
#include <libcflat.h>
#include <asm/handlers.h>
#include <asm/ptrace.h>
+#include <asm/ppc_asm.h>
/*
* Generic handler for decrementer exceptions (0x900)
- * Just reset the decrementer back to the value specified when registering the
- * handler
+ * Return with MSR[EE] disabled.
*/
-void dec_except_handler(struct pt_regs *regs __unused, void *data)
+void dec_handler_oneshot(struct pt_regs *regs, void *data)
{
- uint64_t dec = *((uint64_t *) data);
-
- asm volatile ("mtdec %0" : : "r" (dec));
+ regs->msr &= ~(1UL << MSR_EE_BIT);
}
diff --git a/lib/powerpc/processor.c b/lib/powerpc/processor.c
index ec85b9d..e77a240 100644
--- a/lib/powerpc/processor.c
+++ b/lib/powerpc/processor.c
@@ -10,6 +10,8 @@
#include <asm/ptrace.h>
#include <asm/setup.h>
#include <asm/barrier.h>
+#include <asm/hcall.h>
+#include <asm/handlers.h>
static struct {
void (*func)(struct pt_regs *, void *data);
@@ -54,3 +56,43 @@ void udelay(uint64_t us)
{
delay((us * tb_hz) / 1000000);
}
+
+void sleep_tb(uint64_t cycles)
+{
+ uint64_t start, end, now;
+
+ start = now = get_tb();
+ end = start + cycles;
+
+ while (end > now) {
+ uint64_t left = end - now;
+
+ /* Could support large decrementer */
+ if (left > 0x7fffffff)
+ left = 0x7fffffff;
+
+ asm volatile ("mtdec %0" : : "r" (left));
+ handle_exception(0x900, &dec_handler_oneshot, NULL);
Wouldn't it be better to first call handle_exception() before moving
something into the decrementer?
+ /*
+ * H_CEDE is called with MSR[EE] clear and enables it as part
+ * of the hcall, returning with EE enabled. The dec interrupt
+ * is then taken immediately and the handler disables EE.
+ *
+ * If H_CEDE returned for any other interrupt than dec
+ * expiring, that is considered an unhandled interrupt and
+ * the test case would be stopped.
+ */
+ if (hcall(H_CEDE) != H_SUCCESS) {
+ printf("H_CEDE failed\n");
+ abort();
+ }
+ handle_exception(0x900, NULL, NULL);
+
+ now = get_tb();
+ }
+}
Thomas
