Skip to content

[arch][arm64] enable cycle counter #509

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
caseydapro2020 wants to merge 1 commit into from
+40 −4
Closed

[arch][arm64] enable cycle counter #509

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
34 changes: 33 additions & 1 deletion arch/arm64/arch.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -25,9 +25,41 @@

#define LOCAL_TRACE 0

#define ID_AA64DFR0_PMUVER_SHIFT 8
#define ID_AA64DFR0_PMUVER_MASK (0xfU << ID_AA64DFR0_PMUVER_SHIFT)
#define ID_AA64DFR0_PMUVER_NONE 0
#define ID_AA64DFR0_PMUVER_IMPDEF 0xf

#define PMCR_EL0_E (1U << 0)
#define PMCR_EL0_C (1U << 2)
#define PMCR_EL0_D (1U << 3)

#define PMCNTENSET_EL0_C (1U << 31)

/* Defined in start.S. */
extern uint64_t arm64_boot_el;

bool arm64_cycle_counter_enabled;

static void arm64_enable_cycle_counter(void) {
uint64_t dfr0 = ARM64_READ_SYSREG(id_aa64dfr0_el1);
uint pmuver = (dfr0 & ID_AA64DFR0_PMUVER_MASK) >> ID_AA64DFR0_PMUVER_SHIFT;

if (pmuver == ID_AA64DFR0_PMUVER_NONE || pmuver == ID_AA64DFR0_PMUVER_IMPDEF) {
arm64_cycle_counter_enabled = false;
return;
}

uint64_t pmcr = ARM64_READ_SYSREG(pmcr_el0);
pmcr |= PMCR_EL0_E | PMCR_EL0_C;
pmcr &= ~PMCR_EL0_D;

ARM64_WRITE_SYSREG(pmcr_el0, pmcr);
ARM64_WRITE_SYSREG(pmcntenset_el0, PMCNTENSET_EL0_C);

arm64_cycle_counter_enabled = true;
}

// initial setup per cpu immediately after entering C code
void arm64_early_init_percpu(void) {
// set the vector base
Expand Down Expand Up @@ -63,7 +95,7 @@ void arm64_early_init_percpu(void) {
ARM64_WRITE_SYSREG(TPIDRRO_EL0, 0UL);

// TODO: read feature bits on cpu 0
// TODO: enable cycle counter if present
arm64_enable_cycle_counter();

arch_enable_fiqs();
}
Expand Down
10 changes: 7 additions & 3 deletions arch/arm64/include/arch/arch_ops.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,8 @@ __BEGIN_CDECLS

#define ENABLE_CYCLE_COUNTER 1

extern bool arm64_cycle_counter_enabled;

void arch_stacktrace(uint64_t fp, uint64_t pc);

static inline void arch_enable_fiqs(void) {
Expand Down Expand Up @@ -57,8 +59,11 @@ static inline bool arch_fiqs_disabled(void) {
#endif

static inline ulong arch_cycle_count(void) {
//#warning no arch_cycle_count implementation
return 0;
if (!arm64_cycle_counter_enabled) {
return 0;
}

return ARM64_READ_SYSREG(pmccntr_el0);
}

/* use the cpu local thread context pointer to store current_thread */
Expand All @@ -73,4 +78,3 @@ static inline void arch_set_current_thread(struct thread *t) {
__END_CDECLS

#endif // ASSEMBLY

Loading