Files
Matheus 91ec85d8ca panic: print backtrace on panic
Panics currently lack backtraces, which are a very useful thing to
have. Make the profiling backtrace function generic and print backtraces
using it.
2026-10-08 22:14:46 -03:00

131 lines
3.1 KiB
C

#include <kernel/init.h>
#include <string.h>
#include <arch/cpu.h>
#include <arch/cpuid.h>
#include <kernel/prof.h>
#include <logging.h>
#ifdef ENABLE_PROFILING
#define INTEL_TSC_INDEX 2
#define INTEL_TSC_INDEX_OFFSET (1lu << 34)
#define INTEL_TSC_FIXED_CTR_CTRL_OFFSET 8
#define INTEL_TSC_FIXED_CTR_CTRL_ENABLE (1 << (11))
#define INTEL_PERF_FIXED_CTR_CTRL_USER 1
#define INTEL_PERF_FIXED_CTR_CTRL_SUPERVISOR 2
#define TICK_COUNT 3200000
static int intel_get_max_size(void) {
cpuid_results_t cpuid_results;
cpuid(0xa, &cpuid_results);
return 1 << ((cpuid_results.eax >> 16) & 0xff);
}
static int intel_get_version(void) {
cpuid_results_t cpuid_results;
cpuid(0xa, &cpuid_results);
return cpuid_results.eax & 0xff;
}
static bool intel_check_tsc_fixed(void) {
cpuid_results_t cpuid_results;
cpuid(0xa, &cpuid_results);
int fixed_count = cpuid_results.edx & 0x1f;
return fixed_count > INTEL_TSC_INDEX;
}
static void reset_intel_pmc(void) {
// disable PMCs
wrmsr(MSR_PERF_FIXED_CTR_CTRL, 0);
// clear overflow
wrmsr(MSR_PERF_GLOBAL_OVF_CTRL, INTEL_TSC_INDEX_OFFSET);
// program PMC
wrmsr(MSR_PERF_FIXED_CTR2, intel_get_max_size() - TICK_COUNT);
// enable the PMC
wrmsr(MSR_PERF_FIXED_CTR_CTRL,
((INTEL_PERF_FIXED_CTR_CTRL_USER | INTEL_PERF_FIXED_CTR_CTRL_SUPERVISOR) << INTEL_TSC_FIXED_CTR_CTRL_OFFSET) |
INTEL_TSC_FIXED_CTR_CTRL_ENABLE);
}
static void init_intel_pmc(void) {
// check for version 2 PMC
if (intel_get_version() < 2) {
__assert(!"Profiling is not supported on Intel CPUs without at least a version 2 PMC. Recompile without profiling.");
}
// check for support for the tsc fixed counter
__assert(intel_check_tsc_fixed());
// enable fixed PMC
wrmsr(MSR_PERF_GLOBAL_CTRL, rdmsr(MSR_PERF_GLOBAL_CTRL) | INTEL_TSC_INDEX_OFFSET);
reset_intel_pmc();
arch_apic_init_perf();
}
static bool backtrace_fn(void *context, void *ip) {
uint8_t *data = context;
if (data[0] == 255)
return false;
uintptr_t *trace = (uintptr_t *)&data[1];
trace[data[0]] = (uintptr_t)ip;
data[0] += 1;
return true;
}
static bool intel_irq(context_t *context) {
if ((rdmsr(MSR_PERF_GLOBAL_STATUS) & INTEL_TSC_INDEX_OFFSET) == 0)
return false;
uint8_t data[1 + sizeof(uintptr_t) * 255];
data[0] = 0;
arch_get_backtrace(context, backtrace_fn, data);
profiling_insert(data[0], data);
arch_apic_init_perf(); // SDM LVT figure says a PMC irq masks itself, so unmask it
reset_intel_pmc();
return true;
}
static bool amd_irq(context_t *context) {
__assert(!"Unimplemented");
}
static void init_amd_pmc(void) {
__assert(!"Unimplemented");
}
bool arch_profiling_irq(context_t *context) {
if (!strcmp(current_cpu()->vendor, "AuthenticAMD"))
return amd_irq(context);
else if (!strcmp(current_cpu()->vendor, "GenuineIntel"))
return intel_irq(context);
__assert(!"unreachable");
}
void arch_profiling_init(void) {
arch_apic_init_perf();
if (!strcmp(current_cpu()->vendor, "AuthenticAMD"))
init_amd_pmc();
else if (!strcmp(current_cpu()->vendor, "GenuineIntel"))
init_intel_pmc();
else
printf("arch_prof: no PMC for this vendor\n");
}
INIT_ROUTINE_DEFINE(arch_profiling, INIT_ROUTINE_FLAGS_NONE, arch_profiling_init, profiling, cpu);
#endif