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libkvm: catch up with pre-subtracated per-cpu addresses

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Only concerns amd64.

Reported by:	imp
This commit is contained in:
Mateusz Guzik 2020-10-06 02:57:37 +00:00
parent 8741306b3b
commit f165a1df9a
1 changed files with 29 additions and 0 deletions
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29
lib/libkvm/kvm_pcpu.c
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@ -50,15 +50,23 @@ __FBSDID("$FreeBSD$");
#include "kvm_private.h"
#ifdef __amd64__
#define __OFFSET_BY_PCPU
#endif
static struct nlist kvm_pcpu_nl[] = {
{ .n_name = "_cpuid_to_pcpu" },
{ .n_name = "_mp_maxcpus" },
{ .n_name = "_mp_ncpus" },
#ifdef __OFFSET_BY_PCPU
{ .n_name = "___pcpu" },
#endif
{ .n_name = NULL },
};
#define NL_CPUID_TO_PCPU 0
#define NL_MP_MAXCPUS 1
#define NL_MP_NCPUS 2
#define NL___PCPU 3
/*
* Kernel per-CPU data state. We cache this stuff on the first
@ -71,6 +79,9 @@ static struct nlist kvm_pcpu_nl[] = {
static void **pcpu_data;
static int maxcpu;
static int mp_ncpus;
#ifdef __OFFSET_BY_PCPU
static unsigned long __pcpu;
#endif
static int
_kvm_pcpu_init(kvm_t *kd)
@ -103,6 +114,17 @@ _kvm_pcpu_init(kvm_t *kd)
_kvm_err(kd, kd->program, "cannot read mp_ncpus");
return (-1);
}
#ifdef __OFFSET_BY_PCPU
if (kvm_pcpu_nl[NL___PCPU].n_value == 0) {
_kvm_err(kd, kd->program, "unable to find __pcpu");
return (-1);
}
if (kvm_read(kd, kvm_pcpu_nl[NL___PCPU].n_value, &__pcpu,
sizeof(__pcpu)) != sizeof(__pcpu)) {
_kvm_err(kd, kd->program, "cannot read __pcpu");
return (-1);
}
#endif
len = max * sizeof(void *);
data = malloc(len);
if (data == NULL) {
@ -329,6 +351,13 @@ kvm_read_zpcpu(kvm_t *kd, u_long base, void *buf, size_t size, int cpu)
if (!kvm_native(kd))
return (-1);
if (mp_ncpus == 0)
if (_kvm_pcpu_init(kd) < 0)
return (0);
#ifdef __OFFSET_BY_PCPU
base += __pcpu;
#endif
return (kvm_read(kd, (uintptr_t)(base + sizeof(struct pcpu) * cpu),
buf, size));
}