Author: mjg
Date: Tue Oct 6 02:57:37 2020
New Revision: 366468
URL: https://svnweb.freebsd.org/changeset/base/366468
Log:
libkvm: catch up with pre-subtracated per-cpu addresses
Only concerns amd64.
Reported by: imp
Modified:
head/lib/libkvm/kvm_pcpu.c
Modified: head/lib/libkvm/kvm_pcpu.c
==============================================================================
--- head/lib/libkvm/kvm_pcpu.c Mon Oct 5 22:18:04 2020 (r366467)
+++ head/lib/libkvm/kvm_pcpu.c Tue Oct 6 02:57:37 2020 (r366468)
@@ -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
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));
}
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