Add support to libkvm for reading vmcores from other architectures.

- Add a kvaddr_type to represent kernel virtual addresses instead of
  unsigned long.
- Add a struct kvm_nlist which is a stripped down version of struct nlist
  that uses kvaddr_t for n_value.
- Add a kvm_native() routine that returns true if an open kvm descriptor
  is for a native kernel and memory image.
- Add a kvm_open2() function similar to kvm_openfiles().  It drops the
  unused 'swapfile' argument and adds a new function pointer argument for
  a symbol resolving function.  Native kernels still use _fdnlist() from
  libc to resolve symbols if a resolver function is not supplied, but cross
  kernels require a resolver.
- Add a kvm_nlist2() function similar to kvm_nlist() except that it uses
  struct kvm_nlist instead of struct nlist.
- Add a kvm_read2() function similar to kvm_read() except that it uses
  kvaddr_t instead of unsigned long for the kernel virtual address.
- Add a new kvm_arch switch of routines needed by a vmcore backend.
  Each backend is responsible for implementing kvm_read2() for a given
  vmcore format.
- Use libelf to read headers from ELF kernels and cores (except for
  powerpc cores).
- Add internal helper routines for the common page offset hash table used
  by the minidump backends.
- Port all of the existing kvm backends to implement a kvm_arch switch and
  to be cross-friendly by using private constants instead of ones that
  vary by platform (e.g. PAGE_SIZE).  Static assertions are present when
  a given backend is compiled natively to ensure the private constants
  match the real ones.
- Enable all of the existing vmcore backends on all platforms.  This means
  that libkvm on any platform should be able to perform KVA translation
  and read data from a vmcore of any platform.

Tested on:	amd64, i386, sparc64 (marius)
Differential Revision:	https://reviews.freebsd.org/D3341

1 files changed, 11 insertions, 3 deletions

diff --git a/lib/libkvm/kvm_pcpu.c b/lib/libkvm/kvm_pcpu.c
index c4d3176..eaea7e4 100644
--- a/lib/libkvm/kvm_pcpu.c
+++ b/lib/libkvm/kvm_pcpu.c
@@ -216,7 +216,7 @@ _kvm_dpcpu_setcpu(kvm_t *kd, u_int cpu, int report_error)
 static int
 _kvm_dpcpu_init(kvm_t *kd)
 {
-	struct nlist nl[] = {
+	struct kvm_nlist nl[] = {
 #define	NLIST_START_SET_PCPU	0
 		{ .n_name = "___start_" DPCPU_SETNAME },
 #define	NLIST_STOP_SET_PCPU	1
@@ -232,6 +232,12 @@ _kvm_dpcpu_init(kvm_t *kd)
 	u_int dpcpu_maxcpus;
 
 	/*
+	 * XXX: This only works for native kernels for now.
+	 */
+	if (!kvm_native(kd))
+		return (-1);
+
+	/*
 	 * Locate and cache locations of important symbols using the internal
 	 * version of _kvm_nlist, turning off initialization to avoid
 	 * recursion in case of unresolveable symbols.
@@ -279,8 +285,8 @@ _kvm_dpcpu_initialized(kvm_t *kd, int intialize)
  * Check whether the value is within the dpcpu symbol range and only if so
  * adjust the offset relative to the current offset.
  */
-uintptr_t
-_kvm_dpcpu_validaddr(kvm_t *kd, uintptr_t value)
+kvaddr_t
+_kvm_dpcpu_validaddr(kvm_t *kd, kvaddr_t value)
 {
 
 	if (value == 0)
@@ -319,6 +325,8 @@ ssize_t
 kvm_read_zpcpu(kvm_t *kd, u_long base, void *buf, size_t size, int cpu)
 {
 
+	if (!kvm_native(kd))
+		return (-1);
 	return (kvm_read(kd, (uintptr_t)(base + sizeof(struct pcpu) * cpu),
 	    buf, size));
 }