Support crash dumps > 4GB in size on 32 bit platforms. _kvm_kvatop()

returned an lseek offset in a "u_long *" value, which can't express >4GB
offsets on 32 bit machines (eg: PAE).  Change to "off_t *" for all.

Support ELF crashdumps on i386 and amd64.

Support PAE crashdumps on i386.  This is done by auto-detecting the
presence of the IdlePDPT which means that PAE is active.

I used Marcel's _kvm_pa2off strategy and ELF header reader for ELF support
on amd64.  Paul Saab ported the amd64 changes to i386 and we implemented
the PAE support from there.

Note that gdb6 in the src tree uses whatever libkvm supports.  If you want
to debug an old crash dump, you might want to keep an old libkvm.so handy
and use LD_PRELOAD or the like.  This does not detect the old raw dump
format.

Approved by: re

1 files changed, 137 insertions, 39 deletions

diff --git a/lib/libkvm/kvm_amd64.c b/lib/libkvm/kvm_amd64.c
index 0e0366d..534323c 100644
--- a/lib/libkvm/kvm_amd64.c
+++ b/lib/libkvm/kvm_amd64.c
@@ -53,6 +53,7 @@ static char sccsid[] = "@(#)kvm_hp300.c	8.1 (Berkeley) 6/4/93";
 #include <sys/user.h>
 #include <sys/proc.h>
 #include <sys/stat.h>
+#include <sys/mman.h>
 #include <stdlib.h>
 #include <unistd.h>
 #include <nlist.h>
@@ -61,6 +62,8 @@ static char sccsid[] = "@(#)kvm_hp300.c	8.1 (Berkeley) 6/4/93";
 #include <vm/vm.h>
 #include <vm/vm_param.h>
 
+#include <machine/elf.h>
+
 #include <limits.h>
 
 #include "kvm_private.h"
@@ -71,36 +74,92 @@ static char sccsid[] = "@(#)kvm_hp300.c	8.1 (Berkeley) 6/4/93";
 #endif
 
 struct vmstate {
+	void		*mmapbase;
+	size_t		mmapsize;
 	pml4_entry_t	*PML4;
 };
 
+/*
+ * Map the ELF headers into the process' address space. We do this in two
+ * steps: first the ELF header itself and using that information the whole
+ * set of headers. (Taken from kvm_ia64.c)
+ */
+static int
+_kvm_maphdrs(kvm_t *kd, size_t sz)
+{
+	struct vmstate *vm = kd->vmst;
+
+	/* munmap() previous mmap(). */
+	if (vm->mmapbase != NULL) {
+		munmap(vm->mmapbase, vm->mmapsize);
+		vm->mmapbase = NULL;
+	}
+
+	vm->mmapsize = sz;
+	vm->mmapbase = mmap(NULL, sz, PROT_READ, MAP_PRIVATE, kd->pmfd, 0);
+	if (vm->mmapbase == MAP_FAILED) {
+		_kvm_err(kd, kd->program, "cannot mmap corefile");
+		return (-1);
+	}
+	return (0);
+}
+
+/*
+ * Translate a physical memory address to a file-offset in the crash-dump.
+ * (Taken from kvm_ia64.c)
+ */
+static size_t
+_kvm_pa2off(kvm_t *kd, uint64_t pa, off_t *ofs)
+{
+	Elf_Ehdr *e = kd->vmst->mmapbase;
+	Elf_Phdr *p = (Elf_Phdr*)((char*)e + e->e_phoff);
+	int n = e->e_phnum;
+
+	while (n && (pa < p->p_paddr || pa >= p->p_paddr + p->p_memsz))
+		p++, n--;
+	if (n == 0)
+		return (0);
+	*ofs = (pa - p->p_paddr) + p->p_offset;
+	return (PAGE_SIZE - ((size_t)pa & PAGE_MASK));
+}
+
 void
 _kvm_freevtop(kvm_t *kd)
 {
-	if (kd->vmst != 0) {
-		if (kd->vmst->PML4) {
-			free(kd->vmst->PML4);
-		}
-		free(kd->vmst);
-	}
+	struct vmstate *vm = kd->vmst;
+
+	if (vm->mmapbase != NULL)
+		munmap(vm->mmapbase, vm->mmapsize);
+	if (vm->PML4)
+		free(vm->PML4);
+	free(vm);
+	kd->vmst = NULL;
 }
 
 int
 _kvm_initvtop(kvm_t *kd)
 {
-	struct vmstate *vm;
 	struct nlist nlist[2];
 	u_long pa;
 	u_long kernbase;
 	pml4_entry_t	*PML4;
+	Elf_Ehdr *ehdr;
+	size_t hdrsz;
 
-	vm = (struct vmstate *)_kvm_malloc(kd, sizeof(*vm));
-	if (vm == 0) {
+	kd->vmst = (struct vmstate *)_kvm_malloc(kd, sizeof(*kd->vmst));
+	if (kd->vmst == 0) {
 		_kvm_err(kd, kd->program, "cannot allocate vm");
 		return (-1);
 	}
-	kd->vmst = vm;
-	vm->PML4 = 0;
+	kd->vmst->PML4 = 0;
+
+	if (_kvm_maphdrs(kd, sizeof(Elf_Ehdr)) == -1)
+		return (-1);
+
+	ehdr = kd->vmst->mmapbase;
+	hdrsz = ehdr->e_phoff + ehdr->e_phentsize * ehdr->e_phnum;
+	if (_kvm_maphdrs(kd, hdrsz) == -1)
+		return (-1);
 
 	nlist[0].n_name = "kernbase";
 	nlist[1].n_name = 0;
@@ -128,12 +187,12 @@ _kvm_initvtop(kvm_t *kd)
 		_kvm_err(kd, kd->program, "cannot read KPML4phys");
 		return (-1);
 	}
-	vm->PML4 = PML4;
+	kd->vmst->PML4 = PML4;
 	return (0);
 }
 
 static int
-_kvm_vatop(kvm_t *kd, u_long va, u_long *pa)
+_kvm_vatop(kvm_t *kd, u_long va, off_t *pa)
 {
 	struct vmstate *vm;
 	u_long offset;
@@ -149,11 +208,9 @@ _kvm_vatop(kvm_t *kd, u_long va, u_long *pa)
 	u_long pdeindex;
 	u_long pteindex;
 	int i;
-
-	if (ISALIVE(kd)) {
-		_kvm_err(kd, 0, "kvm_vatop called in live kernel!");
-		return((off_t)0);
-	}
+	u_long a;
+	off_t ofs;
+	size_t s;
 
 	vm = kd->vmst;
 	offset = va & (PAGE_SIZE - 1);
@@ -163,20 +220,32 @@ _kvm_vatop(kvm_t *kd, u_long va, u_long *pa)
 	 * not yet set) then return pa == va to avoid infinite recursion.
 	 */
 	if (vm->PML4 == 0) {
-		*pa = va;
-		return (PAGE_SIZE - offset);
+		s = _kvm_pa2off(kd, va, pa);
+		if (s == 0) {
+			_kvm_err(kd, kd->program,
+			    "_kvm_vatop: bootstrap data not in dump");
+			goto invalid;
+		} else
+			return (PAGE_SIZE - offset);
 	}
 
 	pml4eindex = (va >> PML4SHIFT) & (NPML4EPG - 1);
 	pml4e = vm->PML4[pml4eindex];
-	if (((u_long)pml4e & PG_V) == 0)
+	if (((u_long)pml4e & PG_V) == 0) {
+		_kvm_err(kd, kd->program, "_kvm_vatop: pml4e not valid");
 		goto invalid;
+	}
 
 	pdpeindex = (va >> PDPSHIFT) & (NPDPEPG-1);
-	pdpe_pa = ((u_long)pml4e & PG_FRAME) + (pdpeindex * sizeof(pdp_entry_t));
+	pdpe_pa = ((u_long)pml4e & PG_FRAME) +
+	    (pdpeindex * sizeof(pdp_entry_t));
 
-	/* XXX This has to be a physical address read, kvm_read is virtual */
-	if (lseek(kd->pmfd, pdpe_pa, 0) == -1) {
+	s = _kvm_pa2off(kd, pdpe_pa, &ofs);
+	if (s <= sizeof pdpe) {
+		_kvm_err(kd, kd->program, "_kvm_vatop: pdpe_pa not found");
+		goto invalid;
+	}
+	if (lseek(kd->pmfd, ofs, 0) == -1) {
 		_kvm_syserr(kd, kd->program, "_kvm_vatop: lseek pdpe_pa");
 		goto invalid;
 	}
@@ -184,24 +253,31 @@ _kvm_vatop(kvm_t *kd, u_long va, u_long *pa)
 		_kvm_syserr(kd, kd->program, "_kvm_vatop: read pdpe");
 		goto invalid;
 	}
-	if (((u_long)pdpe & PG_V) == 0)
+	if (((u_long)pdpe & PG_V) == 0) {
+		_kvm_err(kd, kd->program, "_kvm_vatop: pdpe not valid");
 		goto invalid;
-
+	}
 
 	pdeindex = (va >> PDRSHIFT) & (NPDEPG-1);
 	pde_pa = ((u_long)pdpe & PG_FRAME) + (pdeindex * sizeof(pd_entry_t));
 
-	/* XXX This has to be a physical address read, kvm_read is virtual */
-	if (lseek(kd->pmfd, pde_pa, 0) == -1) {
-		_kvm_syserr(kd, kd->program, "_kvm_vatop: lseek pde_pa");
+	s = _kvm_pa2off(kd, pde_pa, &ofs);
+	if (s <= sizeof pde) {
+		_kvm_syserr(kd, kd->program, "_kvm_vatop: pde_pa not found");
+		goto invalid;
+	}
+	if (lseek(kd->pmfd, ofs, 0) == -1) {
+		_kvm_err(kd, kd->program, "_kvm_vatop: lseek pde_pa");
 		goto invalid;
 	}
 	if (read(kd->pmfd, &pde, sizeof pde) != sizeof pde) {
 		_kvm_syserr(kd, kd->program, "_kvm_vatop: read pde");
 		goto invalid;
 	}
-	if (((u_long)pde & PG_V) == 0)
+	if (((u_long)pde & PG_V) == 0) {
+		_kvm_err(kd, kd->program, "_kvm_vatop: pde not valid");
 		goto invalid;
+	}
 
 	if ((u_long)pde & PG_PS) {
 	      /*
@@ -209,15 +285,25 @@ _kvm_vatop(kvm_t *kd, u_long va, u_long *pa)
 	       */
 #define	PAGE2M_MASK	(NBPDR - 1)
 #define	PG_FRAME2M	(~PAGE2M_MASK)
-		*pa = ((u_long)pde & PG_FRAME2M) + (va & PAGE2M_MASK);
-		return (NBPDR - (va & PAGE2M_MASK));
+		a = ((u_long)pde & PG_FRAME2M) + (va & PAGE2M_MASK);
+		s = _kvm_pa2off(kd, a, pa);
+		if (s == 0) {
+			_kvm_err(kd, kd->program,
+			    "_kvm_vatop: 2MB page address not in dump");
+			goto invalid;
+		} else
+			return (NBPDR - (va & PAGE2M_MASK));
 	}
 
 	pteindex = (va >> PAGE_SHIFT) & (NPTEPG-1);
 	pte_pa = ((u_long)pde & PG_FRAME) + (pteindex * sizeof(pt_entry_t));
 
-	/* XXX This has to be a physical address read, kvm_read is virtual */
-	if (lseek(kd->pmfd, pte_pa, 0) == -1) {
+	s = _kvm_pa2off(kd, pte_pa, &ofs);
+	if (s <= sizeof pte) {
+		_kvm_err(kd, kd->program, "_kvm_vatop: pte_pa not found");
+		goto invalid;
+	}
+	if (lseek(kd->pmfd, ofs, 0) == -1) {
 		_kvm_syserr(kd, kd->program, "_kvm_vatop: lseek");
 		goto invalid;
 	}
@@ -225,19 +311,31 @@ _kvm_vatop(kvm_t *kd, u_long va, u_long *pa)
 		_kvm_syserr(kd, kd->program, "_kvm_vatop: read");
 		goto invalid;
 	}
-	if (((u_long)pte & PG_V) == 0)
+	if (((u_long)pte & PG_V) == 0) {
+		_kvm_err(kd, kd->program, "_kvm_vatop: pte not valid");
 		goto invalid;
+	}
 
-	*pa = ((u_long)pte & PG_FRAME) + offset;
-	return (PAGE_SIZE - offset);
+	a = ((u_long)pte & PG_FRAME) + offset;
+	s = _kvm_pa2off(kd, a, pa);
+	if (s == 0) {
+		_kvm_err(kd, kd->program, "_kvm_vatop: address not in dump");
+		goto invalid;
+	} else
+		return (PAGE_SIZE - offset);
 
 invalid:
-	_kvm_err(kd, 0, "invalid address (%x)", va);
+	_kvm_err(kd, 0, "invalid address (0x%lx)", va);
 	return (0);
 }
 
 int
-_kvm_kvatop(kvm_t *kd, u_long va, u_long *pa)
+_kvm_kvatop(kvm_t *kd, u_long va, off_t *pa)
 {
+
+	if (ISALIVE(kd)) {
+		_kvm_err(kd, 0, "kvm_kvatop called in live kernel!");
+		return (0);
+	}
 	return (_kvm_vatop(kd, va, pa));
 }