kexec-tools: Introduce crashdump-xen.c and Xen support V2

kexec-tools: Introduce crashdump-xen.c and Xen support V2

This patch adds the new file crashdump-xen.c that implements Xen support. The
Xen support is not complete yet in the sense that a special program header
for the hypervisor isn't created. Crash notes for physical cpus are created
so basic support is at least provided by this patch.

Version 2 of this patch includes a cleaner implementation for crashdump-elf.c
together with a bugfix for xen_get_nr_phys_cpus().

Signed-off-by: Magnus Damm <magnus@valinux.co.jp>

Removed trailing whitespace

Signed-off-by: Simon Horman <horms@verge.net.au>

4 files changed, 95 insertions, 3 deletions

diff --git a/kexec/Makefile b/kexec/Makefile
index 4ff1bdf..6ad9461 100644
--- a/kexec/Makefile
+++ b/kexec/Makefile
@@ -18,6 +18,7 @@ KEXEC_C_SRCS+= kexec/kexec-elf-rel.c
 KEXEC_C_SRCS+= kexec/kexec-elf-boot.c 
 KEXEC_C_SRCS+= kexec/kexec-iomem.c
 KEXEC_C_SRCS+= kexec/crashdump.c
+KEXEC_C_SRCS+= kexec/crashdump-xen.c
 KEXEC_C_GENERATED_SRCS+= $(PURGATORY_HEX_C)
 KEXEC_S_SRCS:= 
 KEXEC_S_GENERATED_SRCS:=
diff --git a/kexec/crashdump-elf.c b/kexec/crashdump-elf.c
index 9e3121f..4c55baf 100644
--- a/kexec/crashdump-elf.c
+++ b/kexec/crashdump-elf.c
@@ -18,7 +18,11 @@ int FUNC(struct kexec_info *info,
 	uint64_t notes_addr, notes_len;
 	int (*get_note_info)(int cpu, uint64_t *addr, uint64_t *len);
 
-	nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
+	if (xen_present())
+		nr_cpus = xen_get_nr_phys_cpus();
+	else
+		nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
+
 	if (nr_cpus < 0) {
 		return -1;
 	}
@@ -45,7 +49,7 @@ int FUNC(struct kexec_info *info,
 	 * PT_LOAD program header and in the physical RAM program headers.
 	 */
 
-	if (info->kern_size) {
+	if (info->kern_size && !xen_present()) {
 		sz += sizeof(PHDR);
 	}
 
@@ -87,6 +91,9 @@ int FUNC(struct kexec_info *info,
 	if (!get_note_info)
 		get_note_info = get_crash_notes_per_cpu;
 
+	if (xen_present())
+		get_note_info = xen_get_note;
+
 	/* PT_NOTE program headers. One per cpu */
 
 	for (i = 0; i < nr_cpus; i++) {
@@ -118,7 +125,7 @@ int FUNC(struct kexec_info *info,
 	 * Kernel is mapped if info->kern_size is non-zero.
 	 */
 
-	if (info->kern_size) {
+	if (info->kern_size && !xen_present()) {
 		phdr = (PHDR *) bufp;
 		bufp += sizeof(PHDR);
 		phdr->p_type	= PT_LOAD;
diff --git a/kexec/crashdump-xen.c b/kexec/crashdump-xen.c
new file mode 100644
index 0000000..aa096e6
--- /dev/null
+++ b/kexec/crashdump-xen.c
@@ -0,0 +1,80 @@
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdarg.h>
+#include <string.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <limits.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include "kexec.h"
+#include "crashdump.h"
+
+struct crash_note_info {
+	unsigned long base;
+	unsigned long length;
+};
+
+int xen_phys_cpus = 0;
+struct crash_note_info *xen_phys_notes;
+
+int xen_present(void)
+{
+	struct stat buf;
+
+	return stat("/proc/xen", &buf) == 0;
+}
+
+static int xen_crash_note_callback(void *data, int nr,
+				   char *str,
+				   unsigned long base,
+				   unsigned long length)
+{
+	struct crash_note_info *note = xen_phys_notes + nr;
+
+	note->base = base;
+	note->length = length;
+
+	return 0;
+}
+
+int xen_get_nr_phys_cpus(void)
+{
+	char *match = "Crash note\n";
+	int cpus, n;
+
+	if (xen_phys_cpus)
+		return xen_phys_cpus;
+
+	if ((cpus = kexec_iomem_for_each_line(match, NULL, NULL))) {
+		n = sizeof(struct crash_note_info) * cpus;
+		xen_phys_notes = malloc(n);
+		if (xen_phys_notes) {
+			memset(xen_phys_notes, 0, n);
+			kexec_iomem_for_each_line(match,
+						  xen_crash_note_callback,
+						  NULL);
+		}
+
+		xen_phys_cpus = cpus;
+	}
+
+	return cpus;
+}
+
+int xen_get_note(int cpu, uint64_t *addr, uint64_t *len)
+{
+	struct crash_note_info *note;
+
+	if (xen_phys_cpus <= 0)
+		return -1;
+
+	note = xen_phys_notes + cpu;
+
+	*addr = note->base;
+	*len = note->length;
+
+	return 0;
+}
diff --git a/kexec/crashdump.h b/kexec/crashdump.h
index 4dbecf8..10cffe0 100644
--- a/kexec/crashdump.h
+++ b/kexec/crashdump.h
@@ -34,4 +34,8 @@ int crash_create_elf64_headers(struct kexec_info *info,
 			       struct memory_range *range, int ranges,
 			       void **buf, unsigned long *size);
 
+int xen_present(void);
+int xen_get_nr_phys_cpus(void);
+int xen_get_note(int cpu, uint64_t *addr, uint64_t *len);
+
 #endif /* CRASHDUMP_H */