kexec-tools: i386 sys interface changes compatibility

On Wed, Dec 14, 2005 at 02:50:52PM -0600, Milton Miller wrote:

[..]
> >>(2) why do you stat the files instead of just trying to open them and
> >>check for ENOENT?
> >>
> >>milton
> >>
> >
> >I wanted to differentiate between two cases. One being sysfs not
> >mounted
> >and other being file not being present (Due to kernel bug or cpu not
> >present), hence used stat(). In case of sysfs not being mounted, we
> >simply exit after giving an error message. In other case we continue
> >to loop through other cpus and ignore cpu, which is not present.
> >
>
> Ok, but try to open the file first.  IF you want to do this diagnostic
> after the open fails, that is ok.  But don't do this check n times (n =
> number of cpus) when the file exists.
>

I have moved the sysfs mounted check in failure condition.

>
> >
> >On Tue, Dec 13, 2005 at 09:36:26AM -0800, Haren Myneni wrote:
> >>Vivek, I believe, we should push this func into arch independent code.
> >>Otherwise, we have to copy it for every platform.
> >>
> >
> >We have reworked the patch and moved this code to architecture
> >independent
> >portion.
> >
>
>
> Only the x86 code has the fallback the old name, not the genric code.
>

Only i386 port of kdump was available when crash_notes was exported
through /sys/kernel/crash_notes. Rest of the architectures see new arch-
independent percpu crash_notes sysfs interface only. Hence thought no
point copying backward compatibility code in generic code.

>
> Also, there are error paths that do not set the address, others that
> zero it.
>

The error paths which do not set address to zero are non return path. They
call die() which inturn calls exit(1) after printing appropriate error
messasge.

> What happens if the base kernel is too old for kexec-panic, where
> neiter file will exist?
>

In that case kexec will fail much earlier. There will be  no reserved
memory area for loading second kernel (crashkernel=X&Y) hence attempt to
load the second kernel will fail and control will not reach this place at
all.

Modifed patch appended.

Thanks
Vivek

o This patch moves per cpu interface to retrieve crash_notes address to
  architecture independent section. (As suggested by Haren)

o For i386, kernels older than 2.6.15-rc1-mm2 used to export crash_notes
  through /sys/kernel/crash_notes. This patch also provides backward
  compatibility with older kernel versions.

o Definition of MAX_NOTE_BYTES moved to architecture independent header
  file as everybody is using same definition.

o Definition of MAX_LINE moved to architecture independent header file.
  Seems to be a better option than defining it in many C files.

Signed-off-by: Maneesh Soni <maneesh@in.ibm.com>
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Maneesh Soni <maneesh@in.ibm.com>

6 files changed, 31 insertions, 84 deletions

diff --git a/kexec/arch/i386/crashdump-x86.c b/kexec/arch/i386/crashdump-x86.c
index 9553faf..03995d8 100644
--- a/kexec/arch/i386/crashdump-x86.c
+++ b/kexec/arch/i386/crashdump-x86.c
@@ -29,12 +29,11 @@
 #include "../../kexec.h"
 #include "../../kexec-elf.h"
 #include "../../kexec-syscall.h"
+#include "../../crashdump.h"
 #include "kexec-x86.h"
 #include "crashdump-x86.h"
 #include <x86/x86-linux.h>
 
-#define MAX_LINE	160
-
 extern struct arch_options_t arch_options;
 
 /* Forward Declaration. */
@@ -429,41 +428,36 @@ static int cmdline_add_elfcorehdr(char *cmdline, unsigned long addr)
 	return 0;
 }
 
-/* Returns the virtual address of start of crash notes buffer for a cpu. */
-static int get_crash_notes_section_addr(int cpu, unsigned long long *addr)
+
+/*
+ * This routine is specific to i386 architecture to maintain the
+ * backward compatibility, other architectures can use the per
+ * cpu version get_crash_notes_per_cpu() directly.
+ */
+static int get_crash_notes(int cpu, uint64_t *addr)
 {
-#define MAX_SYSFS_PATH_LEN	70
-	char crash_notes[MAX_SYSFS_PATH_LEN];
+	char crash_notes[PATH_MAX];
 	char line[MAX_LINE];
 	FILE *fp;
-	struct stat cpu_stat;
+	unsigned long vaddr;
+	int count;
 
-	sprintf(crash_notes, "/sys/devices/system/cpu");
-	if (stat(crash_notes, &cpu_stat)) {
-		die("Cannot stat %s: %s\nTry mounting sysfs\n",
-			crash_notes, strerror(errno));
-	}
-
-	sprintf(crash_notes, "/sys/devices/system/cpu/cpu%d/crash_notes", cpu);
+	sprintf(crash_notes, "/sys/kernel/crash_notes");
 	fp = fopen(crash_notes, "r");
-	if (!fp) {
-		/* CPU is not physically present.*/
-		*addr = 0;
-		return -1;
-	}
-
-	if (fgets(line, sizeof(line), fp) != 0) {
-		int count;
-		count = sscanf(line, "%Lx", addr);
-		if (count != 1) {
-			*addr = 0;
-			return -1;
+	if (fp) {
+		if (fgets(line, sizeof(line), fp) != 0) {
+			count = sscanf(line, "%lx", &vaddr);
+			if (count != 1)
+				die("Cannot parse %s: %s\n", crash_notes,
+						strerror(errno));
 		}
+		*addr = __pa(vaddr + (cpu * MAX_NOTE_BYTES));
 #if 0
 		printf("crash_notes addr = %Lx\n", *addr);
 #endif
-	}
-	return 0;
+		return 0;
+	} else
+		return get_crash_notes_per_cpu(cpu, addr);
 }
 
 /* Prepares the crash memory elf64 headers and stores in supplied buffer. */
@@ -475,7 +469,7 @@ static int prepare_crash_memory_elf64_headers(struct kexec_info *info,
 	int i;
 	char *bufp;
 	long int nr_cpus = 0;
-	unsigned long long notes_addr;
+	uint64_t notes_addr;
 
 	bufp = (char*) buf;
 
@@ -508,11 +502,8 @@ static int prepare_crash_memory_elf64_headers(struct kexec_info *info,
 		return -1;
 	}
 
-	/* Need to find a better way to determine per cpu notes section size. */
-#define MAX_NOTE_BYTES	1024
-
 	for (i = 0; i < nr_cpus; i++) {
-		if (get_crash_notes_section_addr (i, &notes_addr) < 0) {
+		if (get_crash_notes(i, &notes_addr) < 0) {
 			/* This cpu is not present. Skip it. */
 			continue;
 		}
@@ -571,7 +562,7 @@ static int prepare_crash_memory_elf32_headers(struct kexec_info *info,
 	int i;
 	char *bufp;
 	long int nr_cpus = 0;
-	unsigned long long notes_addr;
+	uint64_t notes_addr;
 
 	bufp = (char*) buf;
 
@@ -607,7 +598,7 @@ static int prepare_crash_memory_elf32_headers(struct kexec_info *info,
 	/* Need to find a better way to determine per cpu notes section size. */
 #define MAX_NOTE_BYTES	1024
 	for (i = 0; i < nr_cpus; i++) {
-		if (get_crash_notes_section_addr (i, &notes_addr) < 0) {
+		if (get_crash_notes(i, &notes_addr) < 0) {
 			/* This cpu is not present. Skip it. */
 			return -1;
 		}
diff --git a/kexec/arch/i386/kexec-x86.c b/kexec/arch/i386/kexec-x86.c
index 26cbbb0..1c8d188 100644
--- a/kexec/arch/i386/kexec-x86.c
+++ b/kexec/arch/i386/kexec-x86.c
@@ -33,8 +33,6 @@
 #include "crashdump-x86.h"
 #include <arch/options.h>
 
-#define MAX_LINE 160
-
 static struct memory_range memory_range[MAX_MEMORY_RANGES];
 
 /* Return a sorted list of memory ranges. */
diff --git a/kexec/arch/ia64/kexec-ia64.c b/kexec/arch/ia64/kexec-ia64.c
index a2221e6..f631cef 100644
--- a/kexec/arch/ia64/kexec-ia64.c
+++ b/kexec/arch/ia64/kexec-ia64.c
@@ -34,7 +34,6 @@
 #include <arch/options.h>
 
 #define MAX_MEMORY_RANGES 64
-#define MAX_LINE 160
 static struct memory_range memory_range[MAX_MEMORY_RANGES];
 
 /* Return a sorted list of available memory ranges. */
diff --git a/kexec/arch/ppc/kexec-ppc.c b/kexec/arch/ppc/kexec-ppc.c
index 455febf..16ea584 100644
--- a/kexec/arch/ppc/kexec-ppc.c
+++ b/kexec/arch/ppc/kexec-ppc.c
@@ -19,7 +19,6 @@
 #include <arch/options.h>
 
 #define MAX_MEMORY_RANGES  64
-#define MAX_LINE          160
 static struct memory_range memory_range[MAX_MEMORY_RANGES];
 
 /* Return a sorted list of memory ranges. */
diff --git a/kexec/arch/x86_64/crashdump-x86_64.c b/kexec/arch/x86_64/crashdump-x86_64.c
index f104b89..3d0f3a5 100644
--- a/kexec/arch/x86_64/crashdump-x86_64.c
+++ b/kexec/arch/x86_64/crashdump-x86_64.c
@@ -30,12 +30,11 @@
 #include "../../kexec.h"
 #include "../../kexec-elf.h"
 #include "../../kexec-syscall.h"
+#include "../../crashdump.h"
 #include "kexec-x86_64.h"
 #include "crashdump-x86_64.h"
 #include <x86/x86-linux.h>
 
-#define MAX_LINE	160
-
 extern struct arch_options_t arch_options;
 
 /* Forward Declaration. */
@@ -471,44 +470,6 @@ static int cmdline_add_memmap_acpi(char *cmdline, unsigned long start,
 	return 0;
 }
 
-/* Returns the virtual address of start of crash notes buffer for a cpu. */
-static int get_crash_notes_section_addr(int cpu, unsigned long long *addr)
-{
-
-#define MAX_SYSFS_PATH_LEN	70
-	char crash_notes[MAX_SYSFS_PATH_LEN];
-	char line[MAX_LINE];
-	FILE *fp;
-	struct stat cpu_stat;
-
-	sprintf(crash_notes, "/sys/devices/system/cpu");
-	if (stat(crash_notes, &cpu_stat)) {
-		die("Cannot stat %s: %s\nTry mounting sysfs\n",
-				crash_notes, strerror(errno));
-	}
-
-	sprintf(crash_notes, "/sys/devices/system/cpu/cpu%d/crash_notes", cpu);
-	fp = fopen(crash_notes, "r");
-	if (!fp) {
-		/* CPU is not physically present.*/
-		*addr = 0;
-		return -1;
-	}
-
-	if (fgets(line, sizeof(line), fp) != 0) {
-		int count;
-		count = sscanf(line, "%Lx", addr);
-		if (count != 1) {
-			*addr = 0;
-			return -1;
-		}
-#if 0
-		printf("crash_notes addr = %Lx\n", *addr);
-#endif
-	}
-	return 0;
-}
-
 /* Prepares the crash memory elf64 headers and stores in supplied buffer. */
 static int prepare_crash_memory_elf64_headers(struct kexec_info *info,
 						void *buf, unsigned long size)
@@ -518,7 +479,7 @@ static int prepare_crash_memory_elf64_headers(struct kexec_info *info,
 	int i;
 	char *bufp;
 	long int nr_cpus = 0;
-	unsigned long long notes_addr;
+	uint64_t notes_addr;
 
 	bufp = (char*) buf;
 
@@ -554,7 +515,7 @@ static int prepare_crash_memory_elf64_headers(struct kexec_info *info,
 	/* Need to find a better way to determine per cpu notes section size. */
 #define MAX_NOTE_BYTES	1024
 	for (i = 0; i < nr_cpus; i++) {
-		if (get_crash_notes_section_addr (i, &notes_addr) < 0) {
+		if (get_crash_notes_per_cpu(i, &notes_addr) < 0) {
 			/* This cpu is not present. Skip it. */
 			continue;
 		}
@@ -624,7 +585,7 @@ static int prepare_crash_memory_elf32_headers(struct kexec_info *info,
 	int i;
 	char *bufp;
 	long int nr_cpus = 0;
-	unsigned long long notes_addr;
+	uint64_t notes_addr;
 
 	bufp = (char*) buf;
 
@@ -660,7 +621,7 @@ static int prepare_crash_memory_elf32_headers(struct kexec_info *info,
 	/* Need to find a better way to determine per cpu notes section size. */
 #define MAX_NOTE_BYTES	1024
 	for (i = 0; i < nr_cpus; i++) {
-		if (get_crash_notes_section_addr (i, &notes_addr) < 0) {
+		if (get_crash_notes_per_cpu(i, &notes_addr) < 0) {
 			/* This cpu is not present. Skip it. */
 			return -1;
 		}
diff --git a/kexec/arch/x86_64/kexec-x86_64.c b/kexec/arch/x86_64/kexec-x86_64.c
index 3ed3844..db3e5d4 100644
--- a/kexec/arch/x86_64/kexec-x86_64.c
+++ b/kexec/arch/x86_64/kexec-x86_64.c
@@ -34,7 +34,6 @@
 #include <arch/options.h>
 
 #define MAX_MEMORY_RANGES 64
-#define MAX_LINE 160
 static struct memory_range memory_range[MAX_MEMORY_RANGES];
 
 /* Return a sorted list of memory ranges. */