crash: remove dependency of FA_DUMP on CRASH_DUMP

In kdump kernel, /proc/vmcore is an elf file mapping the crashed kernel's
old memory content. Its elf header is constructed in 1st kernel and passed
to kdump kernel via elfcorehdr_addr. Config CRASH_DUMP enables the code
of 1st kernel's old memory accessing in different architectures.

Currently, config FA_DUMP has dependency on CRASH_DUMP because fadump
needs access global variable 'elfcorehdr_addr' to judge if it's in
kdump kernel within function is_kdump_kernel(). In the current
kernel/crash_dump.c, variable 'elfcorehdr_addr' is defined, and function
setup_elfcorehdr() used to parse kernel parameter to fetch the passed
value of elfcorehdr_addr. Only for accessing elfcorehdr_addr, FA_DUMP
really doesn't have to depends on CRASH_DUMP.

To remove the dependency of FA_DUMP on CRASH_DUMP to avoid confusion,
rename kernel/crash_dump.c to kernel/elfcorehdr.c, and build it when
CONFIG_VMCORE_INFO is ebabled. With this, FA_DUMP doesn't need to depend
on CRASH_DUMP.

[bhe@redhat.com: power/fadump: make FA_DUMP select CRASH_DUMP]
Link: https://lkml.kernel.org/r/Zb8D1ASrgX0qVm9z@MiWiFi-R3L-srv
Link: https://lkml.kernel.org/r/20240124051254.67105-4-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Acked-by: Hari Bathini <hbathini@linux.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Pingfan Liu <piliu@redhat.com>
Cc: Klara Modin <klarasmodin@gmail.com>
Cc: Michael Kelley <mhklinux@outlook.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 495d197c9b2751edcffd555df217414bdfdbc22c..a9efaf87966dfd154372c5703c52d0e249ba0235 100644 (file)
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -690,8 +690,6 @@ config ARCH_SELECTS_CRASH_DUMP
 config FA_DUMP
        bool "Firmware-assisted dump"
        depends on PPC64 && (PPC_RTAS || PPC_POWERNV)
-       select VMCORE_INFO
-       select CRASH_RESERVE
        select CRASH_DUMP
        help
          A robust mechanism to get reliable kernel crash dump with

diff --git a/kernel/Makefile b/kernel/Makefile
index 649272a1d6b9f8202d08eb96be03afa4c048a6a5..35abc65e1f1ade0f087eeb73295877c687b59377 100644 (file)
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -68,7 +68,7 @@ obj-$(CONFIG_MODULE_SIG_FORMAT) += module_signature.o
 obj-$(CONFIG_KALLSYMS) += kallsyms.o
 obj-$(CONFIG_KALLSYMS_SELFTEST) += kallsyms_selftest.o
 obj-$(CONFIG_BSD_PROCESS_ACCT) += acct.o
-obj-$(CONFIG_VMCORE_INFO) += vmcore_info.o
+obj-$(CONFIG_VMCORE_INFO) += vmcore_info.o elfcorehdr.o
 obj-$(CONFIG_CRASH_RESERVE) += crash_reserve.o
 obj-$(CONFIG_KEXEC_CORE) += kexec_core.o crash_core.o
 obj-$(CONFIG_KEXEC) += kexec.o
@@ -121,7 +121,6 @@ obj-$(CONFIG_PERF_EVENTS) += events/
 
 obj-$(CONFIG_USER_RETURN_NOTIFIER) += user-return-notifier.o
 obj-$(CONFIG_PADATA) += padata.o
-obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
 obj-$(CONFIG_JUMP_LABEL) += jump_label.o
 obj-$(CONFIG_CONTEXT_TRACKING) += context_tracking.o
 obj-$(CONFIG_TORTURE_TEST) += torture.o

diff --git a/kernel/crash_dump.c b/kernel/crash_dump.c
deleted file mode 100644 (file)
index 92da322..0000000
--- a/kernel/crash_dump.c
+++ /dev/null
@@ -1,41 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-#include <linux/kernel.h>
-#include <linux/crash_dump.h>
-#include <linux/init.h>
-#include <linux/errno.h>
-#include <linux/export.h>
-
-/*
- * stores the physical address of elf header of crash image
- *
- * Note: elfcorehdr_addr is not just limited to vmcore. It is also used by
- * is_kdump_kernel() to determine if we are booting after a panic. Hence put
- * it under CONFIG_CRASH_DUMP and not CONFIG_PROC_VMCORE.
- */
-unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX;
-EXPORT_SYMBOL_GPL(elfcorehdr_addr);
-
-/*
- * stores the size of elf header of crash image
- */
-unsigned long long elfcorehdr_size;
-
-/*
- * elfcorehdr= specifies the location of elf core header stored by the crashed
- * kernel. This option will be passed by kexec loader to the capture kernel.
- *
- * Syntax: elfcorehdr=[size[KMG]@]offset[KMG]
- */
-static int __init setup_elfcorehdr(char *arg)
-{
-       char *end;
-       if (!arg)
-               return -EINVAL;
-       elfcorehdr_addr = memparse(arg, &end);
-       if (*end == '@') {
-               elfcorehdr_size = elfcorehdr_addr;
-               elfcorehdr_addr = memparse(end + 1, &end);
-       }
-       return end > arg ? 0 : -EINVAL;
-}
-early_param("elfcorehdr", setup_elfcorehdr);

diff --git a/kernel/elfcorehdr.c b/kernel/elfcorehdr.c
new file mode 100644 (file)
index 0000000..92da322
--- /dev/null
+++ b/kernel/elfcorehdr.c
@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/kernel.h>
+#include <linux/crash_dump.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/export.h>
+
+/*
+ * stores the physical address of elf header of crash image
+ *
+ * Note: elfcorehdr_addr is not just limited to vmcore. It is also used by
+ * is_kdump_kernel() to determine if we are booting after a panic. Hence put
+ * it under CONFIG_CRASH_DUMP and not CONFIG_PROC_VMCORE.
+ */
+unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX;
+EXPORT_SYMBOL_GPL(elfcorehdr_addr);
+
+/*
+ * stores the size of elf header of crash image
+ */
+unsigned long long elfcorehdr_size;
+
+/*
+ * elfcorehdr= specifies the location of elf core header stored by the crashed
+ * kernel. This option will be passed by kexec loader to the capture kernel.
+ *
+ * Syntax: elfcorehdr=[size[KMG]@]offset[KMG]
+ */
+static int __init setup_elfcorehdr(char *arg)
+{
+       char *end;
+       if (!arg)
+               return -EINVAL;
+       elfcorehdr_addr = memparse(arg, &end);
+       if (*end == '@') {
+               elfcorehdr_size = elfcorehdr_addr;
+               elfcorehdr_addr = memparse(end + 1, &end);
+       }
+       return end > arg ? 0 : -EINVAL;
+}
+early_param("elfcorehdr", setup_elfcorehdr);

diff --git a/kernel/kexec_internal.h b/kernel/kexec_internal.h
index 74da1409cd14b5db50c60832eb7445a747ae0447..2595defe8c0d92dd3ec395da082b3c0909ff06eb 100644 (file)
--- a/kernel/kexec_internal.h
+++ b/kernel/kexec_internal.h
@@ -4,6 +4,8 @@
 
 #include <linux/kexec.h>
 
+struct kexec_segment;
+
 struct kimage *do_kimage_alloc_init(void);
 int sanity_check_segment_list(struct kimage *image);
 void kimage_free_page_list(struct list_head *list);