From 57cac4d1880527e0baf6c2fda529d2ad1d815aec Mon Sep 17 00:00:00 2001 From: Vivek Goyal Date: Sat, 18 Oct 2008 20:28:25 -0700 Subject: kdump: make elfcorehdr_addr independent of CONFIG_PROC_VMCORE o elfcorehdr_addr is used by not only the code under CONFIG_PROC_VMCORE but also by the code which is not inside CONFIG_PROC_VMCORE. For example, is_kdump_kernel() is used by powerpc code to determine if kernel is booting after a panic then use previous kernel's TCE table. So even if CONFIG_PROC_VMCORE is not set in second kernel, one should be able to correctly determine that we are booting after a panic and setup calgary iommu accordingly. o So remove the assumption that elfcorehdr_addr is under CONFIG_PROC_VMCORE. o Move definition of elfcorehdr_addr to arch dependent crash files. (Unfortunately crash dump does not have an arch independent file otherwise that would have been the best place). o kexec.c is not the right place as one can Have CRASH_DUMP enabled in second kernel without KEXEC being enabled. o I don't see sh setup code parsing the command line for elfcorehdr_addr. I am wondering how does vmcore interface work on sh. Anyway, I am atleast defining elfcoredhr_addr so that compilation is not broken on sh. Signed-off-by: Vivek Goyal Acked-by: "Eric W. Biederman" Acked-by: Simon Horman Acked-by: Paul Mundt Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/crash_dump.h | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) (limited to 'include/linux/crash_dump.h') diff --git a/include/linux/crash_dump.h b/include/linux/crash_dump.h index 025e4f57510..de027d1db74 100644 --- a/include/linux/crash_dump.h +++ b/include/linux/crash_dump.h @@ -9,11 +9,7 @@ #define ELFCORE_ADDR_MAX (-1ULL) -#ifdef CONFIG_PROC_VMCORE extern unsigned long long elfcorehdr_addr; -#else -static const unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX; -#endif extern ssize_t copy_oldmem_page(unsigned long, char *, size_t, unsigned long, int); @@ -28,6 +24,16 @@ extern struct proc_dir_entry *proc_vmcore; #define vmcore_elf_check_arch(x) (elf_check_arch(x) || vmcore_elf_check_arch_cross(x)) +/* + * is_kdump_kernel() checks whether this kernel is booting after a panic of + * previous kernel or not. This is determined by checking if previous kernel + * has passed the elf core header address on command line. + * + * This is not just a test if CONFIG_CRASH_DUMP is enabled or not. It will + * return 1 if CONFIG_CRASH_DUMP=y and if kernel is booting after a panic of + * previous kernel. + */ + static inline int is_kdump_kernel(void) { return (elfcorehdr_addr != ELFCORE_ADDR_MAX) ? 1 : 0; -- cgit v1.2.3 From 85a0ee342e0c06c19d78fdf48307211c6cf18fcb Mon Sep 17 00:00:00 2001 From: Simon Horman Date: Sat, 18 Oct 2008 20:28:29 -0700 Subject: kdump: add is_vmcore_usable() and vmcore_unusable() The usage of elfcorehdr_addr has changed recently such that being set to ELFCORE_ADDR_MAX is used by is_kdump_kernel() to indicate if the code is executing in a kernel executed as a crash kernel. However, arch/ia64/kernel/setup.c:reserve_elfcorehdr will rest elfcorehdr_addr to ELFCORE_ADDR_MAX on error, which means any subsequent calls to is_kdump_kernel() will return 0, even though they should return 1. Ok, at this point in time there are no subsequent calls, but I think its fair to say that there is ample scope for error or at the very least confusion. This patch add an extra state, ELFCORE_ADDR_ERR, which indicates that elfcorehdr_addr was passed on the command line, and thus execution is taking place in a crashdump kernel, but vmcore can't be used for some reason. This is tested for using is_vmcore_usable() and set using vmcore_unusable(). A subsequent patch makes use of this new code. To summarise, the states that elfcorehdr_addr can now be in are as follows: ELFCORE_ADDR_MAX: not a crashdump kernel ELFCORE_ADDR_ERR: crashdump kernel but vmcore is unusable any other value: crash dump kernel and vmcore is usable Signed-off-by: Simon Horman Cc: Vivek Goyal Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/crash_dump.h | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) (limited to 'include/linux/crash_dump.h') diff --git a/include/linux/crash_dump.h b/include/linux/crash_dump.h index de027d1db74..0acf3b737e2 100644 --- a/include/linux/crash_dump.h +++ b/include/linux/crash_dump.h @@ -8,6 +8,7 @@ #include #define ELFCORE_ADDR_MAX (-1ULL) +#define ELFCORE_ADDR_ERR (-2ULL) extern unsigned long long elfcorehdr_addr; @@ -38,6 +39,29 @@ static inline int is_kdump_kernel(void) { return (elfcorehdr_addr != ELFCORE_ADDR_MAX) ? 1 : 0; } + +/* is_vmcore_usable() checks if the kernel is booting after a panic and + * the vmcore region is usable. + * + * This makes use of the fact that due to alignment -2ULL is not + * a valid pointer, much in the vain of IS_ERR(), except + * dealing directly with an unsigned long long rather than a pointer. + */ + +static inline int is_vmcore_usable(void) +{ + return is_kdump_kernel() && elfcorehdr_addr != ELFCORE_ADDR_ERR ? 1 : 0; +} + +/* vmcore_unusable() marks the vmcore as unusable, + * without disturbing the logic of is_kdump_kernel() + */ + +static inline void vmcore_unusable(void) +{ + if (is_kdump_kernel()) + elfcorehdr_addr = ELFCORE_ADDR_ERR; +} #else /* !CONFIG_CRASH_DUMP */ static inline int is_kdump_kernel(void) { return 0; } #endif /* CONFIG_CRASH_DUMP */ -- cgit v1.2.3