[PATCH] makedumpfile: Enable --mem-usage for s390x

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>On 10/23/14 at 06:56am, Atsushi Kumagai wrote:
>> >On Tue, 14 Oct 2014 07:19:13 +0000
>> >Atsushi Kumagai <kumagai-atsushi at mxc.nes.nec.co.jp> wrote:
>> >
>> >[snip]
>> >
>> >>
>> >> I understand why your patch works on s390x, so how about this way ?
>> >>
>> >>  1. Define "is_phys_addr()" for --mem-usage.
>> >>  2. Implement is_phys_addr() using is_iomem_phys_addr() for s390x
>> >>     while x86_64 uses is_vmalloc_addr_x86_64().
>> >>  3. Use is_phys_addr() instead of is_vmalloc_addr() in get_kcore_dump_loads().
>> >
>> >Hello Atsushi,
>> >
>> >Great, so let's do that.
>> >
>> >@Baoquan:
>> >If you want to use the is_iomem_phys_addr() function also for x86,
>> >you could perhaps add an additional patch.
>>
>> I noticed that is_vmalloc_addr_x86_64() can't be used as is_phys_addr()
>> due to the "kaslr issue". I fixed it in the common path as below, but
>> --mem-usage still has the same issue since initial() will be invoked
>> after get_kcore_dump_loads().
>>
>>   http://lists.infradead.org/pipermail/kexec/2014-October/012743.html
>>
>> I know it's so late, but I began to think the current implementation
>> that invokes vaddr_to_paddr_XXX() before initial() is bad:
>>
>> show_mem_usage()
>>   + get_kcore_dump_loads()
>>     + process_dump_load()
>>       + vaddr_to_paddr_XXX()
>>   + initial()
>
>This is a bug. Seems that get_kcore_dump_loads() has to be called in
>initial(). Since dumped vmcore need contains kernel text segment.
>Without setting correct value for MODULES_VADDR, it will be equal to
>__START_KERNEL_map, then calling is_vmalloc_addr() will filter kernel
>text mapping segment too.
>
>Now it seems only one way to solve this, that is moving
>get_kcore_dump_loads() into initial() just after
>get_value_for_old_linux() is called.

I agree, I'll do it, thanks.


Atsushi Kumagai

>>   ...
>>
>> vaddr_to_paddr_XXX() does VtoP translation *properly*, so it needs
>> several symbols. This design is OK since it's a general method.
>> OTOH, we need a kludge which can be used under any situations and
>> should use it for --mem-usage:
>>
>>   VtoP_kludge_s390x(unsigned long vaddr)
>>   {
>> 	/* s390 has 1:1 VtoP mapping that starts with zero. */
>>   	return vaddr;
>>   }
>>
>> also x86_64's can be implemented like below:
>>
>>   VtoP_kludge_x86_64(unsigned long vaddr)
>>   {
>> 	/* if the address is direct mapped, it's easy to translate. */
>> 	unsigned long paddr = vaddr - PAGE_OFFSET;
>> 	return paddr;
>>   }
>>
>> >Here the updated patch:
>> >---
>> >[PATCH] makedumpfile: Enable --mem-usage for s390x
>> >
>> >Replace is_vmalloc_addr() by is_phys_addr() and implement is_phys_addr()
>> >using /proc/iommem parsing to enable the new makedumpfile option "--mem-usage"
>> >on s390x.
>> >
>> >Signed-off-by: Michael Holzheu <holzheu at linux.vnet.ibm.com>
>> >---
>> > elf_info.c     |    4 ++--
>> > makedumpfile.c |   26 ++++++++++++++++++++++++++
>> > makedumpfile.h |   15 ++++++++-------
>> > 3 files changed, 36 insertions(+), 9 deletions(-)
>> >
>> >--- a/elf_info.c
>> >+++ b/elf_info.c
>> >@@ -854,7 +854,7 @@ int get_kcore_dump_loads(void)
>> >
>> > 	for (i = 0; i < num_pt_loads; ++i) {
>> > 		struct pt_load_segment *p = &pt_loads[i];
>> >-		if (is_vmalloc_addr(p->virt_start))
>> >+		if (!is_phys_addr(p->virt_start))
>>
>> This part implicitly does VtoP translation.
>> Actually it works for s390x but it's not suitable as a general code,
>> so we should use VtoP_kludge(should be better name!) too.
>> Then we can use is_iomem_phys_addr() also for other architecture.
>>
>>
>> Thanks,
>> Atsushi Kumagai
>>
>> > 			continue;
>> > 		loads++;
>> > 	}
>> >@@ -874,7 +874,7 @@ int get_kcore_dump_loads(void)
>> >
>> > 	for (i = 0, j = 0; i < num_pt_loads; ++i) {
>> > 		struct pt_load_segment *p = &pt_loads[i];
>> >-		if (is_vmalloc_addr(p->virt_start))
>> >+		if (!is_phys_addr(p->virt_start))
>> > 			continue;
>> > 		if (j >= loads)
>> > 			return FALSE;
>> >--- a/makedumpfile.c
>> >+++ b/makedumpfile.c
>> >@@ -9227,6 +9227,32 @@ int is_crashkernel_mem_reserved(void)
>> > 	return !!crash_reserved_mem_nr;
>> > }
>> >
>> >+struct addr_check {
>> >+	unsigned long addr;
>> >+	int found;
>> >+};
>> >+
>> >+static int phys_addr_callback(void *data, int nr, char *str,
>> >+			      unsigned long base, unsigned long length)
>> >+{
>> >+	struct addr_check *addr_check = data;
>> >+	unsigned long addr = addr_check->addr;
>> >+
>> >+	if (addr >= base && addr < base + length) {
>> >+		addr_check->found = 1;
>> >+		return -1;
>> >+	}
>> >+	return 0;
>> >+}
>> >+
>> >+int is_iomem_phys_addr(unsigned long addr)
>> >+{
>> >+	struct addr_check addr_check = {addr, 0};
>> >+
>> >+	iomem_for_each_line("System RAM\n", phys_addr_callback, &addr_check);
>> >+	return addr_check.found;
>> >+}
>> >+
>> > static int get_page_offset(void)
>> > {
>> > 	struct utsname utsname;
>> >--- a/makedumpfile.h
>> >+++ b/makedumpfile.h
>> >@@ -765,7 +765,7 @@ unsigned long long vaddr_to_paddr_arm(un
>> > #define get_machdep_info()	get_machdep_info_arm()
>> > #define get_versiondep_info()	TRUE
>> > #define vaddr_to_paddr(X)	vaddr_to_paddr_arm(X)
>> >-#define is_vmalloc_addr(X)	TRUE
>> >+#define is_phys_addr(X)		TRUE
>> > #endif /* arm */
>> >
>> > #ifdef __x86__
>> >@@ -776,7 +776,7 @@ unsigned long long vaddr_to_paddr_x86(un
>> > #define get_machdep_info()	get_machdep_info_x86()
>> > #define get_versiondep_info()	get_versiondep_info_x86()
>> > #define vaddr_to_paddr(X)	vaddr_to_paddr_x86(X)
>> >-#define is_vmalloc_addr(X)	TRUE
>> >+#define is_phys_addr(X)		TRUE
>> > #endif /* x86 */
>> >
>> > #ifdef __x86_64__
>> >@@ -789,7 +789,7 @@ unsigned long long vaddr_to_paddr_x86_64
>> > #define get_machdep_info()	get_machdep_info_x86_64()
>> > #define get_versiondep_info()	get_versiondep_info_x86_64()
>> > #define vaddr_to_paddr(X)	vaddr_to_paddr_x86_64(X)
>> >-#define is_vmalloc_addr(X)	is_vmalloc_addr_x86_64(X)
>> >+#define is_phys_addr(X)		(!is_vmalloc_addr_x86_64(X)
>> > #endif /* x86_64 */
>> >
>> > #ifdef __powerpc64__ /* powerpc64 */
>> >@@ -800,7 +800,7 @@ unsigned long long vaddr_to_paddr_ppc64(
>> > #define get_machdep_info()	get_machdep_info_ppc64()
>> > #define get_versiondep_info()	get_versiondep_info_ppc64()
>> > #define vaddr_to_paddr(X)	vaddr_to_paddr_ppc64(X)
>> >-#define is_vmalloc_addr(X)	TRUE
>> >+#define is_phys_addr(X)		TRUE
>> > #endif          /* powerpc64 */
>> >
>> > #ifdef __powerpc32__ /* powerpc32 */
>> >@@ -810,7 +810,7 @@ unsigned long long vaddr_to_paddr_ppc(un
>> > #define get_machdep_info()	get_machdep_info_ppc()
>> > #define get_versiondep_info()	TRUE
>> > #define vaddr_to_paddr(X)	vaddr_to_paddr_ppc(X)
>> >-#define is_vmalloc_addr(X)	TRUE
>> >+#define is_phys_addr(X)		TRUE
>> > #endif          /* powerpc32 */
>> >
>> > #ifdef __s390x__ /* s390x */
>> >@@ -820,7 +820,7 @@ unsigned long long vaddr_to_paddr_s390x(
>> > #define get_machdep_info()	get_machdep_info_s390x()
>> > #define get_versiondep_info()	TRUE
>> > #define vaddr_to_paddr(X)	vaddr_to_paddr_s390x(X)
>> >-#define is_vmalloc_addr(X)	TRUE
>> >+#define is_phys_addr(X)		is_iomem_phys_addr(X)
>> > #endif          /* s390x */
>> >
>> > #ifdef __ia64__ /* ia64 */
>> >@@ -832,7 +832,7 @@ unsigned long long vaddr_to_paddr_ia64(u
>> > #define get_versiondep_info()	TRUE
>> > #define vaddr_to_paddr(X)	vaddr_to_paddr_ia64(X)
>> > #define VADDR_REGION(X)		(((unsigned long)(X)) >> REGION_SHIFT)
>> >-#define is_vmalloc_addr(X)	TRUE
>> >+#define is_phys_addr(X)		TRUE
>> > #endif          /* ia64 */
>> >
>> > typedef unsigned long long mdf_pfn_t;
>> >@@ -1567,6 +1567,7 @@ int read_disk_dump_header(struct disk_du
>> > int read_kdump_sub_header(struct kdump_sub_header *kh, char *filename);
>> > void close_vmcoreinfo(void);
>> > int close_files_for_creating_dumpfile(void);
>> >+int is_iomem_phys_addr(unsigned long addr);
>> >
>> >
>> > /*
>>



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