On Wed, Apr 28, 2010 at 05:28:55PM +0200, ext Dave Anderson wrote:
> ----- "Mika Westerberg" <ext-mika.1.westerberg at nokia.com> wrote:
> > > But for x86, their is no concept of a mapped kernel region in addition
> > > to the unity-mapped region(s), as there is with x86_64 and ia64. It's
> > > presumed that the primary kernel is based at physical adress 0, so when
> > > the PAGE_OFFSET is stripped off, you have the physical address.
> >
> > With ARM we have (for the kernel direct mapped region):
> >
> > paddr = vaddr - PAGE_OFFSET + PHYS_OFFSET
> >
> > so it is related to PHYS_OFFSET.
> >
> > Is there any (other) way of doing this so that we could get p_vaddr correct? I
> > checked makedumpfile but it seems not to handle p_vaddr at all so it probably
> > won't help if we run the dump through it.
>
> When you say "we" do you mean ARM only?
Yes :)
> All I'm saying is that things "just work" for the currently-supported
> architectures. The most recent sample x86 kdump vmcore I have looks like this:
>
> Program Headers:
> Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
> NOTE 0x0000b4 0x00000000 0x00000000 0x00450 0x00450 0
> LOAD 0x000504 0xc0000000 0x00000000 0xa0000 0xa0000 RWE 0
> LOAD 0x0a0504 0xc0100000 0x00100000 0xf00000 0xf00000 RWE 0
> LOAD 0xfa0504 0xc5000000 0x05000000 0x1afc0000 0x1afc0000 RWE 0
>
> Regardless whether the virtual address is in the static kernel text and
> data section (which is mapped in a special region on x86_64 and ia64) or
> just generic physical memory above that, it's all zero-based, where the
> virtual-to-physical translation simply requires stripping of the PAGE_OFFSET.
> The p_vaddr values above match the kernel virtual addresses used by the
> corresponding x86 vmlinux.
>
> So all I'm asking is that you don't muck with that! ;-)
I'll promise that I don't break it.
So how about following? This allows ARM (and maybe some future archs as well) to
redefine phys_to_virt() but default implementation should work with others.
Thanks,
MW
>From dcfda0e78ae9bfe3c9ff5d186c660e5ce1892fbb Mon Sep 17 00:00:00 2001
From: Mika Westerberg <ext-mika.1.westerberg@xxxxxxxxx>
Date: Thu, 29 Apr 2010 11:07:14 +0300
Subject: [PATCH] kexec: introduce phys_to_virt() function
This function is used by ELF crashdump code which prepares crash memory headers
for the dump capture kernel. Most architecture can use default version which
just adds PAGE_OFFSET to the virtual address but some architectures might need
some special handling.
Signed-off-by: Mika Westerberg <ext-mika.1.westerberg at nokia.com>
---
kexec/Makefile | 2 ++
kexec/crashdump-elf.c | 2 +-
kexec/crashdump.h | 3 +++
kexec/phys_to_virt.c | 16 ++++++++++++++++
4 files changed, 22 insertions(+), 1 deletions(-)
create mode 100644 kexec/phys_to_virt.c
diff --git a/kexec/Makefile b/kexec/Makefile
index 4e091ba..77f37ae 100644
--- a/kexec/Makefile
+++ b/kexec/Makefile
@@ -39,6 +39,8 @@ $(ARCH)_PROC_IOMEM = kexec/proc_iomem.c
KEXEC_SRCS += $($(ARCH)_PROC_IOMEM)
$(ARCH)_VIRT_TO_PHYS = kexec/virt_to_phys.c
KEXEC_SRCS += $($(ARCH)_VIRT_TO_PHYS)
+$(ARCH)_PHYS_TO_VIRT = kexec/phys_to_virt.c
+KEXEC_SRCS += $($(ARCH)_PHYS_TO_VIRT)
$(ARCH)_ADD_SEGMENT = kexec/add_segment.c
KEXEC_SRCS += $($(ARCH)_ADD_SEGMENT)
$(ARCH)_ADD_BUFFER = kexec/add_buffer.c
diff --git a/kexec/crashdump-elf.c b/kexec/crashdump-elf.c
index 6bcef8d..f000e42 100644
--- a/kexec/crashdump-elf.c
+++ b/kexec/crashdump-elf.c
@@ -236,7 +236,7 @@ int FUNC(struct kexec_info *info,
* memory region.
*/
phdr->p_paddr = mstart;
- phdr->p_vaddr = mstart + elf_info->page_offset;
+ phdr->p_vaddr = phys_to_virt(elf_info, mstart);
phdr->p_filesz = phdr->p_memsz = mend - mstart + 1;
/* Do we need any alignment of segments? */
phdr->p_align = 0;
diff --git a/kexec/crashdump.h b/kexec/crashdump.h
index 30d6f29..b6e60cc 100644
--- a/kexec/crashdump.h
+++ b/kexec/crashdump.h
@@ -46,6 +46,9 @@ int crash_create_elf64_headers(struct kexec_info *info,
unsigned long crash_architecture(struct crash_elf_info *elf_info);
+unsigned long phys_to_virt(struct crash_elf_info *elf_info,
+ unsigned long paddr);
+
int xen_present(void);
unsigned long xen_architecture(struct crash_elf_info *elf_info);
int xen_get_nr_phys_cpus(void);
diff --git a/kexec/phys_to_virt.c b/kexec/phys_to_virt.c
new file mode 100644
index 0000000..2370e56
--- /dev/null
+++ b/kexec/phys_to_virt.c
@@ -0,0 +1,16 @@
+#include "kexec.h"
+#include "crashdump.h"
+
+/**
+ * virt_to_phys() - translate physical address to virtual address
+ * @paddr: physical address to translate
+ *
+ * For most architectures physical address is simply virtual address minus
+ * PAGE_OFFSET. Architectures that don't follow this convention should provide
+ * their own implementation.
+ */
+unsigned long
+phys_to_virt(struct crash_elf_info *elf_info, unsigned long paddr)
+{
+ return paddr + elf_info->page_offset;
+}
--
1.5.6.5
