On 10/27/14 at 03:57pm, Baoquan He wrote:
> On 10/23/14 at 06:56am, Atsushi Kumagai wrote:
> > >On Tue, 14 Oct 2014 07:19:13 +0000
> > >Atsushi Kumagai <[email protected]> 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.
Hi Atsushi,
Checking code again, I found with kaslr support we need move vmcoreinfo
reading earlier to initialize the MODULES_VADDR, otherwise
get_phys_base_x86_64() will be wrong. Since not initializing
MODULES_VADDR explicitly its value is equal to __START_KERNEL_map, that
means kernel text mapping segment is filtered by
is_vmalloc_addr_x86_64().
So could we move below code earlier?
diff --git a/makedumpfile.c b/makedumpfile.c
index b27ea1e..1dac19f 100644
--- a/makedumpfile.c
+++ b/makedumpfile.c
@@ -3092,6 +3092,23 @@ initial(void)
return FALSE;
}
+ /*
+ * Get the debug information from /proc/vmcore.
+ * NOTE: Don't move this code to the above, because the debugging
+ * information token by -x/-i option is overwritten by vmcoreinfo
+ * in /proc/vmcore. vmcoreinfo in /proc/vmcore is more reliable
+ * than -x/-i option.
+ */
+ if (has_vmcoreinfo()) {
+ get_vmcoreinfo(&offset, &size);
+ if (!read_vmcoreinfo_from_vmcore(offset, size, FALSE))
+ return FALSE;
+ debug_info = TRUE;
+ }
+
+ if (!get_value_for_old_linux())
+ return FALSE;
+
if (info->flag_refiltering) {
if (info->flag_elf_dumpfile) {
MSG("'-E' option is disable, ");
@@ -3189,23 +3206,6 @@ initial(void)
}
}
- /*
- * Get the debug information from /proc/vmcore.
- * NOTE: Don't move this code to the above, because the debugging
- * information token by -x/-i option is overwritten by vmcoreinfo
- * in /proc/vmcore. vmcoreinfo in /proc/vmcore is more reliable
- * than -x/-i option.
- */
- if (has_vmcoreinfo()) {
- get_vmcoreinfo(&offset, &size);
- if (!read_vmcoreinfo_from_vmcore(offset, size, FALSE))
- return FALSE;
- debug_info = TRUE;
- }
-
- if (!get_value_for_old_linux())
- return FALSE;
-
out:
if (!info->page_size) {
/*
_______________________________________________
kexec mailing list
[email protected]
http://lists.infradead.org/mailman/listinfo/kexec
