| |
|
 |
|
 |
|
|
|
| |
|
|
xen-devel
Re: [Xen-devel] [PATCH] Elf loader fixes
This is a good start as the PHYS vs. VIRT stuff in the ELF loader
is all a bit overloaded. However, I believe these changes aren't
quite complete and for example would break the released OpenSolaris Xen
client. It has multiple PT_LOAD sections in the Elf file,
some with p_vaddr == p_paddr on purpose and some which don't. We rely on a
"boot loader" (ie grub or domain builder) that only cares about p_paddr.
The identity mapped PT_LOAD section contains the OS entry point and
has the code to remap the other of the sections to the final VA by
creating/installing new page table entries.
For example, I think the xc_load_elf.c change:
@@ -189,7 +189,18 @@
for ( done = 0; done < phdr->p_filesz; done += chunksz )
{
- pa = (phdr->p_paddr + done) - dsi->v_start;
+ if (phdr->p_paddr == phdr->p_vaddr) {
+ /*
+ * Bug compatibility alert: In older linux kernels
+ * p_paddr is broken, it doesn't contain the physical
+ * address but instead is identical to p_vaddr. Thus
+ * we can't use it directly, instead we'll guess it
+ * using dsi->v_start.
+ */
+ pa = (phdr->p_vaddr + done) - dsi->v_start;
+ } else {
+ pa = (phdr->p_paddr + done);
+ }
va = xc_map_foreign_range(
xch, dom, PAGE_SIZE, PROT_WRITE, parray[pa>>PAGE_SHIFT]);
chunksz = phdr->p_filesz - done;
needs to have the line:
pa = (phdr->p_paddr + done);
be more like:
pa = (phdr->p_paddr + done) - kernstart;
or better yet add a dsi->p_start and dsi->p_end to use. The same
applies to your change to xen/common/elf.c for dom0.
To save you downloading OpenSolaris. Here's sample values from
the domU/dom0 ELF image:
In the xenguest section we currently specify VIRT_BASE=0x40000000, as
there was no PHYS_BASE=. In the flavor of your other changes, I'd expect
you could add PHYS_BASE= and OpenSolaris would change to use that.
e_entry: 0x40800000
Program Header[0]:
p_vaddr: 0x40800000 p_flags: [ PF_X PF_W PF_R ]
p_paddr: 0x40800000 p_type: [ PT_LOAD ]
p_filesz: 0xe95c p_memsz: 0xe95c
p_offset: 0xd4 p_align: 0
Program Header[1]:
p_vaddr: 0xfb400000 p_flags: [ PF_X PF_R ]
p_paddr: 0x40000000 p_type: [ PT_LOAD ]
p_filesz: 0x2aa362 p_memsz: 0x2aa362
p_offset: 0xea40 p_align: 0
Program Header[2]:
p_vaddr: 0xfb800000 p_flags: [ PF_X PF_W PF_R ]
p_paddr: 0x40400000 p_type: [ PT_LOAD ]
p_filesz: 0x16515 p_memsz: 0x94a44
p_offset: 0x2b8dc0 p_align: 0
Here's sample values we use for the 64 bit Xen OS image:
e_entry: 0x40800000
Program Header[0]:
p_vaddr: 0x40800000 p_flags: [ PF_X PF_W PF_R ]
p_paddr: 0x40800000 p_type: [ PT_LOAD ]
p_filesz: 0xed28 p_memsz: 0xed28
p_offset: 0x190 p_align: 0
Program Header[1]:
p_vaddr: 0xfffffffffb800000 p_flags: [ PF_X PF_R ]
p_paddr: 0x40000000 p_type: [ PT_LOAD ]
p_filesz: 0x39adca p_memsz: 0x39adca
p_offset: 0xeec0 p_align: 0
Program Header[2]:
p_vaddr: 0xfffffffffbc00000 p_flags: [ PF_X PF_W PF_R ]
p_paddr: 0x40400000 p_type: [ PT_LOAD ]
p_filesz: 0x20fe9 p_memsz: 0xe36c0
p_offset: 0x3a9cc0 p_align: 0
Joe
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
|
|
|
| |
|
Home