svn commit: r284870 - in head/sys: amd64/amd64 conf
Roger Pau Monné
royger at FreeBSD.org
Fri Jun 26 07:12:18 UTC 2015
Author: royger
Date: Fri Jun 26 07:12:17 2015
New Revision: 284870
URL: https://svnweb.freebsd.org/changeset/base/284870
Log:
amd64: set the correct LMA values
The current linker script generates program headers with VMA == LMA:
Entry point 0xffffffff802e7000
There are 6 program headers, starting at offset 64
Program Headers:
Type Offset VirtAddr PhysAddr
FileSiz MemSiz Flags Align
PHDR 0x0000000000000040 0xffffffff80200040 0xffffffff80200040
0x0000000000000150 0x0000000000000150 R E 8
INTERP 0x0000000000000190 0xffffffff80200190 0xffffffff80200190
0x000000000000000d 0x000000000000000d R 1
[Requesting program interpreter: /red/herring]
LOAD 0x0000000000000000 0xffffffff80200000 0xffffffff80200000
0x00000000010559b0 0x00000000010559b0 R E 200000
LOAD 0x0000000001056000 0xffffffff81456000 0xffffffff81456000
0x0000000000132638 0x000000000052ecf8 RW 200000
DYNAMIC 0x0000000001056000 0xffffffff81456000 0xffffffff81456000
0x00000000000000d0 0x00000000000000d0 RW 8
GNU_STACK 0x0000000000000000 0x0000000000000000 0x0000000000000000
0x0000000000000000 0x0000000000000000 RWE 8
This is fine for the FreeBSD loader, because it completely ignores p_paddr
and instead uses p_vaddr with a hardcoded offset. Other loaders however
acknowledge p_paddr (like the Xen ELF loader), in which case they will try
to load the kernel at the wrong place. Fix this by adding an AT keyword to
the first section specifying the physical address, other sections will
follow suit, so it ends up looking like:
Entry point 0xffffffff802e7000
There are 6 program headers, starting at offset 64
Program Headers:
Type Offset VirtAddr PhysAddr
FileSiz MemSiz Flags Align
PHDR 0x0000000000000040 0xffffffff80200040 0x0000000000200040
0x0000000000000150 0x0000000000000150 R E 8
INTERP 0x0000000000000190 0xffffffff80200190 0x0000000000200190
0x000000000000000d 0x000000000000000d R 1
[Requesting program interpreter: /red/herring]
LOAD 0x0000000000000000 0xffffffff80200000 0x0000000000200000
0x00000000010559b0 0x00000000010559b0 R E 200000
LOAD 0x0000000001056000 0xffffffff81456000 0x0000000001456000
0x0000000000132638 0x000000000052ecf8 RW 200000
DYNAMIC 0x0000000001056000 0xffffffff81456000 0x0000000001456000
0x00000000000000d0 0x00000000000000d0 RW 8
GNU_STACK 0x0000000000000000 0x0000000000000000 0x0000000000000000
0x0000000000000000 0x0000000000000000 RWE 8
Tested on bare metal using the native FreeBSD loader and grub2 from TRUEOS.
Sponsored by: Citrix Systems R&D
Reviewed by: kib
Differential Revision: https://reviews.freebsd.org/D2783
Modified:
head/sys/amd64/amd64/xen-locore.S
head/sys/conf/ldscript.amd64
Modified: head/sys/amd64/amd64/xen-locore.S
==============================================================================
--- head/sys/amd64/amd64/xen-locore.S Fri Jun 26 07:01:29 2015 (r284869)
+++ head/sys/amd64/amd64/xen-locore.S Fri Jun 26 07:12:17 2015 (r284870)
@@ -47,7 +47,7 @@
ELFNOTE(Xen, XEN_ELFNOTE_GUEST_VERSION, .asciz, __XSTRING(__FreeBSD_version))
ELFNOTE(Xen, XEN_ELFNOTE_XEN_VERSION, .asciz, "xen-3.0")
ELFNOTE(Xen, XEN_ELFNOTE_VIRT_BASE, .quad, KERNBASE)
- ELFNOTE(Xen, XEN_ELFNOTE_PADDR_OFFSET, .quad, KERNBASE) /* Xen honours elf->p_paddr; compensate for this */
+ ELFNOTE(Xen, XEN_ELFNOTE_PADDR_OFFSET, .quad, 0)
ELFNOTE(Xen, XEN_ELFNOTE_ENTRY, .quad, xen_start)
ELFNOTE(Xen, XEN_ELFNOTE_HYPERCALL_PAGE, .quad, hypercall_page)
ELFNOTE(Xen, XEN_ELFNOTE_HV_START_LOW, .quad, HYPERVISOR_VIRT_START)
Modified: head/sys/conf/ldscript.amd64
==============================================================================
--- head/sys/conf/ldscript.amd64 Fri Jun 26 07:01:29 2015 (r284869)
+++ head/sys/conf/ldscript.amd64 Fri Jun 26 07:12:17 2015 (r284870)
@@ -8,7 +8,12 @@ SECTIONS
/* Read-only sections, merged into text segment: */
kernphys = CONSTANT (MAXPAGESIZE);
. = kernbase + kernphys + SIZEOF_HEADERS;
- .interp : { *(.interp) }
+ /*
+ * Use the AT keyword in order to set the right LMA that contains
+ * the physical address where the section should be loaded. This is
+ * needed for the Xen loader which honours the LMA.
+ */
+ .interp : AT (kernphys + SIZEOF_HEADERS) { *(.interp) }
.hash : { *(.hash) }
.gnu.hash : { *(.gnu.hash) }
.dynsym : { *(.dynsym) }
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