[PATCH] kexec: x86_64: add CONFIG_PHYSICAL_START
For one kernel to report a crash another kernel has created we need
to have 2 kernels loaded simultaneously in memory. To accomplish this
the two kernels need to built to run at different physical addresses.
This patch adds the CONFIG_PHYSICAL_START option to the x86_64 kernel
so we can do just that. You need to know what you are doing and
the ramifications are before changing this value, and most users
won't care so I have made it depend on CONFIG_EMBEDDED
bzImage kernels will work and run at a different address when compiled
with this option but they will still load at 1MB. If you need a kernel
loaded at a different address as well you need to boot a vmlinux.
Signed-off-by: Eric Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/x86_64/Kconfig b/arch/x86_64/Kconfig
index a853d87..56c02cf 100644
--- a/arch/x86_64/Kconfig
+++ b/arch/x86_64/Kconfig
@@ -369,6 +369,17 @@
Additional support for intel specific MCE features such as
the thermal monitor.
+config PHYSICAL_START
+ hex "Physical address where the kernel is loaded" if EMBEDDED
+ default "0x100000"
+ help
+ This gives the physical address where the kernel is loaded.
+ Primarily used in the case of kexec on panic where the
+ fail safe kernel needs to run at a different address than
+ the panic-ed kernel.
+
+ Don't change this unless you know what you are doing.
+
config SECCOMP
bool "Enable seccomp to safely compute untrusted bytecode"
depends on PROC_FS
diff --git a/arch/x86_64/boot/compressed/head.S b/arch/x86_64/boot/compressed/head.S
index 27264db..b0df2ae 100644
--- a/arch/x86_64/boot/compressed/head.S
+++ b/arch/x86_64/boot/compressed/head.S
@@ -28,6 +28,7 @@
#include <linux/linkage.h>
#include <asm/segment.h>
+#include <asm/page.h>
.code32
.globl startup_32
@@ -77,7 +78,7 @@
jnz 3f
addl $8,%esp
xorl %ebx,%ebx
- ljmp $(__KERNEL_CS), $0x100000
+ ljmp $(__KERNEL_CS), $__PHYSICAL_START
/*
* We come here, if we were loaded high.
@@ -103,7 +104,7 @@
popl %ecx # lcount
popl %edx # high_buffer_start
popl %eax # hcount
- movl $0x100000,%edi
+ movl $__PHYSICAL_START,%edi
cli # make sure we don't get interrupted
ljmp $(__KERNEL_CS), $0x1000 # and jump to the move routine
@@ -128,7 +129,7 @@
movsl
movl %ebx,%esi # Restore setup pointer
xorl %ebx,%ebx
- ljmp $(__KERNEL_CS), $0x100000
+ ljmp $(__KERNEL_CS), $__PHYSICAL_START
move_routine_end:
diff --git a/arch/x86_64/boot/compressed/misc.c b/arch/x86_64/boot/compressed/misc.c
index c8b9216..c43cedb 100644
--- a/arch/x86_64/boot/compressed/misc.c
+++ b/arch/x86_64/boot/compressed/misc.c
@@ -11,6 +11,7 @@
#include "miscsetup.h"
#include <asm/io.h>
+#include <asm/page.h>
/*
* gzip declarations
@@ -284,7 +285,7 @@
#else
if ((ALT_MEM_K > EXT_MEM_K ? ALT_MEM_K : EXT_MEM_K) < 1024) error("Less than 2MB of memory");
#endif
- output_data = (char *)0x100000; /* Points to 1M */
+ output_data = (char *)__PHYSICAL_START; /* Normally Points to 1M */
free_mem_end_ptr = (long)real_mode;
}
@@ -307,8 +308,8 @@
low_buffer_size = low_buffer_end - LOW_BUFFER_START;
high_loaded = 1;
free_mem_end_ptr = (long)high_buffer_start;
- if ( (0x100000 + low_buffer_size) > ((ulg)high_buffer_start)) {
- high_buffer_start = (uch *)(0x100000 + low_buffer_size);
+ if ( (__PHYSICAL_START + low_buffer_size) > ((ulg)high_buffer_start)) {
+ high_buffer_start = (uch *)(__PHYSICAL_START + low_buffer_size);
mv->hcount = 0; /* say: we need not to move high_buffer */
}
else mv->hcount = -1;
diff --git a/arch/x86_64/kernel/head.S b/arch/x86_64/kernel/head.S
index 9bd2e7a..8d765aa 100644
--- a/arch/x86_64/kernel/head.S
+++ b/arch/x86_64/kernel/head.S
@@ -248,23 +248,23 @@
*/
.org 0x1000
ENTRY(init_level4_pgt)
- .quad 0x0000000000102007 /* -> level3_ident_pgt */
+ .quad 0x0000000000002007 + __PHYSICAL_START /* -> level3_ident_pgt */
.fill 255,8,0
- .quad 0x000000000010a007
+ .quad 0x000000000000a007 + __PHYSICAL_START
.fill 254,8,0
/* (2^48-(2*1024*1024*1024))/(2^39) = 511 */
- .quad 0x0000000000103007 /* -> level3_kernel_pgt */
+ .quad 0x0000000000003007 + __PHYSICAL_START /* -> level3_kernel_pgt */
.org 0x2000
ENTRY(level3_ident_pgt)
- .quad 0x0000000000104007
+ .quad 0x0000000000004007 + __PHYSICAL_START
.fill 511,8,0
.org 0x3000
ENTRY(level3_kernel_pgt)
.fill 510,8,0
/* (2^48-(2*1024*1024*1024)-((2^39)*511))/(2^30) = 510 */
- .quad 0x0000000000105007 /* -> level2_kernel_pgt */
+ .quad 0x0000000000005007 + __PHYSICAL_START /* -> level2_kernel_pgt */
.fill 1,8,0
.org 0x4000
@@ -337,17 +337,17 @@
.org 0xa000
ENTRY(level3_physmem_pgt)
- .quad 0x0000000000105007 /* -> level2_kernel_pgt (so that __va works even before pagetable_init) */
+ .quad 0x0000000000005007 + __PHYSICAL_START /* -> level2_kernel_pgt (so that __va works even before pagetable_init) */
.org 0xb000
#ifdef CONFIG_ACPI_SLEEP
ENTRY(wakeup_level4_pgt)
- .quad 0x0000000000102007 /* -> level3_ident_pgt */
+ .quad 0x0000000000002007 + __PHYSICAL_START /* -> level3_ident_pgt */
.fill 255,8,0
- .quad 0x000000000010a007
+ .quad 0x000000000000a007 + __PHYSICAL_START
.fill 254,8,0
/* (2^48-(2*1024*1024*1024))/(2^39) = 511 */
- .quad 0x0000000000103007 /* -> level3_kernel_pgt */
+ .quad 0x0000000000003007 + __PHYSICAL_START /* -> level3_kernel_pgt */
#endif
.data
diff --git a/include/asm-x86_64/page.h b/include/asm-x86_64/page.h
index 60130f4..4313187 100644
--- a/include/asm-x86_64/page.h
+++ b/include/asm-x86_64/page.h
@@ -64,12 +64,14 @@
#define __pgd(x) ((pgd_t) { (x) } )
#define __pgprot(x) ((pgprot_t) { (x) } )
-#define __START_KERNEL 0xffffffff80100000UL
+#define __PHYSICAL_START ((unsigned long)CONFIG_PHYSICAL_START)
+#define __START_KERNEL (__START_KERNEL_map + __PHYSICAL_START)
#define __START_KERNEL_map 0xffffffff80000000UL
#define __PAGE_OFFSET 0xffff810000000000UL
#else
-#define __START_KERNEL 0xffffffff80100000
+#define __PHYSICAL_START CONFIG_PHYSICAL_START
+#define __START_KERNEL (__START_KERNEL_map + __PHYSICAL_START)
#define __START_KERNEL_map 0xffffffff80000000
#define __PAGE_OFFSET 0xffff810000000000
#endif /* !__ASSEMBLY__ */