* [PATCH 1/11] i386: Distinguish absolute symbols
2006-10-23 19:24 [RFC][PATCH 0/11] i386: Relocatable BzImage (V3) Vivek Goyal
@ 2006-10-23 19:26 ` Vivek Goyal
2006-10-23 19:29 ` [PATCH 2/11] i386: Remove unnecessary ALIGN() in vmlinux.lds.S Vivek Goyal
` (10 subsequent siblings)
11 siblings, 0 replies; 17+ messages in thread
From: Vivek Goyal @ 2006-10-23 19:26 UTC (permalink / raw)
To: linux kernel mailing list
Cc: Reloc Kernel List, ebiederm, akpm, ak, hpa, magnus.damm, lwang,
dzickus, maneesh
Ld knows about 2 kinds of symbols, absolute and section
relative. Section relative symbols symbols change value
when a section is moved and absolute symbols do not.
Currently in the linker script we have several labels
marking the beginning and ending of sections that
are outside of sections, making them absolute symbols.
Having a mixture of absolute and section relative
symbols refereing to the same data is currently harmless
but it is confusing.
This must be done carefully as newer revs of ld do not place
symbols that appear in sections without data and instead
ld makes those symbols global :(
My ultimate goal is to build a relocatable kernel. The
safest and least intrusive technique is to generate
relocation entries so the kernel can be relocated at load
time. The only penalty would be an increase in the size
of the kernel binary. The problem is that if absolute and
relocatable symbols are not properly specified absolute symbols
will be relocated or section relative symbols won't be, which
is fatal.
The practical motivation is that when generating kernels that
will run from a reserved area for analyzing what caused
a kernel panic, it is simpler if you don't need to hard code
the physical memory location they will run at, especially
for the distributions.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
---
arch/i386/kernel/vmlinux.lds.S | 109 ++++++++++++++++++++------------------
include/asm-generic/vmlinux.lds.h | 10 +--
2 files changed, 63 insertions(+), 56 deletions(-)
diff -puN arch/i386/kernel/vmlinux.lds.S~i386-vmlinux.lds.S-Distinguish-absolute-symbols arch/i386/kernel/vmlinux.lds.S
--- linux-2.6.19-rc2-git7-reloc/arch/i386/kernel/vmlinux.lds.S~i386-vmlinux.lds.S-Distinguish-absolute-symbols 2006-10-23 12:55:12.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/i386/kernel/vmlinux.lds.S 2006-10-23 15:09:04.000000000 -0400
@@ -24,31 +24,32 @@ SECTIONS
. = __KERNEL_START;
phys_startup_32 = startup_32 - LOAD_OFFSET;
/* read-only */
- _text = .; /* Text and read-only data */
.text : AT(ADDR(.text) - LOAD_OFFSET) {
+ _text = .; /* Text and read-only data */
*(.text)
SCHED_TEXT
LOCK_TEXT
KPROBES_TEXT
*(.fixup)
*(.gnu.warning)
- } :text = 0x9090
-
- _etext = .; /* End of text section */
+ _etext = .; /* End of text section */
+ } :text = 0x9090
. = ALIGN(16); /* Exception table */
- __start___ex_table = .;
- __ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) { *(__ex_table) }
- __stop___ex_table = .;
+ __ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) {
+ __start___ex_table = .;
+ *(__ex_table)
+ __stop___ex_table = .;
+ }
RODATA
. = ALIGN(4);
- __tracedata_start = .;
.tracedata : AT(ADDR(.tracedata) - LOAD_OFFSET) {
+ __tracedata_start = .;
*(.tracedata)
+ __tracedata_end = .;
}
- __tracedata_end = .;
/* writeable */
.data : AT(ADDR(.data) - LOAD_OFFSET) { /* Data */
@@ -57,10 +58,12 @@ SECTIONS
} :data
. = ALIGN(4096);
- __nosave_begin = .;
- .data_nosave : AT(ADDR(.data_nosave) - LOAD_OFFSET) { *(.data.nosave) }
- . = ALIGN(4096);
- __nosave_end = .;
+ .data_nosave : AT(ADDR(.data_nosave) - LOAD_OFFSET) {
+ __nosave_begin = .;
+ *(.data.nosave)
+ . = ALIGN(4096);
+ __nosave_end = .;
+ }
. = ALIGN(4096);
.data.page_aligned : AT(ADDR(.data.page_aligned) - LOAD_OFFSET) {
@@ -74,8 +77,10 @@ SECTIONS
/* rarely changed data like cpu maps */
. = ALIGN(32);
- .data.read_mostly : AT(ADDR(.data.read_mostly) - LOAD_OFFSET) { *(.data.read_mostly) }
- _edata = .; /* End of data section */
+ .data.read_mostly : AT(ADDR(.data.read_mostly) - LOAD_OFFSET) {
+ *(.data.read_mostly)
+ _edata = .; /* End of data section */
+ }
#ifdef CONFIG_STACK_UNWIND
. = ALIGN(4);
@@ -93,39 +98,41 @@ SECTIONS
/* might get freed after init */
. = ALIGN(4096);
- __smp_alt_begin = .;
- __smp_alt_instructions = .;
.smp_altinstructions : AT(ADDR(.smp_altinstructions) - LOAD_OFFSET) {
+ __smp_alt_begin = .;
+ __smp_alt_instructions = .;
*(.smp_altinstructions)
+ __smp_alt_instructions_end = .;
}
- __smp_alt_instructions_end = .;
. = ALIGN(4);
- __smp_locks = .;
.smp_locks : AT(ADDR(.smp_locks) - LOAD_OFFSET) {
+ __smp_locks = .;
*(.smp_locks)
+ __smp_locks_end = .;
}
- __smp_locks_end = .;
.smp_altinstr_replacement : AT(ADDR(.smp_altinstr_replacement) - LOAD_OFFSET) {
*(.smp_altinstr_replacement)
+ . = ALIGN(4096);
+ __smp_alt_end = .;
}
- . = ALIGN(4096);
- __smp_alt_end = .;
/* will be freed after init */
. = ALIGN(4096); /* Init code and data */
- __init_begin = .;
.init.text : AT(ADDR(.init.text) - LOAD_OFFSET) {
+ __init_begin = .;
_sinittext = .;
*(.init.text)
_einittext = .;
}
.init.data : AT(ADDR(.init.data) - LOAD_OFFSET) { *(.init.data) }
. = ALIGN(16);
- __setup_start = .;
- .init.setup : AT(ADDR(.init.setup) - LOAD_OFFSET) { *(.init.setup) }
- __setup_end = .;
- __initcall_start = .;
+ .init.setup : AT(ADDR(.init.setup) - LOAD_OFFSET) {
+ __setup_start = .;
+ *(.init.setup)
+ __setup_end = .;
+ }
.initcall.init : AT(ADDR(.initcall.init) - LOAD_OFFSET) {
+ __initcall_start = .;
*(.initcall1.init)
*(.initcall2.init)
*(.initcall3.init)
@@ -133,20 +140,20 @@ SECTIONS
*(.initcall5.init)
*(.initcall6.init)
*(.initcall7.init)
+ __initcall_end = .;
}
- __initcall_end = .;
- __con_initcall_start = .;
.con_initcall.init : AT(ADDR(.con_initcall.init) - LOAD_OFFSET) {
+ __con_initcall_start = .;
*(.con_initcall.init)
+ __con_initcall_end = .;
}
- __con_initcall_end = .;
SECURITY_INIT
. = ALIGN(4);
- __alt_instructions = .;
.altinstructions : AT(ADDR(.altinstructions) - LOAD_OFFSET) {
+ __alt_instructions = .;
*(.altinstructions)
+ __alt_instructions_end = .;
}
- __alt_instructions_end = .;
.altinstr_replacement : AT(ADDR(.altinstr_replacement) - LOAD_OFFSET) {
*(.altinstr_replacement)
}
@@ -155,32 +162,32 @@ SECTIONS
.exit.text : AT(ADDR(.exit.text) - LOAD_OFFSET) { *(.exit.text) }
.exit.data : AT(ADDR(.exit.data) - LOAD_OFFSET) { *(.exit.data) }
. = ALIGN(4096);
- __initramfs_start = .;
- .init.ramfs : AT(ADDR(.init.ramfs) - LOAD_OFFSET) { *(.init.ramfs) }
- __initramfs_end = .;
+ .init.ramfs : AT(ADDR(.init.ramfs) - LOAD_OFFSET) {
+ __initramfs_start = .;
+ *(.init.ramfs)
+ __initramfs_end = .;
+ }
. = ALIGN(L1_CACHE_BYTES);
- __per_cpu_start = .;
- .data.percpu : AT(ADDR(.data.percpu) - LOAD_OFFSET) { *(.data.percpu) }
- __per_cpu_end = .;
+ .data.percpu : AT(ADDR(.data.percpu) - LOAD_OFFSET) {
+ __per_cpu_start = .;
+ *(.data.percpu)
+ __per_cpu_end = .;
+ }
. = ALIGN(4096);
- __init_end = .;
/* freed after init ends here */
- __bss_start = .; /* BSS */
- .bss.page_aligned : AT(ADDR(.bss.page_aligned) - LOAD_OFFSET) {
- *(.bss.page_aligned)
- }
.bss : AT(ADDR(.bss) - LOAD_OFFSET) {
+ __init_end = .;
+ __bss_start = .; /* BSS */
+ *(.bss.page_aligned)
*(.bss)
+ . = ALIGN(4);
+ __bss_stop = .;
+ _end = . ;
+ /* This is where the kernel creates the early boot page tables */
+ . = ALIGN(4096);
+ pg0 = . ;
}
- . = ALIGN(4);
- __bss_stop = .;
-
- _end = . ;
-
- /* This is where the kernel creates the early boot page tables */
- . = ALIGN(4096);
- pg0 = .;
/* Sections to be discarded */
/DISCARD/ : {
diff -puN include/asm-generic/vmlinux.lds.h~i386-vmlinux.lds.S-Distinguish-absolute-symbols include/asm-generic/vmlinux.lds.h
--- linux-2.6.19-rc2-git7-reloc/include/asm-generic/vmlinux.lds.h~i386-vmlinux.lds.S-Distinguish-absolute-symbols 2006-10-23 12:55:12.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/include/asm-generic/vmlinux.lds.h 2006-10-23 13:15:14.000000000 -0400
@@ -11,8 +11,8 @@
#define RODATA \
. = ALIGN(4096); \
- __start_rodata = .; \
.rodata : AT(ADDR(.rodata) - LOAD_OFFSET) { \
+ VMLINUX_SYMBOL(__start_rodata) = .; \
*(.rodata) *(.rodata.*) \
*(__vermagic) /* Kernel version magic */ \
} \
@@ -119,17 +119,17 @@
*(__ksymtab_strings) \
} \
\
+ /* Unwind data binary search table */ \
+ EH_FRAME_HDR \
+ \
/* Built-in module parameters. */ \
__param : AT(ADDR(__param) - LOAD_OFFSET) { \
VMLINUX_SYMBOL(__start___param) = .; \
*(__param) \
VMLINUX_SYMBOL(__stop___param) = .; \
+ VMLINUX_SYMBOL(__end_rodata) = .; \
} \
\
- /* Unwind data binary search table */ \
- EH_FRAME_HDR \
- \
- __end_rodata = .; \
. = ALIGN(4096);
#define SECURITY_INIT \
_
^ permalink raw reply [flat|nested] 17+ messages in thread* [PATCH 2/11] i386: Remove unnecessary ALIGN() in vmlinux.lds.S
2006-10-23 19:24 [RFC][PATCH 0/11] i386: Relocatable BzImage (V3) Vivek Goyal
2006-10-23 19:26 ` [PATCH 1/11] i386: Distinguish absolute symbols Vivek Goyal
@ 2006-10-23 19:29 ` Vivek Goyal
2006-10-23 19:30 ` [PATCH 3/11] i386: Force data segment to be 4K aligned Vivek Goyal
` (9 subsequent siblings)
11 siblings, 0 replies; 17+ messages in thread
From: Vivek Goyal @ 2006-10-23 19:29 UTC (permalink / raw)
To: linux kernel mailing list
Cc: Reloc Kernel List, ebiederm, akpm, ak, hpa, magnus.damm, lwang,
dzickus, maneesh
o There seems to be one extra ALIGN(4096) before symbol __smp_alt_end. The
only usage of __smp_alt_end is to mark the end of smp alternative
sections so that this memory can be freed. As a physical page is freed
one has to just make sure that there is no other data on the same page
where __smp_alt_end is pointing. There is already a ALIGN(4096) after
this section which should take care of the above issue. Hence it looks
like the ALIGN(4096) before __smp_alt_end is redundant and not required.
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
---
arch/i386/kernel/vmlinux.lds.S | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff -puN arch/i386/kernel/vmlinux.lds.S~i386-remove-unnecessary-align-option arch/i386/kernel/vmlinux.lds.S
--- linux-2.6.19-rc2-git7-reloc/arch/i386/kernel/vmlinux.lds.S~i386-remove-unnecessary-align-option 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/i386/kernel/vmlinux.lds.S 2006-10-23 15:09:02.000000000 -0400
@@ -112,11 +112,15 @@ SECTIONS
}
.smp_altinstr_replacement : AT(ADDR(.smp_altinstr_replacement) - LOAD_OFFSET) {
*(.smp_altinstr_replacement)
- . = ALIGN(4096);
__smp_alt_end = .;
}
- /* will be freed after init */
+ /* will be freed after init
+ * Following ALIGN() is required to make sure no other data falls on the
+ * same page where __smp_alt_end is pointing as that page might be freed
+ * after boot. Always make sure that ALIGN() directive is present after
+ * the section which contains __smp_alt_end.
+ */
. = ALIGN(4096); /* Init code and data */
.init.text : AT(ADDR(.init.text) - LOAD_OFFSET) {
__init_begin = .;
_
^ permalink raw reply [flat|nested] 17+ messages in thread* [PATCH 3/11] i386: Force data segment to be 4K aligned
2006-10-23 19:24 [RFC][PATCH 0/11] i386: Relocatable BzImage (V3) Vivek Goyal
2006-10-23 19:26 ` [PATCH 1/11] i386: Distinguish absolute symbols Vivek Goyal
2006-10-23 19:29 ` [PATCH 2/11] i386: Remove unnecessary ALIGN() in vmlinux.lds.S Vivek Goyal
@ 2006-10-23 19:30 ` Vivek Goyal
2006-10-23 19:32 ` [PATCH 4/11] i386: define __pa_symbol() Vivek Goyal
` (8 subsequent siblings)
11 siblings, 0 replies; 17+ messages in thread
From: Vivek Goyal @ 2006-10-23 19:30 UTC (permalink / raw)
To: linux kernel mailing list
Cc: Reloc Kernel List, ebiederm, akpm, ak, hpa, magnus.damm, lwang,
dzickus, maneesh
o Currently there is no specific alignment restriction in linker script
and in some cases it can be placed non 4K aligned addresses. This fails
kexec which checks that segment to be loaded is page aligned.
o I guess, it does not harm data segment to be 4K aligned.
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
---
arch/i386/kernel/vmlinux.lds.S | 1 +
1 file changed, 1 insertion(+)
diff -puN arch/i386/kernel/vmlinux.lds.S~i386-force-data-section-to-4K-aligned arch/i386/kernel/vmlinux.lds.S
--- linux-2.6.19-rc2-git7-reloc/arch/i386/kernel/vmlinux.lds.S~i386-force-data-section-to-4K-aligned 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/i386/kernel/vmlinux.lds.S 2006-10-23 15:08:55.000000000 -0400
@@ -52,6 +52,7 @@ SECTIONS
}
/* writeable */
+ . = ALIGN(4096);
.data : AT(ADDR(.data) - LOAD_OFFSET) { /* Data */
*(.data)
CONSTRUCTORS
_
^ permalink raw reply [flat|nested] 17+ messages in thread* [PATCH 4/11] i386: define __pa_symbol()
2006-10-23 19:24 [RFC][PATCH 0/11] i386: Relocatable BzImage (V3) Vivek Goyal
` (2 preceding siblings ...)
2006-10-23 19:30 ` [PATCH 3/11] i386: Force data segment to be 4K aligned Vivek Goyal
@ 2006-10-23 19:32 ` Vivek Goyal
2006-10-23 19:33 ` [PATCH 5/11] i386: Reserve kernel memory starting from _text Vivek Goyal
` (7 subsequent siblings)
11 siblings, 0 replies; 17+ messages in thread
From: Vivek Goyal @ 2006-10-23 19:32 UTC (permalink / raw)
To: linux kernel mailing list
Cc: Reloc Kernel List, ebiederm, akpm, ak, hpa, magnus.damm, lwang,
dzickus, maneesh
On x86_64 we have to be careful with calculating the physical
address of kernel symbols. Both because of compiler odditities
and because the symbols live in a different range of the virtual
address space.
Having a defintition of __pa_symbol that works on both x86_64 and
i386 simplifies writing code that works for both x86_64 and
i386 that has these kinds of dependencies.
So this patch adds the trivial i386 __pa_symbol definition.
Added assembly magic similar to RELOC_HIDE as suggested by Andi Kleen.
Just picked it up from x86_64.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
---
include/asm-i386/page.h | 3 +++
1 file changed, 3 insertions(+)
diff -puN include/asm-i386/page.h~i386-define-__pa_symbol include/asm-i386/page.h
--- linux-2.6.19-rc2-git7-reloc/include/asm-i386/page.h~i386-define-__pa_symbol 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/include/asm-i386/page.h 2006-10-23 15:08:55.000000000 -0400
@@ -124,6 +124,9 @@ extern int page_is_ram(unsigned long pag
#define VMALLOC_RESERVE ((unsigned long)__VMALLOC_RESERVE)
#define MAXMEM (-__PAGE_OFFSET-__VMALLOC_RESERVE)
#define __pa(x) ((unsigned long)(x)-PAGE_OFFSET)
+/* __pa_symbol should be used for C visible symbols.
+ This seems to be the official gcc blessed way to do such arithmetic. */
+#define __pa_symbol(x) __pa(RELOC_HIDE((unsigned long)(x),0))
#define __va(x) ((void *)((unsigned long)(x)+PAGE_OFFSET))
#define pfn_to_kaddr(pfn) __va((pfn) << PAGE_SHIFT)
#ifdef CONFIG_FLATMEM
_
^ permalink raw reply [flat|nested] 17+ messages in thread* [PATCH 5/11] i386: Reserve kernel memory starting from _text
2006-10-23 19:24 [RFC][PATCH 0/11] i386: Relocatable BzImage (V3) Vivek Goyal
` (3 preceding siblings ...)
2006-10-23 19:32 ` [PATCH 4/11] i386: define __pa_symbol() Vivek Goyal
@ 2006-10-23 19:33 ` Vivek Goyal
2006-10-23 19:36 ` [PATCH 6/11] i386: CONFIG_PHYSICAL_START cleanup Vivek Goyal
` (6 subsequent siblings)
11 siblings, 0 replies; 17+ messages in thread
From: Vivek Goyal @ 2006-10-23 19:33 UTC (permalink / raw)
To: linux kernel mailing list
Cc: Reloc Kernel List, ebiederm, akpm, ak, hpa, magnus.damm, lwang,
dzickus, maneesh
Currently when we are reserving the memory the kernel text
resides in we start at __PHYSICAL_START which happens to be
correct but not very obvious. In addition when we start relocating
the kernel __PHYSICAL_START is the wrong value, as it is an
absolute symbol that does not get relocated.
By starting the reservation at __pa_symbol(_text)
the code is clearer and will be correct when relocated.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
---
arch/i386/kernel/setup.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff -puN arch/i386/kernel/setup.c~i386-setup.c-Reserve-kernel-memory-starting-from-_text arch/i386/kernel/setup.c
--- linux-2.6.19-rc2-git7-reloc/arch/i386/kernel/setup.c~i386-setup.c-Reserve-kernel-memory-starting-from-_text 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/i386/kernel/setup.c 2006-10-23 13:15:21.000000000 -0400
@@ -1118,8 +1118,8 @@ void __init setup_bootmem_allocator(void
* the (very unlikely) case of us accidentally initializing the
* bootmem allocator with an invalid RAM area.
*/
- reserve_bootmem(__PHYSICAL_START, (PFN_PHYS(min_low_pfn) +
- bootmap_size + PAGE_SIZE-1) - (__PHYSICAL_START));
+ reserve_bootmem(__pa_symbol(_text), (PFN_PHYS(min_low_pfn) +
+ bootmap_size + PAGE_SIZE-1) - __pa_symbol(_text));
/*
* reserve physical page 0 - it's a special BIOS page on many boxes,
_
^ permalink raw reply [flat|nested] 17+ messages in thread* [PATCH 6/11] i386: CONFIG_PHYSICAL_START cleanup
2006-10-23 19:24 [RFC][PATCH 0/11] i386: Relocatable BzImage (V3) Vivek Goyal
` (4 preceding siblings ...)
2006-10-23 19:33 ` [PATCH 5/11] i386: Reserve kernel memory starting from _text Vivek Goyal
@ 2006-10-23 19:36 ` Vivek Goyal
2006-10-23 19:37 ` [PATCH 7/11] i386: Kallsyms generate relocatable symbols Vivek Goyal
` (5 subsequent siblings)
11 siblings, 0 replies; 17+ messages in thread
From: Vivek Goyal @ 2006-10-23 19:36 UTC (permalink / raw)
To: linux kernel mailing list
Cc: Reloc Kernel List, ebiederm, akpm, ak, hpa, magnus.damm, lwang,
dzickus, maneesh
Defining __PHYSICAL_START and __KERNEL_START in asm-i386/page.h works but
it triggers a full kernel rebuild for the silliest of reasons. This
modifies the users to directly use CONFIG_PHYSICAL_START and linux/config.h
which prevents the full rebuild problem, which makes the code much
more maintainer and hopefully user friendly.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
---
arch/i386/boot/compressed/head.S | 7 +++----
arch/i386/boot/compressed/misc.c | 7 +++----
arch/i386/kernel/vmlinux.lds.S | 2 +-
include/asm-i386/page.h | 3 ---
4 files changed, 7 insertions(+), 12 deletions(-)
diff -puN arch/i386/boot/compressed/head.S~i386-CONFIG_PHYSICAL_START-cleanup arch/i386/boot/compressed/head.S
--- linux-2.6.19-rc2-git7-reloc/arch/i386/boot/compressed/head.S~i386-CONFIG_PHYSICAL_START-cleanup 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/i386/boot/compressed/head.S 2006-10-23 15:08:50.000000000 -0400
@@ -25,7 +25,6 @@
#include <linux/linkage.h>
#include <asm/segment.h>
-#include <asm/page.h>
.globl startup_32
@@ -75,7 +74,7 @@ startup_32:
popl %esi # discard address
popl %esi # real mode pointer
xorl %ebx,%ebx
- ljmp $(__BOOT_CS), $__PHYSICAL_START
+ ljmp $(__BOOT_CS), $CONFIG_PHYSICAL_START
/*
* We come here, if we were loaded high.
@@ -100,7 +99,7 @@ startup_32:
popl %ecx # lcount
popl %edx # high_buffer_start
popl %eax # hcount
- movl $__PHYSICAL_START,%edi
+ movl $CONFIG_PHYSICAL_START,%edi
cli # make sure we don't get interrupted
ljmp $(__BOOT_CS), $0x1000 # and jump to the move routine
@@ -125,5 +124,5 @@ move_routine_start:
movsl
movl %ebx,%esi # Restore setup pointer
xorl %ebx,%ebx
- ljmp $(__BOOT_CS), $__PHYSICAL_START
+ ljmp $(__BOOT_CS), $CONFIG_PHYSICAL_START
move_routine_end:
diff -puN arch/i386/boot/compressed/misc.c~i386-CONFIG_PHYSICAL_START-cleanup arch/i386/boot/compressed/misc.c
--- linux-2.6.19-rc2-git7-reloc/arch/i386/boot/compressed/misc.c~i386-CONFIG_PHYSICAL_START-cleanup 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/i386/boot/compressed/misc.c 2006-10-23 15:08:50.000000000 -0400
@@ -13,7 +13,6 @@
#include <linux/vmalloc.h>
#include <linux/screen_info.h>
#include <asm/io.h>
-#include <asm/page.h>
/*
* gzip declarations
@@ -303,7 +302,7 @@ static void setup_normal_output_buffer(v
#else
if ((RM_ALT_MEM_K > RM_EXT_MEM_K ? RM_ALT_MEM_K : RM_EXT_MEM_K) < 1024) error("Less than 2MB of memory");
#endif
- output_data = (unsigned char *)__PHYSICAL_START; /* Normally Points to 1M */
+ output_data = (unsigned char *)CONFIG_PHYSICAL_START; /* Normally Points to 1M */
free_mem_end_ptr = (long)real_mode;
}
@@ -326,8 +325,8 @@ static void setup_output_buffer_if_we_ru
low_buffer_size = low_buffer_end - LOW_BUFFER_START;
high_loaded = 1;
free_mem_end_ptr = (long)high_buffer_start;
- if ( (__PHYSICAL_START + low_buffer_size) > ((ulg)high_buffer_start)) {
- high_buffer_start = (uch *)(__PHYSICAL_START + low_buffer_size);
+ if ( (CONFIG_PHYSICAL_START + low_buffer_size) > ((ulg)high_buffer_start)) {
+ high_buffer_start = (uch *)(CONFIG_PHYSICAL_START + low_buffer_size);
mv->hcount = 0; /* say: we need not to move high_buffer */
}
else mv->hcount = -1;
diff -puN arch/i386/kernel/vmlinux.lds.S~i386-CONFIG_PHYSICAL_START-cleanup arch/i386/kernel/vmlinux.lds.S
--- linux-2.6.19-rc2-git7-reloc/arch/i386/kernel/vmlinux.lds.S~i386-CONFIG_PHYSICAL_START-cleanup 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/i386/kernel/vmlinux.lds.S 2006-10-23 15:08:45.000000000 -0400
@@ -21,7 +21,7 @@ PHDRS {
}
SECTIONS
{
- . = __KERNEL_START;
+ . = LOAD_OFFSET + CONFIG_PHYSICAL_START;
phys_startup_32 = startup_32 - LOAD_OFFSET;
/* read-only */
.text : AT(ADDR(.text) - LOAD_OFFSET) {
diff -puN include/asm-i386/page.h~i386-CONFIG_PHYSICAL_START-cleanup include/asm-i386/page.h
--- linux-2.6.19-rc2-git7-reloc/include/asm-i386/page.h~i386-CONFIG_PHYSICAL_START-cleanup 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/include/asm-i386/page.h 2006-10-23 13:15:21.000000000 -0400
@@ -112,12 +112,9 @@ extern int page_is_ram(unsigned long pag
#ifdef __ASSEMBLY__
#define __PAGE_OFFSET CONFIG_PAGE_OFFSET
-#define __PHYSICAL_START CONFIG_PHYSICAL_START
#else
#define __PAGE_OFFSET ((unsigned long)CONFIG_PAGE_OFFSET)
-#define __PHYSICAL_START ((unsigned long)CONFIG_PHYSICAL_START)
#endif
-#define __KERNEL_START (__PAGE_OFFSET + __PHYSICAL_START)
#define PAGE_OFFSET ((unsigned long)__PAGE_OFFSET)
_
^ permalink raw reply [flat|nested] 17+ messages in thread* [PATCH 7/11] i386: Kallsyms generate relocatable symbols
2006-10-23 19:24 [RFC][PATCH 0/11] i386: Relocatable BzImage (V3) Vivek Goyal
` (5 preceding siblings ...)
2006-10-23 19:36 ` [PATCH 6/11] i386: CONFIG_PHYSICAL_START cleanup Vivek Goyal
@ 2006-10-23 19:37 ` Vivek Goyal
2006-11-06 14:48 ` Haavard Skinnemoen
2006-10-23 19:39 ` [PATCH 8/11] i386: Relocatable kernel support Vivek Goyal
` (4 subsequent siblings)
11 siblings, 1 reply; 17+ messages in thread
From: Vivek Goyal @ 2006-10-23 19:37 UTC (permalink / raw)
To: linux kernel mailing list
Cc: Reloc Kernel List, ebiederm, akpm, ak, hpa, magnus.damm, lwang,
dzickus, maneesh
Print the addresses of non-absolute symbols relative to _text
so that ld will generate relocations. Allowing a relocatable
kernel to relocate them. We can't actually use the symbol names
because kallsyms includes static symbols that are not exported
from their object files.
Add the _text symbol definitions to the architectures which don't
define it otherwise linker will fail.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
---
arch/h8300/kernel/vmlinux.lds.S | 1 +
arch/m68knommu/kernel/vmlinux.lds.S | 1 +
arch/powerpc/kernel/vmlinux.lds.S | 1 +
arch/ppc/kernel/vmlinux.lds.S | 1 +
arch/sparc/kernel/vmlinux.lds.S | 1 +
arch/sparc64/kernel/vmlinux.lds.S | 1 +
arch/v850/kernel/vmlinux.lds.S | 1 +
scripts/kallsyms.c | 20 +++++++++++++++++---
8 files changed, 24 insertions(+), 3 deletions(-)
diff -puN arch/h8300/kernel/vmlinux.lds.S~kallsyms.c-Generate-relocatable-symbols arch/h8300/kernel/vmlinux.lds.S
--- linux-2.6.19-rc2-git7-reloc/arch/h8300/kernel/vmlinux.lds.S~kallsyms.c-Generate-relocatable-symbols 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/h8300/kernel/vmlinux.lds.S 2006-10-23 13:15:21.000000000 -0400
@@ -70,6 +70,7 @@ SECTIONS
#endif
.text :
{
+ _text = .;
#if defined(CONFIG_ROMKERNEL)
*(.int_redirect)
#endif
diff -puN arch/m68knommu/kernel/vmlinux.lds.S~kallsyms.c-Generate-relocatable-symbols arch/m68knommu/kernel/vmlinux.lds.S
--- linux-2.6.19-rc2-git7-reloc/arch/m68knommu/kernel/vmlinux.lds.S~kallsyms.c-Generate-relocatable-symbols 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/m68knommu/kernel/vmlinux.lds.S 2006-10-23 13:15:21.000000000 -0400
@@ -60,6 +60,7 @@ SECTIONS {
#endif
.text : {
+ _text = .;
_stext = . ;
*(.text)
SCHED_TEXT
diff -puN arch/powerpc/kernel/vmlinux.lds.S~kallsyms.c-Generate-relocatable-symbols arch/powerpc/kernel/vmlinux.lds.S
--- linux-2.6.19-rc2-git7-reloc/arch/powerpc/kernel/vmlinux.lds.S~kallsyms.c-Generate-relocatable-symbols 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/powerpc/kernel/vmlinux.lds.S 2006-10-23 13:15:21.000000000 -0400
@@ -33,6 +33,7 @@ SECTIONS
/* Text and gots */
.text : {
+ _text = .;
*(.text .text.*)
SCHED_TEXT
LOCK_TEXT
diff -puN arch/ppc/kernel/vmlinux.lds.S~kallsyms.c-Generate-relocatable-symbols arch/ppc/kernel/vmlinux.lds.S
--- linux-2.6.19-rc2-git7-reloc/arch/ppc/kernel/vmlinux.lds.S~kallsyms.c-Generate-relocatable-symbols 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/ppc/kernel/vmlinux.lds.S 2006-10-23 13:15:21.000000000 -0400
@@ -31,6 +31,7 @@ SECTIONS
.plt : { *(.plt) }
.text :
{
+ _text = .;
*(.text)
SCHED_TEXT
LOCK_TEXT
diff -puN arch/sparc64/kernel/vmlinux.lds.S~kallsyms.c-Generate-relocatable-symbols arch/sparc64/kernel/vmlinux.lds.S
--- linux-2.6.19-rc2-git7-reloc/arch/sparc64/kernel/vmlinux.lds.S~kallsyms.c-Generate-relocatable-symbols 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/sparc64/kernel/vmlinux.lds.S 2006-10-23 13:15:21.000000000 -0400
@@ -13,6 +13,7 @@ SECTIONS
. = 0x4000;
.text 0x0000000000404000 :
{
+ _text = .;
*(.text)
SCHED_TEXT
LOCK_TEXT
diff -puN arch/sparc/kernel/vmlinux.lds.S~kallsyms.c-Generate-relocatable-symbols arch/sparc/kernel/vmlinux.lds.S
--- linux-2.6.19-rc2-git7-reloc/arch/sparc/kernel/vmlinux.lds.S~kallsyms.c-Generate-relocatable-symbols 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/sparc/kernel/vmlinux.lds.S 2006-10-23 13:15:21.000000000 -0400
@@ -11,6 +11,7 @@ SECTIONS
. = 0x10000 + SIZEOF_HEADERS;
.text 0xf0004000 :
{
+ _text = .;
*(.text)
SCHED_TEXT
LOCK_TEXT
diff -puN arch/v850/kernel/vmlinux.lds.S~kallsyms.c-Generate-relocatable-symbols arch/v850/kernel/vmlinux.lds.S
--- linux-2.6.19-rc2-git7-reloc/arch/v850/kernel/vmlinux.lds.S~kallsyms.c-Generate-relocatable-symbols 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/v850/kernel/vmlinux.lds.S 2006-10-23 13:15:21.000000000 -0400
@@ -90,6 +90,7 @@
/* Kernel text segment, and some constant data areas. */
#define TEXT_CONTENTS \
+ _text = .; \
__stext = . ; \
*(.text) \
SCHED_TEXT \
diff -puN scripts/kallsyms.c~kallsyms.c-Generate-relocatable-symbols scripts/kallsyms.c
--- linux-2.6.19-rc2-git7-reloc/scripts/kallsyms.c~kallsyms.c-Generate-relocatable-symbols 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/scripts/kallsyms.c 2006-10-23 13:15:21.000000000 -0400
@@ -43,7 +43,7 @@ struct sym_entry {
static struct sym_entry *table;
static unsigned int table_size, table_cnt;
-static unsigned long long _stext, _etext, _sinittext, _einittext, _sextratext, _eextratext;
+static unsigned long long _text, _stext, _etext, _sinittext, _einittext, _sextratext, _eextratext;
static int all_symbols = 0;
static char symbol_prefix_char = '\0';
@@ -91,7 +91,9 @@ static int read_symbol(FILE *in, struct
sym++;
/* Ignore most absolute/undefined (?) symbols. */
- if (strcmp(sym, "_stext") == 0)
+ if (strcmp(sym, "_text") == 0)
+ _text = s->addr;
+ else if (strcmp(sym, "_stext") == 0)
_stext = s->addr;
else if (strcmp(sym, "_etext") == 0)
_etext = s->addr;
@@ -265,9 +267,21 @@ static void write_src(void)
printf(".data\n");
+ /* Provide proper symbols relocatability by their '_text'
+ * relativeness. The symbol names cannot be used to construct
+ * normal symbol references as the list of symbols contains
+ * symbols that are declared static and are private to their
+ * .o files. This prevents .tmp_kallsyms.o or any other
+ * object from referencing them.
+ */
output_label("kallsyms_addresses");
for (i = 0; i < table_cnt; i++) {
- printf("\tPTR\t%#llx\n", table[i].addr);
+ if (toupper(table[i].sym[0]) != 'A') {
+ printf("\tPTR\t_text + %#llx\n",
+ table[i].addr - _text);
+ } else {
+ printf("\tPTR\t%#llx\n", table[i].addr);
+ }
}
printf("\n");
_
^ permalink raw reply [flat|nested] 17+ messages in thread* Re: [PATCH 7/11] i386: Kallsyms generate relocatable symbols
2006-10-23 19:37 ` [PATCH 7/11] i386: Kallsyms generate relocatable symbols Vivek Goyal
@ 2006-11-06 14:48 ` Haavard Skinnemoen
2006-11-06 16:03 ` Vivek Goyal
2006-11-06 16:34 ` H. Peter Anvin
0 siblings, 2 replies; 17+ messages in thread
From: Haavard Skinnemoen @ 2006-11-06 14:48 UTC (permalink / raw)
To: vgoyal
Cc: linux kernel mailing list, Reloc Kernel List, ebiederm, akpm, ak,
hpa, magnus.damm, lwang, dzickus, maneesh
On Mon, 23 Oct 2006 15:37:48 -0400
Vivek Goyal <vgoyal@in.ibm.com> wrote:
> Add the _text symbol definitions to the architectures which don't
> define it otherwise linker will fail.
I get lots of this when building latest -mm for avr32:
.tmp_kallsyms2.S:643: Warning: right operand is a bignum; integer 0
assumed
Reverting this patch makes the warnings go away. I think it's
because on avr32, .init is the first section, not .text, so many of the
offsets become negative and kallsyms doesn't seem to handle this very
well. Here's a few lines from .tmp_kallsyms2.S:
kallsyms_addresses:
PTR _text + 0xffffffffffff4000
PTR _text + 0xffffffffffff4000
Any idea how to fix this? Could we introduce a new symbol that always
marks the start of the image perhaps?
Haavard
^ permalink raw reply [flat|nested] 17+ messages in thread* Re: [PATCH 7/11] i386: Kallsyms generate relocatable symbols
2006-11-06 14:48 ` Haavard Skinnemoen
@ 2006-11-06 16:03 ` Vivek Goyal
2006-11-06 16:13 ` Haavard Skinnemoen
2006-11-06 16:34 ` H. Peter Anvin
1 sibling, 1 reply; 17+ messages in thread
From: Vivek Goyal @ 2006-11-06 16:03 UTC (permalink / raw)
To: Haavard Skinnemoen
Cc: linux kernel mailing list, Reloc Kernel List, ebiederm, akpm, ak,
hpa, magnus.damm, lwang, dzickus, maneesh
On Mon, Nov 06, 2006 at 03:48:57PM +0100, Haavard Skinnemoen wrote:
> On Mon, 23 Oct 2006 15:37:48 -0400
> Vivek Goyal <vgoyal@in.ibm.com> wrote:
>
> > Add the _text symbol definitions to the architectures which don't
> > define it otherwise linker will fail.
>
> I get lots of this when building latest -mm for avr32:
>
> .tmp_kallsyms2.S:643: Warning: right operand is a bignum; integer 0
> assumed
>
> Reverting this patch makes the warnings go away. I think it's
> because on avr32, .init is the first section, not .text, so many of the
> offsets become negative and kallsyms doesn't seem to handle this very
> well. Here's a few lines from .tmp_kallsyms2.S:
>
> kallsyms_addresses:
> PTR _text + 0xffffffffffff4000
> PTR _text + 0xffffffffffff4000
>
> Any idea how to fix this? Could we introduce a new symbol that always
> marks the start of the image perhaps?
>
Hi Haavard,
Does the attached patch solve the issue for you?
Thanks
Vivek
o On some platforms like avr32, section init comes before .text and
not necessarily a symbol's relative position w.r.t _text is positive.
In such cases assembler detects the overflow and emits warning. This
patch fixes it.
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
---
scripts/kallsyms.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff -puN scripts/kallsyms.c~i386-reloc-kallsyms-_text-symbol-relative-address-fix scripts/kallsyms.c
--- linux-2.6.19-rc4-reloc/scripts/kallsyms.c~i386-reloc-kallsyms-_text-symbol-relative-address-fix 2006-11-06 10:47:01.000000000 -0500
+++ linux-2.6.19-rc4-reloc-root/scripts/kallsyms.c 2006-11-06 10:47:01.000000000 -0500
@@ -277,8 +277,12 @@ static void write_src(void)
output_label("kallsyms_addresses");
for (i = 0; i < table_cnt; i++) {
if (toupper(table[i].sym[0]) != 'A') {
- printf("\tPTR\t_text + %#llx\n",
- table[i].addr - _text);
+ if (_text <= table[i].addr)
+ printf("\tPTR\t_text + %#llx\n",
+ table[i].addr - _text);
+ else
+ printf("\tPTR\t_text - %#llx\n",
+ _text - table[i].addr);
} else {
printf("\tPTR\t%#llx\n", table[i].addr);
}
_
^ permalink raw reply [flat|nested] 17+ messages in thread* Re: [PATCH 7/11] i386: Kallsyms generate relocatable symbols
2006-11-06 16:03 ` Vivek Goyal
@ 2006-11-06 16:13 ` Haavard Skinnemoen
0 siblings, 0 replies; 17+ messages in thread
From: Haavard Skinnemoen @ 2006-11-06 16:13 UTC (permalink / raw)
To: vgoyal
Cc: linux kernel mailing list, Reloc Kernel List, ebiederm, akpm, ak,
hpa, magnus.damm, lwang, dzickus, maneesh
On Mon, 6 Nov 2006 11:03:53 -0500
Vivek Goyal <vgoyal@in.ibm.com> wrote:
> On Mon, Nov 06, 2006 at 03:48:57PM +0100, Haavard Skinnemoen wrote:
> > kallsyms_addresses:
> > PTR _text + 0xffffffffffff4000
> > PTR _text + 0xffffffffffff4000
> >
> > Any idea how to fix this? Could we introduce a new symbol that
> > always marks the start of the image perhaps?
> >
>
> Hi Haavard,
>
> Does the attached patch solve the issue for you?
Yes it does, thanks. I tested it by forcing a crash in a __init
function, and the resulting Oops looks correct.
Haavard
^ permalink raw reply [flat|nested] 17+ messages in thread
* Re: [PATCH 7/11] i386: Kallsyms generate relocatable symbols
2006-11-06 14:48 ` Haavard Skinnemoen
2006-11-06 16:03 ` Vivek Goyal
@ 2006-11-06 16:34 ` H. Peter Anvin
1 sibling, 0 replies; 17+ messages in thread
From: H. Peter Anvin @ 2006-11-06 16:34 UTC (permalink / raw)
To: Haavard Skinnemoen
Cc: vgoyal, linux kernel mailing list, Reloc Kernel List, ebiederm,
akpm, ak, magnus.damm, lwang, dzickus, maneesh
Haavard Skinnemoen wrote:
> On Mon, 23 Oct 2006 15:37:48 -0400
> Vivek Goyal <vgoyal@in.ibm.com> wrote:
>
>> Add the _text symbol definitions to the architectures which don't
>> define it otherwise linker will fail.
>
> I get lots of this when building latest -mm for avr32:
>
> .tmp_kallsyms2.S:643: Warning: right operand is a bignum; integer 0
> assumed
>
> Reverting this patch makes the warnings go away. I think it's
> because on avr32, .init is the first section, not .text, so many of the
> offsets become negative and kallsyms doesn't seem to handle this very
> well. Here's a few lines from .tmp_kallsyms2.S:
>
> kallsyms_addresses:
> PTR _text + 0xffffffffffff4000
> PTR _text + 0xffffffffffff4000
>
> Any idea how to fix this? Could we introduce a new symbol that always
> marks the start of the image perhaps?
>
Maybe we should generate it as a signed value (-0x8000) instead of an
unsigned value.
-hpa
^ permalink raw reply [flat|nested] 17+ messages in thread
* [PATCH 8/11] i386: Relocatable kernel support
2006-10-23 19:24 [RFC][PATCH 0/11] i386: Relocatable BzImage (V3) Vivek Goyal
` (6 preceding siblings ...)
2006-10-23 19:37 ` [PATCH 7/11] i386: Kallsyms generate relocatable symbols Vivek Goyal
@ 2006-10-23 19:39 ` Vivek Goyal
2006-10-23 19:40 ` [PATCH 9/11] i386: Warn upon absolute relocations being present Vivek Goyal
` (3 subsequent siblings)
11 siblings, 0 replies; 17+ messages in thread
From: Vivek Goyal @ 2006-10-23 19:39 UTC (permalink / raw)
To: linux kernel mailing list
Cc: Reloc Kernel List, ebiederm, akpm, ak, hpa, magnus.damm, lwang,
dzickus, maneesh
This patch modifies the x86 kernel so that if CONFIG_RELOCATABLE is
selected it will be able to be loaded at any 4K aligned address below
1G. The technique used is to compile the decompressor with -fPIC and
modify it so the decompressor is fully relocatable. For the main
kernel relocations are generated. Resulting in a kernel that is relocatable
with no runtime overhead and no need to modify the source code.
A reserved 32bit word in the parameters has been assigned
to serve as a stack so we figure out where are running.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
---
arch/i386/Kconfig | 12
arch/i386/Makefile | 4
arch/i386/boot/compressed/Makefile | 28 +
arch/i386/boot/compressed/head.S | 190 +++++++----
arch/i386/boot/compressed/misc.c | 267 ++++++++--------
arch/i386/boot/compressed/relocs.c | 563 ++++++++++++++++++++++++++++++++++
arch/i386/boot/compressed/vmlinux.lds | 43 ++
arch/i386/boot/compressed/vmlinux.scr | 3
arch/i386/boot/setup.S | 29 +
include/linux/screen_info.h | 3
10 files changed, 926 insertions(+), 216 deletions(-)
diff -puN arch/i386/boot/compressed/head.S~i386-Relocatable-kernel-support arch/i386/boot/compressed/head.S
--- linux-2.6.19-rc2-git7-reloc/arch/i386/boot/compressed/head.S~i386-Relocatable-kernel-support 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/i386/boot/compressed/head.S 2006-10-23 15:08:45.000000000 -0400
@@ -25,9 +25,11 @@
#include <linux/linkage.h>
#include <asm/segment.h>
+#include <asm/page.h>
+.section ".text.head"
.globl startup_32
-
+
startup_32:
cld
cli
@@ -36,93 +38,141 @@ startup_32:
movl %eax,%es
movl %eax,%fs
movl %eax,%gs
+ movl %eax,%ss
- lss stack_start,%esp
- xorl %eax,%eax
-1: incl %eax # check that A20 really IS enabled
- movl %eax,0x000000 # loop forever if it isn't
- cmpl %eax,0x100000
- je 1b
+/* Calculate the delta between where we were compiled to run
+ * at and where we were actually loaded at. This can only be done
+ * with a short local call on x86. Nothing else will tell us what
+ * address we are running at. The reserved chunk of the real-mode
+ * data at 0x34-0x3f are used as the stack for this calculation.
+ * Only 4 bytes are needed.
+ */
+ leal 0x40(%esi), %esp
+ call 1f
+1: popl %ebp
+ subl $1b, %ebp
+
+/* Compute the delta between where we were compiled to run at
+ * and where the code will actually run at.
+ */
+ /* Start with the delta to where the kernel will run at. If we are
+ * a relocatable kernel this is the delta to our load address otherwise
+ * this is the delta to CONFIG_PHYSICAL start.
+ */
+#ifdef CONFIG_RELOCATABLE
+ movl %ebp, %ebx
+#else
+ movl $(CONFIG_PHYSICAL_START - startup_32), %ebx
+#endif
+
+ /* Replace the compressed data size with the uncompressed size */
+ subl input_len(%ebp), %ebx
+ movl output_len(%ebp), %eax
+ addl %eax, %ebx
+ /* Add 8 bytes for every 32K input block */
+ shrl $12, %eax
+ addl %eax, %ebx
+ /* Add 32K + 18 bytes of extra slack */
+ addl $(32768 + 18), %ebx
+ /* Align on a 4K boundary */
+ addl $4095, %ebx
+ andl $~4095, %ebx
+
+/* Copy the compressed kernel to the end of our buffer
+ * where decompression in place becomes safe.
+ */
+ pushl %esi
+ leal _end(%ebp), %esi
+ leal _end(%ebx), %edi
+ movl $(_end - startup_32), %ecx
+ std
+ rep
+ movsb
+ cld
+ popl %esi
+
+/* Compute the kernel start address.
+ */
+#ifdef CONFIG_RELOCATABLE
+ leal startup_32(%ebp), %ebp
+#else
+ movl $CONFIG_PHYSICAL_START, %ebp
+#endif
/*
- * Initialize eflags. Some BIOS's leave bits like NT set. This would
- * confuse the debugger if this code is traced.
- * XXX - best to initialize before switching to protected mode.
+ * Jump to the relocated address.
*/
- pushl $0
- popfl
+ leal relocated(%ebx), %eax
+ jmp *%eax
+.section ".text"
+relocated:
+
/*
* Clear BSS
*/
xorl %eax,%eax
- movl $_edata,%edi
- movl $_end,%ecx
+ leal _edata(%ebx),%edi
+ leal _end(%ebx), %ecx
subl %edi,%ecx
cld
rep
stosb
+
+/*
+ * Setup the stack for the decompressor
+ */
+ leal stack_end(%ebx), %esp
+
/*
* Do the decompression, and jump to the new kernel..
*/
- subl $16,%esp # place for structure on the stack
- movl %esp,%eax
+ movl output_len(%ebx), %eax
+ pushl %eax
+ pushl %ebp # output address
+ movl input_len(%ebx), %eax
+ pushl %eax # input_len
+ leal input_data(%ebx), %eax
+ pushl %eax # input_data
+ leal _end(%ebx), %eax
+ pushl %eax # end of the image as third argument
pushl %esi # real mode pointer as second arg
- pushl %eax # address of structure as first arg
call decompress_kernel
- orl %eax,%eax
- jnz 3f
- popl %esi # discard address
- popl %esi # real mode pointer
- xorl %ebx,%ebx
- ljmp $(__BOOT_CS), $CONFIG_PHYSICAL_START
+ addl $20, %esp
+ popl %ecx
+
+#if CONFIG_RELOCATABLE
+/* Find the address of the relocations.
+ */
+ movl %ebp, %edi
+ addl %ecx, %edi
+
+/* Calculate the delta between where vmlinux was compiled to run
+ * and where it was actually loaded.
+ */
+ movl %ebp, %ebx
+ subl $CONFIG_PHYSICAL_START, %ebx
/*
- * We come here, if we were loaded high.
- * We need to move the move-in-place routine down to 0x1000
- * and then start it with the buffer addresses in registers,
- * which we got from the stack.
- */
-3:
- movl $move_routine_start,%esi
- movl $0x1000,%edi
- movl $move_routine_end,%ecx
- subl %esi,%ecx
- addl $3,%ecx
- shrl $2,%ecx
- cld
- rep
- movsl
+ * Process relocations.
+ */
- popl %esi # discard the address
- popl %ebx # real mode pointer
- popl %esi # low_buffer_start
- popl %ecx # lcount
- popl %edx # high_buffer_start
- popl %eax # hcount
- movl $CONFIG_PHYSICAL_START,%edi
- cli # make sure we don't get interrupted
- ljmp $(__BOOT_CS), $0x1000 # and jump to the move routine
-
-/*
- * Routine (template) for moving the decompressed kernel in place,
- * if we were high loaded. This _must_ PIC-code !
- */
-move_routine_start:
- movl %ecx,%ebp
- shrl $2,%ecx
- rep
- movsl
- movl %ebp,%ecx
- andl $3,%ecx
- rep
- movsb
- movl %edx,%esi
- movl %eax,%ecx # NOTE: rep movsb won't move if %ecx == 0
- addl $3,%ecx
- shrl $2,%ecx
- rep
- movsl
- movl %ebx,%esi # Restore setup pointer
+1: subl $4, %edi
+ movl 0(%edi), %ecx
+ testl %ecx, %ecx
+ jz 2f
+ addl %ebx, -__PAGE_OFFSET(%ebx, %ecx)
+ jmp 1b
+2:
+#endif
+
+/*
+ * Jump to the decompressed kernel.
+ */
xorl %ebx,%ebx
- ljmp $(__BOOT_CS), $CONFIG_PHYSICAL_START
-move_routine_end:
+ jmp *%ebp
+
+.bss
+.balign 4
+stack:
+ .fill 4096, 1, 0
+stack_end:
diff -puN arch/i386/boot/compressed/Makefile~i386-Relocatable-kernel-support arch/i386/boot/compressed/Makefile
--- linux-2.6.19-rc2-git7-reloc/arch/i386/boot/compressed/Makefile~i386-Relocatable-kernel-support 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/i386/boot/compressed/Makefile 2006-10-23 15:08:47.000000000 -0400
@@ -4,22 +4,42 @@
# create a compressed vmlinux image from the original vmlinux
#
-targets := vmlinux vmlinux.bin vmlinux.bin.gz head.o misc.o piggy.o
+targets := vmlinux vmlinux.bin vmlinux.bin.gz head.o misc.o piggy.o \
+ vmlinux.bin.all vmlinux.relocs
EXTRA_AFLAGS := -traditional
-LDFLAGS_vmlinux := -Ttext $(IMAGE_OFFSET) -e startup_32
+LDFLAGS_vmlinux := -T
+CFLAGS_misc.o += -fPIC
+hostprogs-y := relocs
-$(obj)/vmlinux: $(obj)/head.o $(obj)/misc.o $(obj)/piggy.o FORCE
+$(obj)/vmlinux: $(src)/vmlinux.lds $(obj)/head.o $(obj)/misc.o $(obj)/piggy.o FORCE
$(call if_changed,ld)
@:
$(obj)/vmlinux.bin: vmlinux FORCE
$(call if_changed,objcopy)
+quiet_cmd_relocs = RELOCS $@
+ cmd_relocs = $(obj)/relocs $< > $@
+$(obj)/vmlinux.relocs: vmlinux $(obj)/relocs FORCE
+ $(call if_changed,relocs)
+
+vmlinux.bin.all-y := $(obj)/vmlinux.bin
+vmlinux.bin.all-$(CONFIG_RELOCATABLE) += $(obj)/vmlinux.relocs
+quiet_cmd_relocbin = BUILD $@
+ cmd_relocbin = cat $(filter-out FORCE,$^) > $@
+$(obj)/vmlinux.bin.all: $(vmlinux.bin.all-y) FORCE
+ $(call if_changed,relocbin)
+
+ifdef CONFIG_RELOCATABLE
+$(obj)/vmlinux.bin.gz: $(obj)/vmlinux.bin.all FORCE
+ $(call if_changed,gzip)
+else
$(obj)/vmlinux.bin.gz: $(obj)/vmlinux.bin FORCE
$(call if_changed,gzip)
+endif
LDFLAGS_piggy.o := -r --format binary --oformat elf32-i386 -T
-$(obj)/piggy.o: $(obj)/vmlinux.scr $(obj)/vmlinux.bin.gz FORCE
+$(obj)/piggy.o: $(src)/vmlinux.scr $(obj)/vmlinux.bin.gz FORCE
$(call if_changed,ld)
diff -puN arch/i386/boot/compressed/misc.c~i386-Relocatable-kernel-support arch/i386/boot/compressed/misc.c
--- linux-2.6.19-rc2-git7-reloc/arch/i386/boot/compressed/misc.c~i386-Relocatable-kernel-support 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/i386/boot/compressed/misc.c 2006-10-23 15:08:45.000000000 -0400
@@ -13,6 +13,88 @@
#include <linux/vmalloc.h>
#include <linux/screen_info.h>
#include <asm/io.h>
+#include <asm/page.h>
+
+/* WARNING!!
+ * This code is compiled with -fPIC and it is relocated dynamically
+ * at run time, but no relocation processing is performed.
+ * This means that it is not safe to place pointers in static structures.
+ */
+
+/*
+ * Getting to provable safe in place decompression is hard.
+ * Worst case behaviours need to be analized.
+ * Background information:
+ *
+ * The file layout is:
+ * magic[2]
+ * method[1]
+ * flags[1]
+ * timestamp[4]
+ * extraflags[1]
+ * os[1]
+ * compressed data blocks[N]
+ * crc[4] orig_len[4]
+ *
+ * resulting in 18 bytes of non compressed data overhead.
+ *
+ * Files divided into blocks
+ * 1 bit (last block flag)
+ * 2 bits (block type)
+ *
+ * 1 block occurs every 32K -1 bytes or when there 50% compression has been achieved.
+ * The smallest block type encoding is always used.
+ *
+ * stored:
+ * 32 bits length in bytes.
+ *
+ * fixed:
+ * magic fixed tree.
+ * symbols.
+ *
+ * dynamic:
+ * dynamic tree encoding.
+ * symbols.
+ *
+ *
+ * The buffer for decompression in place is the length of the
+ * uncompressed data, plus a small amount extra to keep the algorithm safe.
+ * The compressed data is placed at the end of the buffer. The output
+ * pointer is placed at the start of the buffer and the input pointer
+ * is placed where the compressed data starts. Problems will occur
+ * when the output pointer overruns the input pointer.
+ *
+ * The output pointer can only overrun the input pointer if the input
+ * pointer is moving faster than the output pointer. A condition only
+ * triggered by data whose compressed form is larger than the uncompressed
+ * form.
+ *
+ * The worst case at the block level is a growth of the compressed data
+ * of 5 bytes per 32767 bytes.
+ *
+ * The worst case internal to a compressed block is very hard to figure.
+ * The worst case can at least be boundined by having one bit that represents
+ * 32764 bytes and then all of the rest of the bytes representing the very
+ * very last byte.
+ *
+ * All of which is enough to compute an amount of extra data that is required
+ * to be safe. To avoid problems at the block level allocating 5 extra bytes
+ * per 32767 bytes of data is sufficient. To avoind problems internal to a block
+ * adding an extra 32767 bytes (the worst case uncompressed block size) is
+ * sufficient, to ensure that in the worst case the decompressed data for
+ * block will stop the byte before the compressed data for a block begins.
+ * To avoid problems with the compressed data's meta information an extra 18
+ * bytes are needed. Leading to the formula:
+ *
+ * extra_bytes = (uncompressed_size >> 12) + 32768 + 18 + decompressor_size.
+ *
+ * Adding 8 bytes per 32K is a bit excessive but much easier to calculate.
+ * Adding 32768 instead of 32767 just makes for round numbers.
+ * Adding the decompressor_size is necessary as it musht live after all
+ * of the data as well. Last I measured the decompressor is about 14K.
+ * 10K of actuall data and 4K of bss.
+ *
+ */
/*
* gzip declarations
@@ -29,15 +111,20 @@ typedef unsigned char uch;
typedef unsigned short ush;
typedef unsigned long ulg;
-#define WSIZE 0x8000 /* Window size must be at least 32k, */
- /* and a power of two */
-
-static uch *inbuf; /* input buffer */
-static uch window[WSIZE]; /* Sliding window buffer */
-
-static unsigned insize = 0; /* valid bytes in inbuf */
-static unsigned inptr = 0; /* index of next byte to be processed in inbuf */
-static unsigned outcnt = 0; /* bytes in output buffer */
+#define WSIZE 0x80000000 /* Window size must be at least 32k,
+ * and a power of two
+ * We don't actually have a window just
+ * a huge output buffer so I report
+ * a 2G windows size, as that should
+ * always be larger than our output buffer.
+ */
+
+static uch *inbuf; /* input buffer */
+static uch *window; /* Sliding window buffer, (and final output buffer) */
+
+static unsigned insize; /* valid bytes in inbuf */
+static unsigned inptr; /* index of next byte to be processed in inbuf */
+static unsigned outcnt; /* bytes in output buffer */
/* gzip flag byte */
#define ASCII_FLAG 0x01 /* bit 0 set: file probably ASCII text */
@@ -88,8 +175,6 @@ extern unsigned char input_data[];
extern int input_len;
static long bytes_out = 0;
-static uch *output_data;
-static unsigned long output_ptr = 0;
static void *malloc(int size);
static void free(void *where);
@@ -99,17 +184,10 @@ static void *memcpy(void *dest, const vo
static void putstr(const char *);
-extern int end;
-static long free_mem_ptr = (long)&end;
-static long free_mem_end_ptr;
-
-#define INPLACE_MOVE_ROUTINE 0x1000
-#define LOW_BUFFER_START 0x2000
-#define LOW_BUFFER_MAX 0x90000
+static unsigned long free_mem_ptr;
+static unsigned long free_mem_end_ptr;
+
#define HEAP_SIZE 0x3000
-static unsigned int low_buffer_end, low_buffer_size;
-static int high_loaded =0;
-static uch *high_buffer_start /* = (uch *)(((ulg)&end) + HEAP_SIZE)*/;
static char *vidmem = (char *)0xb8000;
static int vidport;
@@ -150,7 +228,7 @@ static void gzip_mark(void **ptr)
static void gzip_release(void **ptr)
{
- free_mem_ptr = (long) *ptr;
+ free_mem_ptr = (unsigned long) *ptr;
}
static void scroll(void)
@@ -178,7 +256,7 @@ static void putstr(const char *s)
y--;
}
} else {
- vidmem [ ( x + cols * y ) * 2 ] = c;
+ vidmem [ ( x + cols * y ) * 2 ] = c;
if ( ++x >= cols ) {
x = 0;
if ( ++y >= lines ) {
@@ -223,58 +301,31 @@ static void* memcpy(void* dest, const vo
*/
static int fill_inbuf(void)
{
- if (insize != 0) {
- error("ran out of input data");
- }
-
- inbuf = input_data;
- insize = input_len;
- inptr = 1;
- return inbuf[0];
+ error("ran out of input data");
+ return 0;
}
/* ===========================================================================
* Write the output window window[0..outcnt-1] and update crc and bytes_out.
* (Used for the decompressed data only.)
*/
-static void flush_window_low(void)
-{
- ulg c = crc; /* temporary variable */
- unsigned n;
- uch *in, *out, ch;
-
- in = window;
- out = &output_data[output_ptr];
- for (n = 0; n < outcnt; n++) {
- ch = *out++ = *in++;
- c = crc_32_tab[((int)c ^ ch) & 0xff] ^ (c >> 8);
- }
- crc = c;
- bytes_out += (ulg)outcnt;
- output_ptr += (ulg)outcnt;
- outcnt = 0;
-}
-
-static void flush_window_high(void)
-{
- ulg c = crc; /* temporary variable */
- unsigned n;
- uch *in, ch;
- in = window;
- for (n = 0; n < outcnt; n++) {
- ch = *output_data++ = *in++;
- if ((ulg)output_data == low_buffer_end) output_data=high_buffer_start;
- c = crc_32_tab[((int)c ^ ch) & 0xff] ^ (c >> 8);
- }
- crc = c;
- bytes_out += (ulg)outcnt;
- outcnt = 0;
-}
-
static void flush_window(void)
{
- if (high_loaded) flush_window_high();
- else flush_window_low();
+ /* With my window equal to my output buffer
+ * I only need to compute the crc here.
+ */
+ ulg c = crc; /* temporary variable */
+ unsigned n;
+ uch *in, ch;
+
+ in = window;
+ for (n = 0; n < outcnt; n++) {
+ ch = *in++;
+ c = crc_32_tab[((int)c ^ ch) & 0xff] ^ (c >> 8);
+ }
+ crc = c;
+ bytes_out += (ulg)outcnt;
+ outcnt = 0;
}
static void error(char *x)
@@ -286,66 +337,8 @@ static void error(char *x)
while(1); /* Halt */
}
-#define STACK_SIZE (4096)
-
-long user_stack [STACK_SIZE];
-
-struct {
- long * a;
- short b;
- } stack_start = { & user_stack [STACK_SIZE] , __BOOT_DS };
-
-static void setup_normal_output_buffer(void)
-{
-#ifdef STANDARD_MEMORY_BIOS_CALL
- if (RM_EXT_MEM_K < 1024) error("Less than 2MB of memory");
-#else
- if ((RM_ALT_MEM_K > RM_EXT_MEM_K ? RM_ALT_MEM_K : RM_EXT_MEM_K) < 1024) error("Less than 2MB of memory");
-#endif
- output_data = (unsigned char *)CONFIG_PHYSICAL_START; /* Normally Points to 1M */
- free_mem_end_ptr = (long)real_mode;
-}
-
-struct moveparams {
- uch *low_buffer_start; int lcount;
- uch *high_buffer_start; int hcount;
-};
-
-static void setup_output_buffer_if_we_run_high(struct moveparams *mv)
-{
- high_buffer_start = (uch *)(((ulg)&end) + HEAP_SIZE);
-#ifdef STANDARD_MEMORY_BIOS_CALL
- if (RM_EXT_MEM_K < (3*1024)) error("Less than 4MB of memory");
-#else
- if ((RM_ALT_MEM_K > RM_EXT_MEM_K ? RM_ALT_MEM_K : RM_EXT_MEM_K) < (3*1024)) error("Less than 4MB of memory");
-#endif
- mv->low_buffer_start = output_data = (unsigned char *)LOW_BUFFER_START;
- low_buffer_end = ((unsigned int)real_mode > LOW_BUFFER_MAX
- ? LOW_BUFFER_MAX : (unsigned int)real_mode) & ~0xfff;
- low_buffer_size = low_buffer_end - LOW_BUFFER_START;
- high_loaded = 1;
- free_mem_end_ptr = (long)high_buffer_start;
- if ( (CONFIG_PHYSICAL_START + low_buffer_size) > ((ulg)high_buffer_start)) {
- high_buffer_start = (uch *)(CONFIG_PHYSICAL_START + low_buffer_size);
- mv->hcount = 0; /* say: we need not to move high_buffer */
- }
- else mv->hcount = -1;
- mv->high_buffer_start = high_buffer_start;
-}
-
-static void close_output_buffer_if_we_run_high(struct moveparams *mv)
-{
- if (bytes_out > low_buffer_size) {
- mv->lcount = low_buffer_size;
- if (mv->hcount)
- mv->hcount = bytes_out - low_buffer_size;
- } else {
- mv->lcount = bytes_out;
- mv->hcount = 0;
- }
-}
-
-asmlinkage int decompress_kernel(struct moveparams *mv, void *rmode)
+asmlinkage void decompress_kernel(void *rmode, unsigned long end,
+ uch *input_data, unsigned long input_len, uch *output)
{
real_mode = rmode;
@@ -360,13 +353,25 @@ asmlinkage int decompress_kernel(struct
lines = RM_SCREEN_INFO.orig_video_lines;
cols = RM_SCREEN_INFO.orig_video_cols;
- if (free_mem_ptr < 0x100000) setup_normal_output_buffer();
- else setup_output_buffer_if_we_run_high(mv);
+ window = output; /* Output buffer (Normally at 1M) */
+ free_mem_ptr = end; /* Heap */
+ free_mem_end_ptr = end + HEAP_SIZE;
+ inbuf = input_data; /* Input buffer */
+ insize = input_len;
+ inptr = 0;
+
+ if (((u32)output - CONFIG_PHYSICAL_START) & 0x3fffff)
+ error("Destination address not 4M aligned");
+ if (end > ((-__PAGE_OFFSET-(512 <<20)-1) & 0x7fffffff))
+ error("Destination address too large");
+#ifndef CONFIG_RELOCATABLE
+ if ((u32)output != CONFIG_PHYSICAL_START)
+ error("Wrong destination address");
+#endif
makecrc();
putstr("Uncompressing Linux... ");
gunzip();
putstr("Ok, booting the kernel.\n");
- if (high_loaded) close_output_buffer_if_we_run_high(mv);
- return high_loaded;
+ return;
}
diff -puN /dev/null arch/i386/boot/compressed/relocs.c
--- /dev/null 2006-10-23 14:50:11.327499618 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/i386/boot/compressed/relocs.c 2006-10-23 15:08:47.000000000 -0400
@@ -0,0 +1,563 @@
+#include <stdio.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <errno.h>
+#include <unistd.h>
+#include <elf.h>
+#include <byteswap.h>
+#define USE_BSD
+#include <endian.h>
+
+#define MAX_SHDRS 100
+static Elf32_Ehdr ehdr;
+static Elf32_Shdr shdr[MAX_SHDRS];
+static Elf32_Sym *symtab[MAX_SHDRS];
+static Elf32_Rel *reltab[MAX_SHDRS];
+static char *strtab[MAX_SHDRS];
+static unsigned long reloc_count, reloc_idx;
+static unsigned long *relocs;
+
+static void die(char *fmt, ...)
+{
+ va_list ap;
+ va_start(ap, fmt);
+ vfprintf(stderr, fmt, ap);
+ va_end(ap);
+ exit(1);
+}
+
+static const char *sym_type(unsigned type)
+{
+ static const char *type_name[] = {
+#define SYM_TYPE(X) [X] = #X
+ SYM_TYPE(STT_NOTYPE),
+ SYM_TYPE(STT_OBJECT),
+ SYM_TYPE(STT_FUNC),
+ SYM_TYPE(STT_SECTION),
+ SYM_TYPE(STT_FILE),
+ SYM_TYPE(STT_COMMON),
+ SYM_TYPE(STT_TLS),
+#undef SYM_TYPE
+ };
+ const char *name = "unknown sym type name";
+ if (type < sizeof(type_name)/sizeof(type_name[0])) {
+ name = type_name[type];
+ }
+ return name;
+}
+
+static const char *sym_bind(unsigned bind)
+{
+ static const char *bind_name[] = {
+#define SYM_BIND(X) [X] = #X
+ SYM_BIND(STB_LOCAL),
+ SYM_BIND(STB_GLOBAL),
+ SYM_BIND(STB_WEAK),
+#undef SYM_BIND
+ };
+ const char *name = "unknown sym bind name";
+ if (bind < sizeof(bind_name)/sizeof(bind_name[0])) {
+ name = bind_name[bind];
+ }
+ return name;
+}
+
+static const char *sym_visibility(unsigned visibility)
+{
+ static const char *visibility_name[] = {
+#define SYM_VISIBILITY(X) [X] = #X
+ SYM_VISIBILITY(STV_DEFAULT),
+ SYM_VISIBILITY(STV_INTERNAL),
+ SYM_VISIBILITY(STV_HIDDEN),
+ SYM_VISIBILITY(STV_PROTECTED),
+#undef SYM_VISIBILITY
+ };
+ const char *name = "unknown sym visibility name";
+ if (visibility < sizeof(visibility_name)/sizeof(visibility_name[0])) {
+ name = visibility_name[visibility];
+ }
+ return name;
+}
+
+static const char *rel_type(unsigned type)
+{
+ static const char *type_name[] = {
+#define REL_TYPE(X) [X] = #X
+ REL_TYPE(R_386_NONE),
+ REL_TYPE(R_386_32),
+ REL_TYPE(R_386_PC32),
+ REL_TYPE(R_386_GOT32),
+ REL_TYPE(R_386_PLT32),
+ REL_TYPE(R_386_COPY),
+ REL_TYPE(R_386_GLOB_DAT),
+ REL_TYPE(R_386_JMP_SLOT),
+ REL_TYPE(R_386_RELATIVE),
+ REL_TYPE(R_386_GOTOFF),
+ REL_TYPE(R_386_GOTPC),
+#undef REL_TYPE
+ };
+ const char *name = "unknown type rel type name";
+ if (type < sizeof(type_name)/sizeof(type_name[0])) {
+ name = type_name[type];
+ }
+ return name;
+}
+
+static const char *sec_name(unsigned shndx)
+{
+ const char *sec_strtab;
+ const char *name;
+ sec_strtab = strtab[ehdr.e_shstrndx];
+ name = "<noname>";
+ if (shndx < ehdr.e_shnum) {
+ name = sec_strtab + shdr[shndx].sh_name;
+ }
+ else if (shndx == SHN_ABS) {
+ name = "ABSOLUTE";
+ }
+ else if (shndx == SHN_COMMON) {
+ name = "COMMON";
+ }
+ return name;
+}
+
+static const char *sym_name(const char *sym_strtab, Elf32_Sym *sym)
+{
+ const char *name;
+ name = "<noname>";
+ if (sym->st_name) {
+ name = sym_strtab + sym->st_name;
+ }
+ else {
+ name = sec_name(shdr[sym->st_shndx].sh_name);
+ }
+ return name;
+}
+
+
+
+#if BYTE_ORDER == LITTLE_ENDIAN
+#define le16_to_cpu(val) (val)
+#define le32_to_cpu(val) (val)
+#endif
+#if BYTE_ORDER == BIG_ENDIAN
+#define le16_to_cpu(val) bswap_16(val)
+#define le32_to_cpu(val) bswap_32(val)
+#endif
+
+static uint16_t elf16_to_cpu(uint16_t val)
+{
+ return le16_to_cpu(val);
+}
+
+static uint32_t elf32_to_cpu(uint32_t val)
+{
+ return le32_to_cpu(val);
+}
+
+static void read_ehdr(FILE *fp)
+{
+ if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1) {
+ die("Cannot read ELF header: %s\n",
+ strerror(errno));
+ }
+ if (memcmp(ehdr.e_ident, ELFMAG, 4) != 0) {
+ die("No ELF magic\n");
+ }
+ if (ehdr.e_ident[EI_CLASS] != ELFCLASS32) {
+ die("Not a 32 bit executable\n");
+ }
+ if (ehdr.e_ident[EI_DATA] != ELFDATA2LSB) {
+ die("Not a LSB ELF executable\n");
+ }
+ if (ehdr.e_ident[EI_VERSION] != EV_CURRENT) {
+ die("Unknown ELF version\n");
+ }
+ /* Convert the fields to native endian */
+ ehdr.e_type = elf16_to_cpu(ehdr.e_type);
+ ehdr.e_machine = elf16_to_cpu(ehdr.e_machine);
+ ehdr.e_version = elf32_to_cpu(ehdr.e_version);
+ ehdr.e_entry = elf32_to_cpu(ehdr.e_entry);
+ ehdr.e_phoff = elf32_to_cpu(ehdr.e_phoff);
+ ehdr.e_shoff = elf32_to_cpu(ehdr.e_shoff);
+ ehdr.e_flags = elf32_to_cpu(ehdr.e_flags);
+ ehdr.e_ehsize = elf16_to_cpu(ehdr.e_ehsize);
+ ehdr.e_phentsize = elf16_to_cpu(ehdr.e_phentsize);
+ ehdr.e_phnum = elf16_to_cpu(ehdr.e_phnum);
+ ehdr.e_shentsize = elf16_to_cpu(ehdr.e_shentsize);
+ ehdr.e_shnum = elf16_to_cpu(ehdr.e_shnum);
+ ehdr.e_shstrndx = elf16_to_cpu(ehdr.e_shstrndx);
+
+ if ((ehdr.e_type != ET_EXEC) && (ehdr.e_type != ET_DYN)) {
+ die("Unsupported ELF header type\n");
+ }
+ if (ehdr.e_machine != EM_386) {
+ die("Not for x86\n");
+ }
+ if (ehdr.e_version != EV_CURRENT) {
+ die("Unknown ELF version\n");
+ }
+ if (ehdr.e_ehsize != sizeof(Elf32_Ehdr)) {
+ die("Bad Elf header size\n");
+ }
+ if (ehdr.e_phentsize != sizeof(Elf32_Phdr)) {
+ die("Bad program header entry\n");
+ }
+ if (ehdr.e_shentsize != sizeof(Elf32_Shdr)) {
+ die("Bad section header entry\n");
+ }
+ if (ehdr.e_shstrndx >= ehdr.e_shnum) {
+ die("String table index out of bounds\n");
+ }
+}
+
+static void read_shdrs(FILE *fp)
+{
+ int i;
+ if (ehdr.e_shnum > MAX_SHDRS) {
+ die("%d section headers supported: %d\n",
+ ehdr.e_shnum, MAX_SHDRS);
+ }
+ if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) {
+ die("Seek to %d failed: %s\n",
+ ehdr.e_shoff, strerror(errno));
+ }
+ if (fread(&shdr, sizeof(shdr[0]), ehdr.e_shnum, fp) != ehdr.e_shnum) {
+ die("Cannot read ELF section headers: %s\n",
+ strerror(errno));
+ }
+ for(i = 0; i < ehdr.e_shnum; i++) {
+ shdr[i].sh_name = elf32_to_cpu(shdr[i].sh_name);
+ shdr[i].sh_type = elf32_to_cpu(shdr[i].sh_type);
+ shdr[i].sh_flags = elf32_to_cpu(shdr[i].sh_flags);
+ shdr[i].sh_addr = elf32_to_cpu(shdr[i].sh_addr);
+ shdr[i].sh_offset = elf32_to_cpu(shdr[i].sh_offset);
+ shdr[i].sh_size = elf32_to_cpu(shdr[i].sh_size);
+ shdr[i].sh_link = elf32_to_cpu(shdr[i].sh_link);
+ shdr[i].sh_info = elf32_to_cpu(shdr[i].sh_info);
+ shdr[i].sh_addralign = elf32_to_cpu(shdr[i].sh_addralign);
+ shdr[i].sh_entsize = elf32_to_cpu(shdr[i].sh_entsize);
+ }
+
+}
+
+static void read_strtabs(FILE *fp)
+{
+ int i;
+ for(i = 0; i < ehdr.e_shnum; i++) {
+ if (shdr[i].sh_type != SHT_STRTAB) {
+ continue;
+ }
+ strtab[i] = malloc(shdr[i].sh_size);
+ if (!strtab[i]) {
+ die("malloc of %d bytes for strtab failed\n",
+ shdr[i].sh_size);
+ }
+ if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
+ die("Seek to %d failed: %s\n",
+ shdr[i].sh_offset, strerror(errno));
+ }
+ if (fread(strtab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
+ die("Cannot read symbol table: %s\n",
+ strerror(errno));
+ }
+ }
+}
+
+static void read_symtabs(FILE *fp)
+{
+ int i,j;
+ for(i = 0; i < ehdr.e_shnum; i++) {
+ if (shdr[i].sh_type != SHT_SYMTAB) {
+ continue;
+ }
+ symtab[i] = malloc(shdr[i].sh_size);
+ if (!symtab[i]) {
+ die("malloc of %d bytes for symtab failed\n",
+ shdr[i].sh_size);
+ }
+ if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
+ die("Seek to %d failed: %s\n",
+ shdr[i].sh_offset, strerror(errno));
+ }
+ if (fread(symtab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
+ die("Cannot read symbol table: %s\n",
+ strerror(errno));
+ }
+ for(j = 0; j < shdr[i].sh_size/sizeof(symtab[i][0]); j++) {
+ symtab[i][j].st_name = elf32_to_cpu(symtab[i][j].st_name);
+ symtab[i][j].st_value = elf32_to_cpu(symtab[i][j].st_value);
+ symtab[i][j].st_size = elf32_to_cpu(symtab[i][j].st_size);
+ symtab[i][j].st_shndx = elf16_to_cpu(symtab[i][j].st_shndx);
+ }
+ }
+}
+
+
+static void read_relocs(FILE *fp)
+{
+ int i,j;
+ for(i = 0; i < ehdr.e_shnum; i++) {
+ if (shdr[i].sh_type != SHT_REL) {
+ continue;
+ }
+ reltab[i] = malloc(shdr[i].sh_size);
+ if (!reltab[i]) {
+ die("malloc of %d bytes for relocs failed\n",
+ shdr[i].sh_size);
+ }
+ if (fseek(fp, shdr[i].sh_offset, SEEK_SET) < 0) {
+ die("Seek to %d failed: %s\n",
+ shdr[i].sh_offset, strerror(errno));
+ }
+ if (fread(reltab[i], 1, shdr[i].sh_size, fp) != shdr[i].sh_size) {
+ die("Cannot read symbol table: %s\n",
+ strerror(errno));
+ }
+ for(j = 0; j < shdr[i].sh_size/sizeof(reltab[0][0]); j++) {
+ reltab[i][j].r_offset = elf32_to_cpu(reltab[i][j].r_offset);
+ reltab[i][j].r_info = elf32_to_cpu(reltab[i][j].r_info);
+ }
+ }
+}
+
+
+static void print_absolute_symbols(void)
+{
+ int i;
+ printf("Absolute symbols\n");
+ printf(" Num: Value Size Type Bind Visibility Name\n");
+ for(i = 0; i < ehdr.e_shnum; i++) {
+ char *sym_strtab;
+ Elf32_Sym *sh_symtab;
+ int j;
+ if (shdr[i].sh_type != SHT_SYMTAB) {
+ continue;
+ }
+ sh_symtab = symtab[i];
+ sym_strtab = strtab[shdr[i].sh_link];
+ for(j = 0; j < shdr[i].sh_size/sizeof(symtab[0][0]); j++) {
+ Elf32_Sym *sym;
+ const char *name;
+ sym = &symtab[i][j];
+ name = sym_name(sym_strtab, sym);
+ if (sym->st_shndx != SHN_ABS) {
+ continue;
+ }
+ printf("%5d %08x %5d %10s %10s %12s %s\n",
+ j, sym->st_value, sym->st_size,
+ sym_type(ELF32_ST_TYPE(sym->st_info)),
+ sym_bind(ELF32_ST_BIND(sym->st_info)),
+ sym_visibility(ELF32_ST_VISIBILITY(sym->st_other)),
+ name);
+ }
+ }
+ printf("\n");
+}
+
+static void print_absolute_relocs(void)
+{
+ int i;
+ printf("Absolute relocations\n");
+ printf("Offset Info Type Sym.Value Sym.Name\n");
+ for(i = 0; i < ehdr.e_shnum; i++) {
+ char *sym_strtab;
+ Elf32_Sym *sh_symtab;
+ unsigned sec_applies, sec_symtab;
+ int j;
+ if (shdr[i].sh_type != SHT_REL) {
+ continue;
+ }
+ sec_symtab = shdr[i].sh_link;
+ sec_applies = shdr[i].sh_info;
+ if (!(shdr[sec_applies].sh_flags & SHF_ALLOC)) {
+ continue;
+ }
+ sh_symtab = symtab[sec_symtab];
+ sym_strtab = strtab[shdr[sec_symtab].sh_link];
+ for(j = 0; j < shdr[i].sh_size/sizeof(reltab[0][0]); j++) {
+ Elf32_Rel *rel;
+ Elf32_Sym *sym;
+ const char *name;
+ rel = &reltab[i][j];
+ sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
+ name = sym_name(sym_strtab, sym);
+ if (sym->st_shndx != SHN_ABS) {
+ continue;
+ }
+ printf("%08x %08x %10s %08x %s\n",
+ rel->r_offset,
+ rel->r_info,
+ rel_type(ELF32_R_TYPE(rel->r_info)),
+ sym->st_value,
+ name);
+ }
+ }
+ printf("\n");
+}
+
+static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym))
+{
+ int i;
+ /* Walk through the relocations */
+ for(i = 0; i < ehdr.e_shnum; i++) {
+ char *sym_strtab;
+ Elf32_Sym *sh_symtab;
+ unsigned sec_applies, sec_symtab;
+ int j;
+ if (shdr[i].sh_type != SHT_REL) {
+ continue;
+ }
+ sec_symtab = shdr[i].sh_link;
+ sec_applies = shdr[i].sh_info;
+ if (!(shdr[sec_applies].sh_flags & SHF_ALLOC)) {
+ continue;
+ }
+ sh_symtab = symtab[sec_symtab];
+ sym_strtab = strtab[shdr[sec_symtab].sh_link];
+ for(j = 0; j < shdr[i].sh_size/sizeof(reltab[0][0]); j++) {
+ Elf32_Rel *rel;
+ Elf32_Sym *sym;
+ unsigned r_type;
+ rel = &reltab[i][j];
+ sym = &sh_symtab[ELF32_R_SYM(rel->r_info)];
+ r_type = ELF32_R_TYPE(rel->r_info);
+ /* Don't visit relocations to absolute symbols */
+ if (sym->st_shndx == SHN_ABS) {
+ continue;
+ }
+ if (r_type == R_386_PC32) {
+ /* PC relative relocations don't need to be adjusted */
+ }
+ else if (r_type == R_386_32) {
+ /* Visit relocations that need to be adjusted */
+ visit(rel, sym);
+ }
+ else {
+ die("Unsupported relocation type: %d\n", r_type);
+ }
+ }
+ }
+}
+
+static void count_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
+{
+ reloc_count += 1;
+}
+
+static void collect_reloc(Elf32_Rel *rel, Elf32_Sym *sym)
+{
+ /* Remember the address that needs to be adjusted. */
+ relocs[reloc_idx++] = rel->r_offset;
+}
+
+static int cmp_relocs(const void *va, const void *vb)
+{
+ const unsigned long *a, *b;
+ a = va; b = vb;
+ return (*a == *b)? 0 : (*a > *b)? 1 : -1;
+}
+
+static void emit_relocs(int as_text)
+{
+ int i;
+ /* Count how many relocations I have and allocate space for them. */
+ reloc_count = 0;
+ walk_relocs(count_reloc);
+ relocs = malloc(reloc_count * sizeof(relocs[0]));
+ if (!relocs) {
+ die("malloc of %d entries for relocs failed\n",
+ reloc_count);
+ }
+ /* Collect up the relocations */
+ reloc_idx = 0;
+ walk_relocs(collect_reloc);
+
+ /* Order the relocations for more efficient processing */
+ qsort(relocs, reloc_count, sizeof(relocs[0]), cmp_relocs);
+
+ /* Print the relocations */
+ if (as_text) {
+ /* Print the relocations in a form suitable that
+ * gas will like.
+ */
+ printf(".section \".data.reloc\",\"a\"\n");
+ printf(".balign 4\n");
+ for(i = 0; i < reloc_count; i++) {
+ printf("\t .long 0x%08lx\n", relocs[i]);
+ }
+ printf("\n");
+ }
+ else {
+ unsigned char buf[4];
+ buf[0] = buf[1] = buf[2] = buf[3] = 0;
+ /* Print a stop */
+ printf("%c%c%c%c", buf[0], buf[1], buf[2], buf[3]);
+ /* Now print each relocation */
+ for(i = 0; i < reloc_count; i++) {
+ buf[0] = (relocs[i] >> 0) & 0xff;
+ buf[1] = (relocs[i] >> 8) & 0xff;
+ buf[2] = (relocs[i] >> 16) & 0xff;
+ buf[3] = (relocs[i] >> 24) & 0xff;
+ printf("%c%c%c%c", buf[0], buf[1], buf[2], buf[3]);
+ }
+ }
+}
+
+static void usage(void)
+{
+ die("i386_reloc [--abs | --text] vmlinux\n");
+}
+
+int main(int argc, char **argv)
+{
+ int show_absolute;
+ int as_text;
+ const char *fname;
+ FILE *fp;
+ int i;
+
+ show_absolute = 0;
+ as_text = 0;
+ fname = NULL;
+ for(i = 1; i < argc; i++) {
+ char *arg = argv[i];
+ if (*arg == '-') {
+ if (strcmp(argv[1], "--abs") == 0) {
+ show_absolute = 1;
+ continue;
+ }
+ else if (strcmp(argv[1], "--text") == 0) {
+ as_text = 1;
+ continue;
+ }
+ }
+ else if (!fname) {
+ fname = arg;
+ continue;
+ }
+ usage();
+ }
+ if (!fname) {
+ usage();
+ }
+ fp = fopen(fname, "r");
+ if (!fp) {
+ die("Cannot open %s: %s\n",
+ fname, strerror(errno));
+ }
+ read_ehdr(fp);
+ read_shdrs(fp);
+ read_strtabs(fp);
+ read_symtabs(fp);
+ read_relocs(fp);
+ if (show_absolute) {
+ print_absolute_symbols();
+ print_absolute_relocs();
+ return 0;
+ }
+ emit_relocs(as_text);
+ return 0;
+}
diff -puN /dev/null arch/i386/boot/compressed/vmlinux.lds
--- /dev/null 2006-10-23 14:50:11.327499618 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/i386/boot/compressed/vmlinux.lds 2006-10-23 13:15:21.000000000 -0400
@@ -0,0 +1,43 @@
+OUTPUT_FORMAT("elf32-i386", "elf32-i386", "elf32-i386")
+OUTPUT_ARCH(i386)
+ENTRY(startup_32)
+SECTIONS
+{
+ /* Be careful parts of head.S assume startup_32 is at
+ * address 0.
+ */
+ . = 0 ;
+ .text.head : {
+ _head = . ;
+ *(.text.head)
+ _ehead = . ;
+ }
+ .data.compressed : {
+ *(.data.compressed)
+ }
+ .text : {
+ _text = .; /* Text */
+ *(.text)
+ *(.text.*)
+ _etext = . ;
+ }
+ .rodata : {
+ _rodata = . ;
+ *(.rodata) /* read-only data */
+ *(.rodata.*)
+ _erodata = . ;
+ }
+ .data : {
+ _data = . ;
+ *(.data)
+ *(.data.*)
+ _edata = . ;
+ }
+ .bss : {
+ _bss = . ;
+ *(.bss)
+ *(.bss.*)
+ *(COMMON)
+ _end = . ;
+ }
+}
diff -puN arch/i386/boot/compressed/vmlinux.scr~i386-Relocatable-kernel-support arch/i386/boot/compressed/vmlinux.scr
--- linux-2.6.19-rc2-git7-reloc/arch/i386/boot/compressed/vmlinux.scr~i386-Relocatable-kernel-support 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/i386/boot/compressed/vmlinux.scr 2006-10-23 13:15:21.000000000 -0400
@@ -1,9 +1,10 @@
SECTIONS
{
- .data : {
+ .data.compressed : {
input_len = .;
LONG(input_data_end - input_data) input_data = .;
*(.data)
+ output_len = . - 4;
input_data_end = .;
}
}
diff -puN arch/i386/boot/setup.S~i386-Relocatable-kernel-support arch/i386/boot/setup.S
--- linux-2.6.19-rc2-git7-reloc/arch/i386/boot/setup.S~i386-Relocatable-kernel-support 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/i386/boot/setup.S 2006-10-23 15:08:42.000000000 -0400
@@ -588,11 +588,6 @@ rmodeswtch_normal:
call default_switch
rmodeswtch_end:
-# we get the code32 start address and modify the below 'jmpi'
-# (loader may have changed it)
- movl %cs:code32_start, %eax
- movl %eax, %cs:code32
-
# Now we move the system to its rightful place ... but we check if we have a
# big-kernel. In that case we *must* not move it ...
testb $LOADED_HIGH, %cs:loadflags
@@ -788,11 +783,12 @@ a20_err_msg:
a20_done:
#endif /* CONFIG_X86_VOYAGER */
-# set up gdt and idt
+# set up gdt and idt and 32bit start address
lidt idt_48 # load idt with 0,0
xorl %eax, %eax # Compute gdt_base
movw %ds, %ax # (Convert %ds:gdt to a linear ptr)
shll $4, %eax
+ addl %eax, code32
addl $gdt, %eax
movl %eax, (gdt_48+2)
lgdt gdt_48 # load gdt with whatever is
@@ -851,9 +847,26 @@ flush_instr:
# Manual, Mixing 16-bit and 32-bit code, page 16-6)
.byte 0x66, 0xea # prefix + jmpi-opcode
-code32: .long 0x1000 # will be set to 0x100000
- # for big kernels
+code32: .long startup_32 # will be set to %cs+startup_32
.word __BOOT_CS
+.code32
+startup_32:
+ movl $(__BOOT_DS), %eax
+ movl %eax, %ds
+ movl %eax, %es
+ movl %eax, %fs
+ movl %eax, %gs
+ movl %eax, %ss
+
+ xorl %eax, %eax
+1: incl %eax # check that A20 really IS enabled
+ movl %eax, 0x00000000 # loop forever if it isn't
+ cmpl %eax, 0x00100000
+ je 1b
+
+ # Jump to the 32bit entry point
+ jmpl *(code32_start - start + (DELTA_INITSEG << 4))(%esi)
+.code16
# Here's a bunch of information about your current kernel..
kernel_version: .ascii UTS_RELEASE
diff -puN arch/i386/Kconfig~i386-Relocatable-kernel-support arch/i386/Kconfig
--- linux-2.6.19-rc2-git7-reloc/arch/i386/Kconfig~i386-Relocatable-kernel-support 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/i386/Kconfig 2006-10-23 15:08:45.000000000 -0400
@@ -773,6 +773,18 @@ config CRASH_DUMP
PHYSICAL_START.
For more details see Documentation/kdump/kdump.txt
+config RELOCATABLE
+ bool "Build a relocatable kernel"
+ help
+ This build a kernel image that retains relocation information
+ so it can be loaded someplace besides the default 1MB.
+ The relocations tend to the kernel binary about 10% larger,
+ but are discarded at runtime.
+
+ One use is for the kexec on panic case where the recovery kernel
+ must live at a different physical address than the primary
+ kernel.
+
config PHYSICAL_START
hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
diff -puN arch/i386/Makefile~i386-Relocatable-kernel-support arch/i386/Makefile
--- linux-2.6.19-rc2-git7-reloc/arch/i386/Makefile~i386-Relocatable-kernel-support 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/i386/Makefile 2006-10-23 13:15:21.000000000 -0400
@@ -26,7 +26,9 @@ endif
LDFLAGS := -m elf_i386
OBJCOPYFLAGS := -O binary -R .note -R .comment -S
-LDFLAGS_vmlinux :=
+ifdef CONFIG_RELOCATABLE
+LDFLAGS_vmlinux := --emit-relocs
+endif
CHECKFLAGS += -D__i386__
CFLAGS += -pipe -msoft-float
diff -puN include/linux/screen_info.h~i386-Relocatable-kernel-support include/linux/screen_info.h
--- linux-2.6.19-rc2-git7-reloc/include/linux/screen_info.h~i386-Relocatable-kernel-support 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/include/linux/screen_info.h 2006-10-23 13:15:21.000000000 -0400
@@ -42,7 +42,8 @@ struct screen_info {
u16 pages; /* 0x32 */
u16 vesa_attributes; /* 0x34 */
u32 capabilities; /* 0x36 */
- /* 0x3a -- 0x3f reserved for future expansion */
+ /* 0x3a -- 0x3b reserved for future expansion */
+ /* 0x3c -- 0x3f micro stack for relocatable kernels */
};
extern struct screen_info screen_info;
_
^ permalink raw reply [flat|nested] 17+ messages in thread* [PATCH 9/11] i386: Warn upon absolute relocations being present
2006-10-23 19:24 [RFC][PATCH 0/11] i386: Relocatable BzImage (V3) Vivek Goyal
` (7 preceding siblings ...)
2006-10-23 19:39 ` [PATCH 8/11] i386: Relocatable kernel support Vivek Goyal
@ 2006-10-23 19:40 ` Vivek Goyal
2006-10-23 19:42 ` [PATCH 10/11] i386: Implement CONFIG_PHYSICAL_ALIGN Vivek Goyal
` (2 subsequent siblings)
11 siblings, 0 replies; 17+ messages in thread
From: Vivek Goyal @ 2006-10-23 19:40 UTC (permalink / raw)
To: linux kernel mailing list
Cc: Reloc Kernel List, ebiederm, akpm, ak, hpa, magnus.damm, lwang,
dzickus, maneesh
o Relocations generated w.r.t absolute symbols are not processed as by
definition, absolute symbols are not to be relocated. Explicitly warn
user about absolutions relocations present at compile time.
o These relocations get introduced either due to linker optimizations or
some programming oversights.
o Also create a list of symbols which have been audited to be safe and
don't emit warnings for these.
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
---
arch/i386/boot/compressed/Makefile | 2
arch/i386/boot/compressed/relocs.c | 82 ++++++++++++++++++++++++++++++++-----
2 files changed, 73 insertions(+), 11 deletions(-)
diff -puN arch/i386/boot/compressed/Makefile~i386-explicitly-warn-about-absolute-symbols-during-compile arch/i386/boot/compressed/Makefile
--- linux-2.6.19-rc2-git7-reloc/arch/i386/boot/compressed/Makefile~i386-explicitly-warn-about-absolute-symbols-during-compile 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/i386/boot/compressed/Makefile 2006-10-23 13:15:21.000000000 -0400
@@ -20,7 +20,7 @@ $(obj)/vmlinux.bin: vmlinux FORCE
$(call if_changed,objcopy)
quiet_cmd_relocs = RELOCS $@
- cmd_relocs = $(obj)/relocs $< > $@
+ cmd_relocs = $(obj)/relocs $< > $@;$(obj)/relocs --abs-relocs $<
$(obj)/vmlinux.relocs: vmlinux $(obj)/relocs FORCE
$(call if_changed,relocs)
diff -puN arch/i386/boot/compressed/relocs.c~i386-explicitly-warn-about-absolute-symbols-during-compile arch/i386/boot/compressed/relocs.c
--- linux-2.6.19-rc2-git7-reloc/arch/i386/boot/compressed/relocs.c~i386-explicitly-warn-about-absolute-symbols-during-compile 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/i386/boot/compressed/relocs.c 2006-10-23 13:15:21.000000000 -0400
@@ -19,6 +19,33 @@ static char *strtab[MAX_SHDRS];
static unsigned long reloc_count, reloc_idx;
static unsigned long *relocs;
+/*
+ * Following symbols have been audited. There values are constant and do
+ * not change if bzImage is loaded at a different physical address than
+ * the address for which it has been compiled. Don't warn user about
+ * absolute relocations present w.r.t these symbols.
+ */
+static const char* safe_abs_relocs[] = {
+ "__kernel_vsyscall",
+ "__kernel_rt_sigreturn",
+ "__kernel_sigreturn",
+ "SYSENTER_RETURN",
+};
+
+static int is_safe_abs_reloc(const char* sym_name)
+{
+ int i, array_size;
+
+ array_size = sizeof(safe_abs_relocs)/sizeof(char*);
+
+ for(i = 0; i < array_size; i++) {
+ if (!strcmp(sym_name, safe_abs_relocs[i]))
+ /* Match found */
+ return 1;
+ }
+ return 0;
+}
+
static void die(char *fmt, ...)
{
va_list ap;
@@ -359,9 +386,8 @@ static void print_absolute_symbols(void)
static void print_absolute_relocs(void)
{
- int i;
- printf("Absolute relocations\n");
- printf("Offset Info Type Sym.Value Sym.Name\n");
+ int i, printed = 0;
+
for(i = 0; i < ehdr.e_shnum; i++) {
char *sym_strtab;
Elf32_Sym *sh_symtab;
@@ -387,6 +413,31 @@ static void print_absolute_relocs(void)
if (sym->st_shndx != SHN_ABS) {
continue;
}
+
+ /* Absolute symbols are not relocated if bzImage is
+ * loaded at a non-compiled address. Display a warning
+ * to user at compile time about the absolute
+ * relocations present.
+ *
+ * User need to audit the code to make sure
+ * some symbols which should have been section
+ * relative have not become absolute because of some
+ * linker optimization or wrong programming usage.
+ *
+ * Before warning check if this absolute symbol
+ * relocation is harmless.
+ */
+ if (is_safe_abs_reloc(name))
+ continue;
+
+ if (!printed) {
+ printf("WARNING: Absolute relocations"
+ " present\n");
+ printf("Offset Info Type Sym.Value "
+ "Sym.Name\n");
+ printed = 1;
+ }
+
printf("%08x %08x %10s %08x %s\n",
rel->r_offset,
rel->r_info,
@@ -395,7 +446,9 @@ static void print_absolute_relocs(void)
name);
}
}
- printf("\n");
+
+ if (printed)
+ printf("\n");
}
static void walk_relocs(void (*visit)(Elf32_Rel *rel, Elf32_Sym *sym))
@@ -508,25 +561,31 @@ static void emit_relocs(int as_text)
static void usage(void)
{
- die("i386_reloc [--abs | --text] vmlinux\n");
+ die("relocs [--abs-syms |--abs-relocs | --text] vmlinux\n");
}
int main(int argc, char **argv)
{
- int show_absolute;
+ int show_absolute_syms, show_absolute_relocs;
int as_text;
const char *fname;
FILE *fp;
int i;
- show_absolute = 0;
+ show_absolute_syms = 0;
+ show_absolute_relocs = 0;
as_text = 0;
fname = NULL;
for(i = 1; i < argc; i++) {
char *arg = argv[i];
if (*arg == '-') {
- if (strcmp(argv[1], "--abs") == 0) {
- show_absolute = 1;
+ if (strcmp(argv[1], "--abs-syms") == 0) {
+ show_absolute_syms = 1;
+ continue;
+ }
+
+ if (strcmp(argv[1], "--abs-relocs") == 0) {
+ show_absolute_relocs = 1;
continue;
}
else if (strcmp(argv[1], "--text") == 0) {
@@ -553,8 +612,11 @@ int main(int argc, char **argv)
read_strtabs(fp);
read_symtabs(fp);
read_relocs(fp);
- if (show_absolute) {
+ if (show_absolute_syms) {
print_absolute_symbols();
+ return 0;
+ }
+ if (show_absolute_relocs) {
print_absolute_relocs();
return 0;
}
_
^ permalink raw reply [flat|nested] 17+ messages in thread* [PATCH 10/11] i386: Implement CONFIG_PHYSICAL_ALIGN
2006-10-23 19:24 [RFC][PATCH 0/11] i386: Relocatable BzImage (V3) Vivek Goyal
` (8 preceding siblings ...)
2006-10-23 19:40 ` [PATCH 9/11] i386: Warn upon absolute relocations being present Vivek Goyal
@ 2006-10-23 19:42 ` Vivek Goyal
2006-10-23 19:44 ` [PATCH 11/11] i386: Extend bzImage protocol for relocatable protected mode kernel Vivek Goyal
2006-10-24 13:44 ` [RFC][PATCH 0/11] i386: Relocatable BzImage (V3) Andi Kleen
11 siblings, 0 replies; 17+ messages in thread
From: Vivek Goyal @ 2006-10-23 19:42 UTC (permalink / raw)
To: linux kernel mailing list
Cc: Reloc Kernel List, ebiederm, akpm, ak, hpa, magnus.damm, lwang,
dzickus, maneesh
o Now CONFIG_PHYSICAL_START is being replaced with CONFIG_PHYSICAL_ALIGN.
Hardcoding the kernel physical start value creates a problem in relocatable
kernel context due to boot loader limitations. For ex, if somebody
compiles a relocatable kernel to be run from address 4MB, but this kernel
will run from location 1MB as grub loads the kernel at physical address
1MB. Kernel thinks that I am a relocatable kernel and I should run from
the address I have been loaded at. So somebody wanting to run kernel
from 4MB alignment location (for improved performance regions) can't do
that.
o Hence, Eric proposed that probably CONFIG_PHYSICAL_ALIGN will make
more sense in relocatable kernel context. At run time kernel will move
itself to a physical addr location which meets user specified alignment
restrictions.
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
---
arch/i386/Kconfig | 33 ++++++++++++++++++---------------
arch/i386/boot/compressed/head.S | 26 ++++++++++++++------------
arch/i386/boot/compressed/misc.c | 7 ++++---
arch/i386/kernel/vmlinux.lds.S | 3 ++-
include/asm-i386/boot.h | 6 +++++-
5 files changed, 43 insertions(+), 32 deletions(-)
diff -puN arch/i386/boot/compressed/head.S~i386-implement-config-physical-align-option arch/i386/boot/compressed/head.S
--- linux-2.6.19-rc2-git7-reloc/arch/i386/boot/compressed/head.S~i386-implement-config-physical-align-option 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/i386/boot/compressed/head.S 2006-10-23 13:15:21.000000000 -0400
@@ -26,6 +26,7 @@
#include <linux/linkage.h>
#include <asm/segment.h>
#include <asm/page.h>
+#include <asm/boot.h>
.section ".text.head"
.globl startup_32
@@ -52,17 +53,17 @@ startup_32:
1: popl %ebp
subl $1b, %ebp
-/* Compute the delta between where we were compiled to run at
- * and where the code will actually run at.
+/* %ebp contains the address we are loaded at by the boot loader and %ebx
+ * contains the address where we should move the kernel image temporarily
+ * for safe in-place decompression.
*/
- /* Start with the delta to where the kernel will run at. If we are
- * a relocatable kernel this is the delta to our load address otherwise
- * this is the delta to CONFIG_PHYSICAL start.
- */
+
#ifdef CONFIG_RELOCATABLE
- movl %ebp, %ebx
+ movl %ebp, %ebx
+ addl $(CONFIG_PHYSICAL_ALIGN - 1), %ebx
+ andl $(~(CONFIG_PHYSICAL_ALIGN - 1)), %ebx
#else
- movl $(CONFIG_PHYSICAL_START - startup_32), %ebx
+ movl $LOAD_PHYSICAL_ADDR, %ebx
#endif
/* Replace the compressed data size with the uncompressed size */
@@ -94,9 +95,10 @@ startup_32:
/* Compute the kernel start address.
*/
#ifdef CONFIG_RELOCATABLE
- leal startup_32(%ebp), %ebp
+ addl $(CONFIG_PHYSICAL_ALIGN - 1), %ebp
+ andl $(~(CONFIG_PHYSICAL_ALIGN - 1)), %ebp
#else
- movl $CONFIG_PHYSICAL_START, %ebp
+ movl $LOAD_PHYSICAL_ADDR, %ebp
#endif
/*
@@ -150,8 +152,8 @@ relocated:
* and where it was actually loaded.
*/
movl %ebp, %ebx
- subl $CONFIG_PHYSICAL_START, %ebx
-
+ subl $LOAD_PHYSICAL_ADDR, %ebx
+ jz 2f /* Nothing to be done if loaded at compiled addr. */
/*
* Process relocations.
*/
diff -puN arch/i386/boot/compressed/misc.c~i386-implement-config-physical-align-option arch/i386/boot/compressed/misc.c
--- linux-2.6.19-rc2-git7-reloc/arch/i386/boot/compressed/misc.c~i386-implement-config-physical-align-option 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/i386/boot/compressed/misc.c 2006-10-23 13:15:21.000000000 -0400
@@ -14,6 +14,7 @@
#include <linux/screen_info.h>
#include <asm/io.h>
#include <asm/page.h>
+#include <asm/boot.h>
/* WARNING!!
* This code is compiled with -fPIC and it is relocated dynamically
@@ -360,12 +361,12 @@ asmlinkage void decompress_kernel(void *
insize = input_len;
inptr = 0;
- if (((u32)output - CONFIG_PHYSICAL_START) & 0x3fffff)
- error("Destination address not 4M aligned");
+ if ((u32)output & (CONFIG_PHYSICAL_ALIGN -1))
+ error("Destination address not CONFIG_PHYSICAL_ALIGN aligned");
if (end > ((-__PAGE_OFFSET-(512 <<20)-1) & 0x7fffffff))
error("Destination address too large");
#ifndef CONFIG_RELOCATABLE
- if ((u32)output != CONFIG_PHYSICAL_START)
+ if ((u32)output != LOAD_PHYSICAL_ADDR)
error("Wrong destination address");
#endif
diff -puN arch/i386/Kconfig~i386-implement-config-physical-align-option arch/i386/Kconfig
--- linux-2.6.19-rc2-git7-reloc/arch/i386/Kconfig~i386-implement-config-physical-align-option 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/i386/Kconfig 2006-10-23 13:15:21.000000000 -0400
@@ -785,23 +785,26 @@ config RELOCATABLE
must live at a different physical address than the primary
kernel.
-config PHYSICAL_START
- hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
-
- default "0x1000000" if CRASH_DUMP
+config PHYSICAL_ALIGN
+ hex "Alignment value to which kernel should be aligned"
default "0x100000"
+ range 0x2000 0x400000
help
- This gives the physical address where the kernel is loaded. Normally
- for regular kernels this value is 0x100000 (1MB). But in the case
- of kexec on panic the fail safe kernel needs to run at a different
- address than the panic-ed kernel. This option is used to set the load
- address for kernels used to capture crash dump on being kexec'ed
- after panic. The default value for crash dump kernels is
- 0x1000000 (16MB). This can also be set based on the "X" value as
- specified in the "crashkernel=YM@XM" command line boot parameter
- passed to the panic-ed kernel. Typically this parameter is set as
- crashkernel=64M@16M. Please take a look at
- Documentation/kdump/kdump.txt for more details about crash dumps.
+ This value puts the alignment restrictions on physical address
+ where kernel is loaded and run from. Kernel is compiled for an
+ address which meets above alignment restriction.
+
+ If bootloader loads the kernel at a non-aligned address and
+ CONFIG_RELOCATABLE is set, kernel will move itself to nearest
+ address aligned to above value and run from there.
+
+ If bootloader loads the kernel at a non-aligned address and
+ CONFIG_RELOCATABLE is not set, kernel will ignore the run time
+ load address and decompress itself to the address it has been
+ compiled for and run from there. The address for which kernel is
+ compiled already meets above alignment restrictions. Hence the
+ end result is that kernel runs from a physical address meeting
+ above alignment restrictions.
Don't change this unless you know what you are doing.
diff -puN arch/i386/kernel/vmlinux.lds.S~i386-implement-config-physical-align-option arch/i386/kernel/vmlinux.lds.S
--- linux-2.6.19-rc2-git7-reloc/arch/i386/kernel/vmlinux.lds.S~i386-implement-config-physical-align-option 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/i386/kernel/vmlinux.lds.S 2006-10-23 13:15:21.000000000 -0400
@@ -8,6 +8,7 @@
#include <asm/thread_info.h>
#include <asm/page.h>
#include <asm/cache.h>
+#include <asm/boot.h>
OUTPUT_FORMAT("elf32-i386", "elf32-i386", "elf32-i386")
OUTPUT_ARCH(i386)
@@ -21,7 +22,7 @@ PHDRS {
}
SECTIONS
{
- . = LOAD_OFFSET + CONFIG_PHYSICAL_START;
+ . = LOAD_OFFSET + LOAD_PHYSICAL_ADDR;
phys_startup_32 = startup_32 - LOAD_OFFSET;
/* read-only */
.text : AT(ADDR(.text) - LOAD_OFFSET) {
diff -puN include/asm-i386/boot.h~i386-implement-config-physical-align-option include/asm-i386/boot.h
--- linux-2.6.19-rc2-git7-reloc/include/asm-i386/boot.h~i386-implement-config-physical-align-option 2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/include/asm-i386/boot.h 2006-10-23 13:15:21.000000000 -0400
@@ -12,4 +12,8 @@
#define EXTENDED_VGA 0xfffe /* 80x50 mode */
#define ASK_VGA 0xfffd /* ask for it at bootup */
-#endif
+/* Physical address where kenrel should be loaded. */
+#define LOAD_PHYSICAL_ADDR ((0x100000 + CONFIG_PHYSICAL_ALIGN - 1) \
+ & ~(CONFIG_PHYSICAL_ALIGN - 1))
+
+#endif /* _LINUX_BOOT_H */
_
^ permalink raw reply [flat|nested] 17+ messages in thread* [PATCH 11/11] i386: Extend bzImage protocol for relocatable protected mode kernel
2006-10-23 19:24 [RFC][PATCH 0/11] i386: Relocatable BzImage (V3) Vivek Goyal
` (9 preceding siblings ...)
2006-10-23 19:42 ` [PATCH 10/11] i386: Implement CONFIG_PHYSICAL_ALIGN Vivek Goyal
@ 2006-10-23 19:44 ` Vivek Goyal
2006-10-24 13:44 ` [RFC][PATCH 0/11] i386: Relocatable BzImage (V3) Andi Kleen
11 siblings, 0 replies; 17+ messages in thread
From: Vivek Goyal @ 2006-10-23 19:44 UTC (permalink / raw)
To: linux kernel mailing list
Cc: Reloc Kernel List, ebiederm, akpm, ak, hpa, magnus.damm, lwang,
dzickus, maneesh
o Extend bzImage protocol to enable bootloaders to load a completely
relocatable bzImage. Now protected mode component of kernel is also
relocatable and a boot-loader can load the protected mode component
at a differnt physical address than 1MB. (If kernel was built with
CONFIG_RELOCATABLE)
o Kexec can make use of it to load this kernel at a different physical
address to capture kernel crash dumps.
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com>
---
Documentation/i386/boot.txt | 4 ++++
arch/i386/boot/setup.S | 13 ++++++++++++-
2 files changed, 16 insertions(+), 1 deletion(-)
diff -puN arch/i386/boot/setup.S~extend-bzImage-protocol-for-relocatable-protected-mode-kernel arch/i386/boot/setup.S
--- linux-2.6.19-rc2-git7-reloc/arch/i386/boot/setup.S~extend-bzImage-protocol-for-relocatable-protected-mode-kernel 2006-10-23 15:09:28.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/i386/boot/setup.S 2006-10-23 15:09:28.000000000 -0400
@@ -81,7 +81,7 @@ start:
# This is the setup header, and it must start at %cs:2 (old 0x9020:2)
.ascii "HdrS" # header signature
- .word 0x0204 # header version number (>= 0x0105)
+ .word 0x0205 # header version number (>= 0x0105)
# or else old loadlin-1.5 will fail)
realmode_swtch: .word 0, 0 # default_switch, SETUPSEG
start_sys_seg: .word SYSSEG
@@ -160,6 +160,17 @@ ramdisk_max: .long (-__PAGE_OFFSET-(512
# The highest safe address for
# the contents of an initrd
+kernel_alignment: .long CONFIG_PHYSICAL_ALIGN #physical addr alignment
+ #required for protected mode
+ #kernel
+#ifdef CONFIG_RELOCATABLE
+relocatable_kernel: .byte 1
+#else
+relocatable_kernel: .byte 0
+#endif
+pad2: .byte 0
+pad3: .word 0
+
trampoline: call start_of_setup
.align 16
# The offset at this point is 0x240
diff -puN Documentation/i386/boot.txt~extend-bzImage-protocol-for-relocatable-protected-mode-kernel Documentation/i386/boot.txt
--- linux-2.6.19-rc2-git7-reloc/Documentation/i386/boot.txt~extend-bzImage-protocol-for-relocatable-protected-mode-kernel 2006-10-23 15:09:28.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/Documentation/i386/boot.txt 2006-10-23 15:09:28.000000000 -0400
@@ -35,6 +35,8 @@ Protocol 2.03: (Kernel 2.4.18-pre1) Expl
initrd address available to the bootloader.
Protocol 2.04: (Kernel 2.6.14) Extend the syssize field to four bytes.
+Protocol 2.05: (Kernel 2.6.20) Make protected mode kernel relocatable.
+ Introduce relocatable_kernel and kernel_alignment fields.
**** MEMORY LAYOUT
@@ -129,6 +131,8 @@ Offset Proto Name Meaning
0226/2 N/A pad1 Unused
0228/4 2.02+ cmd_line_ptr 32-bit pointer to the kernel command line
022C/4 2.03+ initrd_addr_max Highest legal initrd address
+0230/4 2.04+ kernel_alignment Physical addr alignment required for kernel
+0234/1 2.04+ relocatable_kernel Whether kernel is relocatable or not
(1) For backwards compatibility, if the setup_sects field contains 0, the
real value is 4.
_
^ permalink raw reply [flat|nested] 17+ messages in thread* Re: [RFC][PATCH 0/11] i386: Relocatable BzImage (V3)
2006-10-23 19:24 [RFC][PATCH 0/11] i386: Relocatable BzImage (V3) Vivek Goyal
` (10 preceding siblings ...)
2006-10-23 19:44 ` [PATCH 11/11] i386: Extend bzImage protocol for relocatable protected mode kernel Vivek Goyal
@ 2006-10-24 13:44 ` Andi Kleen
11 siblings, 0 replies; 17+ messages in thread
From: Andi Kleen @ 2006-10-24 13:44 UTC (permalink / raw)
To: vgoyal
Cc: linux kernel mailing list, Reloc Kernel List, ebiederm, akpm, hpa,
magnus.damm, lwang, dzickus, maneesh
On Monday 23 October 2006 12:24, Vivek Goyal wrote:
> Hi,
>
> Here is the third attempt on implementing relocatable bzImage for i386.
> Eric has done all the ground work and I am just giving it final finish.
> Generated patches against (2.6.19-rc2-git7).
I merged them now. Didn't see anything that i didn't like, but I admit
i haven't read everything closely
-Andi
^ permalink raw reply [flat|nested] 17+ messages in thread