| Summary: | ld lma assignment change breaks x86-64 Linux 2.6 kernel | ||
|---|---|---|---|
| Product: | binutils | Reporter: | H.J. Lu <hjl.tools> |
| Component: | ld | Assignee: | Alan Modra <amodra> |
| Status: | RESOLVED FIXED | ||
| Severity: | normal | CC: | amodra, bug-binutils |
| Priority: | P2 | ||
| Version: | 2.18 | ||
| Target Milestone: | --- | ||
| Host: | Target: | ||
| Build: | Last reconfirmed: | 2006-08-16 07:58:44 | |
| Attachments: | A testcase | ||
|
Description
H.J. Lu
2006-08-14 22:49:36 UTC
The linker script in question:
.vsyscall_0 -10*1024*1024: AT ((LOADADDR(.data.cacheline_aligned) +
SIZEOF(.data.cacheline_aligned) + 4095) & ~(4095)) { *(.vsyscall_0) }
__vsyscall_0 = LOADADDR(.vsyscall_0);
. = ALIGN(64);
.xtime_lock : AT ((LOADADDR(.vsyscall_0) + SIZEOF(.vsyscall_0) + 63) & ~(63))
{ *(.xtime_lock) }
xtime_lock = LOADADDR(.xtime_lock);
. = ALIGN(16);
.vxtime : AT ((LOADADDR(.xtime_lock) + SIZEOF(.xtime_lock) + 15) & ~(15)) {
*(.vxtime) }
vxtime = LOADADDR(.vxtime);
. = ALIGN(16);
.wall_jiffies : AT ((LOADADDR(.vxtime) + SIZEOF(.vxtime) + 15) & ~(15)) {
*(.wall_jiffies) }
wall_jiffies = LOADADDR(.wall_jiffies);
. = ALIGN(16);
.sys_tz : AT ((LOADADDR(.wall_jiffies) + SIZEOF(.wall_jiffies) + 15) & ~(15))
{ *(.sys_tz) }
sys_tz = LOADADDR(.sys_tz);
. = ALIGN(16);
.sysctl_vsyscall : AT ((LOADADDR(.sys_tz) + SIZEOF(.sys_tz) + 15) & ~(15)) {
*(.sysctl_vsyscall) }
sysctl_vsyscall = LOADADDR(.sysctl_vsyscall);
. = ALIGN(16);
.jiffies : AT ((LOADADDR(.sysctl_vsyscall) + SIZEOF(.sysctl_vsyscall) + 15) &
~(15)) { *(.jiffies) }
jiffies = LOADADDR(.jiffies);
. = ALIGN(16);
.xtime : AT ((LOADADDR(.jiffies) + SIZEOF(.jiffies) + 15) & ~(15)) { *(.xtime) }
xtime = LOADADDR(.xtime);
.vsyscall_1 ADDR(.vsyscall_0) + 1024: AT (LOADADDR(.vsyscall_0) + 1024) {
*(.vsyscall_1) }
. = LOADADDR(.vsyscall_0) + 4096;
. = ALIGN(8192); /* init_task */
.data.init_task : { *(.data.init_task) }
The resulting sections should be
[14] .data.cacheline_a PROGBITS ffffffff804dd500 4dd500 009600 00 WA
0 0 128
[15] .vsyscall_0 PROGBITS ffffffffff600000 600000 000103 00 AX
0 0 1
[16] .xtime_lock PROGBITS ffffffffff600140 600140 00000c 00 WA
0 0 64
[17] .vxtime PROGBITS ffffffffff600150 600150 000038 00 WA
0 0 16
[18] .wall_jiffies PROGBITS ffffffffff600190 600190 000008 00 WA
0 0 16
[19] .sys_tz PROGBITS ffffffffff6001a0 6001a0 000008 00 WA
0 0 16
[20] .sysctl_vsyscall PROGBITS ffffffffff6001b0 6001b0 000004 00 WA
0 0 16
[21] .jiffies PROGBITS ffffffffff6001c0 6001c0 000008 00 WA
0 0 16
[22] .xtime PROGBITS ffffffffff6001d0 6001d0 000010 00 WA
0 0 16
[23] .vsyscall_1 PROGBITS ffffffffff600400 600400 000028 00 AX
0 0 1
[24] .data.init_task PROGBITS ffffffff804e8000 6e8000 003000 00 WA
0 0 32
This change:
last = r->last_os->output_section_statement.bfd_section;
/* If the current vma overlaps the previous section,
then set the current lma to that at the end of
the previous section. The previous section was
probably an overlay. */
if ((dot >= last->vma
&& dot < last->vma + last->size)
|| (last->vma >= dot
&& last->vma < dot + os->bfd_section->size))
lma = last->lma + last->size;
/* Otherwise, keep the same lma to vma relationship
as the previous section. */
else
lma = dot + last->lma - last->vma;
if (os->section_alignment != -1)
lma = align_power (lma, os->section_alignment);
os->bfd_section->lma = lma;
mishandles it.
This change
--- ldlang.c.foo 2006-08-15 14:53:05.000000000 -0700
+++ ldlang.c 2006-08-15 14:44:19.000000000 -0700
@@ -4742,11 +4742,14 @@ lang_do_assignments_1 (lang_statement_un
|| (last->vma >= dot
&& last->vma < dot + os->bfd_section->size))
lma = last->lma + last->size;
-
+ else
+ lma = dot;
+#if 0
/* Otherwise, keep the same lma to vma relationship
as the previous section. */
else
lma = dot + last->lma - last->vma;
+#endif
if (os->section_alignment != -1)
lma = align_power (lma, os->section_alignment);
seems to generate a working kernel.
The lma values set by lang_do_assignments_1 are used for _bfd_elf_map_sections_to_segments and those lma values later are overridden by lang_size_sections_1 with a different logic. The values set up by lang_do_assignments_1 may incorrect. Created attachment 1226 [details]
A testcase
Here is a testcase. old.sec has the dump from the correct output:
[hjl@gnu-16 lma]$ make LD=ld
as -o foo.o foo.s
ld -o foo -T foo.t foo.o
readelf -S -l --wide foo > foo.sec
diff -up foo.sec old.sec
--- foo.sec 2006-08-15 18:07:37.000000000 -0700
+++ old.sec 2006-08-15 18:04:38.000000000 -0700
@@ -1,15 +1,15 @@
-There are 8 section headers, starting at offset 0x400058:
+There are 8 section headers, starting at offset 0x302058:
Section Headers:
[Nr] Name Type Address Off Size ES Flg
Lk Inf Al
[ 0] NULL 0000000000000000 000000 000000 00
0 0 0
- [ 1] .text PROGBITS ffffffff80100000 300000 000001 00 AX
0 0 4
- [ 2] .data.cacheline_a PROGBITS ffffffff80100040 300040 000001 00 WA
0 0 1
- [ 3] .vsyscall_0 PROGBITS ffffffffff600000 400000 000001 00 AX
0 0 1
- [ 4] .data.init_task PROGBITS ffffffff80102000 102000 000001 00 WA
0 0 1
- [ 5] .shstrtab STRTAB 0000000000000000 400001 000055 00
0 0 1
- [ 6] .symtab SYMTAB 0000000000000000 400258 000078 18
7 5 8
- [ 7] .strtab STRTAB 0000000000000000 4002d0 000001 00
0 0 1
+ [ 1] .text PROGBITS ffffffff80100000 100000 000001 00 AX
0 0 4
+ [ 2] .data.cacheline_a PROGBITS ffffffff80100040 100040 000001 00 WA
0 0 1
+ [ 3] .vsyscall_0 PROGBITS ffffffffff600000 200000 000001 00 AX
0 0 1
+ [ 4] .data.init_task PROGBITS ffffffff80102000 302000 000001 00 WA
0 0 1
+ [ 5] .shstrtab STRTAB 0000000000000000 302001 000055 00
0 0 1
+ [ 6] .symtab SYMTAB 0000000000000000 302258 000078 18
7 5 8
+ [ 7] .strtab STRTAB 0000000000000000 3022d0 000001 00
0 0 1
Key to Flags:
W (write), A (alloc), X (execute), M (merge), S (strings)
I (info), L (link order), G (group), x (unknown)
@@ -21,12 +21,12 @@ There are 3 program headers, starting at
Program Headers:
Type Offset VirtAddr PhysAddr FileSiz
MemSiz Flg Align
- LOAD 0x000000 0xffffffff80000000 0xffffffff00b01000 0x102001
0x102001 RW 0x200000
- LOAD 0x300000 0xffffffff80100000 0xffffffff80100000 0x000041
0x000041 RWE 0x200000
- LOAD 0x400000 0xffffffffff600000 0xffffffff80101000 0x000001
0x000001 R E 0x200000
+ LOAD 0x000000 0xffffffff80000000 0xffffffff80000000 0x100041
0x100041 RWE 0x200000
+ LOAD 0x200000 0xffffffffff600000 0xffffffff80101000 0x000001
0x000001 R E 0x200000
+ LOAD 0x302000 0xffffffff80102000 0xffffffff80102000 0x000001
0x000001 RW 0x200000
Section to Segment mapping:
Segment Sections...
- 00 .text .data.cacheline_aligned .data.init_task
- 01 .text .data.cacheline_aligned
- 02 .vsyscall_0
+ 00 .text .data.cacheline_aligned
+ 01 .vsyscall_0
+ 02 .data.init_task
make: *** [all] Error 1
[hjl@gnu-16 lma]$
According to the ld docs, this testcase script (and the x86_64 kernel script) is invalid because dot is moved backwards. Nevertheless, I'll see if I can make ld do something reasonable. Fixed |