This requires making the .dynamic section writable, as the
dynamic linker will change the value of the DT_DEBUG tag at
runtime. The DT_DEBUG tag is used by gdb to find all loaded
shared libraries.
R=rsc
CC=golang-dev
https://golang.org/cl/5189044
src/cmd/5c/reg.c:
. Added USED() attribute.
src/cmd/6c/cgen.c:
. Revised code around "REGARG" to resemble use in "8c" and
consequently remove a warning.
src/cmd/6l/asm.c:
. Added USED() attributes.
. Removed an unnecessary assignment.
R=golang-dev
CC=golang-dev, rsc
https://golang.org/cl/4836045
The dynamic ELF sections were pointing to the proper data,
but that data was already owned by the rodata and text sections.
Some ELF references explicitly prohibit multiple sections from
owning the same data, and strip behaves accordingly.
The data for these sections was moved out and their ranges are
now owned by their respective sections. This change makes strip
happy both with and without -s being provided at link time.
A test was added in debug/elf to ensure there are no regressions
on this area in the future.
Fixes#1242.
Fixes#2022.
NOTE: Tested on Linux amd64/386/arm only.
R=rsc
CC=golang-dev
https://golang.org/cl/4808043
Reduces number of write+seek's from 88516 to 2080
when linking godoc with 6l.
Thanks to Alex Brainman for pointing out the
many small writes.
R=golang-dev, r, alex.brainman, robert.hencke
CC=golang-dev
https://golang.org/cl/4743043
Per the TIS ELF spec, if a PHDR entry is present in the
program header table, it must be part of the memory image of
the program. Failure to do this makes elflint complain, and
causes some tools that manipulate ELF to crash.
R=iant, rsc
CC=dave, golang-dev
https://golang.org/cl/4650067
The gosymtab and gopclntab sections were pointing to the proper
data, but that data was already owned by the rodata section.
Some ELF references explicitly prohibit multiple sections from
owning the same data, and strip behaves accordingly.
The data for these sections was moved to after rodata, and the
gosymtab and gopclntab sections now own their respective ranges.
This change makes strip happy both with and without -s being
provided at link time. Note that it won't remove these sections
because they are still allocated, and that's by design since
they are necessary at runtime for generating proper backtraces
and similar introspection operations.
Unlike the previous behavior, -s will now maintain zero-sized
gosymtab and gopclntab sections. This makes the implementation
slightly cleaner.
Fixes#1242.
NOTE: Tested on Linux amd64/386/arm only.
R=ality, rsc
CC=golang-dev
https://golang.org/cl/4639077
I started looking at this code because the nm in GNU
binutils was ignoring the first symbol in the .symtab
section. Apparently, the System V ABI reserves the
first entry and requires all fields inside to be set
to zero.
The list of changes is as follows:
· reserve the first symbol entry (as noted above)
· fix the section indices for .data and .bss symbols
· factor out common code for Elf32 and Elf64
· remove the special case for elfsymo in [568]l/asm.c:/^asmb
· add the "etext" symbol in 6l
· add static symbols
R=rsc
CC=golang-dev
https://golang.org/cl/4524075
Reenable dwarf output on Mac.
Was writing headers but no actual dwarf data.
Fixes#1877 (accidentally).
Workaround for issue 1878.
R=lvd
CC=golang-dev
https://golang.org/cl/4515139
The ld time was dominated by symbol table processing, so
* increase hash table size
* emit fewer symbols in gc (just 1 per string, 1 per type)
* add read-only lookup to avoid creating spurious symbols
* add linked list to speed whole-table traversals
Breaks dwarf generator (no idea why), so disable dwarf.
Reduces time for 6l to link godoc by 25%.
R=ken2
CC=golang-dev
https://golang.org/cl/4383047
Much of the bulk of Go binaries is the symbol tables,
which give a name to every C string, Go string,
and reflection type symbol. These names are not worth
much other than seeing what's where in a binary.
This CL deletes all those names from the symbol table,
instead aggregating the symbols into contiguous blocks
and giving them the names "string.*", "go.string.*", and "type.*".
Before:
$ 6nm $(which godoc.old) | sort | grep ' string\.' | tail -10
59eda4 D string."aa87ca22be8b05378eb1c71...
59ee08 D string."b3312fa7e23ee7e4988e056...
59ee6c D string."func(*token.FileSet, st...
59eed0 D string."func(io.Writer, []uint8...
59ef34 D string."func(*tls.Config, *tls....
59ef98 D string."func(*bool, **template....
59effc D string."method(p *printer.print...
59f060 D string."method(S *scanner.Scann...
59f12c D string."func(*struct { begin in...
59f194 D string."method(ka *tls.ecdheRSA...
$
After:
$ 6nm $(which godoc) | sort | grep ' string\.' | tail -10
5e6a30 D string.*
$
Those names in the "Before" are truncated for the CL.
In the real binary they are the complete string, up to
a certain length, or else a unique identifier.
The same applies to the type and go.string symbols.
Removing the names cuts godoc by more than half:
-rwxr-xr-x 1 rsc rsc 9153405 2011-03-07 23:19 godoc.old
-rwxr-xr-x 1 rsc rsc 4290071 2011-03-07 23:19 godoc
For what it's worth, only 80% of what's left gets loaded
into memory; the other 20% is dwarf debugging information
only ever accessed by gdb:
-rwxr-xr-x 1 rsc rsc 3397787 2011-03-07 23:19 godoc.nodwarf
R=r, cw
CC=golang-dev
https://golang.org/cl/4245072
A reference to the address of weak.foo resolves at link time
to the address of the symbol foo if foo would end up in the
binary anyway, or to zero if foo would not be in the binary.
For example:
int xxx = 1;
int yyy = 2;
int weak·xxx;
int weak·yyy;
void main·main(void) {
runtime·printf("%p %p %p\n", &xxx, &weak·xxx, &weak·yyy);
}
prints the same non-nil address twice, then 0 (because yyy is not
referenced so it was dropped from the binary).
This will be used by the reflection tables.
R=iant
CC=golang-dev
https://golang.org/cl/4223044
Fix problems found.
On amd64, various library routines had bigger
stack frames than expected, because large function
calls had been added.
runtime.assertI2T: nosplit stack overflow
120 assumed on entry to runtime.assertI2T
8 after runtime.assertI2T uses 112
0 on entry to runtime.newTypeAssertionError
-8 on entry to runtime.morestack01
runtime.assertE2E: nosplit stack overflow
120 assumed on entry to runtime.assertE2E
16 after runtime.assertE2E uses 104
8 on entry to runtime.panic
0 on entry to runtime.morestack16
-8 after runtime.morestack16 uses 8
runtime.assertE2T: nosplit stack overflow
120 assumed on entry to runtime.assertE2T
16 after runtime.assertE2T uses 104
8 on entry to runtime.panic
0 on entry to runtime.morestack16
-8 after runtime.morestack16 uses 8
runtime.newselect: nosplit stack overflow
120 assumed on entry to runtime.newselect
56 after runtime.newselect uses 64
48 on entry to runtime.printf
8 after runtime.printf uses 40
0 on entry to vprintf
-8 on entry to runtime.morestack16
runtime.selectdefault: nosplit stack overflow
120 assumed on entry to runtime.selectdefault
56 after runtime.selectdefault uses 64
48 on entry to runtime.printf
8 after runtime.printf uses 40
0 on entry to vprintf
-8 on entry to runtime.morestack16
runtime.selectgo: nosplit stack overflow
120 assumed on entry to runtime.selectgo
0 after runtime.selectgo uses 120
-8 on entry to runtime.gosched
On arm, 5c was tagging functions NOSPLIT that should
not have been, like the recursive function printpanics:
printpanics: nosplit stack overflow
124 assumed on entry to printpanics
112 after printpanics uses 12
108 on entry to printpanics
96 after printpanics uses 12
92 on entry to printpanics
80 after printpanics uses 12
76 on entry to printpanics
64 after printpanics uses 12
60 on entry to printpanics
48 after printpanics uses 12
44 on entry to printpanics
32 after printpanics uses 12
28 on entry to printpanics
16 after printpanics uses 12
12 on entry to printpanics
0 after printpanics uses 12
-4 on entry to printpanics
R=r, r2
CC=golang-dev
https://golang.org/cl/4188061
The linker avoids a GOT indirection by turning a MOV into
a LEA, but with x86-64 GCC has started emitting CMOV*
instructions which break the existing logic.
This will generate errors such as:
unexpected GOT reloc for non-dynamic symbol luaO_nilobject_
The CMOV* instructions may be emitted with normal code like:
if (o >= L->top) return cast(TValue *, luaO_nilobject);
else return o;
Which gets compiled into (relocation offset at 1b):
13: 48 3b 47 10 cmp 0x10(%rdi),%rax
17: 48 0f 43 05 00 00 00 cmovae 0x0(%rip),%rax
1e: 00
This change will allow the indirection through the GOT to
avoid the problem in those cases.
R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/4071044
* Avoid confusion between imported and exported symbols.
* Record number of imported and exported symbols correctly.
* Explictly relocate SMACHOSYM section, since it is not in datap.
R=rsc
CC=golang-dev
https://golang.org/cl/3920042
#pragma dynexport is no longer needed for
this use of cgo, since the gcc and gc code are
now linked together into the same binary.
It may still be necessary later.
On the Mac, you cannot use the GOT to resolve
symbols that exist in the current binary, so 6l and 8l
translate the GOT-loading mov instructions into lea
instructions.
On ELF systems, we could use the GOT for those
symbols, but for consistency 6l and 8l apply the
same translation.
The translation is sketchy in the extreme
(depending on the relocation being in a mov
instruction) but it verifies that the instruction
is a mov before rewriting it to lea.
Also makes typedefs global across files.
Fixes#1335.
Fixes#1345.
R=iant, r
CC=golang-dev
https://golang.org/cl/3650042
The recent linker changes broke NaCl support
a month ago, and there are no known users of it.
The NaCl code can always be recovered from the
repository history.
R=adg, r
CC=golang-dev
https://golang.org/cl/3671042
