Commit Graph

9 Commits

Author SHA1 Message Date
Fangrui Song 00809c8889 [ELF] Apply version script patterns to non-default version symbols
Currently version script patterns are ignored for .symver produced
non-default version (single @) symbols. This makes such symbols
not localizable by `local:`, e.g.

```
.symver foo3_v1,foo3@v1
.globl foo_v1
foo3_v1:

ld.lld --version-script=a.ver -shared a.o
```

This patch adds the support:

* Move `config->versionDefinitions[VER_NDX_LOCAL].patterns` to `config->versionDefinitions[versionId].localPatterns`
* Rename `config->versionDefinitions[versionId].patterns` to `config->versionDefinitions[versionId].nonLocalPatterns`
* Allow `findAllByVersion` to find non-default version symbols when `includeNonDefault` is true. (Note: `symtab` keys do not have `@@`)
* Make each pattern check both the unversioned `pat.name` and the versioned `${pat.name}@${v.name}`
* `localPatterns` can localize `${pat.name}@${v.name}`. `nonLocalPatterns` can prevent localization by assigning `verdefIndex` (before `parseSymbolVersion`).

---

If a user notices new `undefined symbol` errors with a version script containing
`local: *;`, the issue is likely due to a missing `global:` pattern.

Reviewed By: peter.smith

Differential Revision: https://reviews.llvm.org/D107234
2021-08-04 23:52:56 -07:00
Fangrui Song a533eb7423 Revert "[ELF] Apply version script patterns to non-default version symbols"
This reverts commit 7ed22a6fa9.

buf is not cleared so the commit misses some cases.
2021-08-04 23:52:55 -07:00
Fangrui Song 66d4430492 [ELF] Combine foo@v1 and foo with the same versionId if both are defined
Due to an assembler design flaw (IMO), `.symver foo,foo@v1` produces two symbols `foo` and `foo@v1` if `foo` is defined.

* `v1 {};` produces both `foo` and `foo@v1`, but GNU ld only produces `foo@v1`
* `v1 { foo; };` produces both `foo@@v1` and `foo@v1`, but GNU ld only produces `foo@v1`
* `v2 { foo; };` produces both `foo@@v2` and `foo@v1`, matching GNU ld. (Tested by symver.s)

This patch implements the GNU ld behavior by reusing the symbol redirection mechanism
in D92259. The new test symver-non-default.s checks the first two cases.

Without the patch, the second case will produce `foo@v1` and `foo@@v1` which
looks weird and makes foo unnecessarily default versioned.

Note: `.symver foo,foo@v1,remove` exists but the unfortunate `foo` will not go
away anytime soon.

Reviewed By: peter.smith

Differential Revision: https://reviews.llvm.org/D107235
2021-08-04 09:06:05 -07:00
Fangrui Song 7ed22a6fa9 [ELF] Apply version script patterns to non-default version symbols
Currently version script patterns are ignored for .symver produced
non-default version (single @) symbols. This makes such symbols
not localizable by `local:`, e.g.

```
.symver foo3_v1,foo3@v1
.globl foo_v1
foo3_v1:

ld.lld --version-script=a.ver -shared a.o
# In a.out, foo3@v1 is incorrectly exported.
```

This patch adds the support:

* Move `config->versionDefinitions[VER_NDX_LOCAL].patterns` to `config->versionDefinitions[versionId].localPatterns`
* Rename `config->versionDefinitions[versionId].patterns` to `config->versionDefinitions[versionId].nonLocalPatterns`
* Allow `findAllByVersion` to find non-default version symbols when `includeNonDefault` is true. (Note: `symtab` keys do not have `@@`)
* Make each pattern check both the unversioned `pat.name` and the versioned `${pat.name}@${v.name}`
* `localPatterns` can localize `${pat.name}@${v.name}`. `nonLocalPatterns` can prevent localization by assigning `verdefIndex` (before `parseSymbolVersion`).

---

If a user notices new `undefined symbol` errors with a version script containing
`local: *;`, the issue is likely due to a missing `global:` pattern.

Reviewed By: peter.smith

Differential Revision: https://reviews.llvm.org/D107234
2021-08-04 09:02:11 -07:00
Fangrui Song 52f35c9f14 [ELF][test] Improve .symver & --version-script tests
And delete redundant tests.
2021-07-31 18:57:19 -07:00
Fangrui Song 40a9f2251b [ELF] Replace unused output filenames with /dev/null in tests
Post commit review at rLLD335992

llvm-svn: 336129
2018-07-02 17:48:23 +00:00
George Rimar 4d2f976208 [ELF] - Resolve references properly when using .symver directive
This is PR28414. 
Previously LLD was unable to link following:
(failed with undefined symbol bar)

Version script:
SOME_VERSION { global: *; };

.global _start
.global bar
.symver _start, bar@@SOME_VERSION
_start:
  jmp bar
Manual has next description:

.symver name, name2@@nodename
In this case, the symbol name must exist and be defined within the file being assembled. It is similar to name2@nodename. 
The difference is name2@@nodename will also be used to resolve references to name2 by the linker
https://sourceware.org/binutils/docs/as/Symver.html

Patch implements that. If we have name@@ver symbol and name is undefined, name@@ver is used to resolve references to name.
If name is defined then multiple definition error is emited, that is consistent with what bfd do.

Differential revision: https://reviews.llvm.org/D33680

llvm-svn: 307077
2017-07-04 13:19:13 +00:00
Rui Ueyama 80cbc776cb Revert r306813: "[ELF] - Resolve references properly when using .symver directive"
This reverts commit r306813 because it broke linking of the
FreeBSD base system.

llvm-svn: 306996
2017-07-03 03:26:07 +00:00
George Rimar aad84e2ee2 [ELF] - Resolve references properly when using .symver directive
This is PR28414. 
Previously LLD was unable to link following:
(failed with undefined symbol bar)

```
Version script:
SOME_VERSION { global: *; };

.global _start
.global bar
.symver _start, bar@@SOME_VERSION
_start:
  jmp bar
```

Manual has next description:
//
.symver name, name2@@nodename
In this case, the symbol name must exist and be defined within the file being assembled. It is similar to name2@nodename. 
**The difference is name2@@nodename will also be used to resolve references to name2 by the linker**
https://sourceware.org/binutils/docs/as/Symver.html
//

Patch implements that. If we have name@@ver symbol and name is undefined, 
name@@ver is used to resolve references to name.

Differential revision: https://reviews.llvm.org/D33680

llvm-svn: 306813
2017-06-30 10:19:54 +00:00