| commit | c4fea3905617af89d1ad87319893e250f5b72dd6 | [log] [tgz] |
|---|---|---|
| author | Amilendra Kodithuwakku <Amilendra.Kodithuwakku@arm.com> | Wed Jun 21 12:48:33 2023 +0100 |
| committer | Amilendra Kodithuwakku <Amilendra.Kodithuwakku@arm.com> | Wed Jun 21 14:47:34 2023 +0100 |
| tree | 323c82e60a01a8bcb0ad8ffa4eaafeb8b688534e | |
| parent | afc5cca0d4016f09f0d7e2683d5a920c7ecf9397 [diff] |
[LLD][ELF] Cortex-M Security Extensions (CMSE) Support
This commit provides linker support for Cortex-M Security Extensions (CMSE).
The specification for this feature can be found in ARM v8-M Security Extensions:
Requirements on Development Tools.
The linker synthesizes a security gateway veneer in a special section;
`.gnu.sgstubs`, when it finds non-local symbols `__acle_se_<entry>` and `<entry>`,
defined relative to the same text section and having the same address. The
address of `<entry>` is retargeted to the starting address of the
linker-synthesized security gateway veneer in section `.gnu.sgstubs`.
In summary, the linker translates input:
```
.text
entry:
__acle_se_entry:
[entry_code]
```
into:
```
.section .gnu.sgstubs
entry:
SG
B.W __acle_se_entry
.text
__acle_se_entry:
[entry_code]
```
If addresses of `__acle_se_<entry>` and `<entry>` are not equal, the linker
considers that `<entry>` already defines a secure gateway veneer so does not
synthesize one.
If `--out-implib=<out.lib>` is specified, the linker writes the list of secure
gateway veneers into a CMSE import library `<out.lib>`. The CMSE import library
will have 3 sections: `.symtab`, `.strtab`, `.shstrtab`. For every secure gateway
veneer <entry> at address `<addr>`, `.symtab` contains a `SHN_ABS` symbol `<entry>` with
value `<addr>`.
If `--in-implib=<in.lib>` is specified, the linker reads the existing CMSE import
library `<in.lib>` and preserves the entry function addresses in the resulting
executable and new import library.
Reviewed By: MaskRay, peter.smith
Differential Revision: https://reviews.llvm.org/D139092
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