diff options
| author | Soby Mathew <soby.mathew@arm.com> | 2018-10-14 08:09:22 +0100 |
|---|---|---|
| committer | Soby Mathew <soby.mathew@arm.com> | 2018-10-29 09:54:32 +0000 |
| commit | 931f7c615643e5d0fb2cbab68e4093c980b0e271 (patch) | |
| tree | e201012199720fab40e33150fbcb61a0a22e60df /bl31/bl31.ld.S | |
| parent | 12af5ed4fb146d575463bd304027da5a0e6b4a68 (diff) | |
PIE: Position Independant Executable support for BL31
This patch introduces Position Independant Executable(PIE) support
in TF-A. As a initial prototype, only BL31 can support PIE. A trivial
dynamic linker is implemented which supports fixing up Global Offset
Table(GOT) and Dynamic relocations(.rela.dyn). The fixup_gdt_reloc()
helper function implements this linker and this needs to be called
early in the boot sequence prior to invoking C functions. The GOT is
placed in the RO section of BL31 binary for improved security and the
BL31 linker script is modified to export the appropriate symbols
required for the dynamic linker.
The C compiler always generates PC relative addresses to linker symbols
and hence referencing symbols exporting constants are a problem when
relocating the binary. Hence the reference to the
`__PERCPU_TIMESTAMP_SIZE__` symbol in PMF is removed and is now calculated
at runtime based on start and end addresses.
Change-Id: I1228583ff92cf432963b7cef052e95d995cca93d
Signed-off-by: Soby Mathew <soby.mathew@arm.com>
Diffstat (limited to 'bl31/bl31.ld.S')
| -rw-r--r-- | bl31/bl31.ld.S | 28 |
1 files changed, 22 insertions, 6 deletions
diff --git a/bl31/bl31.ld.S b/bl31/bl31.ld.S index 81e7ba3a..43d0ed44 100644 --- a/bl31/bl31.ld.S +++ b/bl31/bl31.ld.S @@ -26,6 +26,8 @@ SECTIONS ASSERT(. == ALIGN(PAGE_SIZE), "BL31_BASE address is not aligned on a page boundary.") + __BL31_START__ = .; + #if SEPARATE_CODE_AND_RODATA .text . : { __TEXT_START__ = .; @@ -63,6 +65,16 @@ SECTIONS KEEP(*(cpu_ops)) __CPU_OPS_END__ = .; + /* + * Keep the .got section in the RO section as the it is patched + * prior to enabling the MMU and having the .got in RO is better for + * security. + */ + . = ALIGN(16); + __GOT_START__ = .; + *(.got) + __GOT_END__ = .; + /* Place pubsub sections for events */ . = ALIGN(8); #include <pubsub_events.h> @@ -153,6 +165,16 @@ SECTIONS __DATA_END__ = .; } >RAM + . = ALIGN(16); + /* + * .rela.dyn needs to come after .data for the read-elf utility to parse + * this section correctly. + */ + __RELA_START__ = .; + .rela.dyn . : { + } >RAM + __RELA_END__ = .; + #ifdef BL31_PROGBITS_LIMIT ASSERT(. <= BL31_PROGBITS_LIMIT, "BL31 progbits has exceeded its limit.") #endif @@ -265,11 +287,5 @@ SECTIONS __RW_END__ = .; __BL31_END__ = .; - __BSS_SIZE__ = SIZEOF(.bss); -#if USE_COHERENT_MEM - __COHERENT_RAM_UNALIGNED_SIZE__ = - __COHERENT_RAM_END_UNALIGNED__ - __COHERENT_RAM_START__; -#endif - ASSERT(. <= BL31_LIMIT, "BL31 image has exceeded its limit.") } |