diff options
| author | James Cowgill <james.cowgill@mips.com> | 2018-03-02 08:33:02 -0800 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2019-01-02 03:08:04 +0000 |
| commit | 59f3f33338f371b3a30163406fbb5fe323503939 (patch) | |
| tree | 96ac1bce6b71f5119c40a8398928669e04beea10 | |
| parent | 048bfb0df170d4a43142adcee8a2dffdfc2c1e9f (diff) | |
| download | klibc-59f3f33338f371b3a30163406fbb5fe323503939.tar.gz | |
[klibc] mips/mips64: simplify crt0 code
Various simplifications and adjustments to the MIPS crt0 files:
- Use NESTED(__start, 0, ra) - this has no effect on the code, but is
arguably more correct since we have no real stack frame.
- Don't allocate extra stack space. We need none on 64-bit, and only 16
bytes on 32-bit.
- Align the stack pointer in the (unlikely) event it is misaligned.
- Don't load the gp register - it is useless in non-PIC code.
- Use jal in 64-bit code.
- Crash if __libc_start returns (teq should causes a trap exception).
Signed-off-by: James Cowgill <james.cowgill@mips.com>
Link: https://www.zytor.com/pipermail/klibc/2018-March/003982.html
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
| -rw-r--r-- | usr/klibc/arch/mips/crt0.S | 13 | ||||
| -rw-r--r-- | usr/klibc/arch/mips64/crt0.S | 20 |
2 files changed, 10 insertions, 23 deletions
diff --git a/usr/klibc/arch/mips/crt0.S b/usr/klibc/arch/mips/crt0.S index 142d9f268c3e2..47d7d8fd2bb76 100644 --- a/usr/klibc/arch/mips/crt0.S +++ b/usr/klibc/arch/mips/crt0.S @@ -10,16 +10,13 @@ #include <machine/asm.h> -NESTED(__start, 32, sp) - subu sp, 32 - sw zero, 16(sp) - - lui gp, %hi(_gp) # Initialize gp - addiu gp, gp, _gp - - addiu a0, sp, 32 # Pointer to ELF entry structure +NESTED(__start, 0, ra) + move a0, sp # Pointer to ELF entry structure move a1, v0 # Kernel-provided atexit() pointer + and sp, -8 # Align stack to 8 bytes + subu sp, 16 # Allocate 16 bytes for function call jal __libc_init + teq zero, zero # Crash if we return END(__start) diff --git a/usr/klibc/arch/mips64/crt0.S b/usr/klibc/arch/mips64/crt0.S index 775a919292787..3f1c2a9ade73c 100644 --- a/usr/klibc/arch/mips64/crt0.S +++ b/usr/klibc/arch/mips64/crt0.S @@ -10,22 +10,12 @@ #include <machine/asm.h> -NESTED(__start, 64, sp) - daddiu sp,sp,-64 - sd zero, 32(sp) - - # Initialize gp - lui gp,%highest(_gp) # load highest "halfword" - daddiu gp,gp,%higher(_gp) # merge next "halfword" - dsll gp,gp,16 # shift by one halfword - daddiu gp,gp,%hi(_gp) # merge next "halfword" - dsll gp,gp,16 # shift into final position - daddiu gp,gp,%lo(_gp) # merge lowest "halfword" - - daddiu a0, sp, 64 # Pointer to ELF entry structure +NESTED(__start, 0, ra) + move a0, sp # Pointer to ELF entry structure move a1, v0 # Kernel-provided atexit() pointer + and sp, -16 # Align stack to 16 bytes - ld t9, %call16(__libc_init)(gp) - jalr t9 + jal __libc_init + teq zero, zero # Crash if we return END(__start) |