klibc-bot for James Cowgill
2019-Jan-18 16:42 UTC
[klibc] [klibc:master] mips/mips64: simplify crt0 code
Commit-ID: 59f3f33338f371b3a30163406fbb5fe323503939 Gitweb: http://git.kernel.org/?p=libs/klibc/klibc.git;a=commit;h=59f3f33338f371b3a30163406fbb5fe323503939 Author: James Cowgill <james.cowgill at mips.com> AuthorDate: Fri, 2 Mar 2018 08:33:02 -0800 Committer: Ben Hutchings <ben at decadent.org.uk> CommitDate: Wed, 2 Jan 2019 03:08:04 +0000 [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 at mips.com> Link: https://www.zytor.com/pipermail/klibc/2018-March/003982.html Signed-off-by: Ben Hutchings <ben at decadent.org.uk> --- usr/klibc/arch/mips/crt0.S | 13 +++++-------- 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 142d9f2..47d7d8f 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 775a919..3f1c2a9 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)
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