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Date: Wed, 18 Sep 2019 07:28:44 -0700
From: Khem Raj <raj.khem@...il.com>
To: musl@...ts.openwall.com
Cc: Andre McCurdy <armccurdy@...il.com>
Subject: Re: [PATCH] arm: avoid conditional branch to PLT in sigsetjmp.s
On Tue, Sep 17, 2019 at 11:04 PM Andre McCurdy <armccurdy@...il.com> wrote:
>
> The R_ARM_THM_JUMP19 relocation type generated for the original code
> when targeting Thumb 2 is not supported by the gold linker:
>
> | .../arm-oe-linux-musleabi/9.2.0/ld: error: conditional branch to PLT in THUMB-2 not supported yet.
> | src/signal/arm/sigsetjmp.s:9: error: unexpected opcode while processing relocation R_ARM_THM_JUMP19
if it is thumb2 specific another option could be to use `it eq` before
beq which should turn branch into an unconditional branch, which then
uses R_ARM_THM_JUMP24 relocation that has a range of 16MB.
> ---
> src/signal/arm/sigsetjmp.s | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/src/signal/arm/sigsetjmp.s b/src/signal/arm/sigsetjmp.s
> index 318addba..69ebbf49 100644
> --- a/src/signal/arm/sigsetjmp.s
> +++ b/src/signal/arm/sigsetjmp.s
> @@ -6,9 +6,10 @@
> sigsetjmp:
> __sigsetjmp:
> tst r1,r1
> - beq setjmp
> + bne 1f
> + b setjmp
>
> - str lr,[r0,#256]
> +1: str lr,[r0,#256]
> str r4,[r0,#260+8]
> mov r4,r0
>
> --
> 2.23.0
>
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