Re: [Minios-devel] [UNIKRAFT PATCH 1/2] plat: Use position independent code (PIC) in thread_start.S

[Simon Kuenzer <simon.kuenzer@xxxxxxxxx>]

Hey Razvan,

this patch looks good to me. I am going to upstream it.
Thanks a lot.

Simon

Reviewed-by: Simon Kuenzer <simon.kuenzer@xxxxxxxxx>

On 23.03.20 16:08, Razvan Deaconescu wrote:
> Use RIP-relative addressing for PIC.
>
> Signed-off-by: Razvan Deaconescu <razvan.deaconescu@xxxxxxxxx>
> ---
>   plat/common/x86/thread_start.S | 7 ++++---
>   1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/plat/common/x86/thread_start.S b/plat/common/x86/thread_start.S
> index b23666a..61f4f1c 100644
> --- a/plat/common/x86/thread_start.S
> +++ b/plat/common/x86/thread_start.S
> @@ -36,7 +36,7 @@ ENTRY(asm_thread_starter)
>         pushq $0
>         xorq %rbp,%rbp
>         call *%rbx
> -       call uk_sched_thread_exit
> +       call *uk_sched_thread_exit@GOTPCREL(%rip)
>   
>   ENTRY(asm_ctx_start)
>         mov %rdi, %rsp      /* set SP */
> @@ -52,10 +52,11 @@ ENTRY(asm_sw_ctx_switch)
>         pushq %r15
>         movq %rsp, OFFSETOF_SW_CTX_SP(%rdi)       /* save ESP */
>         movq OFFSETOF_SW_CTX_SP(%rsi), %rsp       /* restore ESP */
> -       movq $1f, OFFSETOF_SW_CTX_IP(%rdi)        /* save EIP */
> +        lea .Lreturn(%rip), %rbx
> +        movq %rbx, OFFSETOF_SW_CTX_IP(%rdi)       /* save EIP */
>         pushq OFFSETOF_SW_CTX_IP(%rsi)            /* restore EIP */
>         ret
> -1:
> +.Lreturn:
>         popq %r15
>         popq %r14
>         popq %r13