Re: [PATCH 2/4] sh: Rearrange blocks in entry-common.S

[John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>]

On 7/23/20 1:13 AM, Michael Karcher wrote:
> This avoids out-of-range jumps that get auto-replaced by the assembler
> and prepares for the changes needed to implement SECCOMP_FILTER cleanly.
> 
> Signed-off-by: Michael Karcher <kernel@mkarcher.dialup.fu-berlin.de>
> ---
>  arch/sh/kernel/entry-common.S | 57 ++++++++++++++++++-----------------
>  1 file changed, 29 insertions(+), 28 deletions(-)
> 
> diff --git a/arch/sh/kernel/entry-common.S b/arch/sh/kernel/entry-common.S
> index 9bac5bbb67f3..c4d88d61890d 100644
> --- a/arch/sh/kernel/entry-common.S
> +++ b/arch/sh/kernel/entry-common.S
> @@ -178,34 +178,6 @@ syscall_exit_work:
>  	bra	resume_userspace
>  	 nop
>  
> -	.align	2
> -syscall_trace_entry:
> -	!                     	Yes it is traced.
> -	mov     r15, r4
> -	mov.l	7f, r11		! Call do_syscall_trace_enter which notifies
> -	jsr	@r11	    	! superior (will chomp R[0-7])
> -	 nop
> -	mov.l	r0, @(OFF_R0,r15)	! Save return value
> -	!			Reload R0-R4 from kernel stack, where the
> -	!   	    	    	parent may have modified them using
> -	!   	    	    	ptrace(POKEUSR).  (Note that R0-R2 are
> -	!   	    	    	reloaded from the kernel stack by syscall_call
> -	!   	    	    	below, so don't need to be reloaded here.)
> -	!   	    	    	This allows the parent to rewrite system calls
> -	!   	    	    	and args on the fly.
> -	mov.l	@(OFF_R4,r15), r4   ! arg0
> -	mov.l	@(OFF_R5,r15), r5
> -	mov.l	@(OFF_R6,r15), r6
> -	mov.l	@(OFF_R7,r15), r7   ! arg3
> -	mov.l	@(OFF_R3,r15), r3   ! syscall_nr
> -	!
> -	mov.l	6f, r10			! Number of syscalls
> -	cmp/hs	r10, r3
> -	bf	syscall_call
> -	mov	#-ENOSYS, r0
> -	bra	syscall_exit
> -	 mov.l	r0, @(OFF_R0,r15)	! Return value
> -
>  __restore_all:
>  	mov	#OFF_SR, r0
>  	mov.l	@(r0,r15), r0	! get status register
> @@ -388,6 +360,35 @@ syscall_exit:
>  	bf	syscall_exit_work
>  	bra	__restore_all
>  	 nop
> +
> +	.align	2
> +syscall_trace_entry:
> +	!                     	Yes it is traced.
> +	mov     r15, r4
> +	mov.l	7f, r11		! Call do_syscall_trace_enter which notifies
> +	jsr	@r11	    	! superior (will chomp R[0-7])
> +	 nop
> +	mov.l	r0, @(OFF_R0,r15)	! Save return value
> +	!			Reload R0-R4 from kernel stack, where the
> +	!   	    	    	parent may have modified them using
> +	!   	    	    	ptrace(POKEUSR).  (Note that R0-R2 are
> +	!   	    	    	reloaded from the kernel stack by syscall_call
> +	!   	    	    	below, so don't need to be reloaded here.)
> +	!   	    	    	This allows the parent to rewrite system calls
> +	!   	    	    	and args on the fly.
> +	mov.l	@(OFF_R4,r15), r4   ! arg0
> +	mov.l	@(OFF_R5,r15), r5
> +	mov.l	@(OFF_R6,r15), r6
> +	mov.l	@(OFF_R7,r15), r7   ! arg3
> +	mov.l	@(OFF_R3,r15), r3   ! syscall_nr
> +	!
> +	mov.l	6f, r10			! Number of syscalls
> +	cmp/hs	r10, r3
> +	bf	syscall_call
> +	mov	#-ENOSYS, r0
> +	bra	syscall_exit
> +	 mov.l	r0, @(OFF_R0,r15)	! Return value
> +
>  	.align	2
>  #if !defined(CONFIG_CPU_SH2)
>  1:	.long	TRA
> 

Tested-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>

-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer - glaubitz@debian.org
`. `'   Freie Universitaet Berlin - glaubitz@physik.fu-berlin.de
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