Re: git: 70c067062217 - main - dtrace/arm64: Simplify dtrace_getarg() slightly

On 29 Jan 2025, at 02:21, Mark Johnston <markj@FreeBSD.org> wrote:
> 
> The branch main has been updated by markj:
> 
> URL: https://cgit.FreeBSD.org/src/commit/?id=70c067062217a5295ed321427b91cfd857c18b77
> 
> commit 70c067062217a5295ed321427b91cfd857c18b77
> Author:     Mark Johnston <markj@FreeBSD.org>
> AuthorDate: 2025-01-29 01:05:03 +0000
> Commit:     Mark Johnston <markj@FreeBSD.org>
> CommitDate: 2025-01-29 01:05:03 +0000
> 
>    dtrace/arm64: Simplify dtrace_getarg() slightly
> 
>    The use of memcpy here is redundant, and also incorrect since memcpy()
>    might be instrumented by fbt or kinst.  dtrace_bcopy() exists, but we
>    don't need it.
> 
>    MFC after:      2 weeks
>    Sponsored by:   Innovate UK
> ---
> sys/cddl/dev/dtrace/aarch64/dtrace_isa.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/sys/cddl/dev/dtrace/aarch64/dtrace_isa.c b/sys/cddl/dev/dtrace/aarch64/dtrace_isa.c
> index ff0e068006bd..3e36004c6f0d 100644
> --- a/sys/cddl/dev/dtrace/aarch64/dtrace_isa.c
> +++ b/sys/cddl/dev/dtrace/aarch64/dtrace_isa.c
> @@ -256,7 +256,6 @@ dtrace_getarg(int arg, int aframes __unused)
> return (tf->tf_x[arg]);
> } else {
> uintptr_t p;
> - uint64_t val;
> 
> p = (tf->tf_sp + (arg - 8) * sizeof(uint64_t));
> if ((p & 7) != 0) {
> @@ -269,8 +268,7 @@ dtrace_getarg(int arg, int aframes __unused)
> cpu_core[curcpu].cpuc_dtrace_illval = p;
> return (0);
> }
> - memcpy(&val, (void *)p, sizeof(uint64_t));
> - return (val);
> + return (p);

Doesn’t this change from dereferencing p to returning it? Surely p
should be a uint64_t * that is dereferenced?

Jess