[DTrace-devel] [PATCH 2/2] link: no longer add utsname in USDT ELF notes

[Elena Zannoni]

Reviewed-by: Elena Zannoni <elena.zannoni at oracle.com>

On 9/28/26 2:53 PM, Kris Van Hees via DTrace-devel wrote:
 
> USDT ELF notes used to contain utsname information for debugging, but
> this has proven to be troublesome for distributions that expect to be
> able to regenerate build objects with identical data.  Since the
> utsname data contains the system name, the USDT ELF notes were causing
> comparisons between generates and regenerated objects to fail.
> 
> Signed-off-by: Kris Van Hees <kris.van.hees at oracle.com>
> ---
>  libdtrace/dt_link.c | 48 ---------------------------------------------
>  1 file changed, 48 deletions(-)
> 
> diff --git a/libdtrace/dt_link.c b/libdtrace/dt_link.c
> index aa5eb735..d8188881 100644
> --- a/libdtrace/dt_link.c
> +++ b/libdtrace/dt_link.c
> @@ -261,52 +261,6 @@ note_add_version(usdt_elf_t *usdt)
>  	return 0;
>  }
>  
> -static int
> -note_add_utsname(usdt_elf_t *usdt)
> -{
> -	Elf_Data	*dbuf;
> -	char		*buf, *p;
> -	size_t		len, sz;
> -
> -#define UTSN_NOTE_HEADSZ \
> -		((3 * sizeof(uint32_t)) +	/* namesz, descsz, type */ \
> -		 ALIGN(5, 4))			/* "utsn\0" */
> -
> -	/* Ensure the note starts on a 4-byte alignment boundary. */
> -	usdt->base = ALIGN(usdt->base + usdt->size, 4);
> -	usdt->size = 0;
> -
> -	len = sizeof(struct utsname);
> -	sz = UTSN_NOTE_HEADSZ + ALIGN(len, 4);
> -
> -	buf = malloc(sz);
> -	if (buf == NULL)
> -		return dt_set_errno(usdt->dtp, EDT_NOMEM);
> -	memset(buf, 0, sz);
> -
> -	/* Construct the note header. */
> -	*((uint32_t *)&buf[0]) = 5;
> -	*((uint32_t *)&buf[4]) = sz - UTSN_NOTE_HEADSZ;
> -	*((uint32_t *)&buf[8]) = 1;
> -	memcpy(&buf[12], "utsn", 4);
> -
> -	/* Add the data. */
> -	p = buf + UTSN_NOTE_HEADSZ;
> -	memcpy(p, &usdt->dtp->dt_uts, sizeof(struct utsname));
> -
> -	/* Add the note header. */
> -	dbuf = elf_newdata(usdt->note);
> -	dbuf->d_align = sizeof(uint32_t);
> -	dbuf->d_off = usdt->base;
> -	dbuf->d_buf = buf;
> -	dbuf->d_size = sz;
> -	usdt->size = sz;
> -
> -	usdt->notes.next = NULL;
> -
> -	return 0;
> -}
> -
>  static int
>  create_elf64(dtrace_hdl_t *dtp, dtrace_prog_t *pgp, int fd, uint_t flags)
>  {
> @@ -398,8 +352,6 @@ create_elf64(dtrace_hdl_t *dtp, dtrace_prog_t *pgp, int fd, uint_t flags)
>  	if (!(flags & DTRACE_D_STRIP)) {
>  		if (note_add_version(usdt) == -1)
>  			goto fail;
> -		if (note_add_utsname(usdt) == -1)
> -			goto fail;
>  	}
>  
>  	dt_free(dtp, usdt);
> -- 
> 2.52.0
> 
> 
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