Re: [PATCH] libc/arm: add missing .cfi_sections

On Mon, Jun 10, 2024 at 2:38 PM Clément Chigot <[email protected]> wrote:
>
> The modifications added by the series "M-profile PACBTI-enablement"
> (see 9d6b00511e50a54d2472d11f75f7c0f2b4a98b24) have introduced a couple
> of .cfi_* instructions.
>
> Like for e6459123e497409a9e3d845c39829a9602ba55a4, these instructions
> create object files which contain .eh_frame sections.  However, ARM uses
> its own unwind info format, not .eh_frame, which is generated by
> ARM-specific directives, not .cfi_*. The .eh_frame sections are useless,
> but also not removed by strip and may be harmful with some linker
> scripts.
>
> Adding ".cfi_sections .debug_frame" (as in glibc) moves the generated
> directives towards .debug_frame instead of .eh_frame. Making them easier
> to handle.
>
>             * libc/machine/arm/aeabi_memmove-thumb2.S: Use .cfi_sections
>             .debug_frame.
>             * libc/machine/arm/aeabi_memset-thumb2.S: Likewise.
>             * libc/machine/arm/memchr.S: Likewise.
>             * libc/machine/arm/memcpy-armv7m.S: Likewise.
>             * libc/machine/arm/setjmp.S: Likewise.
>             * libc/machine/arm/strlen-armv7.S: Likewise.
>             * libc/machine/arm/strlen-thumb2-Os.S: Likewise.

Gentle ping

> ---
>  newlib/libc/machine/arm/aeabi_memmove-thumb2.S | 1 +
>  newlib/libc/machine/arm/aeabi_memset-thumb2.S  | 1 +
>  newlib/libc/machine/arm/memchr.S               | 1 +
>  newlib/libc/machine/arm/memcpy-armv7m.S        | 1 +
>  newlib/libc/machine/arm/setjmp.S               | 1 +
>  newlib/libc/machine/arm/strlen-armv7.S         | 1 +
>  newlib/libc/machine/arm/strlen-thumb2-Os.S     | 1 +
>  7 files changed, 7 insertions(+)
>
> diff --git a/newlib/libc/machine/arm/aeabi_memmove-thumb2.S b/newlib/libc/machine/arm/aeabi_memmove-thumb2.S
> index 20ca993e5..3018e7412 100644
> --- a/newlib/libc/machine/arm/aeabi_memmove-thumb2.S
> +++ b/newlib/libc/machine/arm/aeabi_memmove-thumb2.S
> @@ -36,6 +36,7 @@
>         ASM_ALIAS __aeabi_memmove8 __aeabi_memmove
>  __aeabi_memmove:
>         .fnstart
> +       .cfi_sections .debug_frame
>         .cfi_startproc
>         prologue 4
>         cmp     r0, r1
> diff --git a/newlib/libc/machine/arm/aeabi_memset-thumb2.S b/newlib/libc/machine/arm/aeabi_memset-thumb2.S
> index 6b77d3820..a1b8f0532 100644
> --- a/newlib/libc/machine/arm/aeabi_memset-thumb2.S
> +++ b/newlib/libc/machine/arm/aeabi_memset-thumb2.S
> @@ -33,6 +33,7 @@
>         .global __aeabi_memset
>         .type   __aeabi_memset, %function
>         .fnstart
> +       .cfi_sections .debug_frame
>         .cfi_startproc
>         ASM_ALIAS __aeabi_memset4 __aeabi_memset
>         ASM_ALIAS __aeabi_memset8 __aeabi_memset
> diff --git a/newlib/libc/machine/arm/memchr.S b/newlib/libc/machine/arm/memchr.S
> index d13ef8d65..f0b3650aa 100644
> --- a/newlib/libc/machine/arm/memchr.S
> +++ b/newlib/libc/machine/arm/memchr.S
> @@ -293,6 +293,7 @@ memchr:
>         .global memchr
>         .type memchr,%function
>         .fnstart
> +       .cfi_sections .debug_frame
>         .cfi_startproc
>  memchr:
>         @ r0 = start of memory to scan
> diff --git a/newlib/libc/machine/arm/memcpy-armv7m.S b/newlib/libc/machine/arm/memcpy-armv7m.S
> index ec1ad6485..13ffdb343 100644
> --- a/newlib/libc/machine/arm/memcpy-armv7m.S
> +++ b/newlib/libc/machine/arm/memcpy-armv7m.S
> @@ -88,6 +88,7 @@
>         .thumb
>         .thumb_func
>         .fnstart
> +       .cfi_sections .debug_frame
>         .cfi_startproc
>         .type   memcpy, %function
>  memcpy:
> diff --git a/newlib/libc/machine/arm/setjmp.S b/newlib/libc/machine/arm/setjmp.S
> index 5e5952296..0070f17cd 100644
> --- a/newlib/libc/machine/arm/setjmp.S
> +++ b/newlib/libc/machine/arm/setjmp.S
> @@ -183,6 +183,7 @@ SYM (.arm_start_of.\name):
>         MODE
>         .globl SYM (\name)
>         .fnstart
> +       .cfi_sections .debug_frame
>         .cfi_startproc
>         TYPE (\name)
>  SYM (\name):
> diff --git a/newlib/libc/machine/arm/strlen-armv7.S b/newlib/libc/machine/arm/strlen-armv7.S
> index 6aa122c07..1c2b5c532 100644
> --- a/newlib/libc/machine/arm/strlen-armv7.S
> +++ b/newlib/libc/machine/arm/strlen-armv7.S
> @@ -106,6 +106,7 @@
>
>  def_fn strlen p2align=6
>         .fnstart
> +       .cfi_sections .debug_frame
>         .cfi_startproc
>         prologue 4 5 push_ip=HAVE_PAC_LEAF
>         pld     [srcin, #0]
> diff --git a/newlib/libc/machine/arm/strlen-thumb2-Os.S b/newlib/libc/machine/arm/strlen-thumb2-Os.S
> index 4adbc61d2..b8a615a15 100644
> --- a/newlib/libc/machine/arm/strlen-thumb2-Os.S
> +++ b/newlib/libc/machine/arm/strlen-thumb2-Os.S
> @@ -47,6 +47,7 @@
>
>  def_fn strlen p2align=1
>         .fnstart
> +       .cfi_sections .debug_frame
>         .cfi_startproc
>         prologue
>         mov     r3, r0
> --
> 2.25.1
>