[PATCH] Makefile: use -gdwarf-{4|5} for assembler for DEBUG_INFO_DWARF{4|5}

[PATCH] Makefile: use -gdwarf-{4|5} for assembler for DEBUG_INFO_DWARF{4|5}

[Nick Desaulniers]

This is _not_ an upstream commit and just for 5.15.y only. It is based
on upstream
commit 32ef9e5054ec ("Makefile.debug: re-enable debug info for .S files").

When the user has chosen not to use their compiler's implicit default
DWARF version (which changes over time) via selecting
- CONFIG_DEBUG_INFO_DWARF4 or
- CONFIG_DEBUG_INFO_DWARF5
we need to tell the compiler this for Asm sources as well as C sources.
(We use the compiler to drive assembler jobs in kbuild, since most asm
needs to be preprocessed first).  Otherwise, we will get object files
built from Asm sources with the compiler's implicit default DWARF
version.

For example, selecting CONFIG_DEBUG_INFO_DWARF4 would produce a DWARFv5
vmlinux, since it was a mix of DWARFv4 object files from C sources and
DWARFv5 object files from Asm sources when using Clang as the assembler
(ex. `make LLVM=1`).

Fixes: 0ee2f0567a56 ("Makefile.debug: re-enable debug info for .S files")
Reported-by: Lecopzer Chen <lecopzer.chen@mediatek.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
 Makefile | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Makefile b/Makefile
index a7b664680ea3..88b2b13bf35b 100644
--- a/Makefile
+++ b/Makefile
@@ -888,6 +888,7 @@ ifndef CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT
 dwarf-version-$(CONFIG_DEBUG_INFO_DWARF4) := 4
 dwarf-version-$(CONFIG_DEBUG_INFO_DWARF5) := 5
 DEBUG_CFLAGS	+= -gdwarf-$(dwarf-version-y)
+KBUILD_AFLAGS	+= -gdwarf-$(dwarf-version-y)
 endif
 
 ifdef CONFIG_DEBUG_INFO_REDUCED
-- 
2.40.0.rc1.284.g88254d51c5-goog

Re: [PATCH] Makefile: use -gdwarf-{4|5} for assembler for DEBUG_INFO_DWARF{4|5}

[Greg Kroah-Hartman]

On Wed, Mar 15, 2023 at 02:40:59PM -0700, Nick Desaulniers wrote:
> This is _not_ an upstream commit and just for 5.15.y only. It is based
> on upstream
> commit 32ef9e5054ec ("Makefile.debug: re-enable debug info for .S files").
> 
> When the user has chosen not to use their compiler's implicit default
> DWARF version (which changes over time) via selecting
> - CONFIG_DEBUG_INFO_DWARF4 or
> - CONFIG_DEBUG_INFO_DWARF5
> we need to tell the compiler this for Asm sources as well as C sources.
> (We use the compiler to drive assembler jobs in kbuild, since most asm
> needs to be preprocessed first).  Otherwise, we will get object files
> built from Asm sources with the compiler's implicit default DWARF
> version.
> 
> For example, selecting CONFIG_DEBUG_INFO_DWARF4 would produce a DWARFv5
> vmlinux, since it was a mix of DWARFv4 object files from C sources and
> DWARFv5 object files from Asm sources when using Clang as the assembler
> (ex. `make LLVM=1`).
> 
> Fixes: 0ee2f0567a56 ("Makefile.debug: re-enable debug info for .S files")
> Reported-by: Lecopzer Chen <lecopzer.chen@mediatek.com>
> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
> ---
>  Makefile | 1 +
>  1 file changed, 1 insertion(+)

Now queued up, thanks,

greg k-h