On Tue, Jan 03, 2023 at 11:58:48AM +0100, Ard Biesheuvel wrote:

On Tue, 3 Jan 2023 at 03:13, Linus Torvalds torvalds@linux-foundation.org wrote:

...

On Mon, Jan 2, 2023 at 5:45 PM Guenter Roeck linux@roeck-us.net wrote:

...

... and reverting commit 99cb0d917ff indeed fixes the problem.

Hmm. My gut feel is that this just exposes some bug in binutils.

That said, maybe that commit should not have added its own /DISCARDS/ thing, and instead just added that "*(.note.GNU-stack)" to the general /DISCARDS/ thing that is defined by the

#define DISCARDS ..

a little bit later, so that we only end up with one single DISCARD list. Something like this (broken patch on purpose):

--- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -897,5 +897,4 @@ */ #define NOTES \

• /DISCARD/ : { *(.note.GNU-stack) }              \
  .notes : AT(ADDR(.notes) - LOAD_OFFSET) {       \
          BOUNDED_SECTION_BY(.note.*, _notes)     \
  

@@ -1016,4 +1015,5 @@ #define DISCARDS \ /DISCARD/ : { \

• *(.note.GNU-stack)                              \
  EXIT_DISCARDS                                   \
  EXIT_CALL                                       \
  
  

But maybe that DISCARDS macrop ends up being used too late?

Masahiro's v1 did something like this, and it caused an issue on RISC-V, which is why we ended up with this approach instead.

...

It really shouldn't matter, but here we are, with a build problem with some random old binutils on an odd platform..

AIUI, the way ld.bfd used to combine output sections may also affect the /DISCARD/ pseudo-section, and so introducing it much earlier results in these discards to be interpreted in a different order.

The purpose of this change is to prevent .note.GNU-stack from deciding the section type of the .notes output section, and so keeping it in its own section should be sufficient. E.g.,

--- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -896,7 +896,7 @@

• Otherwise, the type of .notes section would become PROGBITS

instead of NOTES. */ #define NOTES \

•   /DISCARD/ : { *(.note.GNU-stack) }                              \
  

•   .note.GNU-stack : { *(.note.GNU-stack) }                        \
    .notes : AT(ADDR(.notes) - LOAD_OFFSET) {                       \
            BOUNDED_SECTION_BY(.note.*, _notes)                     \
    } NOTES_HEADERS                                                 \
  
  

The .note.GNU-stack has zero size, so the result should be the same.

+Greg +Nick

This also fixes Build ID on arm64 for stable 5.15, 5.10, and 5.4 which has been broken since backport of: 0d362be5b142 ("Makefile: link with -z noexecstack --no-warn-rwx-segments")

Discussed here:

https://lore.kernel.org/stable/3df32572ec7016e783d37e185f88495831671f5d.1671... https://lore.kernel.org/stable/cover.1670358255.git.tom.saeger@oracle.com/

Perhaps add:

Cc: stable@vger.kernel.org # 5.15, 5.10, 5.4

for stable 5.15, 5.10, 5.4 Tested-by: Tom Saeger tom.saeger@oracle.com