[bisected] clang 15 built kernel fails to boot, stuck at "Loading Linux 6.1.1 ...", gcc 12 built kernel with same config boots fine

[Erhard F.]

Hi!

I did a kernel bisect for an issue I originally posted on https://github.com/ClangBuiltLinux/linux/issues/1774

It is about kernel 6.1.x not booting on my machines when built with clang. A gcc built kernel with the same config just works fine. Turns out kernel v6.2-rc4 and earlier v6.2-rc are still affected.

I did a kernel bisect which revealed this commit:

 # git bisect bad
706460a96fc654e80b6bed1f562b00d2ce9f2f4d is the first bad commit
commit 706460a96fc654e80b6bed1f562b00d2ce9f2f4d
Author: Sandipan Das <sandipan.das@xxxxxxx>
Date:   Thu Aug 11 17:59:51 2022 +0530

    perf/x86/amd/core: Add generic branch record interfaces
    
    AMD processors that are capable of recording branches support either Branch
    Sampling (BRS) or Last Branch Record (LBR). In preparation for adding Last
    Branch Record Extension Version 2 (LbrExtV2) support, introduce new static
    calls which act as gateways to call into the feature-dependent functions
    based on what is available on the processor.
    
    Signed-off-by: Sandipan Das <sandipan.das@xxxxxxx>
    Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/b75dbc32663cb395f0d701167e952c6a6b0445a3.1660211399.git.sandipan.das@xxxxxxx

 arch/x86/events/amd/core.c | 34 ++++++++++++++++++++++------------
 1 file changed, 22 insertions(+), 12 deletions(-)


For more details please have a look at https://github.com/ClangBuiltLinux/linux/issues/1774

Regards,
Erhard