[Bug target/121432] [15/16/17 regression] GCC has a regression on Microblaze since r15-1619-g3b9b8d6cfdf593

[neal.frager at amd dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121432

--- Comment #53 from Neal Frager <neal.frager at amd dot com> ---
@Waldemar(In reply to Waldemar Brodkorb from comment #34)
> Hi,
> 
> with this patch I still get following output on my Numato Mimas A7 Mini:
> [    3.503255] Run /init as init process
> [    3.506819]   with arguments:
> [    3.509763]     /init
> [    3.512005]   with environment:
> [    3.515114]     HOME=/
> [    3.517706]     TERM=linux
> [    3.530417] Illegal opcode exception in kernel mode.
> [    3.534357] Oops: opcode exception, sig: 7
> [    3.538428] CPU: 0 UID: 0 PID: 1 Comm: init Not tainted 6.18.18-1 #2 NONE 
> [    3.545239]  Registers dump: mode=80821ED0
> [    3.549380]  r1=C0821ED0, r2=00000000, r3=FFFFFFFE, r4=C0802980
> [    3.555255]  r5=CFDF3430, r6=00000C5F, r7=C0849000, r8=C0848000
> [    3.561130]  r9=CFE108E0, r10=000065A2, r11=00000C60, r12=CFDE9338
> [    3.567267]  r13=00000000, r14=C0821F68, r15=C00093A8, r16=00000000
> [    3.573486]  r17=C00093B4, r18=3F7B7000, r19=BFCBCAA4, r20=48008E3C
> [    3.579706]  r21=00000000, r22=48000000, r23=48009070, r24=BFCBDF2C
> [    3.585927]  r25=BFCBDF24, r26=BFCBDF38, r27=BFCBDDC0, r28=48009070
> [    3.592148]  r29=00000000, r30=00000001, r31=C082C000, rPC=C00093B4
> [    3.598369]  msr=000046A2, ear=BFCBDF24, esr=BFCBDF38, fsr=BFCBDDC0
> [    3.604963] Kernel panic - not syncing: Attempted to kill init!
> exitcode=0x00000007
> [    3.612280] ---[ end Kernel panic - not syncing: Attempted to kill init!
> exitcode=0x00000007 ]---
> 
> GCC 15.2.0, Binutils 2.46.0, Linux 6.18.18, uClibc-ng 1.0.57 or glibc 2.42.
> An older Linux kernel built with Buildroot 2018.11 does boot fine, so I do
> not think it is my bitstream, which is behaving wrong. What could be the
> reason for this panic?

@Waldemar, could you try a new version of the patch?  I think we may have
solved the problem correctly this time.  I am attaching a Linux patch which
works without the gcc v15/v16 work around.  Could you please apply it to one of
your failing Linux kernels and test on your hardware?