[REGRESSION] Cannot boot 6.19-rc1 on riscv64 with BPF enabled.

[Jason Montleon]

When booting riscv64 systems with BPF enabled using 6.19-rc1 the
system produces the following panic. I tried on several boards and
they resulted in the same error.

[ 5.380583] Insufficient stack space to handle exception!
[ 5.385986] Task stack: [0xffffffc600020000..0xffffffc600024000]
[ 5.392339] Overflow stack: [0xffffffd7fef7a070..0xffffffd7fef7b070]
[ 5.398693] CPU: 2 UID: 0 PID: 1 Comm: systemd Tainted: G W
6.19.0-rc1-00001-g74d9cab5b6c1 #15 NONE
[ 5.409302] Tainted: [W]=WARN
[ 5.412271] Hardware name: starfive StarFive VisionFive 2
v1.3B/StarFive VisionFive 2 v1.3B, BIOS 2024.10-rc3 10/01/2024
[ 5.423134] epc : copy_from_kernel_nofault_allowed+0xa/0x28
[ 5.428718] ra : copy_from_kernel_nofault+0x28/0x198
[ 5.433774] epc : ffffffff8024062a ra : ffffffff80240670 sp : ffffffc60001fff0
[ 5.440997] gp : ffffffff82464ce8 tp : 0000000000000000 t0 : ffffffff80024620
[ 5.448219] t1 : ffffffff8017c052 t2 : 0000000000000000 s0 : ffffffc600020030
[ 5.455442] s1 : ffffffd6c2198260 a0 : ffffffd6c2198260 a1 : 0000000000000008
[ 5.462664] a2 : 0000000000000008 a3 : 000000000000009d a4 : 0000000000000000
[ 5.469885] a5 : 0000000000000000 a6 : 0000000000000021 a7 : 0000000000000003
[ 5.477106] s2 : ffffffc600020070 s3 : 0000000000000008 s4 : 0000000000000000
[ 5.484327] s5 : ffffffc600020080 s6 : 0000000000000000 s7 : 0000000000038000
[ 5.491549] s8 : 0000000000008002 s9 : 0000000000380000 s10: ffffffc600023cf8
[ 5.498771] s11: ffffffd6c419bf00 t3 : 0000000077ab9db9 t4 : 00000000113918e7
[ 5.505993] t5 : ffffffff9e9bcc29 t6 : ffffffc600023ad4
[ 5.511304] status: 0000000200000120 badaddr: ffffffc60001fff0 cause:
000000000000000f
[ 5.519221] Kernel panic - not syncing: Kernel stack overflow
[ 5.524967] CPU: 2 UID: 0 PID: 1 Comm: systemd Tainted: G W
6.19.0-rc1-00001-g74d9cab5b6c1 #15 NONE
[ 5.535574] Tainted: [W]=WARN
[ 5.538544] Hardware name: starfive StarFive VisionFive 2
v1.3B/StarFive VisionFive 2 v1.3B, BIOS 2024.10-rc3 10/01/2024
[ 5.549408] Call Trace:
[ 5.551859] [<ffffffff8001e438>] dump_backtrace+0x28/0x38
[ 5.557262] [<ffffffff80002462>] show_stack+0x3a/0x50
[ 5.562317] [<ffffffff80016d02>] dump_stack_lvl+0x5a/0x80
[ 5.567720] [<ffffffff80016d40>] dump_stack+0x18/0x20
[ 5.572776] [<ffffffff80002b7a>] vpanic+0xf2/0x2d0
[ 5.577570] [<ffffffff80002d96>] panic+0x3e/0x48
[ 5.582191] [<ffffffff8001e110>] handle_bad_stack+0x98/0xc0
[ 5.587765] [<ffffffff80240670>] copy_from_kernel_nofault+0x28/0x198
[ 5.594122] SMP: stopping secondary CPUs
[ 5.598070] ---[ end Kernel panic - not syncing: Kernel stack overflow ]---

A bisect identified 47c9214dcb as the problematic commit:
[47c9214dcbea9043ac20441a285c7bb5486b8b2d] bpf: fix the usage of
BPF_TRAMP_F_SKIP_FRAME

This commit reverts cleanly and when building 6.19-rc1 without it I am
able to boot successfully.

A copy of the trace, bisect log, and config used to reproduce the
problem are at:
https://gist.github.com/jmontleon/b8b861352e7b9bc9fd3a93d391926dec

#regzbot introduced: 47c9214dcb

Thank you,
Jason Montleon