Re: [PATCH RFC] arm64: entry: PSTATE_I_SET is leaking on pseudo NMI mode

On Fri, Aug 07, 2026 at 07:58:21AM -0700, Breno Leitao wrote:
> Meanwhile, I will try to ftrace the writes to PMR and regs->pmr to get
> a better grasp of the states machine we are in (probably on Monday).

It seems LLM found a very easy to reproduce this:

	bash-5.1# dmesg

	bash-5.1#  cd /sys/kernel/tracing
	echo 'r:pmr vfs_read bad=+0($retval):u64' >> kprobe_events
	echo 1 > events/kprobes/pmr/enable

	bash-5.1# dmesg
	[   54.997498] ------------[ cut here ]------------
	[   54.997506] WARNING: ./arch/arm64/include/asm/irqflags.h:63 at arm64_exit_to_kernel_mode+0xc0/0xc8, CPU#1: bash/185
	[   54.997530] Modules linked in:
	[   54.997535] CPU: 1 UID: 0 PID: 185 Comm: bash Not tainted 7.2.0-rc6-next-20260806upstream #15 PREEMPT(full)
	[   54.997538] Hardware name: linux,dummy-virt (DT)
	[   54.997540] pstate: 234003c5 (nzCv DAIF +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
	[   54.997542] pc : arm64_exit_to_kernel_mode+0xc0/0xc8
	[   54.997544] lr : el1_abort+0x5c/0x80
	[   54.997547] sp : ffff800088ba35f0
	[   54.997548] pmr: 000000f0
	[   54.997550] x29: ffff800088ba35f0 x28: ffff0000c3cd0000 x27: 0000000000000000
	[   54.997554] x26: ffff0000c3f277d0 x25: 0000000000000030 x24: 0000000000000001
	[   54.997557] x23: 00000000834003c5 x22: 0000000000000000 x21: 0000000000000001
	[   54.997566] x20: ffff800088ba3650 x19: 0000000000000000 x18: 0000000000000000
	[   54.997569] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000001
	[   54.997572] x14: 0000000040000000 x13: ffff800086b171f8 x12: fff080007fe00000
	[   54.997576] x11: 0000000000000001 x10: aaaaaaaaaaaaaaab x9 : 000000000000001f
	[   54.997579] x8 : 00000000000000d0 x7 : 0000000000000000 x6 : ffff0000c0adf02c
	[   54.997582] x5 : ffff0000c0adf034 x4 : ffff800081408b08 x3 : 000000000000000c
	[   54.997585] x2 : 00000000000002fe x1 : 0000000000000000 x0 : ffff800088ba3650
	[   54.997589] Call trace:
	[   54.997590]  arm64_exit_to_kernel_mode+0xc0/0xc8 (P)
	[   54.997593]  el1_abort+0x5c/0x80
	[   54.997595]  el1h_64_sync_handler+0x50/0x100
	[   54.997597]  el1h_64_sync+0x80/0x88
	[   54.997601]  __arch_copy_from_user+0x220/0x240 (P)
	[   54.997604]  process_fetch_insn+0x450/0x8b0
	[   54.997608]  kretprobe_trace_func+0x1b0/0x298
	[   54.997611]  kretprobe_dispatcher+0x5c/0x88
	[   54.997613]  __kretprobe_trampoline_handler+0xc4/0x168
	[   54.997617]  kretprobe_brk_handler+0x40/0x68
	[   54.997620]  call_el1_break_hook+0x74/0xa0
	[   54.997623]  do_el1_brk64+0x30/0x60
	[   54.997624]  el1_brk64+0x2c/0x48
	[   54.997626]  el1h_64_sync_handler+0x80/0x100
	[   54.997628]  el1h_64_sync+0x80/0x88
	[   54.997630]  ksys_read+0x80/0x100 (P)
	[   54.997634]  __arm64_sys_read+0x28/0x40
	[   54.997636]  invoke_syscall+0x54/0xf0
	[   54.997640]  do_el0_svc+0x7c/0xb8
	[   54.997642]  el0_svc+0x60/0x188
	[   54.997644]  el0t_64_sync_handler+0x84/0x130
	[   54.997645]  el0t_64_sync+0x1ac/0x1b0
	[   54.997647] ---[ end trace 0000000000000000 ]---