From: Breno Leitao <leitao@debian.org>
To: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Jinjie Ruan <ruanjinjie@huawei.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, bpf@vger.kernel.org,
rmikey@meta.com, kernel-team@meta.com,
Vladimir Murzin <vladimir.murzin@arm.com>,
Ada Couprie Diaz <ada.coupriediaz@arm.com>
Subject: Re: [PATCH RFC] arm64: entry: PSTATE_I_SET is leaking on pseudo NMI mode
Date: Fri, 7 Aug 2026 09:29:12 -0700 [thread overview]
Message-ID: <anYHjvJ1_4dDjuzw@gmail.com> (raw)
In-Reply-To: <anXqMsJ14r3BAbMG@gmail.com>
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 ]---
prev parent reply other threads:[~2026-08-07 16:29 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-07 11:45 [PATCH RFC] arm64: entry: PSTATE_I_SET is leaking on pseudo NMI mode Breno Leitao
2026-08-07 13:40 ` Will Deacon
2026-08-07 13:57 ` Mark Rutland
2026-08-07 14:49 ` Vladimir Murzin
2026-08-07 14:58 ` Breno Leitao
2026-08-07 16:29 ` Breno Leitao [this message]
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