From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops There's some internal state that ftrace_ops needs to have set, but since it can be declared outside of the ftrace.c code, it calls ftrace_ops_init() on the ops in every global function. The issue is that if two tasks call it on the same ops at the same time it is possible to have the initialization of one corrupt the initialization of the other call. Create a ops_mutex to use to synchronize every initialization of the ftrace_ops. The mutex is taken within checking the ftrace_ops flag that states it was initializied but the flag is checked again after the mutex has been taken. Checking first outside the mutex allows it to shortcut having to take the mutex. But then the check needs to be done again after the mute is taken in case of races. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock") Reported-by: sashiko-bot@kernel.org Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/ Signed-off-by: Steven Rostedt --- arch/powerpc/boot/util.S | 67 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 67 insertions(+) create mode 100644 arch/powerpc/boot/util.S (limited to 'arch/powerpc/boot/util.S') diff --git a/arch/powerpc/boot/util.S b/arch/powerpc/boot/util.S new file mode 100644 index 000000000..6a92376da --- /dev/null +++ b/arch/powerpc/boot/util.S @@ -0,0 +1,67 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Copied from + * + * This file contains miscellaneous low-level functions. + * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org) + * + * Largely rewritten by Cort Dougan (cort@cs.nmt.edu) + * and Paul Mackerras. + * + * kexec bits: + * Copyright (C) 2002-2003 Eric Biederman + * GameCube/ppc32 port Copyright (C) 2004 Albert Herranz + */ +#include "ppc_asm.h" + +#define SPRN_PVR 0x11F /* Processor Version Register */ + + .text + +/* udelay needs to know the period of the + * timebase in nanoseconds. This used to be hardcoded to be 60ns + * (period of 66MHz/4). Now a variable is used that is initialized to + * 60 for backward compatibility, but it can be overridden as necessary + * with code something like this: + * extern unsigned long timebase_period_ns; + * timebase_period_ns = 1000000000 / bd->bi_tbfreq; + */ + .data + .globl timebase_period_ns +timebase_period_ns: + .long 60 + + .text +/* + * Delay for a number of microseconds + */ + .globl udelay +udelay: + mulli r4,r3,1000 /* nanoseconds */ + /* Change r4 to be the number of ticks using: + * (nanoseconds + (timebase_period_ns - 1 )) / timebase_period_ns + * timebase_period_ns defaults to 60 (16.6MHz) */ + mflr r5 + bcl 20,31,0f +0: mflr r6 + mtlr r5 + addis r5,r6,(timebase_period_ns-0b)@ha + lwz r5,(timebase_period_ns-0b)@l(r5) + add r4,r4,r5 + addi r4,r4,-1 + divw r4,r4,r5 /* BUS ticks */ +1: MFTBU(r5) + MFTBL(r6) + MFTBU(r7) + cmpw 0,r5,r7 + bne 1b /* Get [synced] base time */ + addc r9,r6,r4 /* Compute end time */ + addze r8,r5 +2: MFTBU(r5) + cmpw 0,r5,r8 + blt 2b + bgt 3f + MFTBL(r6) + cmpw 0,r6,r9 + blt 2b +3: blr -- cgit v1.3.1