ftrace: Synchronize the initialization of ftrace_opsgrafted

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 <rostedt@goodmis.org>

1 files changed, 99 insertions, 0 deletions

diff --git a/arch/powerpc/boot/pq2.c b/arch/powerpc/boot/pq2.c
new file mode 100644
index 000000000..de27f1c07
--- /dev/null
+++ b/arch/powerpc/boot/pq2.c
@@ -0,0 +1,99 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * PowerQUICC II support functions
+ *
+ * Author: Scott Wood <scottwood@freescale.com>
+ *
+ * Copyright (c) 2007 Freescale Semiconductor, Inc.
+ */
+
+#include "ops.h"
+#include "types.h"
+#include "fsl-soc.h"
+#include "pq2.h"
+#include "stdio.h"
+#include "io.h"
+
+#define PQ2_SCCR (0x10c80/4) /* System Clock Configuration Register */
+#define PQ2_SCMR (0x10c88/4) /* System Clock Mode Register */
+
+static int pq2_corecnf_map[] = {
+	3, 2, 2, 2, 4, 4, 5, 9, 6, 11, 8, 10, 3, 12, 7, -1,
+	6, 5, 13, 2, 14, 4, 15, 9, 0, 11, 8, 10, 16, 12, 7, -1
+};
+
+/* Get various clocks from crystal frequency.
+ * Returns zero on failure and non-zero on success.
+ */
+int pq2_get_clocks(u32 crystal, u32 *sysfreq, u32 *corefreq,
+                   u32 *timebase, u32 *brgfreq)
+{
+	u32 *immr;
+	u32 sccr, scmr, mainclk, busclk;
+	int corecnf, busdf, plldf, pllmf, dfbrg;
+
+	immr = fsl_get_immr();
+	if (!immr) {
+		printf("pq2_get_clocks: Couldn't get IMMR base.\r\n");
+		return 0;
+	}
+
+	sccr = in_be32(&immr[PQ2_SCCR]);
+	scmr = in_be32(&immr[PQ2_SCMR]);
+
+	dfbrg = sccr & 3;
+	corecnf = (scmr >> 24) & 0x1f;
+	busdf = (scmr >> 20) & 0xf;
+	plldf = (scmr >> 12) & 1;
+	pllmf = scmr & 0xfff;
+
+	mainclk = crystal * (pllmf + 1) / (plldf + 1);
+	busclk = mainclk / (busdf + 1);
+
+	if (sysfreq)
+		*sysfreq = mainclk / 2;
+	if (timebase)
+		*timebase = busclk / 4;
+	if (brgfreq)
+		*brgfreq = mainclk / (1 << ((dfbrg + 1) * 2));
+
+	if (corefreq) {
+		int coremult = pq2_corecnf_map[corecnf];
+
+		if (coremult < 0)
+			*corefreq = mainclk / 2;
+		else if (coremult == 0)
+			return 0;
+		else
+			*corefreq = busclk * coremult / 2;
+	}
+
+	return 1;
+}
+
+/* Set common device tree fields based on the given clock frequencies. */
+void pq2_set_clocks(u32 sysfreq, u32 corefreq, u32 timebase, u32 brgfreq)
+{
+	void *node;
+
+	dt_fixup_cpu_clocks(corefreq, timebase, sysfreq);
+
+	node = finddevice("/soc/cpm");
+	if (node)
+		setprop(node, "clock-frequency", &sysfreq, 4);
+
+	node = finddevice("/soc/cpm/brg");
+	if (node)
+		setprop(node, "clock-frequency", &brgfreq, 4);
+}
+
+int pq2_fixup_clocks(u32 crystal)
+{
+	u32 sysfreq, corefreq, timebase, brgfreq;
+
+	if (!pq2_get_clocks(crystal, &sysfreq, &corefreq, &timebase, &brgfreq))
+		return 0;
+
+	pq2_set_clocks(sysfreq, corefreq, timebase, brgfreq);
+	return 1;
+}