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, 72 insertions, 0 deletions

diff --git a/arch/arm/mach-imx/cpu.c b/arch/arm/mach-imx/cpu.c
new file mode 100644
index 000000000..65c7224f5
--- /dev/null
+++ b/arch/arm/mach-imx/cpu.c
@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+
+#include "hardware.h"
+#include "common.h"
+
+unsigned int __mxc_cpu_type;
+static unsigned int imx_soc_revision;
+
+void mxc_set_cpu_type(unsigned int type)
+{
+	__mxc_cpu_type = type;
+}
+
+void imx_set_soc_revision(unsigned int rev)
+{
+	imx_soc_revision = rev;
+}
+
+unsigned int imx_get_soc_revision(void)
+{
+	return imx_soc_revision;
+}
+
+void imx_print_silicon_rev(const char *cpu, int srev)
+{
+	if (srev == IMX_CHIP_REVISION_UNKNOWN)
+		pr_info("CPU identified as %s, unknown revision\n", cpu);
+	else
+		pr_info("CPU identified as %s, silicon rev %d.%d\n",
+				cpu, (srev >> 4) & 0xf, srev & 0xf);
+}
+
+void __init imx_set_aips(void __iomem *base)
+{
+	unsigned int reg;
+/*
+ * Set all MPROTx to be non-bufferable, trusted for R/W,
+ * not forced to user-mode.
+ */
+	imx_writel(0x77777777, base + 0x0);
+	imx_writel(0x77777777, base + 0x4);
+
+/*
+ * Set all OPACRx to be non-bufferable, to not require
+ * supervisor privilege level for access, allow for
+ * write access and untrusted master access.
+ */
+	imx_writel(0x0, base + 0x40);
+	imx_writel(0x0, base + 0x44);
+	imx_writel(0x0, base + 0x48);
+	imx_writel(0x0, base + 0x4C);
+	reg = imx_readl(base + 0x50) & 0x00FFFFFF;
+	imx_writel(reg, base + 0x50);
+}
+
+void __init imx_aips_allow_unprivileged_access(
+		const char *compat)
+{
+	void __iomem *aips_base_addr;
+	struct device_node *np;
+
+	for_each_compatible_node(np, NULL, compat) {
+		aips_base_addr = of_iomap(np, 0);
+		WARN_ON(!aips_base_addr);
+		imx_set_aips(aips_base_addr);
+	}
+}