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, 202 insertions, 0 deletions

diff --git a/arch/xtensa/mm/init.c b/arch/xtensa/mm/init.c
new file mode 100644
index 000000000..fe83a6833
--- /dev/null
+++ b/arch/xtensa/mm/init.c
@@ -0,0 +1,202 @@
+/*
+ * arch/xtensa/mm/init.c
+ *
+ * Derived from MIPS, PPC.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2001 - 2005 Tensilica Inc.
+ * Copyright (C) 2014 - 2016 Cadence Design Systems Inc.
+ *
+ * Chris Zankel	<chris@zankel.net>
+ * Joe Taylor	<joe@tensilica.com, joetylr@yahoo.com>
+ * Marc Gauthier
+ * Kevin Chea
+ */
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/memblock.h>
+#include <linux/gfp.h>
+#include <linux/highmem.h>
+#include <linux/swap.h>
+#include <linux/mman.h>
+#include <linux/nodemask.h>
+#include <linux/mm.h>
+#include <linux/of_fdt.h>
+#include <linux/dma-map-ops.h>
+
+#include <asm/bootparam.h>
+#include <asm/page.h>
+#include <asm/sections.h>
+#include <asm/sysmem.h>
+
+/*
+ * Initialize the bootmem system and give it all low memory we have available.
+ */
+
+void __init bootmem_init(void)
+{
+	/* Reserve all memory below PHYS_OFFSET, as memory
+	 * accounting doesn't work for pages below that address.
+	 *
+	 * If PHYS_OFFSET is zero reserve page at address 0:
+	 * successfull allocations should never return NULL.
+	 */
+	memblock_reserve(0, PHYS_OFFSET ? PHYS_OFFSET : 1);
+
+	early_init_fdt_scan_reserved_mem();
+
+	if (!memblock_phys_mem_size())
+		panic("No memory found!\n");
+
+	min_low_pfn = PFN_UP(memblock_start_of_DRAM());
+	min_low_pfn = max(min_low_pfn, PFN_UP(PHYS_OFFSET));
+	max_pfn = PFN_DOWN(memblock_end_of_DRAM());
+	max_low_pfn = min(max_pfn, MAX_LOW_PFN);
+
+	early_memtest((phys_addr_t)min_low_pfn << PAGE_SHIFT,
+		      (phys_addr_t)max_low_pfn << PAGE_SHIFT);
+
+	memblock_set_current_limit(PFN_PHYS(max_low_pfn));
+	dma_contiguous_reserve(PFN_PHYS(max_low_pfn));
+
+	memblock_dump_all();
+}
+
+static void __init print_vm_layout(void)
+{
+	pr_info("virtual kernel memory layout:\n"
+#ifdef CONFIG_KASAN
+		"    kasan   : 0x%08lx - 0x%08lx  (%5lu MB)\n"
+#endif
+#ifdef CONFIG_MMU
+		"    vmalloc : 0x%08lx - 0x%08lx  (%5lu MB)\n"
+#endif
+#ifdef CONFIG_HIGHMEM
+		"    pkmap   : 0x%08lx - 0x%08lx  (%5lu kB)\n"
+		"    fixmap  : 0x%08lx - 0x%08lx  (%5lu kB)\n"
+#endif
+		"    lowmem  : 0x%08lx - 0x%08lx  (%5lu MB)\n"
+		"    .text   : 0x%08lx - 0x%08lx  (%5lu kB)\n"
+		"    .rodata : 0x%08lx - 0x%08lx  (%5lu kB)\n"
+		"    .data   : 0x%08lx - 0x%08lx  (%5lu kB)\n"
+		"    .init   : 0x%08lx - 0x%08lx  (%5lu kB)\n"
+		"    .bss    : 0x%08lx - 0x%08lx  (%5lu kB)\n",
+#ifdef CONFIG_KASAN
+		KASAN_SHADOW_START, KASAN_SHADOW_START + KASAN_SHADOW_SIZE,
+		KASAN_SHADOW_SIZE >> 20,
+#endif
+#ifdef CONFIG_MMU
+		VMALLOC_START, VMALLOC_END,
+		(VMALLOC_END - VMALLOC_START) >> 20,
+#ifdef CONFIG_HIGHMEM
+		PKMAP_BASE, PKMAP_BASE + LAST_PKMAP * PAGE_SIZE,
+		(LAST_PKMAP*PAGE_SIZE) >> 10,
+		FIXADDR_START, FIXADDR_END,
+		(FIXADDR_END - FIXADDR_START) >> 10,
+#endif
+		PAGE_OFFSET, PAGE_OFFSET +
+		(max_low_pfn - min_low_pfn) * PAGE_SIZE,
+#else
+		min_low_pfn * PAGE_SIZE, max_low_pfn * PAGE_SIZE,
+#endif
+		((max_low_pfn - min_low_pfn) * PAGE_SIZE) >> 20,
+		(unsigned long)_text, (unsigned long)_etext,
+		(unsigned long)(_etext - _text) >> 10,
+		(unsigned long)__start_rodata, (unsigned long)__end_rodata,
+		(unsigned long)(__end_rodata - __start_rodata) >> 10,
+		(unsigned long)_sdata, (unsigned long)_edata,
+		(unsigned long)(_edata - _sdata) >> 10,
+		(unsigned long)__init_begin, (unsigned long)__init_end,
+		(unsigned long)(__init_end - __init_begin) >> 10,
+		(unsigned long)__bss_start, (unsigned long)__bss_stop,
+		(unsigned long)(__bss_stop - __bss_start) >> 10);
+}
+
+void __init arch_zone_limits_init(unsigned long *max_zone_pfns)
+{
+	max_zone_pfns[ZONE_NORMAL] = max_low_pfn;
+#ifdef CONFIG_HIGHMEM
+	max_zone_pfns[ZONE_HIGHMEM] = max_pfn;
+#endif
+}
+
+void __init zones_init(void)
+{
+	print_vm_layout();
+}
+
+static void __init parse_memmap_one(char *p)
+{
+	char *oldp;
+	unsigned long start_at, mem_size;
+
+	if (!p)
+		return;
+
+	oldp = p;
+	mem_size = memparse(p, &p);
+	if (p == oldp)
+		return;
+
+	switch (*p) {
+	case '@':
+		start_at = memparse(p + 1, &p);
+		memblock_add(start_at, mem_size);
+		break;
+
+	case '$':
+		start_at = memparse(p + 1, &p);
+		memblock_reserve(start_at, mem_size);
+		break;
+
+	case 0:
+		memblock_reserve(mem_size, -mem_size);
+		break;
+
+	default:
+		pr_warn("Unrecognized memmap syntax: %s\n", p);
+		break;
+	}
+}
+
+static int __init parse_memmap_opt(char *str)
+{
+	while (str) {
+		char *k = strchr(str, ',');
+
+		if (k)
+			*k++ = 0;
+
+		parse_memmap_one(str);
+		str = k;
+	}
+
+	return 0;
+}
+early_param("memmap", parse_memmap_opt);
+
+#ifdef CONFIG_MMU
+static const pgprot_t protection_map[16] = {
+	[VM_NONE]					= PAGE_NONE,
+	[VM_READ]					= PAGE_READONLY,
+	[VM_WRITE]					= PAGE_COPY,
+	[VM_WRITE | VM_READ]				= PAGE_COPY,
+	[VM_EXEC]					= PAGE_READONLY_EXEC,
+	[VM_EXEC | VM_READ]				= PAGE_READONLY_EXEC,
+	[VM_EXEC | VM_WRITE]				= PAGE_COPY_EXEC,
+	[VM_EXEC | VM_WRITE | VM_READ]			= PAGE_COPY_EXEC,
+	[VM_SHARED]					= PAGE_NONE,
+	[VM_SHARED | VM_READ]				= PAGE_READONLY,
+	[VM_SHARED | VM_WRITE]				= PAGE_SHARED,
+	[VM_SHARED | VM_WRITE | VM_READ]		= PAGE_SHARED,
+	[VM_SHARED | VM_EXEC]				= PAGE_READONLY_EXEC,
+	[VM_SHARED | VM_EXEC | VM_READ]			= PAGE_READONLY_EXEC,
+	[VM_SHARED | VM_EXEC | VM_WRITE]		= PAGE_SHARED_EXEC,
+	[VM_SHARED | VM_EXEC | VM_WRITE | VM_READ]	= PAGE_SHARED_EXEC
+};
+DECLARE_VM_GET_PAGE_PROT
+#endif