1 files changed, 130 insertions, 0 deletions
diff --git a/arch/parisc/kernel/patch.c b/arch/parisc/kernel/patch.c
new file mode 100644
index 000000000..e59574f65
--- /dev/null
+++ b/arch/parisc/kernel/patch.c
@@ -0,0 +1,130 @@
+// SPDX-License-Identifier: GPL-2.0
+ /*
+  * functions to patch RO kernel text during runtime
+  *
+  * Copyright (c) 2019 Sven Schnelle <svens@stackframe.org>
+  */
+
+#include <linux/kernel.h>
+#include <linux/spinlock.h>
+#include <linux/kprobes.h>
+#include <linux/mm.h>
+#include <linux/stop_machine.h>
+
+#include <asm/cacheflush.h>
+#include <asm/fixmap.h>
+#include <asm/patch.h>
+
+struct patch {
+	void *addr;
+	u32 *insn;
+	unsigned int len;
+};
+
+static DEFINE_RAW_SPINLOCK(patch_lock);
+
+static void __kprobes *patch_map(void *addr, int fixmap, unsigned long *flags,
+				 int *need_unmap)
+{
+	unsigned long uintaddr = (uintptr_t) addr;
+	bool module = !core_kernel_text(uintaddr);
+	struct page *page;
+
+	*need_unmap = 0;
+	if (module && IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
+		page = vmalloc_to_page(addr);
+	else if (!module && IS_ENABLED(CONFIG_STRICT_KERNEL_RWX))
+		page = virt_to_page(addr);
+	else
+		return addr;
+
+	*need_unmap = 1;
+	set_fixmap(fixmap, page_to_phys(page));
+	raw_spin_lock_irqsave(&patch_lock, *flags);
+
+	return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK));
+}
+
+static void __kprobes patch_unmap(int fixmap, unsigned long *flags)
+{
+	clear_fixmap(fixmap);
+
+	raw_spin_unlock_irqrestore(&patch_lock, *flags);
+}
+
+void __kprobes __patch_text_multiple(void *addr, u32 *insn, unsigned int len)
+{
+	unsigned long start = (unsigned long)addr;
+	unsigned long end = (unsigned long)addr + len;
+	unsigned long flags;
+	u32 *p, *fixmap;
+	int mapped;
+
+	/* Make sure we don't have any aliases in cache */
+	flush_kernel_dcache_range_asm(start, end);
+	flush_kernel_icache_range_asm(start, end);
+	flush_tlb_kernel_range(start, end);
+
+	p = fixmap = patch_map(addr, FIX_TEXT_POKE0, &flags, &mapped);
+
+	while (len >= 4) {
+		*p++ = *insn++;
+		addr += sizeof(u32);
+		len -= sizeof(u32);
+		if (len && offset_in_page(addr) == 0) {
+			/*
+			 * We're crossing a page boundary, so
+			 * need to remap
+			 */
+			flush_kernel_dcache_range_asm((unsigned long)fixmap,
+						      (unsigned long)p);
+			flush_tlb_kernel_range((unsigned long)fixmap,
+					       (unsigned long)p);
+			if (mapped)
+				patch_unmap(FIX_TEXT_POKE0, &flags);
+			p = fixmap = patch_map(addr, FIX_TEXT_POKE0, &flags,
+						&mapped);
+		}
+	}
+
+	flush_kernel_dcache_range_asm((unsigned long)fixmap, (unsigned long)p);
+	flush_tlb_kernel_range((unsigned long)fixmap, (unsigned long)p);
+	if (mapped)
+		patch_unmap(FIX_TEXT_POKE0, &flags);
+}
+
+void __kprobes __patch_text(void *addr, u32 insn)
+{
+	__patch_text_multiple(addr, &insn, sizeof(insn));
+}
+
+static int __kprobes patch_text_stop_machine(void *data)
+{
+	struct patch *patch = data;
+
+	__patch_text_multiple(patch->addr, patch->insn, patch->len);
+	return 0;
+}
+
+void __kprobes patch_text(void *addr, unsigned int insn)
+{
+	struct patch patch = {
+		.addr = addr,
+		.insn = &insn,
+		.len = sizeof(insn),
+	};
+
+	stop_machine_cpuslocked(patch_text_stop_machine, &patch, NULL);
+}
+
+void __kprobes patch_text_multiple(void *addr, u32 *insn, unsigned int len)
+{
+
+	struct patch patch = {
+		.addr = addr,
+		.insn = insn,
+		.len = len
+	};
+
+	stop_machine_cpuslocked(patch_text_stop_machine, &patch, NULL);
+}