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-rw-r--r--arch/parisc/kernel/patch.c77
1 files changed, 77 insertions, 0 deletions
diff --git a/arch/parisc/kernel/patch.c b/arch/parisc/kernel/patch.c
new file mode 100644
index 000000000000..cdcd981278b3
--- /dev/null
+++ b/arch/parisc/kernel/patch.c
@@ -0,0 +1,77 @@
+// 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;
+ unsigned int insn;
+};
+
+static void __kprobes *patch_map(void *addr, int fixmap)
+{
+ unsigned long uintaddr = (uintptr_t) addr;
+ bool module = !core_kernel_text(uintaddr);
+ struct page *page;
+
+ 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;
+
+ set_fixmap(fixmap, page_to_phys(page));
+
+ return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK));
+}
+
+static void __kprobes patch_unmap(int fixmap)
+{
+ clear_fixmap(fixmap);
+}
+
+void __kprobes __patch_text(void *addr, unsigned int insn)
+{
+ void *waddr = addr;
+ int size;
+
+ waddr = patch_map(addr, FIX_TEXT_POKE0);
+ *(u32 *)waddr = insn;
+ size = sizeof(u32);
+ flush_kernel_vmap_range(waddr, size);
+ patch_unmap(FIX_TEXT_POKE0);
+ flush_icache_range((uintptr_t)(addr),
+ (uintptr_t)(addr) + size);
+}
+
+static int __kprobes patch_text_stop_machine(void *data)
+{
+ struct patch *patch = data;
+
+ __patch_text(patch->addr, patch->insn);
+
+ return 0;
+}
+
+void __kprobes patch_text(void *addr, unsigned int insn)
+{
+ struct patch patch = {
+ .addr = addr,
+ .insn = insn,
+ };
+
+ stop_machine_cpuslocked(patch_text_stop_machine, &patch, NULL);
+}