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-rw-r--r--arch/parisc/kernel/patch.c130
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);
+}