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Diffstat (limited to 'arch/xtensa/kernel/jump_label.c')
-rw-r--r--arch/xtensa/kernel/jump_label.c95
1 files changed, 95 insertions, 0 deletions
diff --git a/arch/xtensa/kernel/jump_label.c b/arch/xtensa/kernel/jump_label.c
new file mode 100644
index 000000000..ad1841cec
--- /dev/null
+++ b/arch/xtensa/kernel/jump_label.c
@@ -0,0 +1,95 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 Cadence Design Systems Inc.
+
+#include <linux/cpu.h>
+#include <linux/jump_label.h>
+#include <linux/kernel.h>
+#include <linux/memory.h>
+#include <linux/stop_machine.h>
+#include <linux/types.h>
+
+#include <asm/cacheflush.h>
+
+#define J_OFFSET_MASK 0x0003ffff
+#define J_SIGN_MASK (~(J_OFFSET_MASK >> 1))
+
+#if defined(__XTENSA_EL__)
+#define J_INSN 0x6
+#define NOP_INSN 0x0020f0
+#elif defined(__XTENSA_EB__)
+#define J_INSN 0x60000000
+#define NOP_INSN 0x0f020000
+#else
+#error Unsupported endianness.
+#endif
+
+struct patch {
+ atomic_t cpu_count;
+ unsigned long addr;
+ size_t sz;
+ const void *data;
+};
+
+static void local_patch_text(unsigned long addr, const void *data, size_t sz)
+{
+ memcpy((void *)addr, data, sz);
+ local_flush_icache_range(addr, addr + sz);
+}
+
+static int patch_text_stop_machine(void *data)
+{
+ struct patch *patch = data;
+
+ if (atomic_inc_return(&patch->cpu_count) == num_online_cpus()) {
+ local_patch_text(patch->addr, patch->data, patch->sz);
+ atomic_inc(&patch->cpu_count);
+ } else {
+ while (atomic_read(&patch->cpu_count) <= num_online_cpus())
+ cpu_relax();
+ __invalidate_icache_range(patch->addr, patch->sz);
+ }
+ return 0;
+}
+
+static void patch_text(unsigned long addr, const void *data, size_t sz)
+{
+ if (IS_ENABLED(CONFIG_SMP)) {
+ struct patch patch = {
+ .cpu_count = ATOMIC_INIT(0),
+ .addr = addr,
+ .sz = sz,
+ .data = data,
+ };
+ stop_machine_cpuslocked(patch_text_stop_machine,
+ &patch, cpu_online_mask);
+ } else {
+ unsigned long flags;
+
+ local_irq_save(flags);
+ local_patch_text(addr, data, sz);
+ local_irq_restore(flags);
+ }
+}
+
+void arch_jump_label_transform(struct jump_entry *e,
+ enum jump_label_type type)
+{
+ u32 d = (jump_entry_target(e) - (jump_entry_code(e) + 4));
+ u32 insn;
+
+ /* Jump only works within 128K of the J instruction. */
+ BUG_ON(!((d & J_SIGN_MASK) == 0 ||
+ (d & J_SIGN_MASK) == J_SIGN_MASK));
+
+ if (type == JUMP_LABEL_JMP) {
+#if defined(__XTENSA_EL__)
+ insn = ((d & J_OFFSET_MASK) << 6) | J_INSN;
+#elif defined(__XTENSA_EB__)
+ insn = ((d & J_OFFSET_MASK) << 8) | J_INSN;
+#endif
+ } else {
+ insn = NOP_INSN;
+ }
+
+ patch_text(jump_entry_code(e), &insn, JUMP_LABEL_NOP_SIZE);
+}