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-rw-r--r--arch/arm64/mm/extable.c78
1 files changed, 78 insertions, 0 deletions
diff --git a/arch/arm64/mm/extable.c b/arch/arm64/mm/extable.c
new file mode 100644
index 0000000000..228d681a87
--- /dev/null
+++ b/arch/arm64/mm/extable.c
@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Based on arch/arm/mm/extable.c
+ */
+
+#include <linux/bitfield.h>
+#include <linux/extable.h>
+#include <linux/uaccess.h>
+
+#include <asm/asm-extable.h>
+#include <asm/ptrace.h>
+
+static inline unsigned long
+get_ex_fixup(const struct exception_table_entry *ex)
+{
+ return ((unsigned long)&ex->fixup + ex->fixup);
+}
+
+static bool ex_handler_uaccess_err_zero(const struct exception_table_entry *ex,
+ struct pt_regs *regs)
+{
+ int reg_err = FIELD_GET(EX_DATA_REG_ERR, ex->data);
+ int reg_zero = FIELD_GET(EX_DATA_REG_ZERO, ex->data);
+
+ pt_regs_write_reg(regs, reg_err, -EFAULT);
+ pt_regs_write_reg(regs, reg_zero, 0);
+
+ regs->pc = get_ex_fixup(ex);
+ return true;
+}
+
+static bool
+ex_handler_load_unaligned_zeropad(const struct exception_table_entry *ex,
+ struct pt_regs *regs)
+{
+ int reg_data = FIELD_GET(EX_DATA_REG_DATA, ex->data);
+ int reg_addr = FIELD_GET(EX_DATA_REG_ADDR, ex->data);
+ unsigned long data, addr, offset;
+
+ addr = pt_regs_read_reg(regs, reg_addr);
+
+ offset = addr & 0x7UL;
+ addr &= ~0x7UL;
+
+ data = *(unsigned long*)addr;
+
+#ifndef __AARCH64EB__
+ data >>= 8 * offset;
+#else
+ data <<= 8 * offset;
+#endif
+
+ pt_regs_write_reg(regs, reg_data, data);
+
+ regs->pc = get_ex_fixup(ex);
+ return true;
+}
+
+bool fixup_exception(struct pt_regs *regs)
+{
+ const struct exception_table_entry *ex;
+
+ ex = search_exception_tables(instruction_pointer(regs));
+ if (!ex)
+ return false;
+
+ switch (ex->type) {
+ case EX_TYPE_BPF:
+ return ex_handler_bpf(ex, regs);
+ case EX_TYPE_UACCESS_ERR_ZERO:
+ case EX_TYPE_KACCESS_ERR_ZERO:
+ return ex_handler_uaccess_err_zero(ex, regs);
+ case EX_TYPE_LOAD_UNALIGNED_ZEROPAD:
+ return ex_handler_load_unaligned_zeropad(ex, regs);
+ }
+
+ BUG();
+}