79 lines
1.7 KiB
C
79 lines
1.7 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Based on arch/arm/mm/extable.c
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*/
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#include <linux/bitfield.h>
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#include <linux/extable.h>
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#include <linux/uaccess.h>
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#include <asm/asm-extable.h>
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#include <asm/ptrace.h>
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static inline unsigned long
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get_ex_fixup(const struct exception_table_entry *ex)
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{
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return ((unsigned long)&ex->fixup + ex->fixup);
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}
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static bool ex_handler_uaccess_err_zero(const struct exception_table_entry *ex,
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struct pt_regs *regs)
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{
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int reg_err = FIELD_GET(EX_DATA_REG_ERR, ex->data);
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int reg_zero = FIELD_GET(EX_DATA_REG_ZERO, ex->data);
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pt_regs_write_reg(regs, reg_err, -EFAULT);
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pt_regs_write_reg(regs, reg_zero, 0);
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regs->pc = get_ex_fixup(ex);
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return true;
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}
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static bool
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ex_handler_load_unaligned_zeropad(const struct exception_table_entry *ex,
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struct pt_regs *regs)
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{
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int reg_data = FIELD_GET(EX_DATA_REG_DATA, ex->data);
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int reg_addr = FIELD_GET(EX_DATA_REG_ADDR, ex->data);
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unsigned long data, addr, offset;
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addr = pt_regs_read_reg(regs, reg_addr);
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offset = addr & 0x7UL;
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addr &= ~0x7UL;
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data = *(unsigned long*)addr;
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#ifndef __AARCH64EB__
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data >>= 8 * offset;
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#else
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data <<= 8 * offset;
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#endif
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pt_regs_write_reg(regs, reg_data, data);
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regs->pc = get_ex_fixup(ex);
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return true;
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}
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bool fixup_exception(struct pt_regs *regs)
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{
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const struct exception_table_entry *ex;
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ex = search_exception_tables(instruction_pointer(regs));
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if (!ex)
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return false;
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switch (ex->type) {
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case EX_TYPE_BPF:
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return ex_handler_bpf(ex, regs);
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case EX_TYPE_UACCESS_ERR_ZERO:
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case EX_TYPE_KACCESS_ERR_ZERO:
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return ex_handler_uaccess_err_zero(ex, regs);
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case EX_TYPE_LOAD_UNALIGNED_ZEROPAD:
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return ex_handler_load_unaligned_zeropad(ex, regs);
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}
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BUG();
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}
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