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454ede3f14
Historically the uaccess code pre-initializes the result of get_user() (and now also __get_kernel_nofault()) to zero and uses the result as input parameter for inline assemblies. This is different to what most, if not all, other architectures are doing, which set the result to zero within the exception handler in case of a fault. Use the new extable mechanism and handle zeroing of the result within the exception handler in case of a fault. Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
82 lines
2.2 KiB
C
82 lines
2.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/bitfield.h>
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#include <linux/extable.h>
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#include <linux/string.h>
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#include <linux/errno.h>
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#include <linux/panic.h>
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#include <asm/asm-extable.h>
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#include <asm/extable.h>
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const struct exception_table_entry *s390_search_extables(unsigned long addr)
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{
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const struct exception_table_entry *fixup;
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size_t num;
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fixup = search_exception_tables(addr);
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if (fixup)
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return fixup;
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num = __stop_amode31_ex_table - __start_amode31_ex_table;
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return search_extable(__start_amode31_ex_table, num, addr);
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}
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static bool ex_handler_fixup(const struct exception_table_entry *ex, struct pt_regs *regs)
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{
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regs->psw.addr = extable_fixup(ex);
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return true;
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}
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static bool ex_handler_ua_store(const struct exception_table_entry *ex, struct pt_regs *regs)
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{
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unsigned int reg_err = FIELD_GET(EX_DATA_REG_ERR, ex->data);
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regs->gprs[reg_err] = -EFAULT;
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regs->psw.addr = extable_fixup(ex);
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return true;
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}
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static bool ex_handler_ua_load_mem(const struct exception_table_entry *ex, struct pt_regs *regs)
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{
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unsigned int reg_addr = FIELD_GET(EX_DATA_REG_ADDR, ex->data);
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unsigned int reg_err = FIELD_GET(EX_DATA_REG_ERR, ex->data);
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size_t len = FIELD_GET(EX_DATA_LEN, ex->data);
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regs->gprs[reg_err] = -EFAULT;
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memset((void *)regs->gprs[reg_addr], 0, len);
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regs->psw.addr = extable_fixup(ex);
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return true;
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}
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static bool ex_handler_ua_load_reg(const struct exception_table_entry *ex, struct pt_regs *regs)
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{
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unsigned int reg_zero = FIELD_GET(EX_DATA_REG_ADDR, ex->data);
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unsigned int reg_err = FIELD_GET(EX_DATA_REG_ERR, ex->data);
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regs->gprs[reg_err] = -EFAULT;
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regs->gprs[reg_zero] = 0;
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regs->psw.addr = extable_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 = s390_search_extables(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_FIXUP:
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return ex_handler_fixup(ex, regs);
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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_UA_STORE:
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return ex_handler_ua_store(ex, regs);
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case EX_TYPE_UA_LOAD_MEM:
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return ex_handler_ua_load_mem(ex, regs);
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case EX_TYPE_UA_LOAD_REG:
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return ex_handler_ua_load_reg(ex, regs);
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}
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panic("invalid exception table entry");
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}
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