linux/arch/riscv/mm/extable.c
Jisheng Zhang f81393a5b2
riscv: extable: fix err reg writing in dedicated uaccess handler
Mayuresh reported commit 20802d8d47 ("riscv: extable: add a dedicated
uaccess handler") breaks the writev02 test case in LTP. This is due to
the err reg isn't correctly set with the errno(-EFAULT in writev02
case). First of all, the err and zero regs are reg numbers rather than
reg offsets in struct pt_regs; Secondly, regs_set_gpr() should write
the regs when offset isn't zero(zero means epc)

Fix it by correcting regs_set_gpr() logic and passing the correct reg
offset to it.

Reported-by: Mayuresh Chitale <mchitale@ventanamicro.com>
Fixes: 20802d8d47 ("riscv: extable: add a dedicated uaccess handler")
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2022-02-08 17:02:47 -08:00

72 lines
1.7 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2009 Sunplus Core Technology Co., Ltd.
* Lennox Wu <lennox.wu@sunplusct.com>
* Chen Liqin <liqin.chen@sunplusct.com>
* Copyright (C) 2013 Regents of the University of California
*/
#include <linux/bitfield.h>
#include <linux/extable.h>
#include <linux/module.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_fixup(const struct exception_table_entry *ex,
struct pt_regs *regs)
{
regs->epc = get_ex_fixup(ex);
return true;
}
static inline void regs_set_gpr(struct pt_regs *regs, unsigned int offset,
unsigned long val)
{
if (unlikely(offset > MAX_REG_OFFSET))
return;
if (offset)
*(unsigned long *)((unsigned long)regs + offset) = val;
}
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);
regs_set_gpr(regs, reg_err * sizeof(unsigned long), -EFAULT);
regs_set_gpr(regs, reg_zero * sizeof(unsigned long), 0);
regs->epc = get_ex_fixup(ex);
return true;
}
bool fixup_exception(struct pt_regs *regs)
{
const struct exception_table_entry *ex;
ex = search_exception_tables(regs->epc);
if (!ex)
return false;
switch (ex->type) {
case EX_TYPE_FIXUP:
return ex_handler_fixup(ex, regs);
case EX_TYPE_BPF:
return ex_handler_bpf(ex, regs);
case EX_TYPE_UACCESS_ERR_ZERO:
return ex_handler_uaccess_err_zero(ex, regs);
}
BUG();
}