diff options
Diffstat (limited to 'arch/s390/mm/extable.c')
| -rw-r--r-- | arch/s390/mm/extable.c | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/arch/s390/mm/extable.c b/arch/s390/mm/extable.c index a046be1715cf..7498e858c401 100644 --- a/arch/s390/mm/extable.c +++ b/arch/s390/mm/extable.c @@ -73,6 +73,49 @@ static bool ex_handler_fpc(const struct exception_table_entry *ex, struct pt_reg return true; } +struct insn_ssf { + u64 opc1 : 8; + u64 r3 : 4; + u64 opc2 : 4; + u64 b1 : 4; + u64 d1 : 12; + u64 b2 : 4; + u64 d2 : 12; +} __packed; + +static bool ex_handler_ua_mvcos(const struct exception_table_entry *ex, + bool from, struct pt_regs *regs) +{ + unsigned long uaddr, remainder; + struct insn_ssf *insn; + + /* + * If the faulting user space access crossed a page boundary retry by + * limiting the access to the first page (adjust length accordingly). + * Then the mvcos instruction will either complete with condition code + * zero, or generate another fault where the user space access did not + * cross a page boundary. + * If the faulting user space access did not cross a page boundary set + * length to zero and retry. In this case no user space access will + * happen, and the mvcos instruction will complete with condition code + * zero. + * In both cases the instruction will complete with condition code + * zero (copying finished), and the register which contains the + * length, indicates the number of bytes copied. + */ + regs->psw.addr = extable_fixup(ex); + insn = (struct insn_ssf *)regs->psw.addr; + if (from) + uaddr = regs->gprs[insn->b2] + insn->d2; + else + uaddr = regs->gprs[insn->b1] + insn->d1; + remainder = PAGE_SIZE - (uaddr & (PAGE_SIZE - 1)); + if (regs->gprs[insn->r3] <= remainder) + remainder = 0; + regs->gprs[insn->r3] = remainder; + return true; +} + bool fixup_exception(struct pt_regs *regs) { const struct exception_table_entry *ex; @@ -95,6 +138,10 @@ bool fixup_exception(struct pt_regs *regs) return ex_handler_zeropad(ex, regs); case EX_TYPE_FPC: return ex_handler_fpc(ex, regs); + case EX_TYPE_UA_MVCOS_TO: + return ex_handler_ua_mvcos(ex, false, regs); + case EX_TYPE_UA_MVCOS_FROM: + return ex_handler_ua_mvcos(ex, true, regs); } panic("invalid exception table entry"); } |