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s390/kernel: expand exception table logic to allow new handling options

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This is a s390 port of commit 548acf1923 ("x86/mm: Expand the
exception table logic to allow new handling options"), which is needed
for implementing BPF_PROBE_MEM on s390.

The new handler field is made 64-bit in order to allow pointing from
dynamically allocated entries to handlers in kernel text. Unlike on x86,
NULL is used instead of ex_handler_default. This is because exception
tables are used by boot/text_dma.S, and it would be a pain to preserve
ex_handler_default.

The new infrastructure is ignored in early_pgm_check_handler, since
there is no pt_regs.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
This commit is contained in:
Ilya Leoshkevich
2020-06-30 20:52:03 +02:00
committed by Heiko Carstens
parent 88aa8939c9
commit 05a68e892e
6 changed files with 94 additions and 17 deletions
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4
arch/s390/kernel/kprobes.c
View File

@@ -523,10 +523,8 @@ static int kprobe_trap_handler(struct pt_regs *regs, int trapnr)
* zero, try to fix up.
*/
entry = s390_search_extables(regs->psw.addr);
if (entry) {
regs->psw.addr = extable_fixup(entry);
if (entry && ex_handle(entry, regs))
return 1;
}
/*
* fixup_exception() could not handle it,

7
arch/s390/kernel/traps.c
View File

@@ -50,11 +50,8 @@ void do_report_trap(struct pt_regs *regs, int si_signo, int si_code, char *str)
} else {
const struct exception_table_entry *fixup;
fixup = s390_search_extables(regs->psw.addr);
if (fixup)
regs->psw.addr = extable_fixup(fixup);
else {
if (!fixup || !ex_handle(fixup, regs))
die(regs, str);
}
}
}
@@ -251,7 +248,7 @@ void monitor_event_exception(struct pt_regs *regs)
case BUG_TRAP_TYPE_NONE:
fixup = s390_search_extables(regs->psw.addr);
if (fixup)
regs->psw.addr = extable_fixup(fixup);
ex_handle(fixup, regs);
break;
case BUG_TRAP_TYPE_WARN:
break;