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authorIlya Leoshkevich <iii@linux.ibm.com>2020-06-30 21:52:03 +0300
committerHeiko Carstens <hca@linux.ibm.com>2020-07-20 11:55:50 +0300
commit05a68e892e89c97df6650cd8cc55058002657cbc (patch)
tree50da3706b76870f99a1acf549c9cbf4227388baf /arch/s390/include/asm/extable.h
parent88aa8939c96781089e5ace3492d818074c5c6fe9 (diff)
downloadlinux-05a68e892e89c97df6650cd8cc55058002657cbc.tar.xz
s390/kernel: expand exception table logic to allow new handling options
This is a s390 port of commit 548acf19234d ("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>
Diffstat (limited to 'arch/s390/include/asm/extable.h')
-rw-r--r--arch/s390/include/asm/extable.h52
1 files changed, 47 insertions, 5 deletions
diff --git a/arch/s390/include/asm/extable.h b/arch/s390/include/asm/extable.h
index ae27f756b409..3beb294fd553 100644
--- a/arch/s390/include/asm/extable.h
+++ b/arch/s390/include/asm/extable.h
@@ -1,12 +1,20 @@
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __S390_EXTABLE_H
#define __S390_EXTABLE_H
+
+#include <asm/ptrace.h>
+#include <linux/compiler.h>
+
/*
- * The exception table consists of pairs of addresses: the first is the
- * address of an instruction that is allowed to fault, and the second is
- * the address at which the program should continue. No registers are
- * modified, so it is entirely up to the continuation code to figure out
- * what to do.
+ * The exception table consists of three addresses:
+ *
+ * - Address of an instruction that is allowed to fault.
+ * - Address at which the program should continue.
+ * - Optional address of handler that takes pt_regs * argument and runs in
+ * interrupt context.
+ *
+ * No registers are modified, so it is entirely up to the continuation code
+ * to figure out what to do.
*
* All the routines below use bits of fixup code that are out of line
* with the main instruction path. This means when everything is well,
@@ -17,6 +25,7 @@
struct exception_table_entry
{
int insn, fixup;
+ long handler;
};
extern struct exception_table_entry *__start_dma_ex_table;
@@ -29,6 +38,39 @@ static inline unsigned long extable_fixup(const struct exception_table_entry *x)
return (unsigned long)&x->fixup + x->fixup;
}
+typedef bool (*ex_handler_t)(const struct exception_table_entry *,
+ struct pt_regs *);
+
+static inline ex_handler_t
+ex_fixup_handler(const struct exception_table_entry *x)
+{
+ if (likely(!x->handler))
+ return NULL;
+ return (ex_handler_t)((unsigned long)&x->handler + x->handler);
+}
+
+static inline bool ex_handle(const struct exception_table_entry *x,
+ struct pt_regs *regs)
+{
+ ex_handler_t handler = ex_fixup_handler(x);
+
+ if (unlikely(handler))
+ return handler(x, regs);
+ regs->psw.addr = extable_fixup(x);
+ return true;
+}
+
#define ARCH_HAS_RELATIVE_EXTABLE
+static inline void swap_ex_entry_fixup(struct exception_table_entry *a,
+ struct exception_table_entry *b,
+ struct exception_table_entry tmp,
+ int delta)
+{
+ a->fixup = b->fixup + delta;
+ b->fixup = tmp.fixup - delta;
+ a->handler = b->handler + delta;
+ b->handler = tmp.handler - delta;
+}
+
#endif