Author: kevans
Date: Thu May 21 02:08:34 2020
New Revision: 361315
URL: https://svnweb.freebsd.org/changeset/base/361315
Log:
MFC r361011: kernel: provide panicky version of __unreachable
__builtin_unreachable doesn't raise any compile-time warnings/errors on its
own, so problems with its usage can't be easily detected. While it would be
nice for this situation to change and compilers to at least add a warning
for trivial cases where local state means the instruction can't be reached,
this isn't the case at the moment and likely will not happen.
This commit adds an __assert_unreachable, whose intent is incredibly clear:
it asserts that this instruction is unreachable. On INVARIANTS builds, it's
a panic(), and on non-INVARIANTS it expands to __unreachable().
Existing users of __unreachable() are converted to __assert_unreachable,
to improve debuggability if this assumption is violated.
Modified:
stable/12/sys/ddb/db_expr.c
stable/12/sys/dev/nvdimm/nvdimm.c
stable/12/sys/dev/ow/ow.c
stable/12/sys/net/mppcc.c
stable/12/sys/sys/systm.h
Directory Properties:
stable/12/ (props changed)
Modified: stable/12/sys/ddb/db_expr.c
==============================================================================
--- stable/12/sys/ddb/db_expr.c Thu May 21 02:04:10 2020 (r361314)
+++ stable/12/sys/ddb/db_expr.c Thu May 21 02:08:34 2020 (r361315)
@@ -34,6 +34,7 @@
__FBSDID("$FreeBSD$");
#include <sys/param.h>
+#include <sys/systm.h>
#include <ddb/ddb.h>
#include <ddb/db_lex.h>
@@ -229,7 +230,7 @@ db_add_expr(db_expr_t *valuep)
lhs |= rhs;
break;
default:
- __unreachable();
+ __assert_unreachable();
}
t = db_read_token();
}
@@ -313,7 +314,7 @@ db_logical_relation_expr(
lhs = (lhs <= rhs);
break;
default:
- __unreachable();
+ __assert_unreachable();
}
t = db_read_token();
}
Modified: stable/12/sys/dev/nvdimm/nvdimm.c
==============================================================================
--- stable/12/sys/dev/nvdimm/nvdimm.c Thu May 21 02:04:10 2020
(r361314)
+++ stable/12/sys/dev/nvdimm/nvdimm.c Thu May 21 02:08:34 2020
(r361315)
@@ -35,6 +35,7 @@ __FBSDID("$FreeBSD$");
#include "opt_ddb.h"
#include <sys/param.h>
+#include <sys/systm.h>
#include <sys/bio.h>
#include <sys/bitstring.h>
#include <sys/bus.h>
@@ -235,7 +236,7 @@ read_label(struct nvdimm_dev *nv, int num)
return (0);
}
}
- __unreachable();
+ __assert_unreachable();
}
static int
Modified: stable/12/sys/dev/ow/ow.c
==============================================================================
--- stable/12/sys/dev/ow/ow.c Thu May 21 02:04:10 2020 (r361314)
+++ stable/12/sys/dev/ow/ow.c Thu May 21 02:08:34 2020 (r361315)
@@ -505,7 +505,7 @@ again:
return (EIO);
goto again;
default: /* NOTREACHED */
- __unreachable();
+ __assert_unreachable();
}
if (dir) {
OWLL_WRITE_ONE(lldev, &timing_regular);
Modified: stable/12/sys/net/mppcc.c
==============================================================================
--- stable/12/sys/net/mppcc.c Thu May 21 02:04:10 2020 (r361314)
+++ stable/12/sys/net/mppcc.c Thu May 21 02:08:34 2020 (r361315)
@@ -232,7 +232,7 @@ int MPPC_Compress(u_char **src, u_char **dst, u_long *
} else if (off < 8192) { /* 16-bit offset; 320 <= offset < 8192
*/
putbits16(*dst, 0xc000|(off-320), 16, &olen, &l);
} else { /* NOTREACHED */
- __unreachable();
+ __assert_unreachable();
rtn &= ~MPPC_OK;
return (rtn);
}
Modified: stable/12/sys/sys/systm.h
==============================================================================
--- stable/12/sys/sys/systm.h Thu May 21 02:04:10 2020 (r361314)
+++ stable/12/sys/sys/systm.h Thu May 21 02:08:34 2020 (r361315)
@@ -108,12 +108,16 @@ void kassert_panic(const char *fmt, ...)
__printflike
kassert_panic msg; \
} \
} while (0)
+#define __assert_unreachable() \
+ panic("executing segment marked as unreachable at %s:%d (%s)\n", \
+ __FILE__, __LINE__, __func__)
#else
#define KASSERT(exp,msg) do { \
} while (0)
#define VNASSERT(exp, vp, msg) do { \
} while (0)
+#define __assert_unreachable() __unreachable()
#endif
#ifndef CTASSERT /* Allow lint to override */
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