Add a 512-byte buffer (ci_panicbuf) to each cpu_info struct on each
platform for use by panic(9). The first panic on a given CPU writes
its message to this buffer. Subsequent panics on a given CPU print
the panic message to the console but do not modify the buffer. This
aids debugging in two cases:
- If 2+ CPUs panic simultaneously there is no risk of garbled messages
in the panic buffer.
- If a CPU panics and then the operator causes a second panic while
using ddb(4), the operator can still recall the first failure on
a particular CPU.
Misc. changes to support this bigger change:
- Set panicstr atomically to identify the first CPU to reach panic().
- Tweak db_show_panic_cmd() to print all panic messages across all
CPUs. Prefix the first panic with an asterisk ('*').
- Prefer db_printf() to printf() during a panic if we have it.
Apparently it disturbs less global state.
- On amd64, tweak fault() to write the local panic buffer. This needs
more work.
Prompted by bluhm@ and deraadt@. Mostly written by deraadt@.
Discussed with bluhm@, deraadt@ and kettenis@.
Borne from a discussion on tech@ about making panic(9) more MP-safe:
https://marc.info/?l=openbsd-tech&m=
162086462316143&w=2
ok kettenis@, visa@, bluhm@, deraadt@
-/* $OpenBSD: cpu.h,v 1.63 2020/06/05 14:25:05 naddy Exp $ */
+/* $OpenBSD: cpu.h,v 1.64 2021/06/02 00:39:26 cheloha Exp $ */
/* $NetBSD: cpu.h,v 1.45 2000/08/21 02:03:12 thorpej Exp $ */
/*-
#ifdef GPROF
struct gmonparam *ci_gmon;
#endif
+ char ci_panicbuf[512];
};
#define CPUF_PRIMARY 0x01 /* CPU is primary CPU */
-/* $OpenBSD: trap.c,v 1.88 2021/05/05 07:29:00 mpi Exp $ */
+/* $OpenBSD: trap.c,v 1.89 2021/06/02 00:39:26 cheloha Exp $ */
/* $NetBSD: trap.c,v 1.2 2003/05/04 23:51:56 fvdl Exp $ */
/*-
#include <machine/psl.h>
#include <machine/trap.h>
#ifdef DDB
+#include <ddb/db_output.h>
#include <machine/db_machdep.h>
#endif
long _type);
static inline void
-fault(const char *format, ...)
+fault(const char *fmt, ...)
{
- static char faultbuf[512];
+ struct cpu_info *ci = curcpu();
va_list ap;
- /*
- * Save the fault info for DDB. Kernel lock protects
- * faultbuf from being overwritten by another CPU.
- */
- va_start(ap, format);
- vsnprintf(faultbuf, sizeof faultbuf, format, ap);
+ atomic_cas_ptr(&panicstr, NULL, ci->ci_panicbuf);
+
+ va_start(ap, fmt);
+ vsnprintf(ci->ci_panicbuf, sizeof(ci->ci_panicbuf), fmt, ap);
va_end(ap);
- printf("%s\n", faultbuf);
- faultstr = faultbuf;
+#ifdef DDB
+ db_printf("%s\n", ci->ci_panicbuf);
+#else
+ printf("%s\n", ci->ci_panicbuf);
+#endif
}
static inline int
-/* $OpenBSD: cpu.h,v 1.137 2020/06/03 06:54:04 dlg Exp $ */
+/* $OpenBSD: cpu.h,v 1.138 2021/06/02 00:39:26 cheloha Exp $ */
/* $NetBSD: cpu.h,v 1.1 2003/04/26 18:39:39 fvdl Exp $ */
/*-
struct vmxon_region *ci_vmxon_region;
int64_t ci_tsc_skew; /* counter skew vs cpu0 */
+
+ char ci_panicbuf[512];
};
#define CPUF_BSP 0x0001 /* CPU is the original BSP */
-/* $OpenBSD: cpu.h,v 1.59 2020/05/31 06:23:57 dlg Exp $ */
+/* $OpenBSD: cpu.h,v 1.60 2021/06/02 00:39:26 cheloha Exp $ */
/* $NetBSD: cpu.h,v 1.34 2003/06/23 11:01:08 martin Exp $ */
/*
#ifdef GPROF
struct gmonparam *ci_gmon;
#endif
+
+ char ci_panicbuf[512];
};
#define CPUF_PRIMARY (1<<0)
-/* $OpenBSD: cpu.h,v 1.20 2021/05/15 11:30:27 kettenis Exp $ */
+/* $OpenBSD: cpu.h,v 1.21 2021/06/02 00:39:26 cheloha Exp $ */
/*
* Copyright (c) 2016 Dale Rahn <drahn@dalerahn.com>
*
#ifdef GPROF
struct gmonparam *ci_gmon;
#endif
+
+ char ci_panicbuf[512];
};
#define CPUF_PRIMARY (1<<0)
-/* $OpenBSD: cpu.h,v 1.93 2020/06/14 20:29:13 naddy Exp $ */
+/* $OpenBSD: cpu.h,v 1.94 2021/06/02 00:39:26 cheloha Exp $ */
/*
* Copyright (c) 2000-2004 Michael Shalayeff
#ifdef GPROF
struct gmonparam *ci_gmon;
#endif
+
+ char ci_panicbuf[512];
} __attribute__((__aligned__(64)));
#define CPUF_RUNNING 0x0001 /* CPU is running. */
-/* $OpenBSD: cpu.h,v 1.173 2021/03/11 11:16:57 jsg Exp $ */
+/* $OpenBSD: cpu.h,v 1.174 2021/06/02 00:39:26 cheloha Exp $ */
/* $NetBSD: cpu.h,v 1.35 1996/05/05 19:29:26 christos Exp $ */
/*-
#if defined(GPROF) || defined(DDBPROF)
struct gmonparam *ci_gmon;
#endif
+ char ci_panicbuf[512];
};
/*
-/* $OpenBSD: cpu.h,v 1.68 2020/05/31 06:23:57 dlg Exp $ */
+/* $OpenBSD: cpu.h,v 1.69 2021/06/02 00:39:26 cheloha Exp $ */
/*
* Copyright (c) 1996 Nivas Madhur
* Copyright (c) 1992, 1993
#ifdef GPROF
struct gmonparam *ci_gmon;
#endif
+ char ci_panicbuf[512];
};
extern cpuid_t master_cpu;
-/* $OpenBSD: cpu.h,v 1.133 2021/05/28 16:33:36 visa Exp $ */
+/* $OpenBSD: cpu.h,v 1.134 2021/06/02 00:39:26 cheloha Exp $ */
/*-
* Copyright (c) 1992, 1993
#define CI_DDB_INDDB 4
#ifdef DIAGNOSTIC
- int ci_mutex_level;
+ int ci_mutex_level;
#endif
#ifdef GPROF
struct gmonparam *ci_gmon;
#endif
+ char ci_panicbuf[512];
};
#define CPUF_PRIMARY 0x01 /* CPU is primary CPU */
-/* $OpenBSD: cpu.h,v 1.68 2020/06/05 14:25:05 naddy Exp $ */
+/* $OpenBSD: cpu.h,v 1.69 2021/06/02 00:39:26 cheloha Exp $ */
/* $NetBSD: cpu.h,v 1.1 1996/09/30 16:34:21 ws Exp $ */
/*
#ifdef GPROF
struct gmonparam *ci_gmon;
#endif
+ char ci_panicbuf[512];
};
static __inline struct cpu_info *
-/* $OpenBSD: cpu.h,v 1.29 2020/12/30 06:06:30 gkoehler Exp $ */
+/* $OpenBSD: cpu.h,v 1.30 2021/06/02 00:39:27 cheloha Exp $ */
/*
* Copyright (c) 2020 Mark Kettenis <kettenis@openbsd.org>
#define CI_DDB_ENTERDDB 3
#define CI_DDB_INDDB 4
#endif
+ char ci_panicbuf[512];
};
#define CPUF_PRIMARY (1 << 0)
-/* $OpenBSD: cpu.h,v 1.6 2021/05/12 01:20:52 jsg Exp $ */
+/* $OpenBSD: cpu.h,v 1.7 2021/06/02 00:39:27 cheloha Exp $ */
/*
* Copyright (c) 2019 Mike Larkin <mlarkin@openbsd.org>
#ifdef GPROF
struct gmonparam *ci_gmon;
#endif
+ char ci_panicbuf[512];
};
#define CPUF_PRIMARY (1<<0)
-/* $OpenBSD: cpu.h,v 1.30 2020/09/25 14:42:39 deraadt Exp $ */
+/* $OpenBSD: cpu.h,v 1.31 2021/06/02 00:39:27 cheloha Exp $ */
/* $NetBSD: cpu.h,v 1.41 2006/01/21 04:24:12 uwe Exp $ */
/*-
#endif
int ci_want_resched;
+
+ char ci_panicbuf[512];
};
extern struct cpu_info cpu_info_store;
-/* $OpenBSD: cpu.h,v 1.96 2020/09/14 20:28:41 deraadt Exp $ */
+/* $OpenBSD: cpu.h,v 1.97 2021/06/02 00:39:27 cheloha Exp $ */
/* $NetBSD: cpu.h,v 1.28 2001/06/14 22:56:58 thorpej Exp $ */
/*
#ifdef GPROF
struct gmonparam *ci_gmon;
#endif
+ char ci_panicbuf[512];
};
#define CPUF_RUNNING 0x0001 /* CPU is running */
-/* $OpenBSD: db_command.c,v 1.90 2020/10/26 18:53:20 deraadt Exp $ */
+/* $OpenBSD: db_command.c,v 1.91 2021/06/02 00:39:25 cheloha Exp $ */
/* $NetBSD: db_command.c,v 1.20 1996/03/30 22:30:05 christos Exp $ */
/*
void
db_show_panic_cmd(db_expr_t addr, int have_addr, db_expr_t count, char *modif)
{
- if (panicstr)
- db_printf("%s\n", panicstr);
- else if (faultstr) {
- db_printf("kernel page fault\n");
- db_printf("%s\n", faultstr);
- db_stack_trace_print(addr, have_addr, 1, modif, db_printf);
+ struct cpu_info *ci;
+ char *prefix;
+ CPU_INFO_ITERATOR cii;
+ int panicked = 0;
+
+ CPU_INFO_FOREACH(cii, ci) {
+ if (ci->ci_panicbuf[0] != '\0') {
+ prefix = (panicstr == ci->ci_panicbuf) ? "*" : " ";
+ db_printf("%scpu%d: %s\n",
+ prefix, CPU_INFO_UNIT(ci), ci->ci_panicbuf);
+ panicked = 1;
+ }
}
- else
+ if (!panicked)
db_printf("the kernel did not panic\n"); /* yet */
}
-/* $OpenBSD: subr_prf.c,v 1.103 2021/05/16 15:10:20 deraadt Exp $ */
+/* $OpenBSD: subr_prf.c,v 1.104 2021/06/02 00:39:25 cheloha Exp $ */
/* $NetBSD: subr_prf.c,v 1.45 1997/10/24 18:14:25 chuck Exp $ */
/*-
extern int log_open; /* subr_log: is /dev/klog open? */
const char *panicstr; /* arg to first call to panic (used as a flag
to indicate that panic has already been called). */
-const char *faultstr; /* page fault string */
#ifdef DDB
/*
* Enter ddb on panic.
log(LOG_ERR, "%s: table is full\n", tab);
}
+/*
+ * If we have panicked, prefer db_printf() and db_vprintf() where
+ * available.
+ */
+#ifdef DDB
+#define panic_printf(...) db_printf(__VA_ARGS__)
+#define panic_vprintf(...) db_vprintf(__VA_ARGS__)
+#else
+#define panic_printf(...) printf(__VA_ARGS__)
+#define panic_vprintf(...) vprintf(__VA_ARGS__)
+#endif
+
/*
* panic: handle an unresolvable fatal error
*
void
panic(const char *fmt, ...)
{
- static char panicbuf[512];
+ struct cpu_info *ci = curcpu();
int bootopt;
va_list ap;
+ bootopt = RB_AUTOBOOT | RB_DUMP;
+ if (atomic_cas_ptr(&panicstr, NULL, ci->ci_panicbuf) != NULL)
+ bootopt |= RB_NOSYNC;
+
/* do not trigger assertions, we know that we are inconsistent */
splassert_ctl = 0;
- /* make sure we see kernel printf output */
- printf_flags |= TOCONS;
+#ifdef BOOT_QUIET
+ printf_flags |= TOCONS; /* make sure we see kernel printf output */
+#endif
- bootopt = RB_AUTOBOOT | RB_DUMP;
- va_start(ap, fmt);
- if (panicstr)
- bootopt |= RB_NOSYNC;
- else {
- vsnprintf(panicbuf, sizeof panicbuf, fmt, ap);
- panicstr = panicbuf;
+ /*
+ * All panic messages are printed, but only the first panic on a
+ * given CPU is written to its panicbuf.
+ */
+ if (ci->ci_panicbuf[0] == '\0') {
+ va_start(ap, fmt);
+ vsnprintf(ci->ci_panicbuf, sizeof(ci->ci_panicbuf), fmt, ap);
+ va_end(ap);
+ panic_printf("panic: %s\n", ci->ci_panicbuf);
+ } else {
+ panic_printf("panic: ");
+ va_start(ap, fmt);
+ panic_vprintf(fmt, ap);
+ va_end(ap);
+ panic_printf("\n");
}
- va_end(ap);
-
- printf("panic: ");
- va_start(ap, fmt);
- vprintf(fmt, ap);
- printf("\n");
- va_end(ap);
#ifdef DDB
if (db_panic)
-/* $OpenBSD: systm.h,v 1.153 2021/04/28 09:42:04 sashan Exp $ */
+/* $OpenBSD: systm.h,v 1.154 2021/06/02 00:39:25 cheloha Exp $ */
/* $NetBSD: systm.h,v 1.50 1996/06/09 04:55:09 briggs Exp $ */
/*-
*/
extern int securelevel; /* system security level */
extern const char *panicstr; /* panic message */
-extern const char *faultstr; /* fault message */
extern const char version[]; /* system version */
extern const char copyright[]; /* system copyright */
extern const char ostype[];
projects / openbsd / commitdiff