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Add sysctl debug.kdb.stack_overflow to conveniently test kernel

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handling of the kstack overflow.

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
This commit is contained in:
Konstantin Belousov 2018-01-13 11:59:49 +00:00
parent 1b54ffc8d2
commit fd94177c70
1 changed files with 35 additions and 0 deletions
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35
sys/kern/subr_kdb.c
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@ -85,6 +85,7 @@ static int kdb_sysctl_enter(SYSCTL_HANDLER_ARGS);
static int kdb_sysctl_panic(SYSCTL_HANDLER_ARGS);
static int kdb_sysctl_trap(SYSCTL_HANDLER_ARGS);
static int kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS);
static int kdb_sysctl_stack_overflow(SYSCTL_HANDLER_ARGS);
static SYSCTL_NODE(_debug, OID_AUTO, kdb, CTLFLAG_RW, NULL, "KDB nodes");
@ -110,6 +111,10 @@ SYSCTL_PROC(_debug_kdb, OID_AUTO, trap_code,
CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
kdb_sysctl_trap_code, "I", "set to cause a page fault via code access");
SYSCTL_PROC(_debug_kdb, OID_AUTO, stack_overflow,
CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_SECURE, NULL, 0,
kdb_sysctl_stack_overflow, "I", "set to cause a stack overflow");
SYSCTL_INT(_debug_kdb, OID_AUTO, break_to_debugger,
CTLFLAG_RWTUN | CTLFLAG_SECURE,
&kdb_break_to_debugger, 0, "Enable break to debugger");
@ -225,6 +230,36 @@ kdb_sysctl_trap_code(SYSCTL_HANDLER_ARGS)
return (0);
}
static void kdb_stack_overflow(volatile int *x) __noinline;
static void
kdb_stack_overflow(volatile int *x)
{
if (*x > 10000000)
return;
kdb_stack_overflow(x);
*x += PCPU_GET(cpuid) / 1000000;
}
static int
kdb_sysctl_stack_overflow(SYSCTL_HANDLER_ARGS)
{
int error, i;
volatile int x;
error = sysctl_wire_old_buffer(req, sizeof(int));
if (error == 0) {
i = 0;
error = sysctl_handle_int(oidp, &i, 0, req);
}
if (error != 0 || req->newptr == NULL)
return (error);
x = 0;
kdb_stack_overflow(&x);
return (0);
}
void
kdb_panic(const char *msg)
{