freebsd-skq/sys/arm64/include/csan.h
Jessica Clarke 05985a7f80 arm64: Improve DDB backtrace support
The existing implementation relies on each trap handler saving a normal
stack frame record, which is a waste of time and space when we're
already saving a trapframe to the stack. It's also wrong as it currently
saves LR not ELR.

Instead of patching it up, rewrite it based on the RISC-V implementation
with inspiration from the amd64 implementation for how to handle
vectored traps to provide an improved implementation. This includes
compressing the information down to one line like other architectures
rather than the highly-verbose old form that repeats itself by printing
LR and FP in one frame only to print them as PC and SP in the next. It
also includes printing out actually useful information about the traps
that occurred, though FAR is not saved in the trapframe so we cannot
print it (in general it can be clobbered between when the trap happened
and now), only ESR.

The AAPCS also allows the stack frame record to be located anywhere in
the frame, not just the top, so the caller's SP is not at a fixed offset
from the callee's FP like on almost all other architectures in
existence. This means there is no way to derive the caller's SP in the
unwinder, and so we have to drop that bit of (unused) state everywhere.

Reviewed by:	jhb, markj
Differential Revision:	https://reviews.freebsd.org/D28026
2021-02-01 14:15:57 +00:00

107 lines
2.7 KiB
C

/* $NetBSD: csan.h,v 1.2 2019/11/06 06:57:22 maxv Exp $ */
/*
* Copyright (c) 2019 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Maxime Villard.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* $FreeBSD$
*/
#include <machine/cpufunc.h>
#include <machine/stack.h>
#include <machine/vmparam.h>
static inline bool
kcsan_md_unsupported(vm_offset_t addr)
{
return false;
}
static inline bool
kcsan_md_is_avail(void)
{
return true;
}
static inline void
kcsan_md_disable_intrs(uint64_t *state)
{
*state = intr_disable();
}
static inline void
kcsan_md_enable_intrs(uint64_t *state)
{
intr_restore(*state);
}
static inline void
kcsan_md_delay(uint64_t us)
{
DELAY(us);
}
static void
kcsan_md_unwind(void)
{
#ifdef DDB
c_db_sym_t sym;
db_expr_t offset;
const char *symname;
#endif
struct unwind_state frame;
int nsym;
frame.fp = (uintptr_t)__builtin_frame_address(0);
frame.pc = (uintptr_t)kcsan_md_unwind;
nsym = 0;
while (1) {
if (!unwind_frame(curthread, &frame))
break;
if (!INKERNEL((vm_offset_t)frame.pc))
break;
#ifdef DDB
sym = db_search_symbol((vm_offset_t)frame.pc, DB_STGY_PROC,
&offset);
db_symbol_values(sym, &symname, NULL);
printf("#%d %p in %s+%#lx\n", nsym, (void *)frame.pc,
symname, offset);
#else
printf("#%d %p\n", nsym, (void *)frame.pc);
#endif
nsym++;
if (nsym >= 15) {
break;
}
}
}