c493ead38a
commit 0c97bf863efce63d6ab7971dad811601e6171d2f upstream.
Starting with GCC 9, -Warray-bounds detects cases when memset is called
starting on a member of a struct but the size to be cleared ends up
writing over further members.
Such a call happens in the trace code to clear, at once, all members
after and including `seq` on struct trace_iterator:
In function 'memset',
inlined from 'ftrace_dump' at kernel/trace/trace.c:8914:3:
./include/linux/string.h:344:9: warning: '__builtin_memset' offset
[8505, 8560] from the object at 'iter' is out of the bounds of
referenced subobject 'seq' with type 'struct trace_seq' at offset
4368 [-Warray-bounds]
344 | return __builtin_memset(p, c, size);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
In order to avoid GCC complaining about it, we compute the address
ourselves by adding the offsetof distance instead of referring
directly to the member.
Since there are two places doing this clear (trace.c and trace_kdb.c),
take the chance to move the workaround into a single place in
the internal header.
Link: http://lkml.kernel.org/r/20190523124535.GA12931@gmail.com
Signed-off-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
[ Removed unnecessary parenthesis around "iter" ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
141 lines
3.1 KiB
C
141 lines
3.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* kdb helper for dumping the ftrace buffer
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*
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* Copyright (C) 2010 Jason Wessel <jason.wessel@windriver.com>
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*
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* ftrace_dump_buf based on ftrace_dump:
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* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
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* Copyright (C) 2008 Ingo Molnar <mingo@redhat.com>
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*
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*/
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#include <linux/init.h>
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#include <linux/kgdb.h>
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#include <linux/kdb.h>
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#include <linux/ftrace.h>
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#include "trace.h"
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#include "trace_output.h"
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static void ftrace_dump_buf(int skip_lines, long cpu_file)
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{
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/* use static because iter can be a bit big for the stack */
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static struct trace_iterator iter;
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static struct ring_buffer_iter *buffer_iter[CONFIG_NR_CPUS];
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struct trace_array *tr;
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unsigned int old_userobj;
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int cnt = 0, cpu;
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trace_init_global_iter(&iter);
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iter.buffer_iter = buffer_iter;
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tr = iter.tr;
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for_each_tracing_cpu(cpu) {
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atomic_inc(&per_cpu_ptr(iter.trace_buffer->data, cpu)->disabled);
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}
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old_userobj = tr->trace_flags;
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/* don't look at user memory in panic mode */
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tr->trace_flags &= ~TRACE_ITER_SYM_USEROBJ;
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kdb_printf("Dumping ftrace buffer:\n");
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trace_iterator_reset(&iter);
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iter.iter_flags |= TRACE_FILE_LAT_FMT;
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if (cpu_file == RING_BUFFER_ALL_CPUS) {
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for_each_tracing_cpu(cpu) {
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iter.buffer_iter[cpu] =
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ring_buffer_read_prepare(iter.trace_buffer->buffer,
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cpu, GFP_ATOMIC);
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ring_buffer_read_start(iter.buffer_iter[cpu]);
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tracing_iter_reset(&iter, cpu);
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}
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} else {
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iter.cpu_file = cpu_file;
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iter.buffer_iter[cpu_file] =
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ring_buffer_read_prepare(iter.trace_buffer->buffer,
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cpu_file, GFP_ATOMIC);
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ring_buffer_read_start(iter.buffer_iter[cpu_file]);
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tracing_iter_reset(&iter, cpu_file);
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}
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while (trace_find_next_entry_inc(&iter)) {
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if (!cnt)
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kdb_printf("---------------------------------\n");
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cnt++;
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if (!skip_lines) {
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print_trace_line(&iter);
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trace_printk_seq(&iter.seq);
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} else {
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skip_lines--;
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}
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if (KDB_FLAG(CMD_INTERRUPT))
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goto out;
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}
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if (!cnt)
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kdb_printf(" (ftrace buffer empty)\n");
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else
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kdb_printf("---------------------------------\n");
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out:
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tr->trace_flags = old_userobj;
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for_each_tracing_cpu(cpu) {
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atomic_dec(&per_cpu_ptr(iter.trace_buffer->data, cpu)->disabled);
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}
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for_each_tracing_cpu(cpu) {
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if (iter.buffer_iter[cpu]) {
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ring_buffer_read_finish(iter.buffer_iter[cpu]);
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iter.buffer_iter[cpu] = NULL;
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}
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}
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}
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/*
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* kdb_ftdump - Dump the ftrace log buffer
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*/
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static int kdb_ftdump(int argc, const char **argv)
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{
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int skip_lines = 0;
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long cpu_file;
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char *cp;
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if (argc > 2)
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return KDB_ARGCOUNT;
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if (argc) {
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skip_lines = simple_strtol(argv[1], &cp, 0);
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if (*cp)
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skip_lines = 0;
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}
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if (argc == 2) {
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cpu_file = simple_strtol(argv[2], &cp, 0);
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if (*cp || cpu_file >= NR_CPUS || cpu_file < 0 ||
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!cpu_online(cpu_file))
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return KDB_BADINT;
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} else {
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cpu_file = RING_BUFFER_ALL_CPUS;
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}
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kdb_trap_printk++;
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ftrace_dump_buf(skip_lines, cpu_file);
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kdb_trap_printk--;
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return 0;
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}
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static __init int kdb_ftrace_register(void)
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{
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kdb_register_flags("ftdump", kdb_ftdump, "[skip_#lines] [cpu]",
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"Dump ftrace log", 0, KDB_ENABLE_ALWAYS_SAFE);
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return 0;
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}
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late_initcall(kdb_ftrace_register);
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