| Message ID | 20250205225104.096389081@goodmis.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | ring-buffer/tracing: Save module information in persistent memory | expand |
On Wed, 05 Feb 2025 17:50:38 -0500 Steven Rostedt <rostedt@goodmis.org> wrote: > From: Steven Rostedt <rostedt@goodmis.org> > > Add the last boot module's names and addresses to the last_boot_info file. > This only shows the module information from a previous boot. If the buffer > is started and is recording the current boot, this file still will only > show "current". > > # cat instances/boot_mapped/last_boot_info > Offset: 10c00000 > ffffffffc00ca000 usb_serial_simple > ffffffffc00ae000 usbserial > ffffffffc008b000 bfq This is just a suggestion, what about using the same format for all lines? For example, # cat instances/boot_mapped/last_boot_info 10c00000 [kernel] ffffffffc00ca000 usb_serial_simple ffffffffc00ae000 usbserial ffffffffc008b000 bfq > > # echo function > instances/boot_mapped/current_tracer > # cat instances/boot_mapped/last_boot_info > Offset: current And this one is empty if it is already for the current. (because last boot information is cleared) Thank you, > > Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> > --- > kernel/trace/trace.c | 103 +++++++++++++++++++++++++++++++++++++------ > 1 file changed, 90 insertions(+), 13 deletions(-) > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index a8e5f7ac2193..7b4027804cd4 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -6005,6 +6005,8 @@ struct trace_scratch { > struct trace_mod_entry entries[]; > }; > > +static DEFINE_MUTEX(scratch_mutex); > + > static int save_mod(struct module *mod, void *data) > { > struct trace_array *tr = data; > @@ -6012,6 +6014,8 @@ static int save_mod(struct module *mod, void *data) > struct trace_mod_entry *entry; > unsigned int size; > > + guard(mutex)(&scratch_mutex); > + > tscratch = tr->scratch; > if (!tscratch) > return -1; > @@ -6882,15 +6886,47 @@ tracing_total_entries_read(struct file *filp, char __user *ubuf, > return simple_read_from_buffer(ubuf, cnt, ppos, buf, r); > } > > -static ssize_t > -tracing_last_boot_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos) > +#define LAST_BOOT_HEADER ((void *)1) > + > +static void *l_next(struct seq_file *m, void *v, loff_t *pos) > { > - struct trace_array *tr = filp->private_data; > + struct trace_array *tr = m->private; > struct trace_scratch *tscratch = tr->scratch; > - struct seq_buf seq; > - char buf[64]; > + unsigned int index = *pos; > + > + (*pos)++; > + > + if (*pos == 1) > + return LAST_BOOT_HEADER; > + > + /* Only show offsets of the last boot data */ > + if (!tscratch || !(tr->flags & TRACE_ARRAY_FL_LAST_BOOT)) > + return NULL; > + > + /* *pos 0 is for the header, 1 is for the first module */ > + index--; > + > + if (index >= tscratch->nr_entries) > + return NULL; > > - seq_buf_init(&seq, buf, 64); > + return &tscratch->entries[index]; > +} > + > +static void *l_start(struct seq_file *m, loff_t *pos) > +{ > + mutex_lock(&scratch_mutex); > + > + return l_next(m, NULL, pos); > +} > + > +static void l_stop(struct seq_file *m, void *p) > +{ > + mutex_unlock(&scratch_mutex); > +} > + > +static void show_last_boot_header(struct seq_file *m, struct trace_array *tr) > +{ > + struct trace_scratch *tscratch = tr->scratch; > > /* > * Do not leak KASLR address. This only shows the KASLR address of > @@ -6900,11 +6936,52 @@ tracing_last_boot_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t > * should not be the same as the current boot. > */ > if (!tscratch || !(tr->flags & TRACE_ARRAY_FL_LAST_BOOT)) > - seq_buf_puts(&seq, "Offset: current\n"); > + seq_puts(m, "Offset: current\n"); > else > - seq_buf_printf(&seq, "Offset: %lx\n", tscratch->kaslr_addr); > + seq_printf(m, "Offset: %lx\n", tscratch->kaslr_addr); > +} > > - return simple_read_from_buffer(ubuf, cnt, ppos, buf, seq_buf_used(&seq)); > +static int l_show(struct seq_file *m, void *v) > +{ > + struct trace_array *tr = m->private; > + struct trace_mod_entry *entry = v; > + > + if (v == LAST_BOOT_HEADER) { > + show_last_boot_header(m, tr); > + return 0; > + } > + > + seq_printf(m, "%lx %s\n", entry->mod_addr, entry->mod_name); > + return 0; > +} > + > +static const struct seq_operations last_boot_seq_ops = { > + .start = l_start, > + .next = l_next, > + .stop = l_stop, > + .show = l_show, > +}; > + > +static int tracing_last_boot_open(struct inode *inode, struct file *file) > +{ > + struct trace_array *tr = inode->i_private; > + struct seq_file *m; > + int ret; > + > + ret = tracing_check_open_get_tr(tr); > + if (ret) > + return ret; > + > + ret = seq_open(file, &last_boot_seq_ops); > + if (ret) { > + trace_array_put(tr); > + return ret; > + } > + > + m = file->private_data; > + m->private = tr; > + > + return 0; > } > > static int tracing_buffer_meta_open(struct inode *inode, struct file *filp) > @@ -7533,10 +7610,10 @@ static const struct file_operations trace_time_stamp_mode_fops = { > }; > > static const struct file_operations last_boot_fops = { > - .open = tracing_open_generic_tr, > - .read = tracing_last_boot_read, > - .llseek = generic_file_llseek, > - .release = tracing_release_generic_tr, > + .open = tracing_last_boot_open, > + .read = seq_read, > + .llseek = seq_lseek, > + .release = tracing_seq_release, > }; > > #ifdef CONFIG_TRACER_SNAPSHOT > -- > 2.45.2 > >
On Fri, 7 Feb 2025 10:51:11 +0900 Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote: > > # cat instances/boot_mapped/last_boot_info > > Offset: 10c00000 > > ffffffffc00ca000 usb_serial_simple > > ffffffffc00ae000 usbserial > > ffffffffc008b000 bfq > > This is just a suggestion, what about using the same format for all > lines? For example, > > # cat instances/boot_mapped/last_boot_info > 10c00000 [kernel] > ffffffffc00ca000 usb_serial_simple > ffffffffc00ae000 usbserial > ffffffffc008b000 bfq This can be confusing because the first is an offset, and the others are addresses. > > > > > # echo function > instances/boot_mapped/current_tracer > > # cat instances/boot_mapped/last_boot_info > > Offset: current > > And this one is empty if it is already for the current. > (because last boot information is cleared) Hmm, I have to think about that. Thanks, -- Steve
On Thu, 6 Feb 2025 21:02:47 -0500 Steven Rostedt <rostedt@goodmis.org> wrote: > On Fri, 7 Feb 2025 10:51:11 +0900 > Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote: > > > > # cat instances/boot_mapped/last_boot_info > > > Offset: 10c00000 > > > ffffffffc00ca000 usb_serial_simple > > > ffffffffc00ae000 usbserial > > > ffffffffc008b000 bfq > > > > This is just a suggestion, what about using the same format for all > > lines? For example, > > > > # cat instances/boot_mapped/last_boot_info > > 10c00000 [kernel] > > ffffffffc00ca000 usb_serial_simple > > ffffffffc00ae000 usbserial > > ffffffffc008b000 bfq > > This can be confusing because the first is an offset, and the others are > addresses. I think both are the offset from the viewpoint of `nm` results. :) $ nm vmlinux | grep " t " | sort | head -n 5 ffffffff81000820 t __pfx_devkmsg_emit ffffffff81000830 t devkmsg_emit ffffffff81000a80 t __pfx_io_queue_deferred ffffffff81000a90 t io_queue_deferred ffffffff81000ca0 t __pfx_io_uring_drop_tctx_refs $ nm samples/trace_events/trace-events-sample.ko | grep " t " | sort | head -n 5 0000000000000440 t __pfx_trace_event_raw_event_foo_bar 0000000000000450 t trace_event_raw_event_foo_bar 0000000000000780 t __pfx_perf_trace_foo_bar 0000000000000790 t perf_trace_foo_bar 0000000000000af0 t __pfx_trace_event_raw_event_foo_bar_with_cond Thank you,
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index a8e5f7ac2193..7b4027804cd4 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -6005,6 +6005,8 @@ struct trace_scratch { struct trace_mod_entry entries[]; }; +static DEFINE_MUTEX(scratch_mutex); + static int save_mod(struct module *mod, void *data) { struct trace_array *tr = data; @@ -6012,6 +6014,8 @@ static int save_mod(struct module *mod, void *data) struct trace_mod_entry *entry; unsigned int size; + guard(mutex)(&scratch_mutex); + tscratch = tr->scratch; if (!tscratch) return -1; @@ -6882,15 +6886,47 @@ tracing_total_entries_read(struct file *filp, char __user *ubuf, return simple_read_from_buffer(ubuf, cnt, ppos, buf, r); } -static ssize_t -tracing_last_boot_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos) +#define LAST_BOOT_HEADER ((void *)1) + +static void *l_next(struct seq_file *m, void *v, loff_t *pos) { - struct trace_array *tr = filp->private_data; + struct trace_array *tr = m->private; struct trace_scratch *tscratch = tr->scratch; - struct seq_buf seq; - char buf[64]; + unsigned int index = *pos; + + (*pos)++; + + if (*pos == 1) + return LAST_BOOT_HEADER; + + /* Only show offsets of the last boot data */ + if (!tscratch || !(tr->flags & TRACE_ARRAY_FL_LAST_BOOT)) + return NULL; + + /* *pos 0 is for the header, 1 is for the first module */ + index--; + + if (index >= tscratch->nr_entries) + return NULL; - seq_buf_init(&seq, buf, 64); + return &tscratch->entries[index]; +} + +static void *l_start(struct seq_file *m, loff_t *pos) +{ + mutex_lock(&scratch_mutex); + + return l_next(m, NULL, pos); +} + +static void l_stop(struct seq_file *m, void *p) +{ + mutex_unlock(&scratch_mutex); +} + +static void show_last_boot_header(struct seq_file *m, struct trace_array *tr) +{ + struct trace_scratch *tscratch = tr->scratch; /* * Do not leak KASLR address. This only shows the KASLR address of @@ -6900,11 +6936,52 @@ tracing_last_boot_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t * should not be the same as the current boot. */ if (!tscratch || !(tr->flags & TRACE_ARRAY_FL_LAST_BOOT)) - seq_buf_puts(&seq, "Offset: current\n"); + seq_puts(m, "Offset: current\n"); else - seq_buf_printf(&seq, "Offset: %lx\n", tscratch->kaslr_addr); + seq_printf(m, "Offset: %lx\n", tscratch->kaslr_addr); +} - return simple_read_from_buffer(ubuf, cnt, ppos, buf, seq_buf_used(&seq)); +static int l_show(struct seq_file *m, void *v) +{ + struct trace_array *tr = m->private; + struct trace_mod_entry *entry = v; + + if (v == LAST_BOOT_HEADER) { + show_last_boot_header(m, tr); + return 0; + } + + seq_printf(m, "%lx %s\n", entry->mod_addr, entry->mod_name); + return 0; +} + +static const struct seq_operations last_boot_seq_ops = { + .start = l_start, + .next = l_next, + .stop = l_stop, + .show = l_show, +}; + +static int tracing_last_boot_open(struct inode *inode, struct file *file) +{ + struct trace_array *tr = inode->i_private; + struct seq_file *m; + int ret; + + ret = tracing_check_open_get_tr(tr); + if (ret) + return ret; + + ret = seq_open(file, &last_boot_seq_ops); + if (ret) { + trace_array_put(tr); + return ret; + } + + m = file->private_data; + m->private = tr; + + return 0; } static int tracing_buffer_meta_open(struct inode *inode, struct file *filp) @@ -7533,10 +7610,10 @@ static const struct file_operations trace_time_stamp_mode_fops = { }; static const struct file_operations last_boot_fops = { - .open = tracing_open_generic_tr, - .read = tracing_last_boot_read, - .llseek = generic_file_llseek, - .release = tracing_release_generic_tr, + .open = tracing_last_boot_open, + .read = seq_read, + .llseek = seq_lseek, + .release = tracing_seq_release, }; #ifdef CONFIG_TRACER_SNAPSHOT