From: Steven Rostedt <rostedt@goodmis.org>
There's no reason to save the KASLR offset for the ring buffer itself.
That is used by the tracer. Now that the tracer has a way to save data in
the persistent memory of the ring buffer, have the tracing infrastructure
take care of the saving of the KASLR offset.
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
include/linux/ring_buffer.h | 1 -
kernel/trace/ring_buffer.c | 47 -------------------------------------
kernel/trace/trace.c | 38 ++++++++++++++++++++++++++----
kernel/trace/trace.h | 6 +++--
4 files changed, 38 insertions(+), 54 deletions(-)
diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h
index b95f940fd07a..d6d9c94e8d8a 100644
--- a/include/linux/ring_buffer.h
+++ b/include/linux/ring_buffer.h
@@ -94,7 +94,6 @@ struct trace_buffer *__ring_buffer_alloc_range(unsigned long size, unsigned flag
unsigned long range_size,
struct lock_class_key *key);
-bool ring_buffer_last_boot_delta(struct trace_buffer *buffer, unsigned long *kaslr_addr);
void *ring_buffer_meta_scratch(struct trace_buffer *buffer, unsigned int *size);
/*
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index 5a81ff785665..a42406287281 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -55,7 +55,6 @@ struct ring_buffer_meta {
};
struct ring_buffer_cpu_meta {
- unsigned long kaslr_addr;
unsigned long first_buffer;
unsigned long head_buffer;
unsigned long commit_buffer;
@@ -557,8 +556,6 @@ struct trace_buffer {
struct ring_buffer_meta *meta;
- unsigned long kaslr_addr;
-
unsigned int subbuf_size;
unsigned int subbuf_order;
unsigned int max_data_size;
@@ -1931,15 +1928,6 @@ static void rb_meta_validate_events(struct ring_buffer_per_cpu *cpu_buffer)
}
}
-static void rb_meta_init_text_addr(struct ring_buffer_cpu_meta *meta)
-{
-#ifdef CONFIG_RANDOMIZE_BASE
- meta->kaslr_addr = kaslr_offset();
-#else
- meta->kaslr_addr = 0;
-#endif
-}
-
static void rb_range_meta_init(struct trace_buffer *buffer, int nr_pages)
{
struct ring_buffer_cpu_meta *meta;
@@ -1967,7 +1955,6 @@ static void rb_range_meta_init(struct trace_buffer *buffer, int nr_pages)
meta->first_buffer += delta;
meta->head_buffer += delta;
meta->commit_buffer += delta;
- buffer->kaslr_addr = meta->kaslr_addr;
continue;
}
@@ -1984,7 +1971,6 @@ static void rb_range_meta_init(struct trace_buffer *buffer, int nr_pages)
subbuf = rb_subbufs_from_meta(meta);
meta->first_buffer = (unsigned long)subbuf;
- rb_meta_init_text_addr(meta);
/*
* The buffers[] array holds the order of the sub-buffers
@@ -2514,27 +2500,6 @@ struct trace_buffer *__ring_buffer_alloc_range(unsigned long size, unsigned flag
return alloc_buffer(size, flags, order, start, start + range_size, key);
}
-/**
- * ring_buffer_last_boot_delta - return the delta offset from last boot
- * @buffer: The buffer to return the delta from
- * @text: Return text delta
- * @data: Return data delta
- *
- * Returns: The true if the delta is non zero
- */
-bool ring_buffer_last_boot_delta(struct trace_buffer *buffer, unsigned long *kaslr_addr)
-{
- if (!buffer)
- return false;
-
- if (!buffer->kaslr_addr)
- return false;
-
- *kaslr_addr = buffer->kaslr_addr;
-
- return true;
-}
-
void *ring_buffer_meta_scratch(struct trace_buffer *buffer, unsigned int *size)
{
if (!buffer || !buffer->meta)
@@ -6098,7 +6063,6 @@ static void reset_disabled_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer)
void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu)
{
struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu];
- struct ring_buffer_cpu_meta *meta;
if (!cpumask_test_cpu(cpu, buffer->cpumask))
return;
@@ -6117,11 +6081,6 @@ void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu)
atomic_dec(&cpu_buffer->record_disabled);
atomic_dec(&cpu_buffer->resize_disabled);
- /* Make sure persistent meta now uses this buffer's addresses */
- meta = rb_range_meta(buffer, 0, cpu_buffer->cpu);
- if (meta)
- rb_meta_init_text_addr(meta);
-
mutex_unlock(&buffer->mutex);
}
EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu);
@@ -6136,7 +6095,6 @@ EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu);
void ring_buffer_reset_online_cpus(struct trace_buffer *buffer)
{
struct ring_buffer_per_cpu *cpu_buffer;
- struct ring_buffer_cpu_meta *meta;
int cpu;
/* prevent another thread from changing buffer sizes */
@@ -6164,11 +6122,6 @@ void ring_buffer_reset_online_cpus(struct trace_buffer *buffer)
reset_disabled_cpu_buffer(cpu_buffer);
- /* Make sure persistent meta now uses this buffer's addresses */
- meta = rb_range_meta(buffer, 0, cpu_buffer->cpu);
- if (meta)
- rb_meta_init_text_addr(meta);
-
atomic_dec(&cpu_buffer->record_disabled);
atomic_sub(RESET_BIT, &cpu_buffer->resize_disabled);
}
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index a9e8eaf1d47e..cb9f8e6878a0 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -5994,8 +5994,14 @@ ssize_t tracing_resize_ring_buffer(struct trace_array *tr,
return ret;
}
+struct trace_scratch {
+ unsigned long kaslr_addr;
+};
+
static void update_last_data(struct trace_array *tr)
{
+ struct trace_scratch *tscratch;
+
if (!(tr->flags & TRACE_ARRAY_FL_LAST_BOOT))
return;
@@ -6010,6 +6016,17 @@ static void update_last_data(struct trace_array *tr)
/* Using current data now */
tr->text_delta = 0;
+ if (!tr->scratch)
+ return;
+
+ tscratch = tr->scratch;
+
+ /* Set the persistent ring buffer meta data to this address */
+#ifdef CONFIG_RANDOMIZE_BASE
+ tscratch->kaslr_addr = kaslr_offset();
+#else
+ tscratch->kaslr_addr = 0;
+#endif
tr->flags &= ~TRACE_ARRAY_FL_LAST_BOOT;
}
@@ -6823,6 +6840,7 @@ static ssize_t
tracing_last_boot_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
{
struct trace_array *tr = filp->private_data;
+ struct trace_scratch *tscratch = tr->scratch;
struct seq_buf seq;
char buf[64];
@@ -6835,10 +6853,10 @@ tracing_last_boot_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t
* Otherwise it shows the KASLR address from the previous boot which
* should not be the same as the current boot.
*/
- if (!(tr->flags & TRACE_ARRAY_FL_LAST_BOOT))
+ if (!tscratch || !(tr->flags & TRACE_ARRAY_FL_LAST_BOOT))
seq_buf_puts(&seq, "Offset: current\n");
else
- seq_buf_printf(&seq, "Offset: %lx\n", tr->kaslr_addr);
+ seq_buf_printf(&seq, "Offset: %lx\n", tscratch->kaslr_addr);
return simple_read_from_buffer(ubuf, cnt, ppos, buf, seq_buf_used(&seq));
}
@@ -9212,6 +9230,8 @@ static int
allocate_trace_buffer(struct trace_array *tr, struct array_buffer *buf, int size)
{
enum ring_buffer_flags rb_flags;
+ unsigned int scratch_size;
+ void *scratch;
rb_flags = tr->trace_flags & TRACE_ITER_OVERWRITE ? RB_FL_OVERWRITE : 0;
@@ -9222,10 +9242,20 @@ allocate_trace_buffer(struct trace_array *tr, struct array_buffer *buf, int size
tr->range_addr_start,
tr->range_addr_size);
+ scratch = ring_buffer_meta_scratch(buf->buffer, &scratch_size);
+ if (scratch) {
+ tr->scratch = scratch;
+ tr->scratch_size = scratch_size;
+
#ifdef CONFIG_RANDOMIZE_BASE
- if (ring_buffer_last_boot_delta(buf->buffer, &tr->kaslr_addr))
- tr->text_delta = kaslr_offset() - tr->kaslr_addr;
+ {
+ struct trace_scratch *tscratch = tr->scratch;
+
+ if (tscratch->kaslr_addr)
+ tr->text_delta = kaslr_offset() - tscratch->kaslr_addr;
+ }
#endif
+ }
/*
* This is basically the same as a mapped buffer,
* with the same restrictions.
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index abe8169c3e87..3a020fb82a34 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -348,8 +348,11 @@ struct trace_array {
unsigned int mapped;
unsigned long range_addr_start;
unsigned long range_addr_size;
- unsigned long kaslr_addr;
long text_delta;
+ void *scratch; /* pointer in persistent memory */
+ int scratch_size;
+
+ int buffer_disabled;
struct trace_pid_list __rcu *filtered_pids;
struct trace_pid_list __rcu *filtered_no_pids;
@@ -367,7 +370,6 @@ struct trace_array {
* CONFIG_TRACER_MAX_TRACE.
*/
arch_spinlock_t max_lock;
- int buffer_disabled;
#ifdef CONFIG_FTRACE_SYSCALLS
int sys_refcount_enter;
int sys_refcount_exit;
--
2.45.2On Wed, 05 Feb 2025 17:50:35 -0500
Steven Rostedt <rostedt@goodmis.org> wrote:
> From: Steven Rostedt <rostedt@goodmis.org>
>
> There's no reason to save the KASLR offset for the ring buffer itself.
> That is used by the tracer. Now that the tracer has a way to save data in
> the persistent memory of the ring buffer, have the tracing infrastructure
> take care of the saving of the KASLR offset.
>
Looks good to me. But note that the scratchpad size may not enough for
module table later, because 1 module requires at least the name[]
(64byte - sizeof(ulong)) and the base address (ulong). This means
1 entry consumes 64byte. Thus there can be only 63 entries + meta
data in 4K page. My ubuntu loads 189(!) modules;
$ lsmod | wc -l
190
so we want 255 entries, which requires 16KB.
Thank you,
> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
> ---
> include/linux/ring_buffer.h | 1 -
> kernel/trace/ring_buffer.c | 47 -------------------------------------
> kernel/trace/trace.c | 38 ++++++++++++++++++++++++++----
> kernel/trace/trace.h | 6 +++--
> 4 files changed, 38 insertions(+), 54 deletions(-)
>
> diff --git a/include/linux/ring_buffer.h b/include/linux/ring_buffer.h
> index b95f940fd07a..d6d9c94e8d8a 100644
> --- a/include/linux/ring_buffer.h
> +++ b/include/linux/ring_buffer.h
> @@ -94,7 +94,6 @@ struct trace_buffer *__ring_buffer_alloc_range(unsigned long size, unsigned flag
> unsigned long range_size,
> struct lock_class_key *key);
>
> -bool ring_buffer_last_boot_delta(struct trace_buffer *buffer, unsigned long *kaslr_addr);
> void *ring_buffer_meta_scratch(struct trace_buffer *buffer, unsigned int *size);
>
> /*
> diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
> index 5a81ff785665..a42406287281 100644
> --- a/kernel/trace/ring_buffer.c
> +++ b/kernel/trace/ring_buffer.c
> @@ -55,7 +55,6 @@ struct ring_buffer_meta {
> };
>
> struct ring_buffer_cpu_meta {
> - unsigned long kaslr_addr;
> unsigned long first_buffer;
> unsigned long head_buffer;
> unsigned long commit_buffer;
> @@ -557,8 +556,6 @@ struct trace_buffer {
>
> struct ring_buffer_meta *meta;
>
> - unsigned long kaslr_addr;
> -
> unsigned int subbuf_size;
> unsigned int subbuf_order;
> unsigned int max_data_size;
> @@ -1931,15 +1928,6 @@ static void rb_meta_validate_events(struct ring_buffer_per_cpu *cpu_buffer)
> }
> }
>
> -static void rb_meta_init_text_addr(struct ring_buffer_cpu_meta *meta)
> -{
> -#ifdef CONFIG_RANDOMIZE_BASE
> - meta->kaslr_addr = kaslr_offset();
> -#else
> - meta->kaslr_addr = 0;
> -#endif
> -}
> -
> static void rb_range_meta_init(struct trace_buffer *buffer, int nr_pages)
> {
> struct ring_buffer_cpu_meta *meta;
> @@ -1967,7 +1955,6 @@ static void rb_range_meta_init(struct trace_buffer *buffer, int nr_pages)
> meta->first_buffer += delta;
> meta->head_buffer += delta;
> meta->commit_buffer += delta;
> - buffer->kaslr_addr = meta->kaslr_addr;
> continue;
> }
>
> @@ -1984,7 +1971,6 @@ static void rb_range_meta_init(struct trace_buffer *buffer, int nr_pages)
> subbuf = rb_subbufs_from_meta(meta);
>
> meta->first_buffer = (unsigned long)subbuf;
> - rb_meta_init_text_addr(meta);
>
> /*
> * The buffers[] array holds the order of the sub-buffers
> @@ -2514,27 +2500,6 @@ struct trace_buffer *__ring_buffer_alloc_range(unsigned long size, unsigned flag
> return alloc_buffer(size, flags, order, start, start + range_size, key);
> }
>
> -/**
> - * ring_buffer_last_boot_delta - return the delta offset from last boot
> - * @buffer: The buffer to return the delta from
> - * @text: Return text delta
> - * @data: Return data delta
> - *
> - * Returns: The true if the delta is non zero
> - */
> -bool ring_buffer_last_boot_delta(struct trace_buffer *buffer, unsigned long *kaslr_addr)
> -{
> - if (!buffer)
> - return false;
> -
> - if (!buffer->kaslr_addr)
> - return false;
> -
> - *kaslr_addr = buffer->kaslr_addr;
> -
> - return true;
> -}
> -
> void *ring_buffer_meta_scratch(struct trace_buffer *buffer, unsigned int *size)
> {
> if (!buffer || !buffer->meta)
> @@ -6098,7 +6063,6 @@ static void reset_disabled_cpu_buffer(struct ring_buffer_per_cpu *cpu_buffer)
> void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu)
> {
> struct ring_buffer_per_cpu *cpu_buffer = buffer->buffers[cpu];
> - struct ring_buffer_cpu_meta *meta;
>
> if (!cpumask_test_cpu(cpu, buffer->cpumask))
> return;
> @@ -6117,11 +6081,6 @@ void ring_buffer_reset_cpu(struct trace_buffer *buffer, int cpu)
> atomic_dec(&cpu_buffer->record_disabled);
> atomic_dec(&cpu_buffer->resize_disabled);
>
> - /* Make sure persistent meta now uses this buffer's addresses */
> - meta = rb_range_meta(buffer, 0, cpu_buffer->cpu);
> - if (meta)
> - rb_meta_init_text_addr(meta);
> -
> mutex_unlock(&buffer->mutex);
> }
> EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu);
> @@ -6136,7 +6095,6 @@ EXPORT_SYMBOL_GPL(ring_buffer_reset_cpu);
> void ring_buffer_reset_online_cpus(struct trace_buffer *buffer)
> {
> struct ring_buffer_per_cpu *cpu_buffer;
> - struct ring_buffer_cpu_meta *meta;
> int cpu;
>
> /* prevent another thread from changing buffer sizes */
> @@ -6164,11 +6122,6 @@ void ring_buffer_reset_online_cpus(struct trace_buffer *buffer)
>
> reset_disabled_cpu_buffer(cpu_buffer);
>
> - /* Make sure persistent meta now uses this buffer's addresses */
> - meta = rb_range_meta(buffer, 0, cpu_buffer->cpu);
> - if (meta)
> - rb_meta_init_text_addr(meta);
> -
> atomic_dec(&cpu_buffer->record_disabled);
> atomic_sub(RESET_BIT, &cpu_buffer->resize_disabled);
> }
> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
> index a9e8eaf1d47e..cb9f8e6878a0 100644
> --- a/kernel/trace/trace.c
> +++ b/kernel/trace/trace.c
> @@ -5994,8 +5994,14 @@ ssize_t tracing_resize_ring_buffer(struct trace_array *tr,
> return ret;
> }
>
> +struct trace_scratch {
> + unsigned long kaslr_addr;
> +};
> +
> static void update_last_data(struct trace_array *tr)
> {
> + struct trace_scratch *tscratch;
> +
> if (!(tr->flags & TRACE_ARRAY_FL_LAST_BOOT))
> return;
>
> @@ -6010,6 +6016,17 @@ static void update_last_data(struct trace_array *tr)
> /* Using current data now */
> tr->text_delta = 0;
>
> + if (!tr->scratch)
> + return;
> +
> + tscratch = tr->scratch;
> +
> + /* Set the persistent ring buffer meta data to this address */
> +#ifdef CONFIG_RANDOMIZE_BASE
> + tscratch->kaslr_addr = kaslr_offset();
> +#else
> + tscratch->kaslr_addr = 0;
> +#endif
> tr->flags &= ~TRACE_ARRAY_FL_LAST_BOOT;
> }
>
> @@ -6823,6 +6840,7 @@ static ssize_t
> tracing_last_boot_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
> {
> struct trace_array *tr = filp->private_data;
> + struct trace_scratch *tscratch = tr->scratch;
> struct seq_buf seq;
> char buf[64];
>
> @@ -6835,10 +6853,10 @@ tracing_last_boot_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t
> * Otherwise it shows the KASLR address from the previous boot which
> * should not be the same as the current boot.
> */
> - if (!(tr->flags & TRACE_ARRAY_FL_LAST_BOOT))
> + if (!tscratch || !(tr->flags & TRACE_ARRAY_FL_LAST_BOOT))
> seq_buf_puts(&seq, "Offset: current\n");
> else
> - seq_buf_printf(&seq, "Offset: %lx\n", tr->kaslr_addr);
> + seq_buf_printf(&seq, "Offset: %lx\n", tscratch->kaslr_addr);
>
> return simple_read_from_buffer(ubuf, cnt, ppos, buf, seq_buf_used(&seq));
> }
> @@ -9212,6 +9230,8 @@ static int
> allocate_trace_buffer(struct trace_array *tr, struct array_buffer *buf, int size)
> {
> enum ring_buffer_flags rb_flags;
> + unsigned int scratch_size;
> + void *scratch;
>
> rb_flags = tr->trace_flags & TRACE_ITER_OVERWRITE ? RB_FL_OVERWRITE : 0;
>
> @@ -9222,10 +9242,20 @@ allocate_trace_buffer(struct trace_array *tr, struct array_buffer *buf, int size
> tr->range_addr_start,
> tr->range_addr_size);
>
> + scratch = ring_buffer_meta_scratch(buf->buffer, &scratch_size);
> + if (scratch) {
> + tr->scratch = scratch;
> + tr->scratch_size = scratch_size;
> +
> #ifdef CONFIG_RANDOMIZE_BASE
> - if (ring_buffer_last_boot_delta(buf->buffer, &tr->kaslr_addr))
> - tr->text_delta = kaslr_offset() - tr->kaslr_addr;
> + {
> + struct trace_scratch *tscratch = tr->scratch;
> +
> + if (tscratch->kaslr_addr)
> + tr->text_delta = kaslr_offset() - tscratch->kaslr_addr;
> + }
> #endif
> + }
> /*
> * This is basically the same as a mapped buffer,
> * with the same restrictions.
> diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
> index abe8169c3e87..3a020fb82a34 100644
> --- a/kernel/trace/trace.h
> +++ b/kernel/trace/trace.h
> @@ -348,8 +348,11 @@ struct trace_array {
> unsigned int mapped;
> unsigned long range_addr_start;
> unsigned long range_addr_size;
> - unsigned long kaslr_addr;
> long text_delta;
> + void *scratch; /* pointer in persistent memory */
> + int scratch_size;
> +
> + int buffer_disabled;
>
> struct trace_pid_list __rcu *filtered_pids;
> struct trace_pid_list __rcu *filtered_no_pids;
> @@ -367,7 +370,6 @@ struct trace_array {
> * CONFIG_TRACER_MAX_TRACE.
> */
> arch_spinlock_t max_lock;
> - int buffer_disabled;
> #ifdef CONFIG_FTRACE_SYSCALLS
> int sys_refcount_enter;
> int sys_refcount_exit;
> --
> 2.45.2
>
>
--
Masami Hiramatsu (Google) <mhiramat@kernel.org>
On Thu, 6 Feb 2025 14:22:32 +0900 Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote: > On Wed, 05 Feb 2025 17:50:35 -0500 > Steven Rostedt <rostedt@goodmis.org> wrote: > > > From: Steven Rostedt <rostedt@goodmis.org> > > > > There's no reason to save the KASLR offset for the ring buffer itself. > > That is used by the tracer. Now that the tracer has a way to save data in > > the persistent memory of the ring buffer, have the tracing infrastructure > > take care of the saving of the KASLR offset. > > > > Looks good to me. But note that the scratchpad size may not enough for > module table later, because 1 module requires at least the name[] > (64byte - sizeof(ulong)) and the base address (ulong). This means > 1 entry consumes 64byte. Thus there can be only 63 entries + meta > data in 4K page. My ubuntu loads 189(!) modules; > > $ lsmod | wc -l > 190 > > so we want 255 entries, which requires 16KB. So, I was thinking of modifying the allocation of the persistent ring buffer, which currently is #define ring_buffer_alloc_range(size, flags, order, start, range_size) [ it's a macro to add lockdep key information in it ] But I should change it to include a scratch size, and allow the tracing system to define how much of the range it should allocate for scratch. Then we could do: buf->buffer = ring_buffer_alloc_range(size, rb_flags, 0, tr->range_addr_start, tr->range_addr_size, struct_size(tscratch, entries, 128)); Which would make sure that the scratch size contains enough memory to hold 128 modules. -- Steve
On Thu, 6 Feb 2025 10:24:25 -0500 Steven Rostedt <rostedt@goodmis.org> wrote: > On Thu, 6 Feb 2025 14:22:32 +0900 > Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote: > > > On Wed, 05 Feb 2025 17:50:35 -0500 > > Steven Rostedt <rostedt@goodmis.org> wrote: > > > > > From: Steven Rostedt <rostedt@goodmis.org> > > > > > > There's no reason to save the KASLR offset for the ring buffer itself. > > > That is used by the tracer. Now that the tracer has a way to save data in > > > the persistent memory of the ring buffer, have the tracing infrastructure > > > take care of the saving of the KASLR offset. > > > > > > > Looks good to me. But note that the scratchpad size may not enough for > > module table later, because 1 module requires at least the name[] > > (64byte - sizeof(ulong)) and the base address (ulong). This means > > 1 entry consumes 64byte. Thus there can be only 63 entries + meta > > data in 4K page. My ubuntu loads 189(!) modules; > > > > $ lsmod | wc -l > > 190 > > > > so we want 255 entries, which requires 16KB. > > So, I was thinking of modifying the allocation of the persistent ring > buffer, which currently is > > #define ring_buffer_alloc_range(size, flags, order, start, range_size) > > [ it's a macro to add lockdep key information in it ] > > But I should change it to include a scratch size, and allow the tracing > system to define how much of the range it should allocate for scratch. > > Then we could do: > > buf->buffer = ring_buffer_alloc_range(size, rb_flags, 0, > tr->range_addr_start, > tr->range_addr_size, > struct_size(tscratch, entries, 128)); > > Which would make sure that the scratch size contains enough memory to hold > 128 modules. Yeah, this idea looks godd to me. BTW, the scratch size will be aligned to the subbuffer size (or page size?) Thanks, > > -- Steve > -- Masami Hiramatsu (Google) <mhiramat@kernel.org>
On Fri, 7 Feb 2025 09:58:44 +0900 Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote: > > Which would make sure that the scratch size contains enough memory to hold > > 128 modules. > > Yeah, this idea looks godd to me. BTW, the scratch size will be aligned to > the subbuffer size (or page size?) I don't think it needs to be. I think it just needs to be aligned to word size. -- Steve
On Thu, 6 Feb 2025 20:03:16 -0500 Steven Rostedt <rostedt@goodmis.org> wrote: > On Fri, 7 Feb 2025 09:58:44 +0900 > Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote: > > > > Which would make sure that the scratch size contains enough memory to hold > > > 128 modules. > > > > Yeah, this idea looks godd to me. BTW, the scratch size will be aligned to > > the subbuffer size (or page size?) > > I don't think it needs to be. I think it just needs to be aligned to word > size. Ah, OK. The first cpu_meta data is not need to be aligned. Thank you, > > -- Steve -- Masami Hiramatsu (Google) <mhiramat@kernel.org>
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