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tracing: Have persistent trace instances save KASLR offset

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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.

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lore.kernel.org/20250305164608.792722274@goodmis.org
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt
2025-03-28 08:39:27 -04:00
committed by Steven Rostedt (Google)
parent 4af0a9c518
commit b65334825f
4 changed files with 46 additions and 57 deletions
Download Patch File Download Diff File Expand all files Collapse all files
include/linux/ring_buffer.h
-1
View File
@@ -95,7 +95,6 @@ struct trace_buffer *__ring_buffer_alloc_range(unsigned long size, unsigned flag
unsigned long scratch_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);
/*
kernel/trace/ring_buffer.c
+10 -49
View File
@@ -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;
@@ -1949,15 +1946,6 @@ 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, int scratch_size)
{
struct ring_buffer_cpu_meta *meta;
@@ -1990,7 +1978,6 @@ static void rb_range_meta_init(struct trace_buffer *buffer, int nr_pages, int sc
meta->first_buffer += delta;
meta->head_buffer += delta;
meta->commit_buffer += delta;
buffer->kaslr_addr = meta->kaslr_addr;
continue;
}
@@ -2007,7 +1994,6 @@ static void rb_range_meta_init(struct trace_buffer *buffer, int nr_pages, int sc
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
@@ -2549,35 +2535,22 @@ struct trace_buffer *__ring_buffer_alloc_range(unsigned long size, unsigned flag
scratch_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)
{
struct ring_buffer_meta *meta;
void *ptr;
if (!buffer || !buffer->meta)
return NULL;
*size = PAGE_SIZE - sizeof(*buffer->meta);
meta = buffer->meta;
return (void *)buffer->meta + sizeof(*buffer->meta);
ptr = (void *)ALIGN((unsigned long)meta + sizeof(*meta), sizeof(long));
if (size)
*size = (void *)meta + meta->buffers_offset - ptr;
return ptr;
}
/**
@@ -6133,7 +6106,6 @@ 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;
@@ -6152,11 +6124,6 @@ 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);
@@ -6171,7 +6138,6 @@ 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 */
@@ -6199,11 +6165,6 @@ 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);
}
kernel/trace/trace.c
+32 -5
View File
@@ -5988,8 +5988,14 @@ ssize_t tracing_resize_ring_buffer(struct trace_array *tr,
return __tracing_resize_ring_buffer(tr, size, cpu_id);
}
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;
@@ -6004,6 +6010,17 @@ 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;
}
@@ -6817,6 +6834,7 @@ 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];
@@ -6829,8 +6847,8 @@ 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)
seq_buf_printf(&seq, "%lx\t[kernel]\n", tr->kaslr_addr);
if (tscratch && (tr->flags & TRACE_ARRAY_FL_LAST_BOOT))
seq_buf_printf(&seq, "%lx\t[kernel]\n", tscratch->kaslr_addr);
else
seq_buf_puts(&seq, "# Current\n");
@@ -9210,6 +9228,8 @@ static int
allocate_trace_buffer(struct trace_array *tr, struct array_buffer *buf, int size)
{
enum ring_buffer_flags rb_flags;
struct trace_scratch *tscratch;
unsigned int scratch_size;
rb_flags = tr->trace_flags & TRACE_ITER_OVERWRITE ? RB_FL_OVERWRITE : 0;
@@ -9218,12 +9238,19 @@ allocate_trace_buffer(struct trace_array *tr, struct array_buffer *buf, int size
if (tr->range_addr_start && tr->range_addr_size) {
buf->buffer = ring_buffer_alloc_range(size, rb_flags, 0,
tr->range_addr_start,
tr->range_addr_size, 0);
tr->range_addr_size,
sizeof(*tscratch));
tscratch = ring_buffer_meta_scratch(buf->buffer, &scratch_size);
if (tscratch) {
tr->scratch = tscratch;
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;
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.
kernel/trace/trace.h
+4 -2
View File
@@ -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;