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Message-ID: <20250331122938.1837255-2-thorsten.blum@linux.dev>
Date: Mon, 31 Mar 2025 14:29:38 +0200
From: Thorsten Blum <thorsten.blum@...ux.dev>
To: Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Namhyung Kim <namhyung@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>,
Ian Rogers <irogers@...gle.com>,
Adrian Hunter <adrian.hunter@...el.com>,
"Liang, Kan" <kan.liang@...ux.intel.com>,
Thomas Gleixner <tglx@...utronix.de>,
Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>,
x86@...nel.org,
"H. Peter Anvin" <hpa@...or.com>
Cc: Thorsten Blum <thorsten.blum@...ux.dev>,
Ingo Molnar <mingo@...nel.org>,
linux-perf-users@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH] perf/x86: Rename bts_buffer variables and use struct_size()
Rename struct bts_buffer objects from 'buf' to 'bb' to improve the
readability when accessing the structure's 'buf' member. For example,
'buf->buf[]' becomes 'bb->buf[]'.
Use struct_size() to calculate the number of bytes to allocate for a new
bts_buffer. Compared to offsetof(), struct_size() provides additional
compile-time checks (e.g., __must_be_array()).
Indent line 327 using tabs to silence a checkpatch warning.
No functional changes intended.
Suggested-by: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Thorsten Blum <thorsten.blum@...ux.dev>
---
arch/x86/events/intel/bts.c | 146 ++++++++++++++++++------------------
1 file changed, 72 insertions(+), 74 deletions(-)
diff --git a/arch/x86/events/intel/bts.c b/arch/x86/events/intel/bts.c
index a95e6c91c4d7..bbc7d914050c 100644
--- a/arch/x86/events/intel/bts.c
+++ b/arch/x86/events/intel/bts.c
@@ -80,54 +78,54 @@ static void *
bts_buffer_setup_aux(struct perf_event *event, void **pages,
int nr_pages, bool overwrite)
{
- struct bts_buffer *buf;
+ struct bts_buffer *bb;
struct page *page;
int cpu = event->cpu;
int node = (cpu == -1) ? cpu : cpu_to_node(cpu);
unsigned long offset;
size_t size = nr_pages << PAGE_SHIFT;
- int pg, nbuf, pad;
+ int pg, nr_buf, pad;
/* count all the high order buffers */
- for (pg = 0, nbuf = 0; pg < nr_pages;) {
+ for (pg = 0, nr_buf = 0; pg < nr_pages;) {
page = virt_to_page(pages[pg]);
pg += buf_nr_pages(page);
- nbuf++;
+ nr_buf++;
}
/*
* to avoid interrupts in overwrite mode, only allow one physical
*/
- if (overwrite && nbuf > 1)
+ if (overwrite && nr_buf > 1)
return NULL;
- buf = kzalloc_node(offsetof(struct bts_buffer, buf[nbuf]), GFP_KERNEL, node);
- if (!buf)
+ bb = kzalloc_node(struct_size(bb, buf, nr_buf), GFP_KERNEL, node);
+ if (!bb)
return NULL;
- buf->nr_pages = nr_pages;
- buf->nr_bufs = nbuf;
- buf->snapshot = overwrite;
- buf->data_pages = pages;
- buf->real_size = size - size % BTS_RECORD_SIZE;
+ bb->nr_pages = nr_pages;
+ bb->nr_bufs = nr_buf;
+ bb->snapshot = overwrite;
+ bb->data_pages = pages;
+ bb->real_size = size - size % BTS_RECORD_SIZE;
- for (pg = 0, nbuf = 0, offset = 0, pad = 0; nbuf < buf->nr_bufs; nbuf++) {
+ for (pg = 0, nr_buf = 0, offset = 0, pad = 0; nr_buf < bb->nr_bufs; nr_buf++) {
unsigned int __nr_pages;
page = virt_to_page(pages[pg]);
__nr_pages = buf_nr_pages(page);
- buf->buf[nbuf].page = page;
- buf->buf[nbuf].offset = offset;
- buf->buf[nbuf].displacement = (pad ? BTS_RECORD_SIZE - pad : 0);
- buf->buf[nbuf].size = buf_size(page) - buf->buf[nbuf].displacement;
- pad = buf->buf[nbuf].size % BTS_RECORD_SIZE;
- buf->buf[nbuf].size -= pad;
+ bb->buf[nr_buf].page = page;
+ bb->buf[nr_buf].offset = offset;
+ bb->buf[nr_buf].displacement = (pad ? BTS_RECORD_SIZE - pad : 0);
+ bb->buf[nr_buf].size = buf_size(page) - bb->buf[nr_buf].displacement;
+ pad = bb->buf[nr_buf].size % BTS_RECORD_SIZE;
+ bb->buf[nr_buf].size -= pad;
pg += __nr_pages;
offset += __nr_pages << PAGE_SHIFT;
}
- return buf;
+ return bb;
}
static void bts_buffer_free_aux(void *data)
@@ -135,25 +133,25 @@ static void bts_buffer_free_aux(void *data)
kfree(data);
}
-static unsigned long bts_buffer_offset(struct bts_buffer *buf, unsigned int idx)
+static unsigned long bts_buffer_offset(struct bts_buffer *bb, unsigned int idx)
{
- return buf->buf[idx].offset + buf->buf[idx].displacement;
+ return bb->buf[idx].offset + bb->buf[idx].displacement;
}
static void
-bts_config_buffer(struct bts_buffer *buf)
+bts_config_buffer(struct bts_buffer *bb)
{
int cpu = raw_smp_processor_id();
struct debug_store *ds = per_cpu(cpu_hw_events, cpu).ds;
- struct bts_phys *phys = &buf->buf[buf->cur_buf];
+ struct bts_phys *phys = &bb->buf[bb->cur_buf];
unsigned long index, thresh = 0, end = phys->size;
struct page *page = phys->page;
- index = local_read(&buf->head);
+ index = local_read(&bb->head);
- if (!buf->snapshot) {
- if (buf->end < phys->offset + buf_size(page))
- end = buf->end - phys->offset - phys->displacement;
+ if (!bb->snapshot) {
+ if (bb->end < phys->offset + buf_size(page))
+ end = bb->end - phys->offset - phys->displacement;
index -= phys->offset + phys->displacement;
@@ -168,7 +166,7 @@ bts_config_buffer(struct bts_buffer *buf)
ds->bts_buffer_base = (u64)(long)page_address(page) + phys->displacement;
ds->bts_index = ds->bts_buffer_base + index;
ds->bts_absolute_maximum = ds->bts_buffer_base + end;
- ds->bts_interrupt_threshold = !buf->snapshot
+ ds->bts_interrupt_threshold = !bb->snapshot
? ds->bts_buffer_base + thresh
: ds->bts_absolute_maximum + BTS_RECORD_SIZE;
}
@@ -184,16 +182,16 @@ static void bts_update(struct bts_ctx *bts)
{
int cpu = raw_smp_processor_id();
struct debug_store *ds = per_cpu(cpu_hw_events, cpu).ds;
- struct bts_buffer *buf = perf_get_aux(&bts->handle);
+ struct bts_buffer *bb = perf_get_aux(&bts->handle);
unsigned long index = ds->bts_index - ds->bts_buffer_base, old, head;
- if (!buf)
+ if (!bb)
return;
- head = index + bts_buffer_offset(buf, buf->cur_buf);
- old = local_xchg(&buf->head, head);
+ head = index + bts_buffer_offset(bb, bb->cur_buf);
+ old = local_xchg(&bb->head, head);
- if (!buf->snapshot) {
+ if (!bb->snapshot) {
if (old == head)
return;
@@ -205,9 +203,9 @@ static void bts_update(struct bts_ctx *bts)
* old and head are always in the same physical buffer, so we
* can subtract them to get the data size.
*/
- local_add(head - old, &buf->data_size);
+ local_add(head - old, &bb->data_size);
} else {
- local_set(&buf->data_size, head);
+ local_set(&bb->data_size, head);
}
/*
@@ -218,7 +216,7 @@ static void bts_update(struct bts_ctx *bts)
}
static int
-bts_buffer_reset(struct bts_buffer *buf, struct perf_output_handle *handle);
+bts_buffer_reset(struct bts_buffer *bb, struct perf_output_handle *handle);
/*
* Ordering PMU callbacks wrt themselves and the PMI is done by means
@@ -232,17 +230,17 @@ bts_buffer_reset(struct bts_buffer *buf, struct perf_output_handle *handle);
static void __bts_event_start(struct perf_event *event)
{
struct bts_ctx *bts = this_cpu_ptr(bts_ctx);
- struct bts_buffer *buf = perf_get_aux(&bts->handle);
+ struct bts_buffer *bb = perf_get_aux(&bts->handle);
u64 config = 0;
- if (!buf->snapshot)
+ if (!bb->snapshot)
config |= ARCH_PERFMON_EVENTSEL_INT;
if (!event->attr.exclude_kernel)
config |= ARCH_PERFMON_EVENTSEL_OS;
if (!event->attr.exclude_user)
config |= ARCH_PERFMON_EVENTSEL_USR;
- bts_config_buffer(buf);
+ bts_config_buffer(bb);
/*
* local barrier to make sure that ds configuration made it
@@ -261,13 +259,13 @@ static void bts_event_start(struct perf_event *event, int flags)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
struct bts_ctx *bts = this_cpu_ptr(bts_ctx);
- struct bts_buffer *buf;
+ struct bts_buffer *bb;
- buf = perf_aux_output_begin(&bts->handle, event);
- if (!buf)
+ bb = perf_aux_output_begin(&bts->handle, event);
+ if (!bb)
goto fail_stop;
- if (bts_buffer_reset(buf, &bts->handle))
+ if (bts_buffer_reset(bb, &bts->handle))
goto fail_end_stop;
bts->ds_back.bts_buffer_base = cpuc->ds->bts_buffer_base;
@@ -306,27 +304,27 @@ static void bts_event_stop(struct perf_event *event, int flags)
{
struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
struct bts_ctx *bts = this_cpu_ptr(bts_ctx);
- struct bts_buffer *buf = NULL;
+ struct bts_buffer *bb = NULL;
int state = READ_ONCE(bts->state);
if (state == BTS_STATE_ACTIVE)
__bts_event_stop(event, BTS_STATE_STOPPED);
if (state != BTS_STATE_STOPPED)
- buf = perf_get_aux(&bts->handle);
+ bb = perf_get_aux(&bts->handle);
event->hw.state |= PERF_HES_STOPPED;
if (flags & PERF_EF_UPDATE) {
bts_update(bts);
- if (buf) {
- if (buf->snapshot)
+ if (bb) {
+ if (bb->snapshot)
bts->handle.head =
- local_xchg(&buf->data_size,
- buf->nr_pages << PAGE_SHIFT);
+ local_xchg(&bb->data_size,
+ bb->nr_pages << PAGE_SHIFT);
perf_aux_output_end(&bts->handle,
- local_xchg(&buf->data_size, 0));
+ local_xchg(&bb->data_size, 0));
}
cpuc->ds->bts_index = bts->ds_back.bts_buffer_base;
@@ -382,19 +380,19 @@ void intel_bts_disable_local(void)
}
static int
-bts_buffer_reset(struct bts_buffer *buf, struct perf_output_handle *handle)
+bts_buffer_reset(struct bts_buffer *bb, struct perf_output_handle *handle)
{
unsigned long head, space, next_space, pad, gap, skip, wakeup;
unsigned int next_buf;
struct bts_phys *phys, *next_phys;
int ret;
- if (buf->snapshot)
+ if (bb->snapshot)
return 0;
- head = handle->head & ((buf->nr_pages << PAGE_SHIFT) - 1);
+ head = handle->head & ((bb->nr_pages << PAGE_SHIFT) - 1);
- phys = &buf->buf[buf->cur_buf];
+ phys = &bb->buf[bb->cur_buf];
space = phys->offset + phys->displacement + phys->size - head;
pad = space;
if (space > handle->size) {
@@ -403,10 +401,10 @@ bts_buffer_reset(struct bts_buffer *buf, struct perf_output_handle *handle)
}
if (space <= BTS_SAFETY_MARGIN) {
/* See if next phys buffer has more space */
- next_buf = buf->cur_buf + 1;
- if (next_buf >= buf->nr_bufs)
+ next_buf = bb->cur_buf + 1;
+ if (next_buf >= bb->nr_bufs)
next_buf = 0;
- next_phys = &buf->buf[next_buf];
+ next_phys = &bb->buf[next_buf];
gap = buf_size(phys->page) - phys->displacement - phys->size +
next_phys->displacement;
skip = pad + gap;
@@ -431,8 +429,8 @@ bts_buffer_reset(struct bts_buffer *buf, struct perf_output_handle *handle)
* anymore, so we must not be racing with
* bts_update().
*/
- buf->cur_buf = next_buf;
- local_set(&buf->head, head);
+ bb->cur_buf = next_buf;
+ local_set(&bb->head, head);
}
}
}
@@ -445,7 +443,7 @@ bts_buffer_reset(struct bts_buffer *buf, struct perf_output_handle *handle)
space -= space % BTS_RECORD_SIZE;
}
- buf->end = head + space;
+ bb->end = head + space;
/*
* If we have no space, the lost notification would have been sent when
@@ -462,7 +460,7 @@ int intel_bts_interrupt(void)
struct debug_store *ds = this_cpu_ptr(&cpu_hw_events)->ds;
struct bts_ctx *bts;
struct perf_event *event;
- struct bts_buffer *buf;
+ struct bts_buffer *bb;
s64 old_head;
int err = -ENOSPC, handled = 0;
@@ -485,8 +483,8 @@ int intel_bts_interrupt(void)
if (READ_ONCE(bts->state) == BTS_STATE_STOPPED)
return handled;
- buf = perf_get_aux(&bts->handle);
- if (!buf)
+ bb = perf_get_aux(&bts->handle);
+ if (!bb)
return handled;
/*
@@ -494,26 +492,26 @@ int intel_bts_interrupt(void)
* there's no other way of telling, because the pointer will
* keep moving
*/
- if (buf->snapshot)
+ if (bb->snapshot)
return 0;
- old_head = local_read(&buf->head);
+ old_head = local_read(&bb->head);
bts_update(bts);
/* no new data */
- if (old_head == local_read(&buf->head))
+ if (old_head == local_read(&bb->head))
return handled;
- perf_aux_output_end(&bts->handle, local_xchg(&buf->data_size, 0));
+ perf_aux_output_end(&bts->handle, local_xchg(&bb->data_size, 0));
- buf = perf_aux_output_begin(&bts->handle, event);
- if (buf)
- err = bts_buffer_reset(buf, &bts->handle);
+ bb = perf_aux_output_begin(&bts->handle, event);
+ if (bb)
+ err = bts_buffer_reset(bb, &bts->handle);
if (err) {
WRITE_ONCE(bts->state, BTS_STATE_STOPPED);
- if (buf) {
+ if (bb) {
/*
* BTS_STATE_STOPPED should be visible before
* cleared handle::event
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