The following commit has been merged into the perf/core branch of tip:

Commit-ID:     38bb8d77d0b932a0773b5de2ef42479409314f96
Gitweb:        
https://git.kernel.org/tip/38bb8d77d0b932a0773b5de2ef42479409314f96
Author:        Alexander Shishkin <alexander.shish...@linux.intel.com>
AuthorDate:    Wed, 21 Aug 2019 15:47:25 +03:00
Committer:     Ingo Molnar <mi...@kernel.org>
CommitterDate: Mon, 26 Aug 2019 12:00:14 +02:00

perf/x86/intel/pt: Split ToPA metadata and page layout

PT uses page sized ToPA tables, where the ToPA table resides at the bottom
and its driver-specific metadata taking up a few words at the top of the
page. The split is currently calculated manually and needs to be redone
every time a field is added to or removed from the metadata structure.
Also, the 32-bit version can be made smaller.

By splitting the table and metadata into separate structures, we are making
the compiler figure out the division of the page.

Signed-off-by: Alexander Shishkin <alexander.shish...@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <a...@redhat.com>
Cc: Jiri Olsa <jo...@redhat.com>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijls...@chello.nl>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Stephane Eranian <eran...@google.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Vince Weaver <vincent.wea...@maine.edu>
Link: 
http://lkml.kernel.org/r/20190821124727.73310-5-alexander.shish...@linux.intel.com
Signed-off-by: Ingo Molnar <mi...@kernel.org>
---
 arch/x86/events/intel/pt.c | 93 +++++++++++++++++++++++--------------
 1 file changed, 60 insertions(+), 33 deletions(-)

diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c
index 188d45f..2e3f068 100644
--- a/arch/x86/events/intel/pt.c
+++ b/arch/x86/events/intel/pt.c
@@ -545,16 +545,8 @@ static void pt_config_buffer(void *buf, unsigned int 
topa_idx,
        wrmsrl(MSR_IA32_RTIT_OUTPUT_MASK, reg);
 }
 
-/*
- * Keep ToPA table-related metadata on the same page as the actual table,
- * taking up a few words from the top
- */
-
-#define TENTS_PER_PAGE (((PAGE_SIZE - 40) / sizeof(struct topa_entry)) - 1)
-
 /**
- * struct topa - page-sized ToPA table with metadata at the top
- * @table:     actual ToPA table entries, as understood by PT hardware
+ * struct topa - ToPA metadata
  * @list:      linkage to struct pt_buffer's list of tables
  * @phys:      physical address of this page
  * @offset:    offset of the first entry in this table in the buffer
@@ -562,7 +554,6 @@ static void pt_config_buffer(void *buf, unsigned int 
topa_idx,
  * @last:      index of the last initialized entry in this table
  */
 struct topa {
-       struct topa_entry       table[TENTS_PER_PAGE];
        struct list_head        list;
        u64                     phys;
        u64                     offset;
@@ -570,8 +561,39 @@ struct topa {
        int                     last;
 };
 
+/*
+ * Keep ToPA table-related metadata on the same page as the actual table,
+ * taking up a few words from the top
+ */
+
+#define TENTS_PER_PAGE \
+       ((PAGE_SIZE - sizeof(struct topa)) / sizeof(struct topa_entry))
+
+/**
+ * struct topa_page - page-sized ToPA table with metadata at the top
+ * @table:     actual ToPA table entries, as understood by PT hardware
+ * @topa:      metadata
+ */
+struct topa_page {
+       struct topa_entry       table[TENTS_PER_PAGE];
+       struct topa             topa;
+};
+
+static inline struct topa_page *topa_to_page(struct topa *topa)
+{
+       return container_of(topa, struct topa_page, topa);
+}
+
+static inline struct topa_page *topa_entry_to_page(struct topa_entry *te)
+{
+       return (struct topa_page *)((unsigned long)te & PAGE_MASK);
+}
+
 /* make -1 stand for the last table entry */
-#define TOPA_ENTRY(t, i) ((i) == -1 ? &(t)->table[(t)->last] : 
&(t)->table[(i)])
+#define TOPA_ENTRY(t, i)                               \
+       ((i) == -1                                      \
+               ? &topa_to_page(t)->table[(t)->last]    \
+               : &topa_to_page(t)->table[(i)])
 #define TOPA_ENTRY_SIZE(t, i) (sizes(TOPA_ENTRY((t), (i))->size))
 
 /**
@@ -584,27 +606,27 @@ struct topa {
 static struct topa *topa_alloc(int cpu, gfp_t gfp)
 {
        int node = cpu_to_node(cpu);
-       struct topa *topa;
+       struct topa_page *tp;
        struct page *p;
 
        p = alloc_pages_node(node, gfp | __GFP_ZERO, 0);
        if (!p)
                return NULL;
 
-       topa = page_address(p);
-       topa->last = 0;
-       topa->phys = page_to_phys(p);
+       tp = page_address(p);
+       tp->topa.last = 0;
+       tp->topa.phys = page_to_phys(p);
 
        /*
         * In case of singe-entry ToPA, always put the self-referencing END
         * link as the 2nd entry in the table
         */
        if (!intel_pt_validate_hw_cap(PT_CAP_topa_multiple_entries)) {
-               TOPA_ENTRY(topa, 1)->base = topa->phys >> TOPA_SHIFT;
-               TOPA_ENTRY(topa, 1)->end = 1;
+               TOPA_ENTRY(&tp->topa, 1)->base = tp->topa.phys;
+               TOPA_ENTRY(&tp->topa, 1)->end = 1;
        }
 
-       return topa;
+       return &tp->topa;
 }
 
 /**
@@ -714,22 +736,23 @@ static void pt_topa_dump(struct pt_buffer *buf)
        struct topa *topa;
 
        list_for_each_entry(topa, &buf->tables, list) {
+               struct topa_page *tp = topa_to_page(topa);
                int i;
 
-               pr_debug("# table @%p (%016Lx), off %llx size %zx\n", 
topa->table,
+               pr_debug("# table @%p (%016Lx), off %llx size %zx\n", tp->table,
                         topa->phys, topa->offset, topa->size);
                for (i = 0; i < TENTS_PER_PAGE; i++) {
                        pr_debug("# entry @%p (%lx sz %u %c%c%c) raw=%16llx\n",
-                                &topa->table[i],
-                                (unsigned long)topa->table[i].base << 
TOPA_SHIFT,
-                                sizes(topa->table[i].size),
-                                topa->table[i].end ?  'E' : ' ',
-                                topa->table[i].intr ? 'I' : ' ',
-                                topa->table[i].stop ? 'S' : ' ',
-                                *(u64 *)&topa->table[i]);
+                                &tp->table[i],
+                                (unsigned long)tp->table[i].base << TOPA_SHIFT,
+                                sizes(tp->table[i].size),
+                                tp->table[i].end ?  'E' : ' ',
+                                tp->table[i].intr ? 'I' : ' ',
+                                tp->table[i].stop ? 'S' : ' ',
+                                *(u64 *)&tp->table[i]);
                        if 
((intel_pt_validate_hw_cap(PT_CAP_topa_multiple_entries) &&
-                            topa->table[i].stop) ||
-                           topa->table[i].end)
+                            tp->table[i].stop) ||
+                           tp->table[i].end)
                                break;
                }
        }
@@ -792,7 +815,7 @@ static void pt_update_head(struct pt *pt)
  */
 static void *pt_buffer_region(struct pt_buffer *buf)
 {
-       return phys_to_virt(buf->cur->table[buf->cur_idx].base << TOPA_SHIFT);
+       return phys_to_virt(TOPA_ENTRY(buf->cur, buf->cur_idx)->base << 
TOPA_SHIFT);
 }
 
 /**
@@ -869,9 +892,11 @@ static void pt_handle_status(struct pt *pt)
 static void pt_read_offset(struct pt_buffer *buf)
 {
        u64 offset, base_topa;
+       struct topa_page *tp;
 
        rdmsrl(MSR_IA32_RTIT_OUTPUT_BASE, base_topa);
-       buf->cur = phys_to_virt(base_topa);
+       tp = phys_to_virt(base_topa);
+       buf->cur = &tp->topa;
 
        rdmsrl(MSR_IA32_RTIT_OUTPUT_MASK, offset);
        /* offset within current output region */
@@ -1021,6 +1046,7 @@ static void pt_buffer_setup_topa_index(struct pt_buffer 
*buf)
  */
 static void pt_buffer_reset_offsets(struct pt_buffer *buf, unsigned long head)
 {
+       struct topa_page *cur_tp;
        int pg;
 
        if (buf->snapshot)
@@ -1029,7 +1055,8 @@ static void pt_buffer_reset_offsets(struct pt_buffer 
*buf, unsigned long head)
        pg = (head >> PAGE_SHIFT) & (buf->nr_pages - 1);
        pg = pt_topa_next_entry(buf, pg);
 
-       buf->cur = (struct topa *)((unsigned long)buf->topa_index[pg] & 
PAGE_MASK);
+       cur_tp = topa_entry_to_page(buf->topa_index[pg]);
+       buf->cur = &cur_tp->topa;
        buf->cur_idx = buf->topa_index[pg] - TOPA_ENTRY(buf->cur, 0);
        buf->output_off = head & (pt_buffer_region_size(buf) - 1);
 
@@ -1294,7 +1321,7 @@ void intel_pt_interrupt(void)
                        return;
                }
 
-               pt_config_buffer(buf->cur->table, buf->cur_idx,
+               pt_config_buffer(topa_to_page(buf->cur)->table, buf->cur_idx,
                                 buf->output_off);
                pt_config(event);
        }
@@ -1359,7 +1386,7 @@ static void pt_event_start(struct perf_event *event, int 
mode)
        WRITE_ONCE(pt->handle_nmi, 1);
        hwc->state = 0;
 
-       pt_config_buffer(buf->cur->table, buf->cur_idx,
+       pt_config_buffer(topa_to_page(buf->cur)->table, buf->cur_idx,
                         buf->output_off);
        pt_config(event);
 

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