[DTrace-devel] [PATCH v4 11/25] libproc: add Pinode_to_file_map()
Nick Alcock
nick.alcock at oracle.com
Fri Oct 7 10:25:10 UTC 2022
This lets you rapidly look up the prmap_file_t that corresponds to a
(dev, ino) pair in a given process's mappings. This is useful when
dealing with uprobes, which work on an *inode* basis, not a process
basis or even a mapping basis: we can use this to see whether a process
we are otherwise interested in has ownership of a given (dev, ino)
mapping rapidly, and what the details of the mapping are.
Do it with a hash table rather than linear iteration because these days
it is getting increasingly common to have processes with a great many
mappings. Chromium has 1638 mappings on my system, of which 411 are
file-backed, but the real mapping king these days is Emacs with native
compilation, which maps every Lisp file as a separate shared object:
3618 mappings, of which 3135 are file-backed!
While we're at it, rename the (Psymtab.c-private) Pprmap_file_by_name
to Pfilename_to_file_map, so that all prmap_file_t functions have
consistent names (and names less terrible than Pprmap_file_by_name).
Signed-off-by: Nick Alcock <nick.alcock at oracle.com>
---
include/sys/sol_procfs.h | 8 +--
libproc/Pcontrol.h | 1 +
libproc/Psymtab.c | 125 ++++++++++++++++++++++++++++++---------
libproc/libproc.h | 5 +-
4 files changed, 106 insertions(+), 33 deletions(-)
diff --git a/include/sys/sol_procfs.h b/include/sys/sol_procfs.h
index 2f7c6a4eafe5..d195a108da2b 100644
--- a/include/sys/sol_procfs.h
+++ b/include/sys/sol_procfs.h
@@ -1,6 +1,6 @@
/*
* Oracle Linux DTrace.
- * Copyright (c) 2006, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2006, 2022, Oracle and/or its affiliates. All rights reserved.
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
@@ -17,17 +17,17 @@ extern "C" {
#include <sys/types.h>
#include <sys/dtrace_types.h>
#include <sys/procfs_isa.h>
-#include <dt_list.h>
#include <link.h>
/*
* The prmap_file points to all mappings corresponding to a single file, sorted
* by address. prmap_files are hashed by name (including the terminating \0,
- * so anonymous maps are all hashed together).
+ * so anonymous maps are all hashed together) and by dev/inode number.
*/
struct prmap;
typedef struct prmap_file {
- struct prmap_file *prf_next; /* next in hash chain */
+ struct prmap_file *prf_name_next; /* next in filename hash chain */
+ struct prmap_file *prf_inum_next; /* next in inode hash chain */
char *prf_mapname; /* name in /proc/<pid>/maps */
struct prmap **prf_mappings; /* sorted by address */
size_t prf_num_mappings; /* number of mappings */
diff --git a/libproc/Pcontrol.h b/libproc/Pcontrol.h
index 9c3340d04d54..77d71d98abf0 100644
--- a/libproc/Pcontrol.h
+++ b/libproc/Pcontrol.h
@@ -247,6 +247,7 @@ struct ps_prochandle {
map_info_t *mappings; /* process mappings, sorted by address */
size_t num_mappings; /* number of mappings */
prmap_file_t **map_files; /* hash of mappings by filename */
+ prmap_file_t **map_inum; /* hash of mappings by (dev, inode) */
uint_t num_files; /* number of file elements in file_list */
dt_list_t file_list; /* list of mapped files w/ symbol table info */
auxv_t *auxv; /* the process's aux vector */
diff --git a/libproc/Psymtab.c b/libproc/Psymtab.c
index aca3382bdde5..3e2f08928eca 100644
--- a/libproc/Psymtab.c
+++ b/libproc/Psymtab.c
@@ -1,6 +1,6 @@
/*
* Oracle Linux DTrace.
- * Copyright (c) 2009, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2009, 2022, Oracle and/or its affiliates. All rights reserved.
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
@@ -36,6 +36,8 @@
static map_info_t *object_to_map(struct ps_prochandle *, Lmid_t, const char *);
static map_info_t *object_name_to_map(struct ps_prochandle *,
Lmid_t, const char *);
+static prmap_file_t *Pfilename_to_file_map(struct ps_prochandle *P,
+ const char *name);
static GElf_Sym *sym_by_name(sym_tbl_t *, const char *, GElf_Sym *, uint_t *);
static file_info_t *file_info_new(struct ps_prochandle *, map_info_t *);
static int byaddr_cmp_common(GElf_Sym *a, char *aname, GElf_Sym *b, char *bname);
@@ -70,6 +72,39 @@ string_hash(const char *key)
return h;
}
+/*
+ * This is Pelle Evensen's NASAM mixer. Since we are only mixing in one value
+ * we don't need anything but a mixing step.
+ */
+
+#define ror(x,y) ((x) >> (y) | (x) << (64 - (y)))
+
+static uint64_t
+nasam_mix(uint64_t h)
+{
+
+ h ^= ror(h, 25) ^ ror(h, 47);
+ h *= 0x9E6C63D0676A9A99UL;
+ h ^= h >> 23 ^ h >> 51;
+ h *= 0x9E6D62D06F6A9A9BUL;
+ h ^= h >> 23 ^ h >> 51;
+
+ return h;
+}
+#undef ror
+
+static ino_t
+dev_inum_hash(dev_t dev, ino_t inum)
+{
+ uint64_t h;
+
+ h = nasam_mix(inum);
+ h += dev;
+ h = nasam_mix(h);
+
+ return (ino_t) h;
+}
+
/*
* Allocation function for a new file_info_t.
*/
@@ -173,7 +208,7 @@ mapping_purge(struct ps_prochandle *P)
prmap_file_t *old_prf = NULL;
for (prf = P->map_files[i]; prf != NULL;
- old_prf = prf, prf = prf->prf_next) {
+ old_prf = prf, prf = prf->prf_name_next) {
free(old_prf);
free(prf->prf_mappings);
free(prf->prf_mapname);
@@ -182,6 +217,7 @@ mapping_purge(struct ps_prochandle *P)
}
memset(P->map_files, 0, sizeof(struct prmap_file *) * MAP_HASH_BUCKETS);
+ memset(P->map_inum, 0, sizeof(struct prmap_file *) * MAP_HASH_BUCKETS);
for (i = 0, fptr = dt_list_next(&P->file_list);
i < P->num_files; i++, fptr = dt_list_next(fptr)) {
@@ -208,6 +244,11 @@ Psym_init(struct ps_prochandle *P)
_dprintf("Out of memory initializing map_files hash\n");
return -ENOMEM;
}
+ P->map_inum = calloc(MAP_HASH_BUCKETS, sizeof(struct prmap_file_t *));
+ if (!P->map_inum) {
+ _dprintf("Out of memory initializing map_inum hash\n");
+ return -ENOMEM;
+ }
return 0;
}
@@ -219,23 +260,8 @@ Psym_free(struct ps_prochandle *P)
{
free(P->map_files);
P->map_files = NULL;
-}
-
-/*
- * Given a process handle, find a corresponding prmap_file by file name, or NULL
- * if none.
- */
-static prmap_file_t *Pprmap_file_by_name(struct ps_prochandle *P,
- const char *name)
-{
- uint_t h = string_hash(name) % MAP_HASH_BUCKETS;
- prmap_file_t *prf;
-
- for (prf = P->map_files[h]; prf != NULL; prf = prf->prf_next)
- if (strcmp(prf->prf_mapname, name) == 0)
- return prf;
-
- return NULL;
+ free(P->map_inum);
+ P->map_inum = NULL;
}
/*
@@ -552,9 +578,13 @@ Pupdate_maps(struct ps_prochandle *P)
goto err;
pmptr = mptr->map_pmap;
memset(pmptr, 0, sizeof(struct prmap));
+ pmptr->pr_dev = makedev(major, minor);
+ pmptr->pr_inum = inode;
- if ((prf = Pprmap_file_by_name(P, fn)) == NULL) {
- uint_t h = string_hash(fn) % MAP_HASH_BUCKETS;
+ if ((prf = Pfilename_to_file_map(P, fn)) == NULL) {
+ uint_t fn_h = string_hash(fn) % MAP_HASH_BUCKETS;
+ uint_t inum_h = dev_inum_hash(pmptr->pr_dev, pmptr->pr_inum) %
+ MAP_HASH_BUCKETS;
if ((prf = malloc(sizeof(struct prmap_file))) == NULL) {
free(mptr->map_pmap);
@@ -563,10 +593,11 @@ Pupdate_maps(struct ps_prochandle *P)
memset(prf, 0, sizeof(struct prmap_file));
prf->prf_mapname = fn;
- prf->prf_next = P->map_files[h];
- P->map_files[h] = prf;
- }
- else {
+ prf->prf_name_next = P->map_files[fn_h];
+ P->map_files[fn_h] = prf;
+ prf->prf_inum_next = P->map_inum[inum_h];
+ P->map_inum[inum_h] = prf;
+ } else {
free(fn);
fn = NULL;
}
@@ -644,8 +675,6 @@ Pupdate_maps(struct ps_prochandle *P)
(strcmp(prf->prf_mapname, exefile) == 0))
P->map_exec = P->num_mappings;
}
- pmptr->pr_dev = makedev(major, minor);
- pmptr->pr_inum = inode;
pmptr->pr_file = prf;
/*
@@ -849,12 +878,52 @@ Plmid_to_map(struct ps_prochandle *P, Lmid_t lmid, const char *name)
return NULL;
}
+/*
+ * Given a process handle, find a corresponding mapping by hunting across all lmids.
+ */
const prmap_t *
Pname_to_map(struct ps_prochandle *P, const char *name)
{
return Plmid_to_map(P, PR_LMID_EVERY, name);
}
+/*
+ * Given a process handle, find a corresponding prmap_file by file name, or NULL
+ * if none.
+ */
+static prmap_file_t *Pfilename_to_file_map(struct ps_prochandle *P,
+ const char *name)
+{
+ uint_t h = string_hash(name) % MAP_HASH_BUCKETS;
+ prmap_file_t *prf;
+
+ for (prf = P->map_files[h]; prf != NULL; prf = prf->prf_name_next)
+ if (strcmp(prf->prf_mapname, name) == 0)
+ return prf;
+
+ return NULL;
+}
+
+
+/*
+ * Given a process handle, find a corresponding prmap_file by (dev_t, inode
+ * number), or NULL if none.
+ */
+const prmap_file_t *
+Pinode_to_file_map(struct ps_prochandle *P, dev_t dev, ino_t inum)
+{
+ uint_t h = dev_inum_hash(dev, inum) % MAP_HASH_BUCKETS;
+
+ prmap_file_t *prf;
+
+ for (prf = P->map_inum[h]; prf != NULL; prf = prf->prf_inum_next)
+ if (prf->first_segment->pr_inum == inum &&
+ prf->first_segment->pr_dev == dev)
+ return prf;
+
+ return NULL;
+}
+
/*
* We wouldn't need these if qsort(3C) took an argument for the callback...
*/
@@ -1384,7 +1453,7 @@ Pbuild_file_symtab(struct ps_prochandle *P, file_info_t *fptr)
size_t nphdrs;
GElf_Phdr hdr;
GElf_Phdr *phdr = &hdr;
- prmap_file_t *prf = Pprmap_file_by_name(P, fptr->file_pname);
+ prmap_file_t *prf = Pfilename_to_file_map(P, fptr->file_pname);
if (!prf) {
_dprintf("%s: mapping not known (internal error)\n.",
diff --git a/libproc/libproc.h b/libproc/libproc.h
index 1f8683e25b31..30d4bd8add5e 100644
--- a/libproc/libproc.h
+++ b/libproc/libproc.h
@@ -1,6 +1,6 @@
/*
* Oracle Linux DTrace.
- * Copyright (c) 2009, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2009, 2022, Oracle and/or its affiliates. All rights reserved.
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
@@ -32,6 +32,7 @@
#include <sys/socket.h>
#include <sys/utsname.h>
#include <sys/time.h>
+#include <sys/types.h>
#include <sys/user.h>
#include <sys/compiler.h>
@@ -242,6 +243,8 @@ extern const prmap_t *Paddr_to_map(struct ps_prochandle *, uintptr_t);
extern const prmap_t *Pname_to_map(struct ps_prochandle *, const char *);
extern const prmap_t *Plmid_to_map(struct ps_prochandle *,
Lmid_t, const char *);
+extern const prmap_file_t *Pinode_to_file_map(struct ps_prochandle *,
+ dev_t, ino_t);
extern char *Pobjname(struct ps_prochandle *, uintptr_t, char *, size_t);
extern int Plmid(struct ps_prochandle *, uintptr_t, Lmid_t *);
--
2.35.1
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