* FILE: dtrace_sdt_core.c
* DESCRIPTION: Dynamic Tracing: SDT probe point registration
*
- * Copyright (C) 2010-2014 Oracle Corporation
+ * Copyright (C) 2010-2016 Oracle Corporation
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/dtrace_os.h>
#include <linux/dtrace_sdt.h>
+#include <linux/jhash.h>
#include <linux/sdt.h>
#include <linux/slab.h>
#include <linux/string.h>
const char *sdt_prefix = "__dtrace_probe_";
+/*
+ * Markers of core-kernel sdt_args and sdt_names sections.
+ */
+extern const char __start_dtrace_sdt_args[];
+extern const char __stop_dtrace_sdt_args[];
+extern const char __start_dtrace_sdt_names[];
+extern const char __stop_dtrace_sdt_names[];
+
static int sdt_probe_set(sdt_probedesc_t *sdp, char *name, char *func,
uintptr_t addr, asm_instr_t **paddr,\
sdt_probedesc_t *prv)
return 1;
}
+ sdp->sdpd_args = NULL;
sdp->sdpd_offset = addr;
sdp->sdpd_next = NULL;
return 0;
}
+/*
+ * Transfer the SDT args section into the sdpd_args field left NULL above.
+ *
+ * The memory pointed to by args_start must have a lifetime at least as long as
+ * that pointed to by sdpd.
+ */
+void dtrace_sdt_stash_args(const char *module_name,
+ sdt_probedesc_t *sdpd, size_t nprobes,
+ const char *names_start, size_t names_len,
+ const char *args_start, size_t args_len)
+{
+ struct probe_name_hashent_t {
+ const char *pnhe_name;
+ const char *pnhe_args;
+ } *args_by_name;
+ int i;
+ const char *namep, *argp;
+ size_t hashsize;
+
+ /*
+ * We need to find the probes (and there may be many) in the sdpd
+ * corresponding to the probe with that name in the argtype section.
+ *
+ * Build a hashtable mapping from probe name -> args string, ignoring
+ * duplicate probe names except to check (in debugging mode) that they
+ * have the same args string as the first. Then cycle over the sdpd
+ * looking up each probe in turn and pointing to the same place.
+ *
+ * We don't know how many entries there are in the table, but we do know
+ * there cannot be more than nprobes (and are probably less).
+ */
+
+ hashsize = nprobes * 4; /* arbitrary expansion factor */
+ args_by_name = vzalloc(hashsize * sizeof (struct probe_name_hashent_t));
+ if (args_by_name == NULL) {
+ pr_warning("%s: cannot allocate hash for sdt args population\n",
+ __func__);
+ return;
+ }
+
+ namep = names_start;
+ argp = args_start;
+ while ((namep < names_start + names_len) &&
+ (argp < args_start + args_len)) {
+
+ size_t l = strlen(namep);
+ u32 h = jhash(namep, l, 0);
+ h = h % hashsize;
+
+ while (args_by_name[h].pnhe_name != NULL &&
+ strcmp(args_by_name[h].pnhe_name, namep) != 0) {
+ h++;
+ h %= hashsize;
+ }
+
+ if (args_by_name[h].pnhe_name == NULL) {
+ args_by_name[h].pnhe_name = namep;
+ args_by_name[h].pnhe_args = argp;
+ }
+#if defined(CONFIG_DT_DEBUG)
+ else if (strcmp(args_by_name[h].pnhe_name, namep) != 0)
+ printk(KERN_WARNING "%s: multiple "
+ "distinct arg strings for probe "
+ "%s found: %s versus %s",
+ module_name, namep,
+ args_by_name[h].pnhe_args,
+ argp);
+#endif
+ namep += l + 1;
+ argp += strlen(argp) + 1;
+ }
+
+#if defined(CONFIG_DT_DEBUG)
+ if ((namep < names_start + names_len) || (argp < args_start + args_len))
+ printk(KERN_WARNING "%s: Not all SDT names or args consumed: %zi "
+ "bytes of names and %zi of args left over. Some arg types "
+ "will be mis-assigned.\n", module_name,
+ namep - (names_start + names_len),
+ argp - (args_start + args_len));
+#endif
+
+ for (i = 0; i < nprobes; i++) {
+ size_t l = strlen(sdpd[i].sdpd_name);
+ u32 h = jhash(sdpd[i].sdpd_name, l, 0);
+ h = h % hashsize;
+
+ while (args_by_name[h].pnhe_name != NULL &&
+ strcmp(sdpd[i].sdpd_name,
+ args_by_name[h].pnhe_name) != 0) {
+ h++;
+ h %= hashsize;
+ }
+
+ if (args_by_name[h].pnhe_name == NULL) {
+ /*
+ * No arg string. Peculiar: report in debugging mode.
+ */
+#if defined(CONFIG_DT_DEBUG)
+ printk(KERN_WARNING "%s: probe %s has no arg string.\n",
+ module_name, sdpd[i].sdpd_name);
+#endif
+ continue;
+ }
+
+ sdpd[i].sdpd_args = args_by_name[h].pnhe_args;
+ }
+ vfree(args_by_name);
+}
+
/*
* Register the SDT probes for the core kernel, i.e. SDT probes that reside in
* vmlinux. For SDT probes in kernel modules, we use dtrace_mod_notifier().
void *nextpi;
sdt_probedesc_t *sdps;
asm_instr_t **addrs;
+ void *args;
+ size_t args_len;
if (mp == NULL) {
pr_warning("%s: no module provided - nothing registered\n",
dtrace_sdt_nop_multi(addrs, cnt);
+ /*
+ * Allocate space for the array of arg types, and copy it in from the
+ * (discardable) kernel section. We will need to keep it. (The
+ * identically-ordered array of probe names is not needed after
+ * initialization.)
+ */
+ args_len = __stop_dtrace_sdt_args - __start_dtrace_sdt_args;
+ args = vmalloc(args_len);
+ if (args == NULL) {
+ pr_warning("%s: cannot allocate table of SDT arg types\n",
+ __func__);
+ goto end;
+ }
+
+ memcpy(args, __start_dtrace_sdt_args, args_len);
+
+ dtrace_sdt_stash_args("vmlinux", sdps, cnt,
+ __start_dtrace_sdt_names,
+ (__stop_dtrace_sdt_names - __start_dtrace_sdt_names),
+ args, args_len);
+
+end:
vfree(addrs);
}
early_param("nosdt", nosdt);
-void dtrace_sdt_register_module(struct module *mp)
+void dtrace_sdt_register_module(struct module *mp,
+ void *sdt_names_addr, size_t sdt_names_len,
+ void *sdt_args_addr, size_t sdt_args_len)
{
int i, cnt;
sdt_probedesc_t *sdp;
dtrace_sdt_nop_multi(addrs, cnt);
+ dtrace_sdt_stash_args(mp->name, mp->sdt_probes, mp->sdt_probec,
+ sdt_names_addr, sdt_names_len,
+ sdt_args_addr, sdt_args_len);
+
vfree(addrs);
}
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