Add per-cpu specifications to the "p" command. This allows to specify
CPUs for a per-cpu symbol after a colon.
Keep in mind that a colon can be part of a valid C expression, e.g. ':'
or the ternary operator, so if the part before the colon is not a
symbol, the colon must be restored. Fortunately, a symbol name followed
by a colon cannot start a valid C expression, so there is never any
ambiguity.
Signed-off-by: Petr Tesarik <ptesarik@xxxxxxx>
[PATCH 3/11] Implement percpu variables for "p"
Add per-cpu specifications to the "p" command. This allows to specify
CPUs for a per-cpu symbol after a colon.
Keep in mind that a colon can be part of a valid C expression, e.g. ':'
or the ternary operator, so if the part before the colon is not a symbol,
the colon must be restored. Fortunately, a symbol name followed by a colon
cannot start a valid C expression, so there is never any ambiguity.
Signed-off-by: Petr Tesarik <ptesarik@xxxxxxx>
---
help.c | 14 +++++++
symbols.c | 113 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-------
2 files changed, 115 insertions(+), 12 deletions(-)
--- a/symbols.c
+++ b/symbols.c
@@ -73,7 +73,7 @@ static void Elf32_Sym_to_common(Elf32_Sy
static void Elf64_Sym_to_common(Elf64_Sym *, struct elf_common *);
static void cmd_datatype_common(ulong);
static void process_gdb_output(char *, unsigned, const char *, int);
-static int display_per_cpu_info(struct syment *);
+static int display_per_cpu_info(struct syment *, int, char *);
static struct load_module *get_module_percpu_sym_owner(struct syment *);
static int is_percpu_symbol(struct syment *);
static void dump_percpu_symbols(struct load_module *);
@@ -6392,6 +6392,7 @@ cmd_p(void)
unsigned radix;
int do_load_module_filter;
char buf1[BUFSIZE];
+ char *cpuspec;
do_load_module_filter = radix = 0;
@@ -6426,19 +6427,32 @@ cmd_p(void)
if (argerrs || !args[optind])
cmd_usage(pc->curcmd, SYNOPSIS);
+ cpuspec = strchr(args[optind], ':');
+ if (cpuspec)
+ *cpuspec++ = NULLCHAR;
+
sp = NULL;
if ((sp = symbol_search(args[optind])) && !args[optind+1]) {
if ((percpu_sp = per_cpu_symbol_search(args[optind])) &&
- display_per_cpu_info(percpu_sp))
+ display_per_cpu_info(percpu_sp, radix, cpuspec))
return;
if (module_symbol(sp->value, NULL, NULL, NULL, *gdb_output_radix))
do_load_module_filter = TRUE;
} else if ((percpu_sp = per_cpu_symbol_search(args[optind])) &&
- display_per_cpu_info(percpu_sp))
+ display_per_cpu_info(percpu_sp, radix, cpuspec))
return;
else if (st->flags & LOAD_MODULE_SYMS)
do_load_module_filter = TRUE;
+ if (cpuspec) {
+ if (sp)
+ error(WARNING, "%s is not percpu; cpuspec ignored.\n",
+ sp->name);
+ else
+ /* maybe a valid C expression (e.g. ':') */
+ *(cpuspec-1) = ':';
+ }
+
process_gdb_output(concat_args(buf1, 0, TRUE), radix,
sp ? sp->name : NULL, do_load_module_filter);
}
@@ -6496,34 +6510,109 @@ process_gdb_output(char *gdb_request, un
}
/*
+ * Get the type of an expression using gdb's "whatis" command.
+ * The returned string is dynamically allocated, and it should
+ * be passed to FREEBUF() when no longer needed.
+ * Return NULL if the type cannot be determined.
+ */
+static char *
+expr_type_name(const char *expr)
+{
+ char buf[BUFSIZE], *p;
+
+ open_tmpfile();
+ sprintf(buf, "whatis %s", expr);
+ if (!gdb_pass_through(buf, fp, GNU_RETURN_ON_ERROR)) {
+ close_tmpfile();
+ return NULL;
+ }
+
+ rewind(pc->tmpfile);
+ while (fgets(buf, BUFSIZE, pc->tmpfile) && !STRNEQ(buf, "type = "))
+ ;
+ p = feof(pc->tmpfile) ? NULL : buf + strlen("type = ");
+ close_tmpfile();
+
+ if (p) {
+ size_t len = strlen(clean_line(p));
+ return strcpy(GETBUF(len + 1), p);
+ }
+ return NULL;
+}
+
+/*
* Display the datatype of the per_cpu__xxx symbol and
* the addresses of each its per-cpu instances.
*/
static int
-display_per_cpu_info(struct syment *sp)
+display_per_cpu_info(struct syment *sp, int radix, char *cpuspec)
{
+ ulong *cpus;
int c;
ulong addr;
char buf[BUFSIZE];
+ char leader[sizeof("&per_cpu(") + strlen(sp->name) +
+ sizeof(", " STR(UINT_MAX) ")")];
+ char *typename;
+ int do_load_module_filter;
if (((kt->flags & (SMP|PER_CPU_OFF)) != (SMP|PER_CPU_OFF)) ||
(!is_percpu_symbol(sp)) ||
!((sp->type == 'd') || (sp->type == 'D') || (sp->type == 'V')))
return FALSE;
- fprintf(fp, "PER-CPU DATA TYPE:\n ");
- sprintf(buf, "whatis %s", sp->name);
- if (!gdb_pass_through(buf, pc->nullfp, GNU_RETURN_ON_ERROR))
- fprintf(fp, "[undetermined type] %s;\n", sp->name);
- else
- whatis_variable(sp);
+ if (cpuspec) {
+ cpus = get_cpumask_buf();
+ if (STREQ(cpuspec, "")) {
+ SET_BIT(cpus, CURRENT_CONTEXT()->processor);
+ } else {
+ make_cpumask(cpuspec, cpus, FAULT_ON_ERROR, NULL);
+ }
+ } else
+ cpus = NULL;
+
+ typename = expr_type_name(sp->name);
+
+ if (!cpus) {
+ fprintf(fp, "PER-CPU DATA TYPE:\n ");
+ if (!typename)
+ fprintf(fp, "[undetermined type] %s;\n", sp->name);
+ else
+ whatis_variable(sp);
+
+ fprintf(fp, "PER-CPU ADDRESSES:\n");
+ }
+
+ do_load_module_filter =
+ module_symbol(sp->value, NULL, NULL, NULL, *gdb_output_radix);
- fprintf(fp, "PER-CPU ADDRESSES:\n");
for (c = 0; c < kt->cpus; c++) {
+ if (cpus && !NUM_IN_BITMAP(cpus, c))
+ continue;
addr = sp->value + kt->__per_cpu_offset[c];
- fprintf(fp, " [%d]: %lx\n", c, addr);
+ if (!cpus)
+ fprintf(fp, " [%d]: %lx\n", c, addr);
+ else if (typename) {
+ snprintf(buf, sizeof buf, "p *(%s*) 0x%lx",
+ typename, addr);
+ sprintf(leader, "per_cpu(%s, %u)",
+ sp->name, c);
+ process_gdb_output(buf, radix, leader,
+ do_load_module_filter);
+ } else {
+ snprintf(buf, sizeof buf, "p (void*) 0x%lx", addr);
+ sprintf(leader, "&per_cpu(%s, %u)",
+ sp->name, c);
+ process_gdb_output(buf, radix, leader,
+ do_load_module_filter);
+ }
}
+ if (typename)
+ FREEBUF(typename);
+ if (cpus)
+ FREEBUF(cpus);
+
return TRUE;
}
--- a/help.c
+++ b/help.c
@@ -1096,6 +1096,13 @@ char *help_p[] = {
" are two other built-in aliases, \"px\" and \"pd\", which force the command",
" output to be displayed in hexadecimal or decimal, without changing the",
" default mode. ",
+"",
+" If expression is a per-cpu variable, you can specify the cpu list after",
+" a colon (':'). The following formats are available:",
+"",
+" : CPU of the currently selected task.",
+" :a all CPUs.",
+" :#[-#][,...] CPU list(s), e.g. \"1,3,5\", \"1-3\", or \"1,3,5-7,10\".",
"\nEXAMPLES",
" Print the contents of jiffies:\n",
" %s> p jiffies",
@@ -1144,6 +1151,13 @@ char *help_p[] = {
" swap_address = 0x0, ",
" segments = 0x0",
" }",
+"",
+" Print the contents of the variable \"blk_cpu_iopoll\" on the current CPU:\n",
+" %s> p blk_cpu_iopoll:",
+" per_cpu(blk_cpu_iopoll, 2) = $1 = {",
+" next = 0xffff88011e290100, ",
+" prev = 0xffff88011e290100",
+" }",
NULL
};
--
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