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authorAdrian Hunter <adrian.hunter@intel.com>2020-05-28 11:00:58 +0300
committerPeter Zijlstra <peterz@infradead.org>2020-06-15 15:09:48 +0300
commitd002b8bc6dbc20e9043e279196cff8795dba05fe (patch)
tree3bfe6187485152698298ba4dd0293e3c1d982fea /kernel/kallsyms.c
parentd769811ca93303deb1d8729d20cceaca7051a6f1 (diff)
downloadlinux-d002b8bc6dbc20e9043e279196cff8795dba05fe.tar.xz
kprobes: Add symbols for kprobe insn pages
Symbols are needed for tools to describe instruction addresses. Pages allocated for kprobe's purposes need symbols to be created for them. Add such symbols to be visible via /proc/kallsyms. Note: kprobe insn pages are not used if ftrace is configured. To see the effect of this patch, the kernel must be configured with: # CONFIG_FUNCTION_TRACER is not set CONFIG_KPROBES=y and for optimised kprobes: CONFIG_OPTPROBES=y Example on x86: # perf probe __schedule Added new event: probe:__schedule (on __schedule) # cat /proc/kallsyms | grep '\[__builtin__kprobes\]' ffffffffc00d4000 t kprobe_insn_page [__builtin__kprobes] ffffffffc00d6000 t kprobe_optinsn_page [__builtin__kprobes] Note: This patch adds "__builtin__kprobes" as a module name in /proc/kallsyms for symbols for pages allocated for kprobes' purposes, even though "__builtin__kprobes" is not a module. Signed-off-by: Adrian Hunter <adrian.hunter@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Link: https://lkml.kernel.org/r/20200528080058.20230-1-adrian.hunter@intel.com
Diffstat (limited to 'kernel/kallsyms.c')
-rw-r--r--kernel/kallsyms.c37
1 files changed, 33 insertions, 4 deletions
diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
index 16c8c605f4b0..c6cc293c0e67 100644
--- a/kernel/kallsyms.c
+++ b/kernel/kallsyms.c
@@ -24,6 +24,7 @@
#include <linux/slab.h>
#include <linux/filter.h>
#include <linux/ftrace.h>
+#include <linux/kprobes.h>
#include <linux/compiler.h>
/*
@@ -437,6 +438,7 @@ struct kallsym_iter {
loff_t pos_arch_end;
loff_t pos_mod_end;
loff_t pos_ftrace_mod_end;
+ loff_t pos_bpf_end;
unsigned long value;
unsigned int nameoff; /* If iterating in core kernel symbols. */
char type;
@@ -496,11 +498,33 @@ static int get_ksymbol_ftrace_mod(struct kallsym_iter *iter)
static int get_ksymbol_bpf(struct kallsym_iter *iter)
{
+ int ret;
+
strlcpy(iter->module_name, "bpf", MODULE_NAME_LEN);
iter->exported = 0;
- return bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end,
- &iter->value, &iter->type,
- iter->name) < 0 ? 0 : 1;
+ ret = bpf_get_kallsym(iter->pos - iter->pos_ftrace_mod_end,
+ &iter->value, &iter->type,
+ iter->name);
+ if (ret < 0) {
+ iter->pos_bpf_end = iter->pos;
+ return 0;
+ }
+
+ return 1;
+}
+
+/*
+ * This uses "__builtin__kprobes" as a module name for symbols for pages
+ * allocated for kprobes' purposes, even though "__builtin__kprobes" is not a
+ * module.
+ */
+static int get_ksymbol_kprobe(struct kallsym_iter *iter)
+{
+ strlcpy(iter->module_name, "__builtin__kprobes", MODULE_NAME_LEN);
+ iter->exported = 0;
+ return kprobe_get_kallsym(iter->pos - iter->pos_bpf_end,
+ &iter->value, &iter->type,
+ iter->name) < 0 ? 0 : 1;
}
/* Returns space to next name. */
@@ -527,6 +551,7 @@ static void reset_iter(struct kallsym_iter *iter, loff_t new_pos)
iter->pos_arch_end = 0;
iter->pos_mod_end = 0;
iter->pos_ftrace_mod_end = 0;
+ iter->pos_bpf_end = 0;
}
}
@@ -551,7 +576,11 @@ static int update_iter_mod(struct kallsym_iter *iter, loff_t pos)
get_ksymbol_ftrace_mod(iter))
return 1;
- return get_ksymbol_bpf(iter);
+ if ((!iter->pos_bpf_end || iter->pos_bpf_end > pos) &&
+ get_ksymbol_bpf(iter))
+ return 1;
+
+ return get_ksymbol_kprobe(iter);
}
/* Returns false if pos at or past end of file. */