diff --git a/kernel/trace/fprobe.c b/kernel/trace/fprobe.c
index b70de44e6d3dc38b01c07e104030847f4b8c01d4..3b21f406325829ceedfb3911ce76ed0f219005b8 100644
--- a/kernel/trace/fprobe.c
+++ b/kernel/trace/fprobe.c
@@ -100,6 +100,12 @@ static void fprobe_kprobe_handler(unsigned long ip, unsigned long parent_ip,
return;
}
+ /*
+ * This user handler is shared with other kprobes and is not expected to be
+ * called recursively. So if any other kprobe handler is running, this will
+ * exit as kprobe does. See the section 'Share the callbacks with kprobes'
+ * in Documentation/trace/fprobe.rst for more information.
+ */
if (unlikely(kprobe_running())) {
fp->nmissed++;
goto recursion_unlock;
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index ed7906b13f0947b565e9d66bc68c843b8a19abab..e1edc2197fc89d2d55827e4991a693fcef62c1ff 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -113,6 +113,8 @@ enum trace_type {
#define MEM_FAIL(condition, fmt, ...) \
DO_ONCE_LITE_IF(condition, pr_err, "ERROR: " fmt, ##__VA_ARGS__)
+#define FAULT_STRING "(fault)"
+
#define HIST_STACKTRACE_DEPTH 16
#define HIST_STACKTRACE_SIZE (HIST_STACKTRACE_DEPTH * sizeof(unsigned long))
#define HIST_STACKTRACE_SKIP 5
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 7ba371da0926e7936fbeb1ef7d7c30b86de38933..b2b726bea1f9e67f39d477509745a5b2a8bc667a 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -67,7 +67,7 @@ int PRINT_TYPE_FUNC_NAME(string)(struct trace_seq *s, void *data, void *ent)
int len = *(u32 *)data >> 16;
if (!len)
- trace_seq_puts(s, "(fault)");
+ trace_seq_puts(s, FAULT_STRING);
else
trace_seq_printf(s, "\"%s\"",
(const char *)get_loc_data(data, ent));
diff --git a/kernel/trace/trace_probe_kernel.h b/kernel/trace/trace_probe_kernel.h
index c4e1d4c03a85f56664f7604975bd2f97cb2496cd..bb723eefd7b71b2396f29ac5cc1e005d669c810a 100644
--- a/kernel/trace/trace_probe_kernel.h
+++ b/kernel/trace/trace_probe_kernel.h
@@ -2,8 +2,6 @@
#ifndef __TRACE_PROBE_KERNEL_H_
#define __TRACE_PROBE_KERNEL_H_
-#define FAULT_STRING "(fault)"
-
/*
* This depends on trace_probe.h, but can not include it due to
* the way trace_probe_tmpl.h is used by trace_kprobe.c and trace_eprobe.c.
@@ -15,16 +13,8 @@ static nokprobe_inline int
fetch_store_strlen_user(unsigned long addr)
{
const void __user *uaddr = (__force const void __user *)addr;
- int ret;
- ret = strnlen_user_nofault(uaddr, MAX_STRING_SIZE);
- /*
- * strnlen_user_nofault returns zero on fault, insert the
- * FAULT_STRING when that occurs.
- */
- if (ret <= 0)
- return strlen(FAULT_STRING) + 1;
- return ret;
+ return strnlen_user_nofault(uaddr, MAX_STRING_SIZE);
}
/* Return the length of string -- including null terminal byte */
@@ -44,18 +34,14 @@ fetch_store_strlen(unsigned long addr)
len++;
} while (c && ret == 0 && len < MAX_STRING_SIZE);
- /* For faults, return enough to hold the FAULT_STRING */
- return (ret < 0) ? strlen(FAULT_STRING) + 1 : len;
+ return (ret < 0) ? ret : len;
}
-static nokprobe_inline void set_data_loc(int ret, void *dest, void *__dest, void *base, int len)
+static nokprobe_inline void set_data_loc(int ret, void *dest, void *__dest, void *base)
{
- if (ret >= 0) {
- *(u32 *)dest = make_data_loc(ret, __dest - base);
- } else {
- strscpy(__dest, FAULT_STRING, len);
- ret = strlen(__dest) + 1;
- }
+ if (ret < 0)
+ ret = 0;
+ *(u32 *)dest = make_data_loc(ret, __dest - base);
}
/*
@@ -76,7 +62,7 @@ fetch_store_string_user(unsigned long addr, void *dest, void *base)
__dest = get_loc_data(dest, base);
ret = strncpy_from_user_nofault(__dest, uaddr, maxlen);
- set_data_loc(ret, dest, __dest, base, maxlen);
+ set_data_loc(ret, dest, __dest, base);
return ret;
}
@@ -107,7 +93,7 @@ fetch_store_string(unsigned long addr, void *dest, void *base)
* probing.
*/
ret = strncpy_from_kernel_nofault(__dest, (void *)addr, maxlen);
- set_data_loc(ret, dest, __dest, base, maxlen);
+ set_data_loc(ret, dest, __dest, base);
return ret;
}
diff --git a/kernel/trace/trace_probe_tmpl.h b/kernel/trace/trace_probe_tmpl.h
index 00707630788d6d4f217d1c211ad425eb2d493dc5..3935b347f874bc23a155d74edd414eff42902cc9 100644
--- a/kernel/trace/trace_probe_tmpl.h
+++ b/kernel/trace/trace_probe_tmpl.h
@@ -156,11 +156,11 @@ process_fetch_insn_bottom(struct fetch_insn *code, unsigned long val,
code++;
goto array;
case FETCH_OP_ST_USTRING:
- ret += fetch_store_strlen_user(val + code->offset);
+ ret = fetch_store_strlen_user(val + code->offset);
code++;
goto array;
case FETCH_OP_ST_SYMSTR:
- ret += fetch_store_symstrlen(val + code->offset);
+ ret = fetch_store_symstrlen(val + code->offset);
code++;
goto array;
default:
@@ -204,6 +204,8 @@ process_fetch_insn_bottom(struct fetch_insn *code, unsigned long val,
array:
/* the last stage: Loop on array */
if (code->op == FETCH_OP_LP_ARRAY) {
+ if (ret < 0)
+ ret = 0;
total += ret;
if (++i < code->param) {
code = s3;
@@ -265,9 +267,7 @@ store_trace_args(void *data, struct trace_probe *tp, void *rec,
if (unlikely(arg->dynamic))
*dl = make_data_loc(maxlen, dyndata - base);
ret = process_fetch_insn(arg->code, rec, dl, base);
- if (unlikely(ret < 0 && arg->dynamic)) {
- *dl = make_data_loc(0, dyndata - base);
- } else {
+ if (arg->dynamic && likely(ret > 0)) {
dyndata += ret;
maxlen -= ret;
}
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index fa09b33ee7315bcf4af61c2faf322bbd12265a05..688bf579f2f1e78be4fd339d15f2093748c09192 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -170,7 +170,8 @@ fetch_store_string(unsigned long addr, void *dest, void *base)
*/
ret++;
*(u32 *)dest = make_data_loc(ret, (void *)dst - base);
- }
+ } else
+ *(u32 *)dest = make_data_loc(0, (void *)dst - base);
return ret;
}