X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=lttng-filter-interpreter.c;h=6e5a5139e3dfd285fe0500c2558b8c1982fb49ba;hb=refs%2Fheads%2Fstable-2.11;hp=bf69549707657ed89fd524f35b74ecb0fc7dcea7;hpb=9f36eaed6f91d5897924b551b44d1edd8cee00e2;p=lttng-modules.git

diff --git a/lttng-filter-interpreter.c b/lttng-filter-interpreter.c
index bf695497..6e5a5139 100644
--- a/lttng-filter-interpreter.c
+++ b/lttng-filter-interpreter.c
@@ -7,8 +7,8 @@
  * Copyright (C) 2010-2016 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  */
 
-#include <linux/uaccess.h>
-#include <wrapper/frame.h>
+#include <wrapper/uaccess.h>
+#include <wrapper/objtool.h>
 #include <wrapper/types.h>
 #include <linux/swab.h>
 
@@ -22,7 +22,7 @@ LTTNG_STACK_FRAME_NON_STANDARD(lttng_filter_interpret_bytecode);
  * to handle user-space read.
  */
 static
-char get_char(struct estack_entry *reg, size_t offset)
+char get_char(const struct estack_entry *reg, size_t offset)
 {
 	if (unlikely(offset >= reg->u.s.seq_len))
 		return '\0';
@@ -30,7 +30,7 @@ char get_char(struct estack_entry *reg, size_t offset)
 		char c;
 
 		/* Handle invalid access as end of string. */
-		if (unlikely(!access_ok(VERIFY_READ,
+		if (unlikely(!lttng_access_ok(VERIFY_READ,
 				reg->u.s.user_str + offset,
 				sizeof(c))))
 			return '\0';
@@ -81,16 +81,14 @@ static
 int stack_star_glob_match(struct estack *stack, int top, const char *cmp_type)
 {
 	bool has_user = false;
-	mm_segment_t old_fs;
 	int result;
 	struct estack_entry *pattern_reg;
 	struct estack_entry *candidate_reg;
 
+	/* Disable the page fault handler when reading from userspace. */
 	if (estack_bx(stack, top)->u.s.user
 			|| estack_ax(stack, top)->u.s.user) {
 		has_user = true;
-		old_fs = get_fs();
-		set_fs(KERNEL_DS);
 		pagefault_disable();
 	}
 
@@ -106,10 +104,8 @@ int stack_star_glob_match(struct estack *stack, int top, const char *cmp_type)
 	/* Perform the match operation. */
 	result = !strutils_star_glob_match_char_cb(get_char_at_cb,
 		pattern_reg, get_char_at_cb, candidate_reg);
-	if (has_user) {
+	if (has_user)
 		pagefault_enable();
-		set_fs(old_fs);
-	}
 
 	return result;
 }
@@ -119,13 +115,10 @@ int stack_strcmp(struct estack *stack, int top, const char *cmp_type)
 {
 	size_t offset_bx = 0, offset_ax = 0;
 	int diff, has_user = 0;
-	mm_segment_t old_fs;
 
 	if (estack_bx(stack, top)->u.s.user
 			|| estack_ax(stack, top)->u.s.user) {
 		has_user = 1;
-		old_fs = get_fs();
-		set_fs(KERNEL_DS);
 		pagefault_disable();
 	}
 
@@ -210,10 +203,9 @@ int stack_strcmp(struct estack *stack, int top, const char *cmp_type)
 		offset_bx++;
 		offset_ax++;
 	}
-	if (has_user) {
+	if (has_user)
 		pagefault_enable();
-		set_fs(old_fs);
-	}
+
 	return diff;
 }
 
@@ -601,6 +593,39 @@ end:
 	return ret;
 }
 
+#ifdef DEBUG
+
+#define DBG_USER_STR_CUTOFF 32
+
+/*
+ * In debug mode, print user string (truncated, if necessary).
+ */
+static inline
+void dbg_load_ref_user_str_printk(const struct estack_entry *user_str_reg)
+{
+	size_t pos = 0;
+	char last_char;
+	char user_str[DBG_USER_STR_CUTOFF];
+
+	pagefault_disable();
+	do {
+		last_char = get_char(user_str_reg, pos);
+		user_str[pos] = last_char;
+		pos++;
+	} while (last_char != '\0' && pos < sizeof(user_str));
+	pagefault_enable();
+
+	user_str[sizeof(user_str) - 1] = '\0';
+	dbg_printk("load field ref user string: '%s%s'\n", user_str,
+		last_char != '\0' ? "[...]" : "");
+}
+#else
+static inline
+void dbg_load_ref_user_str_printk(const struct estack_entry *user_str_reg)
+{
+}
+#endif
+
 /*
  * Return 0 (discard), or raise the 0x1 flag (log event).
  * Currently, other flags are kept for future extensions and have no
@@ -1321,7 +1346,7 @@ uint64_t lttng_filter_interpret_bytecode(void *filter_data,
 			estack_push(stack, top, ax, bx);
 			estack_ax(stack, top)->u.s.user_str =
 				*(const char * const *) &filter_stack_data[ref->offset];
-			if (unlikely(!estack_ax(stack, top)->u.s.str)) {
+			if (unlikely(!estack_ax(stack, top)->u.s.user_str)) {
 				dbg_printk("Filter warning: loading a NULL string.\n");
 				ret = -EINVAL;
 				goto end;
@@ -1330,7 +1355,7 @@ uint64_t lttng_filter_interpret_bytecode(void *filter_data,
 			estack_ax(stack, top)->u.s.literal_type =
 				ESTACK_STRING_LITERAL_TYPE_NONE;
 			estack_ax(stack, top)->u.s.user = 1;
-			dbg_printk("ref load string %s\n", estack_ax(stack, top)->u.s.str);
+			dbg_load_ref_user_str_printk(estack_ax(stack, top));
 			next_pc += sizeof(struct load_op) + sizeof(struct field_ref);
 			PO;
 		}
@@ -1348,7 +1373,7 @@ uint64_t lttng_filter_interpret_bytecode(void *filter_data,
 			estack_ax(stack, top)->u.s.user_str =
 				*(const char **) (&filter_stack_data[ref->offset
 								+ sizeof(unsigned long)]);
-			if (unlikely(!estack_ax(stack, top)->u.s.str)) {
+			if (unlikely(!estack_ax(stack, top)->u.s.user_str)) {
 				dbg_printk("Filter warning: loading a NULL sequence.\n");
 				ret = -EINVAL;
 				goto end;