Commit | Line | Data |
---|---|---|
a1fa2691 MB |
1 | Make sure that statements such as: |
2 | ||
3 | strcpy (dst, "/gnu/store/…"); | |
4 | ||
5 | or | |
6 | ||
7 | static const char str[] = "/gnu/store/…"; | |
8 | … | |
9 | strcpy (dst, str); | |
10 | ||
11 | do not result in chunked /gnu/store strings that are undetectable by | |
12 | Guix's GC and its grafting code. See <https://bugs.gnu.org/24703> | |
13 | and <https://bugs.gnu.org/30395>. | |
14 | ||
15 | --- gcc-5.3.0/gcc/builtins.c 2016-10-18 10:50:46.080616285 +0200 | |
16 | +++ gcc-5.3.0/gcc/builtins.c 2016-11-09 15:26:43.693042737 +0100 | |
17 | @@ -3012,6 +3012,58 @@ determine_block_size (tree len, rtx len_rtx, | |
18 | GET_MODE_MASK (GET_MODE (len_rtx))); | |
19 | } | |
20 | ||
21 | +extern void debug_tree (tree); | |
22 | + | |
23 | +/* Return true if STR contains the string "/gnu/store". */ | |
24 | + | |
25 | +bool | |
26 | +store_reference_p (tree str) | |
27 | +{ | |
28 | + if (getenv ("GUIX_GCC_DEBUG") != NULL) | |
29 | + debug_tree (str); | |
30 | + | |
31 | + if (TREE_CODE (str) == ADDR_EXPR) | |
32 | + str = TREE_OPERAND (str, 0); | |
33 | + | |
34 | + if (TREE_CODE (str) == VAR_DECL | |
35 | + && TREE_STATIC (str) | |
36 | + && TREE_READONLY (str)) | |
37 | + { | |
38 | + /* STR may be a 'static const' variable whose initial value | |
39 | + is a string constant. See <https://bugs.gnu.org/30395>. */ | |
40 | + str = DECL_INITIAL (str); | |
41 | + if (str == NULL_TREE) | |
42 | + return false; | |
43 | + } | |
44 | + | |
45 | + if (TREE_CODE (str) != STRING_CST) | |
46 | + return false; | |
47 | + | |
48 | + int len; | |
49 | + const char *store; | |
50 | + | |
51 | + store = getenv ("NIX_STORE") ? getenv ("NIX_STORE") : "/gnu/store"; | |
52 | + len = strlen (store); | |
53 | + | |
54 | + /* Size of the hash part of store file names, including leading slash and | |
55 | + trailing hyphen. */ | |
56 | + const int hash_len = 34; | |
57 | + | |
58 | + if (TREE_STRING_LENGTH (str) < len + hash_len) | |
59 | + return false; | |
60 | + | |
61 | + /* We cannot use 'strstr' because 'TREE_STRING_POINTER' returns a string | |
62 | + that is not necessarily NUL-terminated. */ | |
63 | + | |
64 | + for (int i = 0; i < TREE_STRING_LENGTH (str) - (len + hash_len); i++) | |
65 | + { | |
66 | + if (strncmp (TREE_STRING_POINTER (str) + i, store, len) == 0) | |
67 | + return true; | |
68 | + } | |
69 | + | |
70 | + return false; | |
71 | +} | |
72 | + | |
73 | /* Try to verify that the sizes and lengths of the arguments to a string | |
74 | manipulation function given by EXP are within valid bounds and that | |
75 | the operation does not lead to buffer overflow or read past the end. | |
76 | @@ -3605,6 +3657,13 @@ expand_builtin_memory_copy_args (tree dest, tree src, tree len, | |
77 | unsigned HOST_WIDE_INT max_size; | |
78 | unsigned HOST_WIDE_INT probable_max_size; | |
79 | ||
80 | + /* Do not emit block moves, which translate to the 'movabs' instruction on | |
81 | + x86_64, when SRC refers to store items. That way, store references | |
82 | + remain visible to the Guix GC and grafting code. See | |
83 | + <https://bugs.gnu.org/24703>. */ | |
84 | + if (store_reference_p (src)) | |
85 | + return NULL_RTX; | |
86 | + | |
87 | /* If DEST is not a pointer type, call the normal function. */ | |
88 | if (dest_align == 0) | |
89 | return NULL_RTX; | |
90 | --- gcc-5.5.0/gcc/gimple-fold.c 2018-03-20 11:36:16.709442004 +0100 | |
91 | +++ gcc-5.5.0/gcc/gimple-fold.c 2018-03-20 11:46:43.838487065 +0100 | |
92 | @@ -635,6 +635,8 @@ var_decl_component_p (tree var) | |
93 | return SSA_VAR_P (inner); | |
94 | } | |
95 | ||
96 | +extern bool store_reference_p (tree); | |
97 | + | |
98 | /* If the SIZE argument representing the size of an object is in a range | |
99 | of values of which exactly one is valid (and that is zero), return | |
100 | true, otherwise false. */ | |
101 | @@ -742,6 +744,9 @@ gimple_fold_builtin_memory_op (gimple_stmt_iterator *gsi, | |
102 | off0 = build_int_cst (build_pointer_type_for_mode (char_type_node, | |
103 | ptr_mode, true), 0); | |
104 | ||
105 | + if (store_reference_p (src)) | |
106 | + return false; | |
107 | + | |
108 | /* If we can perform the copy efficiently with first doing all loads | |
109 | and then all stores inline it that way. Currently efficiently | |
110 | means that we can load all the memory into a single integer |