111 lines
3.5 KiB
Diff
111 lines
3.5 KiB
Diff
Make sure that statements such as:
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strcpy (dst, "/gnu/store/…");
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or
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static const char str[] = "/gnu/store/…";
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…
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strcpy (dst, str);
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do not result in chunked /gnu/store strings that are undetectable by
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Guix's GC and its grafting code. See <https://bugs.gnu.org/24703>
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and <https://bugs.gnu.org/30395>.
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--- gcc-5.3.0/gcc/builtins.c 2016-10-18 10:50:46.080616285 +0200
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+++ gcc-5.3.0/gcc/builtins.c 2016-11-09 15:26:43.693042737 +0100
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@@ -3012,6 +3012,58 @@ determine_block_size (tree len, rtx len_rtx,
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GET_MODE_MASK (GET_MODE (len_rtx)));
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}
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+extern void debug_tree (tree);
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+
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+/* Return true if STR contains the string "/gnu/store". */
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+
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+bool
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+store_reference_p (tree str)
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+{
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+ if (getenv ("GUIX_GCC_DEBUG") != NULL)
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+ debug_tree (str);
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+
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+ if (TREE_CODE (str) == ADDR_EXPR)
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+ str = TREE_OPERAND (str, 0);
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+
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+ if (TREE_CODE (str) == VAR_DECL
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+ && TREE_STATIC (str)
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+ && TREE_READONLY (str))
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+ {
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+ /* STR may be a 'static const' variable whose initial value
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+ is a string constant. See <https://bugs.gnu.org/30395>. */
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+ str = DECL_INITIAL (str);
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+ if (str == NULL_TREE)
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+ return false;
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+ }
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+
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+ if (TREE_CODE (str) != STRING_CST)
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+ return false;
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+
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+ int len;
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+ const char *store;
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+
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+ store = getenv ("NIX_STORE") ? getenv ("NIX_STORE") : "/gnu/store";
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+ len = strlen (store);
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+
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+ /* Size of the hash part of store file names, including leading slash and
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+ trailing hyphen. */
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+ const int hash_len = 34;
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+
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+ if (TREE_STRING_LENGTH (str) < len + hash_len)
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+ return false;
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+
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+ /* We cannot use 'strstr' because 'TREE_STRING_POINTER' returns a string
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+ that is not necessarily NUL-terminated. */
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+
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+ for (int i = 0; i < TREE_STRING_LENGTH (str) - (len + hash_len); i++)
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+ {
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+ if (strncmp (TREE_STRING_POINTER (str) + i, store, len) == 0)
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+ return true;
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+ }
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+
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+ return false;
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+}
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+
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/* Try to verify that the sizes and lengths of the arguments to a string
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manipulation function given by EXP are within valid bounds and that
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the operation does not lead to buffer overflow or read past the end.
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@@ -3605,6 +3657,13 @@ expand_builtin_memory_copy_args (tree dest, tree src, tree len,
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unsigned HOST_WIDE_INT max_size;
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unsigned HOST_WIDE_INT probable_max_size;
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+ /* Do not emit block moves, which translate to the 'movabs' instruction on
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+ x86_64, when SRC refers to store items. That way, store references
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+ remain visible to the Guix GC and grafting code. See
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+ <https://bugs.gnu.org/24703>. */
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+ if (store_reference_p (src))
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+ return NULL_RTX;
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+
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/* If DEST is not a pointer type, call the normal function. */
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if (dest_align == 0)
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return NULL_RTX;
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--- gcc-5.5.0/gcc/gimple-fold.c 2018-03-20 11:36:16.709442004 +0100
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+++ gcc-5.5.0/gcc/gimple-fold.c 2018-03-20 11:46:43.838487065 +0100
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@@ -635,6 +635,8 @@ var_decl_component_p (tree var)
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return SSA_VAR_P (inner);
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}
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+extern bool store_reference_p (tree);
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+
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/* If the SIZE argument representing the size of an object is in a range
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of values of which exactly one is valid (and that is zero), return
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true, otherwise false. */
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@@ -742,6 +744,9 @@ gimple_fold_builtin_memory_op (gimple_stmt_iterator *gsi,
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off0 = build_int_cst (build_pointer_type_for_mode (char_type_node,
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ptr_mode, true), 0);
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+ if (store_reference_p (src))
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+ return false;
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+
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/* If we can perform the copy efficiently with first doing all loads
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and then all stores inline it that way. Currently efficiently
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means that we can load all the memory into a single integer
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