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authorIngo Molnar <mingo@kernel.org>2019-05-13 20:30:15 +0200
committerIngo Molnar <mingo@kernel.org>2019-05-13 20:30:15 +0200
commit82045dd85566d87128dcc66277cf1177d9930a4a (patch)
tree22fea6311a4866293005a1a44f34310e4007a3c9 /tools/objtool
parente0478542cfd4d993e38d5f92a3f3ecd238805e96 (diff)
parentffa6f55eb6188ee73339cab710fabf30d13110a7 (diff)
Merge branch 'linus' into core/urgent, to merge in dependent changes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'tools/objtool')
-rw-r--r--tools/objtool/arch.h8
-rw-r--r--tools/objtool/arch/x86/decode.c21
-rw-r--r--tools/objtool/builtin-check.c4
-rw-r--r--tools/objtool/builtin.h2
-rw-r--r--tools/objtool/check.c401
-rw-r--r--tools/objtool/check.h4
-rw-r--r--tools/objtool/elf.c15
-rw-r--r--tools/objtool/elf.h3
-rw-r--r--tools/objtool/special.c18
-rw-r--r--tools/objtool/special.h1
-rw-r--r--tools/objtool/warn.h8
11 files changed, 383 insertions, 102 deletions
diff --git a/tools/objtool/arch.h b/tools/objtool/arch.h
index b0d7dc3d71b5..7a111a77b7aa 100644
--- a/tools/objtool/arch.h
+++ b/tools/objtool/arch.h
@@ -33,7 +33,11 @@
#define INSN_STACK 8
#define INSN_BUG 9
#define INSN_NOP 10
-#define INSN_OTHER 11
+#define INSN_STAC 11
+#define INSN_CLAC 12
+#define INSN_STD 13
+#define INSN_CLD 14
+#define INSN_OTHER 15
#define INSN_LAST INSN_OTHER
enum op_dest_type {
@@ -41,6 +45,7 @@ enum op_dest_type {
OP_DEST_REG_INDIRECT,
OP_DEST_MEM,
OP_DEST_PUSH,
+ OP_DEST_PUSHF,
OP_DEST_LEAVE,
};
@@ -55,6 +60,7 @@ enum op_src_type {
OP_SRC_REG_INDIRECT,
OP_SRC_CONST,
OP_SRC_POP,
+ OP_SRC_POPF,
OP_SRC_ADD,
OP_SRC_AND,
};
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index 540a209b78ab..472e991f6512 100644
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -357,19 +357,26 @@ int arch_decode_instruction(struct elf *elf, struct section *sec,
/* pushf */
*type = INSN_STACK;
op->src.type = OP_SRC_CONST;
- op->dest.type = OP_DEST_PUSH;
+ op->dest.type = OP_DEST_PUSHF;
break;
case 0x9d:
/* popf */
*type = INSN_STACK;
- op->src.type = OP_SRC_POP;
+ op->src.type = OP_SRC_POPF;
op->dest.type = OP_DEST_MEM;
break;
case 0x0f:
- if (op2 >= 0x80 && op2 <= 0x8f) {
+ if (op2 == 0x01) {
+
+ if (modrm == 0xca)
+ *type = INSN_CLAC;
+ else if (modrm == 0xcb)
+ *type = INSN_STAC;
+
+ } else if (op2 >= 0x80 && op2 <= 0x8f) {
*type = INSN_JUMP_CONDITIONAL;
@@ -444,6 +451,14 @@ int arch_decode_instruction(struct elf *elf, struct section *sec,
*type = INSN_CALL;
break;
+ case 0xfc:
+ *type = INSN_CLD;
+ break;
+
+ case 0xfd:
+ *type = INSN_STD;
+ break;
+
case 0xff:
if (modrm_reg == 2 || modrm_reg == 3)
diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index 694abc628e9b..f3b378126011 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -29,7 +29,7 @@
#include "builtin.h"
#include "check.h"
-bool no_fp, no_unreachable, retpoline, module;
+bool no_fp, no_unreachable, retpoline, module, backtrace, uaccess;
static const char * const check_usage[] = {
"objtool check [<options>] file.o",
@@ -41,6 +41,8 @@ const struct option check_options[] = {
OPT_BOOLEAN('u', "no-unreachable", &no_unreachable, "Skip 'unreachable instruction' warnings"),
OPT_BOOLEAN('r', "retpoline", &retpoline, "Validate retpoline assumptions"),
OPT_BOOLEAN('m', "module", &module, "Indicates the object will be part of a kernel module"),
+ OPT_BOOLEAN('b', "backtrace", &backtrace, "unwind on error"),
+ OPT_BOOLEAN('a', "uaccess", &uaccess, "enable uaccess checking"),
OPT_END(),
};
diff --git a/tools/objtool/builtin.h b/tools/objtool/builtin.h
index 28ff40e19a14..69762f9c5602 100644
--- a/tools/objtool/builtin.h
+++ b/tools/objtool/builtin.h
@@ -20,7 +20,7 @@
#include <subcmd/parse-options.h>
extern const struct option check_options[];
-extern bool no_fp, no_unreachable, retpoline, module;
+extern bool no_fp, no_unreachable, retpoline, module, backtrace, uaccess;
extern int cmd_check(int argc, const char **argv);
extern int cmd_orc(int argc, const char **argv);
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 5dde107083c6..ac743a1d53ab 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -31,6 +31,7 @@
struct alternative {
struct list_head list;
struct instruction *insn;
+ bool skip_orig;
};
const char *objname;
@@ -105,29 +106,6 @@ static struct instruction *next_insn_same_func(struct objtool_file *file,
insn = next_insn_same_sec(file, insn))
/*
- * Check if the function has been manually whitelisted with the
- * STACK_FRAME_NON_STANDARD macro, or if it should be automatically whitelisted
- * due to its use of a context switching instruction.
- */
-static bool ignore_func(struct objtool_file *file, struct symbol *func)
-{
- struct rela *rela;
-
- /* check for STACK_FRAME_NON_STANDARD */
- if (file->whitelist && file->whitelist->rela)
- list_for_each_entry(rela, &file->whitelist->rela->rela_list, list) {
- if (rela->sym->type == STT_SECTION &&
- rela->sym->sec == func->sec &&
- rela->addend == func->offset)
- return true;
- if (rela->sym->type == STT_FUNC && rela->sym == func)
- return true;
- }
-
- return false;
-}
-
-/*
* This checks to see if the given function is a "noreturn" function.
*
* For global functions which are outside the scope of this object file, we
@@ -165,6 +143,7 @@ static int __dead_end_function(struct objtool_file *file, struct symbol *func,
"fortify_panic",
"usercopy_abort",
"machine_real_restart",
+ "rewind_stack_do_exit",
};
if (func->bind == STB_WEAK)
@@ -436,18 +415,107 @@ static void add_ignores(struct objtool_file *file)
struct instruction *insn;
struct section *sec;
struct symbol *func;
+ struct rela *rela;
- for_each_sec(file, sec) {
- list_for_each_entry(func, &sec->symbol_list, list) {
- if (func->type != STT_FUNC)
- continue;
+ sec = find_section_by_name(file->elf, ".rela.discard.func_stack_frame_non_standard");
+ if (!sec)
+ return;
- if (!ignore_func(file, func))
+ list_for_each_entry(rela, &sec->rela_list, list) {
+ switch (rela->sym->type) {
+ case STT_FUNC:
+ func = rela->sym;
+ break;
+
+ case STT_SECTION:
+ func = find_symbol_by_offset(rela->sym->sec, rela->addend);
+ if (!func || func->type != STT_FUNC)
continue;
+ break;
- func_for_each_insn_all(file, func, insn)
- insn->ignore = true;
+ default:
+ WARN("unexpected relocation symbol type in %s: %d", sec->name, rela->sym->type);
+ continue;
}
+
+ func_for_each_insn_all(file, func, insn)
+ insn->ignore = true;
+ }
+}
+
+/*
+ * This is a whitelist of functions that is allowed to be called with AC set.
+ * The list is meant to be minimal and only contains compiler instrumentation
+ * ABI and a few functions used to implement *_{to,from}_user() functions.
+ *
+ * These functions must not directly change AC, but may PUSHF/POPF.
+ */
+static const char *uaccess_safe_builtin[] = {
+ /* KASAN */
+ "kasan_report",
+ "check_memory_region",
+ /* KASAN out-of-line */
+ "__asan_loadN_noabort",
+ "__asan_load1_noabort",
+ "__asan_load2_noabort",
+ "__asan_load4_noabort",
+ "__asan_load8_noabort",
+ "__asan_load16_noabort",
+ "__asan_storeN_noabort",
+ "__asan_store1_noabort",
+ "__asan_store2_noabort",
+ "__asan_store4_noabort",
+ "__asan_store8_noabort",
+ "__asan_store16_noabort",
+ /* KASAN in-line */
+ "__asan_report_load_n_noabort",
+ "__asan_report_load1_noabort",
+ "__asan_report_load2_noabort",
+ "__asan_report_load4_noabort",
+ "__asan_report_load8_noabort",
+ "__asan_report_load16_noabort",
+ "__asan_report_store_n_noabort",
+ "__asan_report_store1_noabort",
+ "__asan_report_store2_noabort",
+ "__asan_report_store4_noabort",
+ "__asan_report_store8_noabort",
+ "__asan_report_store16_noabort",
+ /* KCOV */
+ "write_comp_data",
+ "__sanitizer_cov_trace_pc",
+ "__sanitizer_cov_trace_const_cmp1",
+ "__sanitizer_cov_trace_const_cmp2",
+ "__sanitizer_cov_trace_const_cmp4",
+ "__sanitizer_cov_trace_const_cmp8",
+ "__sanitizer_cov_trace_cmp1",
+ "__sanitizer_cov_trace_cmp2",
+ "__sanitizer_cov_trace_cmp4",
+ "__sanitizer_cov_trace_cmp8",
+ /* UBSAN */
+ "ubsan_type_mismatch_common",
+ "__ubsan_handle_type_mismatch",
+ "__ubsan_handle_type_mismatch_v1",
+ /* misc */
+ "csum_partial_copy_generic",
+ "__memcpy_mcsafe",
+ "ftrace_likely_update", /* CONFIG_TRACE_BRANCH_PROFILING */
+ NULL
+};
+
+static void add_uaccess_safe(struct objtool_file *file)
+{
+ struct symbol *func;
+ const char **name;
+
+ if (!uaccess)
+ return;
+
+ for (name = uaccess_safe_builtin; *name; name++) {
+ func = find_symbol_by_name(file->elf, *name);
+ if (!func)
+ continue;
+
+ func->alias->uaccess_safe = true;
}
}
@@ -457,13 +525,13 @@ static void add_ignores(struct objtool_file *file)
* But it at least allows objtool to understand the control flow *around* the
* retpoline.
*/
-static int add_nospec_ignores(struct objtool_file *file)
+static int add_ignore_alternatives(struct objtool_file *file)
{
struct section *sec;
struct rela *rela;
struct instruction *insn;
- sec = find_section_by_name(file->elf, ".rela.discard.nospec");
+ sec = find_section_by_name(file->elf, ".rela.discard.ignore_alts");
if (!sec)
return 0;
@@ -475,7 +543,7 @@ static int add_nospec_ignores(struct objtool_file *file)
insn = find_insn(file, rela->sym->sec, rela->addend);
if (!insn) {
- WARN("bad .discard.nospec entry");
+ WARN("bad .discard.ignore_alts entry");
return -1;
}
@@ -524,7 +592,8 @@ static int add_jump_destinations(struct objtool_file *file)
continue;
} else {
/* sibling call */
- insn->jump_dest = 0;
+ insn->call_dest = rela->sym;
+ insn->jump_dest = NULL;
continue;
}
@@ -546,25 +615,38 @@ static int add_jump_destinations(struct objtool_file *file)
}
/*
- * For GCC 8+, create parent/child links for any cold
- * subfunctions. This is _mostly_ redundant with a similar
- * initialization in read_symbols().
- *
- * If a function has aliases, we want the *first* such function
- * in the symbol table to be the subfunction's parent. In that
- * case we overwrite the initialization done in read_symbols().
- *
- * However this code can't completely replace the
- * read_symbols() code because this doesn't detect the case
- * where the parent function's only reference to a subfunction
- * is through a switch table.
+ * Cross-function jump.
*/
if (insn->func && insn->jump_dest->func &&
- insn->func != insn->jump_dest->func &&
- !strstr(insn->func->name, ".cold.") &&
- strstr(insn->jump_dest->func->name, ".cold.")) {
- insn->func->cfunc = insn->jump_dest->func;
- insn->jump_dest->func->pfunc = insn->func;
+ insn->func != insn->jump_dest->func) {
+
+ /*
+ * For GCC 8+, create parent/child links for any cold
+ * subfunctions. This is _mostly_ redundant with a
+ * similar initialization in read_symbols().
+ *
+ * If a function has aliases, we want the *first* such
+ * function in the symbol table to be the subfunction's
+ * parent. In that case we overwrite the
+ * initialization done in read_symbols().
+ *
+ * However this code can't completely replace the
+ * read_symbols() code because this doesn't detect the
+ * case where the parent function's only reference to a
+ * subfunction is through a switch table.
+ */
+ if (!strstr(insn->func->name, ".cold.") &&
+ strstr(insn->jump_dest->func->name, ".cold.")) {
+ insn->func->cfunc = insn->jump_dest->func;
+ insn->jump_dest->func->pfunc = insn->func;
+
+ } else if (insn->jump_dest->func->pfunc != insn->func->pfunc &&
+ insn->jump_dest->offset == insn->jump_dest->func->offset) {
+
+ /* sibling class */
+ insn->call_dest = insn->jump_dest->func;
+ insn->jump_dest = NULL;
+ }
}
}
@@ -633,9 +715,6 @@ static int add_call_destinations(struct objtool_file *file)
* conditionally jumps to the _end_ of the entry. We have to modify these
* jumps' destinations to point back to .text rather than the end of the
* entry in .altinstr_replacement.
- *
- * 4. It has been requested that we don't validate the !POPCNT feature path
- * which is a "very very small percentage of machines".
*/
static int handle_group_alt(struct objtool_file *file,
struct special_alt *special_alt,
@@ -651,9 +730,6 @@ static int handle_group_alt(struct objtool_file *file,
if (insn->offset >= special_alt->orig_off + special_alt->orig_len)
break;
- if (special_alt->skip_orig)
- insn->type = INSN_NOP;
-
insn->alt_group = true;
last_orig_insn = insn;
}
@@ -695,6 +771,7 @@ static int handle_group_alt(struct objtool_file *file,
last_new_insn = insn;
insn->ignore = orig_insn->ignore_alts;
+ insn->func = orig_insn->func;
if (insn->type != INSN_JUMP_CONDITIONAL &&
insn->type != INSN_JUMP_UNCONDITIONAL)
@@ -817,6 +894,8 @@ static int add_special_section_alts(struct objtool_file *file)
}
alt->insn = new_insn;
+ alt->skip_orig = special_alt->skip_orig;
+ orig_insn->ignore_alts |= special_alt->skip_alt;
list_add_tail(&alt->list, &orig_insn->alts);
list_del(&special_alt->list);
@@ -1238,8 +1317,9 @@ static int decode_sections(struct objtool_file *file)
return ret;
add_ignores(file);
+ add_uaccess_safe(file);
- ret = add_nospec_ignores(file);
+ ret = add_ignore_alternatives(file);
if (ret)
return ret;
@@ -1319,11 +1399,11 @@ static int update_insn_state_regs(struct instruction *insn, struct insn_state *s
return 0;
/* push */
- if (op->dest.type == OP_DEST_PUSH)
+ if (op->dest.type == OP_DEST_PUSH || op->dest.type == OP_DEST_PUSHF)
cfa->offset += 8;
/* pop */
- if (op->src.type == OP_SRC_POP)
+ if (op->src.type == OP_SRC_POP || op->src.type == OP_SRC_POPF)
cfa->offset -= 8;
/* add immediate to sp */
@@ -1580,6 +1660,7 @@ static int update_insn_state(struct instruction *insn, struct insn_state *state)
break;
case OP_SRC_POP:
+ case OP_SRC_POPF:
if (!state->drap && op->dest.type == OP_DEST_REG &&
op->dest.reg == cfa->base) {
@@ -1644,6 +1725,7 @@ static int update_insn_state(struct instruction *insn, struct insn_state *state)
break;
case OP_DEST_PUSH:
+ case OP_DEST_PUSHF:
state->stack_size += 8;
if (cfa->base == CFI_SP)
cfa->offset += 8;
@@ -1734,7 +1816,7 @@ static int update_insn_state(struct instruction *insn, struct insn_state *state)
break;
case OP_DEST_MEM:
- if (op->src.type != OP_SRC_POP) {
+ if (op->src.type != OP_SRC_POP && op->src.type != OP_SRC_POPF) {
WARN_FUNC("unknown stack-related memory operation",
insn->sec, insn->offset);
return -1;
@@ -1798,6 +1880,50 @@ static bool insn_state_match(struct instruction *insn, struct insn_state *state)
return false;
}
+static inline bool func_uaccess_safe(struct symbol *func)
+{
+ if (func)
+ return func->alias->uaccess_safe;
+
+ return false;
+}
+
+static inline const char *insn_dest_name(struct instruction *insn)
+{
+ if (insn->call_dest)
+ return insn->call_dest->name;
+
+ return "{dynamic}";
+}
+
+static int validate_call(struct instruction *insn, struct insn_state *state)
+{
+ if (state->uaccess && !func_uaccess_safe(insn->call_dest)) {
+ WARN_FUNC("call to %s() with UACCESS enabled",
+ insn->sec, insn->offset, insn_dest_name(insn));
+ return 1;
+ }
+
+ if (state->df) {
+ WARN_FUNC("call to %s() with DF set",
+ insn->sec, insn->offset, insn_dest_name(insn));
+ return 1;
+ }
+
+ return 0;
+}
+
+static int validate_sibling_call(struct instruction *insn, struct insn_state *state)
+{
+ if (has_modified_stack_frame(state)) {
+ WARN_FUNC("sibling call from callable instruction with modified stack frame",
+ insn->sec, insn->offset);
+ return 1;
+ }
+
+ return validate_call(insn, state);
+}
+
/*
* Follow the branch starting at the given instruction, and recursively follow
* any other branches (jumps). Meanwhile, track the frame pointer state at
@@ -1843,7 +1969,9 @@ static int validate_branch(struct objtool_file *file, struct instruction *first,
if (!insn->hint && !insn_state_match(insn, &state))
return 1;
- return 0;
+ /* If we were here with AC=0, but now have AC=1, go again */
+ if (insn->state.uaccess || !state.uaccess)
+ return 0;
}
if (insn->hint) {
@@ -1892,16 +2020,42 @@ static int validate_branch(struct objtool_file *file, struct instruction *first,
insn->visited = true;
if (!insn->ignore_alts) {
+ bool skip_orig = false;
+
list_for_each_entry(alt, &insn->alts, list) {
+ if (alt->skip_orig)
+ skip_orig = true;
+
ret = validate_branch(file, alt->insn, state);
- if (ret)
- return 1;
+ if (ret) {
+ if (backtrace)
+ BT_FUNC("(alt)", insn);
+ return ret;
+ }
}
+
+ if (skip_orig)
+ return 0;
}
switch (insn->type) {
case INSN_RETURN:
+ if (state.uaccess && !func_uaccess_safe(func)) {
+ WARN_FUNC("return with UACCESS enabled", sec, insn->offset);
+ return 1;
+ }
+
+ if (!state.uaccess && func_uaccess_safe(func)) {
+ WARN_FUNC("return with UACCESS disabled from a UACCESS-safe function", sec, insn->offset);
+ return 1;
+ }
+
+ if (state.df) {
+ WARN_FUNC("return with DF set", sec, insn->offset);
+ return 1;
+ }
+
if (func && has_modified_stack_frame(&state)) {
WARN_FUNC("return with modified stack frame",
sec, insn->offset);
@@ -1917,17 +2071,22 @@ static int validate_branch(struct objtool_file *file, struct instruction *first,
return 0;
case INSN_CALL:
- if (is_fentry_call(insn))
- break;
+ case INSN_CALL_DYNAMIC:
+ ret = validate_call(insn, &state);
+ if (ret)
+ return ret;
- ret = dead_end_function(file, insn->call_dest);
- if (ret == 1)
- return 0;
- if (ret == -1)
- return 1;
+ if (insn->type == INSN_CALL) {
+ if (is_fentry_call(insn))
+ break;
+
+ ret = dead_end_function(file, insn->call_dest);
+ if (ret == 1)
+ return 0;
+ if (ret == -1)
+ return 1;
+ }
- /* fallthrough */
- case INSN_CALL_DYNAMIC:
if (!no_fp && func && !has_valid_stack_frame(&state)) {
WARN_FUNC("call without frame pointer save/setup",
sec, insn->offset);
@@ -1937,18 +2096,21 @@ static int validate_branch(struct objtool_file *file, struct instruction *first,
case INSN_JUMP_CONDITIONAL:
case INSN_JUMP_UNCONDITIONAL:
- if (insn->jump_dest &&
- (!func || !insn->jump_dest->func ||
- insn->jump_dest->func->pfunc == func)) {
- ret = validate_branch(file, insn->jump_dest,
- state);
+ if (func && !insn->jump_dest) {
+ ret = validate_sibling_call(insn, &state);
if (ret)
- return 1;
+ return ret;
- } else if (func && has_modified_stack_frame(&state)) {
- WARN_FUNC("sibling call from callable instruction with modified stack frame",
- sec, insn->offset);
- return 1;
+ } else if (insn->jump_dest &&
+ (!func || !insn->jump_dest->func ||
+ insn->jump_dest->func->pfunc == func)) {
+ ret = validate_branch(file, insn->jump_dest,
+ state);
+ if (ret) {
+ if (backtrace)
+ BT_FUNC("(branch)", insn);
+ return ret;
+ }
}
if (insn->type == INSN_JUMP_UNCONDITIONAL)
@@ -1957,11 +2119,10 @@ static int validate_branch(struct objtool_file *file, struct instruction *first,
break;
case INSN_JUMP_DYNAMIC:
- if (func && list_empty(&insn->alts) &&
- has_modified_stack_frame(&state)) {
- WARN_FUNC("sibling call from callable instruction with modified stack frame",
- sec, insn->offset);
- return 1;
+ if (func && list_empty(&insn->alts)) {
+ ret = validate_sibling_call(insn, &state);
+ if (ret)
+ return ret;
}
return 0;
@@ -1978,6 +2139,63 @@ static int validate_branch(struct objtool_file *file, struct instruction *first,
if (update_insn_state(insn, &state))
return 1;
+ if (insn->stack_op.dest.type == OP_DEST_PUSHF) {
+ if (!state.uaccess_stack) {
+ state.uaccess_stack = 1;
+ } else if (state.uaccess_stack >> 31) {
+ WARN_FUNC("PUSHF stack exhausted", sec, insn->offset);
+ return 1;
+ }
+ state.uaccess_stack <<= 1;
+ state.uaccess_stack |= state.uaccess;
+ }
+
+ if (insn->stack_op.src.type == OP_SRC_POPF) {
+ if (state.uaccess_stack) {
+ state.uaccess = state.uaccess_stack & 1;
+ state.uaccess_stack >>= 1;
+ if (state.uaccess_stack == 1)
+ state.uaccess_stack = 0;
+ }
+ }
+
+ break;
+
+ case INSN_STAC:
+ if (state.uaccess) {
+ WARN_FUNC("recursive UACCESS enable", sec, insn->offset);
+ return 1;
+ }
+
+ state.uaccess = true;
+ break;
+
+ case INSN_CLAC:
+ if (!state.uaccess && insn->func) {
+ WARN_FUNC("redundant UACCESS disable", sec, insn->offset);
+ return 1;
+ }
+
+ if (func_uaccess_safe(func) && !state.uaccess_stack) {
+ WARN_FUNC("UACCESS-safe disables UACCESS", sec, insn->offset);
+ return 1;
+ }
+
+ state.uaccess = false;
+ break;
+
+ case INSN_STD:
+ if (state.df)
+ WARN_FUNC("recursive STD", sec, insn->offset);
+
+ state.df = true;
+ break;
+
+ case INSN_CLD:
+ if (!state.df && insn->func)
+ WARN_FUNC("redundant CLD", sec, insn->offset);
+
+ state.df = false;
break;
default:
@@ -2014,6 +2232,8 @@ static int validate_unwind_hints(struct objtool_file *file)
for_each_insn(file, insn) {
if (insn->hint && !insn->visited) {
ret = validate_branch(file, insn, state);
+ if (ret && backtrace)
+ BT_FUNC("<=== (hint)", insn);
warnings += ret;
}
}
@@ -2141,7 +2361,11 @@ static int validate_functions(struct objtool_file *file)
if (!insn || insn->ignore)
continue;
+ state.uaccess = func->alias->uaccess_safe;
+
ret = validate_branch(file, insn, state);
+ if (ret && backtrace)
+ BT_FUNC("<=== (func)", insn);
warnings += ret;
}
}
@@ -2198,7 +2422,6 @@ int check(const char *_objname, bool orc)
INIT_LIST_HEAD(&file.insn_list);
hash_init(file.insn_hash);
- file.whitelist = find_section_by_name(file.elf, ".discard.func_stack_frame_non_standard");
file.c_file = find_section_by_name(file.elf, ".comment");
file.ignore_unreachables = no_unreachable;
file.hints = false;
diff --git a/tools/objtool/check.h b/tools/objtool/check.h
index e6e8a655b556..71e54f97dbcd 100644
--- a/tools/objtool/check.h
+++ b/tools/objtool/check.h
@@ -31,7 +31,8 @@ struct insn_state {
int stack_size;
unsigned char type;
bool bp_scratch;
- bool drap, end;
+ bool drap, end, uaccess, df;
+ unsigned int uaccess_stack;
int drap_reg, drap_offset;
struct cfi_reg vals[CFI_NUM_REGS];
};
@@ -60,7 +61,6 @@ struct objtool_file {
struct elf *elf;
struct list_head insn_list;
DECLARE_HASHTABLE(insn_hash, 16);
- struct section *whitelist;
bool ignore_unreachables, c_file, hints, rodata;
};
diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index b8f3cca8e58b..dd198d53387d 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -219,7 +219,7 @@ static int read_sections(struct elf *elf)
static int read_symbols(struct elf *elf)
{
struct section *symtab, *sec;
- struct symbol *sym, *pfunc;
+ struct symbol *sym, *pfunc, *alias;
struct list_head *entry, *tmp;
int symbols_nr, i;
char *coldstr;
@@ -239,6 +239,7 @@ static int read_symbols(struct elf *elf)
return -1;
}
memset(sym, 0, sizeof(*sym));
+ alias = sym;
sym->idx = i;
@@ -288,11 +289,17 @@ static int read_symbols(struct elf *elf)
break;
}
- if (sym->offset == s->offset && sym->len >= s->len) {
- entry = tmp;
- break;
+ if (sym->offset == s->offset) {
+ if (sym->len == s->len && alias == sym)
+ alias = s;
+
+ if (sym->len >= s->len) {
+ entry = tmp;
+ break;
+ }
}
}
+ sym->alias = alias;
list_add(&sym->list, entry);
hash_add(sym->sec->symbol_hash, &sym->hash, sym->idx);
}
diff --git a/tools/objtool/elf.h b/tools/objtool/elf.h
index bc97ed86b9cd..2cc2ed49322d 100644
--- a/tools/objtool/elf.h
+++ b/tools/objtool/elf.h
@@ -61,7 +61,8 @@ struct symbol {
unsigned char bind, type;
unsigned long offset;
unsigned int len;
- struct symbol *pfunc, *cfunc;
+ struct symbol *pfunc, *cfunc, *alias;
+ bool uaccess_safe;
};
struct rela {
diff --git a/tools/objtool/special.c b/tools/objtool/special.c
index 50af4e1274b3..4e50563d87c6 100644
--- a/tools/objtool/special.c
+++ b/tools/objtool/special.c
@@ -23,6 +23,7 @@
#include <stdlib.h>
#include <string.h>
+#include "builtin.h"
#include "special.h"
#include "warn.h"
@@ -42,6 +43,7 @@
#define ALT_NEW_LEN_OFFSET 11
#define X86_FEATURE_POPCNT (4*32+23)
+#define X86_FEATURE_SMAP (9*32+20)
struct special_entry {
const char *sec;
@@ -110,6 +112,22 @@ static int get_alt_entry(struct elf *elf, struct special_entry *entry,
*/
if (feature == X86_FEATURE_POPCNT)
alt->skip_orig = true;
+
+ /*
+ * If UACCESS validation is enabled; force that alternative;
+ * otherwise force it the other way.
+ *
+ * What we want to avoid is having both the original and the
+ * alternative code flow at the same time, in that case we can
+ * find paths that see the STAC but take the NOP instead of
+ * CLAC and the other way around.
+ */
+ if (feature == X86_FEATURE_SMAP) {
+ if (uaccess)
+ alt->skip_orig = true;
+ else
+ alt->skip_alt = true;
+ }
}
orig_rela = find_rela_by_dest(sec, offset + entry->orig);
diff --git a/tools/objtool/special.h b/tools/objtool/special.h
index fad1d092f679..d5c062e718ef 100644
--- a/tools/objtool/special.h
+++ b/tools/objtool/special.h
@@ -26,6 +26,7 @@ struct special_alt {
bool group;
bool skip_orig;
+ bool skip_alt;
bool jump_or_nop;
struct section *orig_sec;
diff --git a/tools/objtool/warn.h b/tools/objtool/warn.h
index afd9f7a05f6d..f4fbb972b611 100644
--- a/tools/objtool/warn.h
+++ b/tools/objtool/warn.h
@@ -64,6 +64,14 @@ static inline char *offstr(struct section *sec, unsigned long offset)
free(_str); \
})
+#define BT_FUNC(format, insn, ...) \
+({ \
+ struct instruction *_insn = (insn); \
+ char *_str = offstr(_insn->sec, _insn->offset); \
+ WARN(" %s: " format, _str, ##__VA_ARGS__); \
+ free(_str); \
+})
+
#define WARN_ELF(format, ...) \
WARN(format ": %s", ##__VA_ARGS__, elf_errmsg(-1))