objtool: Re-add UNWIND_HINT_{SAVE_RESTORE}

commit 8faea26e611189e933ea2281975ff4dc7c1106b6 upstream.

Commit

  c536ed2fffd5 ("objtool: Remove SAVE/RESTORE hints")

removed the save/restore unwind hints because they were no longer
needed. Now they're going to be needed again so re-add them.

Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/include/asm/unwind_hints.h b/arch/x86/include/asm/unwind_hints.h
index 9cd8214..56664b3 100644 (file)
--- a/arch/x86/include/asm/unwind_hints.h
+++ b/arch/x86/include/asm/unwind_hints.h
@@ -8,11 +8,11 @@
 #ifdef __ASSEMBLY__
 
 .macro UNWIND_HINT_EMPTY
-       UNWIND_HINT sp_reg=ORC_REG_UNDEFINED type=UNWIND_HINT_TYPE_CALL end=1
+       UNWIND_HINT type=UNWIND_HINT_TYPE_CALL end=1
 .endm
 
 .macro UNWIND_HINT_ENTRY
-       UNWIND_HINT sp_reg=ORC_REG_UNDEFINED type=UNWIND_HINT_TYPE_ENTRY end=1
+       UNWIND_HINT type=UNWIND_HINT_TYPE_ENTRY end=1
 .endm
 
 .macro UNWIND_HINT_REGS base=%rsp offset=0 indirect=0 extra=1 partial=0
@@ -56,6 +56,14 @@
        UNWIND_HINT sp_reg=ORC_REG_SP sp_offset=8 type=UNWIND_HINT_TYPE_FUNC
 .endm
 
+.macro UNWIND_HINT_SAVE
+       UNWIND_HINT type=UNWIND_HINT_TYPE_SAVE
+.endm
+
+.macro UNWIND_HINT_RESTORE
+       UNWIND_HINT type=UNWIND_HINT_TYPE_RESTORE
+.endm
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* _ASM_X86_UNWIND_HINTS_H */

diff --git a/include/linux/objtool.h b/include/linux/objtool.h
index 7d1c3a9..a2042c4 100644 (file)
--- a/include/linux/objtool.h
+++ b/include/linux/objtool.h
@@ -40,6 +40,8 @@ struct unwind_hint {
 #define UNWIND_HINT_TYPE_REGS_PARTIAL  2
 #define UNWIND_HINT_TYPE_FUNC          3
 #define UNWIND_HINT_TYPE_ENTRY         4
+#define UNWIND_HINT_TYPE_SAVE          5
+#define UNWIND_HINT_TYPE_RESTORE       6
 
 #ifdef CONFIG_STACK_VALIDATION
 
@@ -102,7 +104,7 @@ struct unwind_hint {
  * the debuginfo as necessary.  It will also warn if it sees any
  * inconsistencies.
  */
-.macro UNWIND_HINT sp_reg:req sp_offset=0 type:req end=0
+.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 end=0
 .Lunwind_hint_ip_\@:
        .pushsection .discard.unwind_hints
                /* struct unwind_hint */
@@ -132,7 +134,7 @@ struct unwind_hint {
 #define STACK_FRAME_NON_STANDARD(func)
 #else
 #define ANNOTATE_INTRA_FUNCTION_CALL
-.macro UNWIND_HINT sp_reg:req sp_offset=0 type:req end=0
+.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 end=0
 .endm
 .macro STACK_FRAME_NON_STANDARD func:req
 .endm

diff --git a/tools/include/linux/objtool.h b/tools/include/linux/objtool.h
index 7d1c3a9..a2042c4 100644 (file)
--- a/tools/include/linux/objtool.h
+++ b/tools/include/linux/objtool.h
@@ -40,6 +40,8 @@ struct unwind_hint {
 #define UNWIND_HINT_TYPE_REGS_PARTIAL  2
 #define UNWIND_HINT_TYPE_FUNC          3
 #define UNWIND_HINT_TYPE_ENTRY         4
+#define UNWIND_HINT_TYPE_SAVE          5
+#define UNWIND_HINT_TYPE_RESTORE       6
 
 #ifdef CONFIG_STACK_VALIDATION
 
@@ -102,7 +104,7 @@ struct unwind_hint {
  * the debuginfo as necessary.  It will also warn if it sees any
  * inconsistencies.
  */
-.macro UNWIND_HINT sp_reg:req sp_offset=0 type:req end=0
+.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 end=0
 .Lunwind_hint_ip_\@:
        .pushsection .discard.unwind_hints
                /* struct unwind_hint */
@@ -132,7 +134,7 @@ struct unwind_hint {
 #define STACK_FRAME_NON_STANDARD(func)
 #else
 #define ANNOTATE_INTRA_FUNCTION_CALL
-.macro UNWIND_HINT sp_reg:req sp_offset=0 type:req end=0
+.macro UNWIND_HINT type:req sp_reg=0 sp_offset=0 end=0
 .endm
 .macro STACK_FRAME_NON_STANDARD func:req
 .endm

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index c22115e..4c18a7e 100644 (file)
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1847,6 +1847,17 @@ static int read_unwind_hints(struct objtool_file *file)
 
                insn->hint = true;
 
+               if (hint->type == UNWIND_HINT_TYPE_SAVE) {
+                       insn->hint = false;
+                       insn->save = true;
+                       continue;
+               }
+
+               if (hint->type == UNWIND_HINT_TYPE_RESTORE) {
+                       insn->restore = true;
+                       continue;
+               }
+
                if (hint->type == UNWIND_HINT_TYPE_REGS_PARTIAL) {
                        struct symbol *sym = find_symbol_by_offset(insn->sec, insn->offset);
 
@@ -3025,6 +3036,35 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
                        state.instr += insn->instr;
 
                if (insn->hint) {
+                       if (insn->restore) {
+                               struct instruction *save_insn, *i;
+
+                               i = insn;
+                               save_insn = NULL;
+
+                               sym_for_each_insn_continue_reverse(file, func, i) {
+                                       if (i->save) {
+                                               save_insn = i;
+                                               break;
+                                       }
+                               }
+
+                               if (!save_insn) {
+                                       WARN_FUNC("no corresponding CFI save for CFI restore",
+                                                 sec, insn->offset);
+                                       return 1;
+                               }
+
+                               if (!save_insn->visited) {
+                                       WARN_FUNC("objtool isn't smart enough to handle this CFI save/restore combo",
+                                                 sec, insn->offset);
+                                       return 1;
+                               }
+
+                               insn->cfi = save_insn->cfi;
+                               nr_cfi_reused++;
+                       }
+
                        state.cfi = *insn->cfi;
                } else {
                        /* XXX track if we actually changed state.cfi */

diff --git a/tools/objtool/include/objtool/check.h b/tools/objtool/include/objtool/check.h
index 0de25d1..4ba041d 100644 (file)
--- a/tools/objtool/include/objtool/check.h
+++ b/tools/objtool/include/objtool/check.h
@@ -47,6 +47,7 @@ struct instruction {
        unsigned long immediate;
        bool dead_end, ignore, ignore_alts;
        bool hint;
+       bool save, restore;
        bool retpoline_safe;
        bool entry;
        s8 instr;