objtool: Support multiple stack_op per instruction

Instruction sets can include more or less complex operations which might
not fit the currently defined set of stack_ops.

Combining more than one stack_op provides more flexibility to describe
the behaviour of an instruction. This also reduces the need to define
new stack_ops specific to a single instruction set.

Allow instruction decoders to generate multiple stack_op per
instruction.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200327152847.15294-11-jthierry@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/tools/objtool/arch.h b/tools/objtool/arch.h
index a9a50a2..f9883c4 100644 (file)
--- a/tools/objtool/arch.h
+++ b/tools/objtool/arch.h
@@ -64,6 +64,7 @@ struct op_src {
 struct stack_op {
        struct op_dest dest;
        struct op_src src;
+       struct list_head list;
 };
 
 struct instruction;
@@ -73,7 +74,8 @@ void arch_initial_func_cfi_state(struct cfi_state *state);
 int arch_decode_instruction(struct elf *elf, struct section *sec,
                            unsigned long offset, unsigned int maxlen,
                            unsigned int *len, enum insn_type *type,
-                           unsigned long *immediate, struct stack_op *op);
+                           unsigned long *immediate,
+                           struct list_head *ops_list);
 
 bool arch_callee_saved_reg(unsigned char reg);
 

diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
index 7ce8650..199b408 100644 (file)
--- a/tools/objtool/arch/x86/decode.c
+++ b/tools/objtool/arch/x86/decode.c
@@ -80,13 +80,15 @@ unsigned long arch_jump_destination(struct instruction *insn)
 int arch_decode_instruction(struct elf *elf, struct section *sec,
                            unsigned long offset, unsigned int maxlen,
                            unsigned int *len, enum insn_type *type,
-                           unsigned long *immediate, struct stack_op *op)
+                           unsigned long *immediate,
+                           struct list_head *ops_list)
 {
        struct insn insn;
        int x86_64, sign;
        unsigned char op1, op2, rex = 0, rex_b = 0, rex_r = 0, rex_w = 0,
                      rex_x = 0, modrm = 0, modrm_mod = 0, modrm_rm = 0,
                      modrm_reg = 0, sib = 0;
+       struct stack_op *op;
 
        x86_64 = is_x86_64(elf);
        if (x86_64 == -1)
@@ -127,6 +129,10 @@ int arch_decode_instruction(struct elf *elf, struct section *sec,
        if (insn.sib.nbytes)
                sib = insn.sib.bytes[0];
 
+       op = calloc(1, sizeof(*op));
+       if (!op)
+               return -1;
+
        switch (op1) {
 
        case 0x1:
@@ -488,6 +494,11 @@ int arch_decode_instruction(struct elf *elf, struct section *sec,
 
        *immediate = insn.immediate.nbytes ? insn.immediate.value : 0;
 
+       if (*type == INSN_STACK)
+               list_add_tail(&op->list, ops_list);
+       else
+               free(op);
+
        return 0;
 }
 

diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index e06a891..9e854fd 100644 (file)
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -260,6 +260,7 @@ static int decode_instructions(struct objtool_file *file)
                        }
                        memset(insn, 0, sizeof(*insn));
                        INIT_LIST_HEAD(&insn->alts);
+                       INIT_LIST_HEAD(&insn->stack_ops);
                        clear_insn_state(&insn->state);
 
                        insn->sec = sec;
@@ -269,7 +270,7 @@ static int decode_instructions(struct objtool_file *file)
                                                      sec->len - offset,
                                                      &insn->len, &insn->type,
                                                      &insn->immediate,
-                                                     &insn->stack_op);
+                                                     &insn->stack_ops);
                        if (ret)
                                goto err;
 
@@ -754,6 +755,7 @@ static int handle_group_alt(struct objtool_file *file,
                }
                memset(fake_jump, 0, sizeof(*fake_jump));
                INIT_LIST_HEAD(&fake_jump->alts);
+               INIT_LIST_HEAD(&fake_jump->stack_ops);
                clear_insn_state(&fake_jump->state);
 
                fake_jump->sec = special_alt->new_sec;
@@ -1452,10 +1454,11 @@ static bool has_valid_stack_frame(struct insn_state *state)
        return false;
 }
 
-static int update_insn_state_regs(struct instruction *insn, struct insn_state *state)
+static int update_insn_state_regs(struct instruction *insn,
+                                 struct insn_state *state,
+                                 struct stack_op *op)
 {
        struct cfi_reg *cfa = &state->cfa;
-       struct stack_op *op = &insn->stack_op;
 
        if (cfa->base != CFI_SP)
                return 0;
@@ -1545,9 +1548,9 @@ static void restore_reg(struct insn_state *state, unsigned char reg)
  *   41 5d                     pop    %r13
  *   c3                                retq
  */
-static int update_insn_state(struct instruction *insn, struct insn_state *state)
+static int update_insn_state(struct instruction *insn, struct insn_state *state,
+                            struct stack_op *op)
 {
-       struct stack_op *op = &insn->stack_op;
        struct cfi_reg *cfa = &state->cfa;
        struct cfi_reg *regs = state->regs;
 
@@ -1561,7 +1564,7 @@ static int update_insn_state(struct instruction *insn, struct insn_state *state)
        }
 
        if (state->type == ORC_TYPE_REGS || state->type == ORC_TYPE_REGS_IRET)
-               return update_insn_state_regs(insn, state);
+               return update_insn_state_regs(insn, state, op);
 
        switch (op->dest.type) {
 
@@ -1898,6 +1901,42 @@ static int update_insn_state(struct instruction *insn, struct insn_state *state)
        return 0;
 }
 
+static int handle_insn_ops(struct instruction *insn, struct insn_state *state)
+{
+       struct stack_op *op;
+
+       list_for_each_entry(op, &insn->stack_ops, list) {
+               int res;
+
+               res = update_insn_state(insn, state, op);
+               if (res)
+                       return res;
+
+               if (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",
+                                         insn->sec, insn->offset);
+                               return 1;
+                       }
+                       state->uaccess_stack <<= 1;
+                       state->uaccess_stack  |= state->uaccess;
+               }
+
+               if (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;
+                       }
+               }
+       }
+
+       return 0;
+}
+
 static bool insn_state_match(struct instruction *insn, struct insn_state *state)
 {
        struct insn_state *state1 = &insn->state, *state2 = state;
@@ -2198,29 +2237,8 @@ static int validate_branch(struct objtool_file *file, struct symbol *func,
                        return 0;
 
                case INSN_STACK:
-                       if (update_insn_state(insn, &state))
+                       if (handle_insn_ops(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:

diff --git a/tools/objtool/check.h b/tools/objtool/check.h
index f0ce8ff..2c55f75 100644 (file)
--- a/tools/objtool/check.h
+++ b/tools/objtool/check.h
@@ -42,7 +42,7 @@ struct instruction {
        struct rela *jump_table;
        struct list_head alts;
        struct symbol *func;
-       struct stack_op stack_op;
+       struct list_head stack_ops;
        struct insn_state state;
        struct orc_entry orc;
 };