Messages in this thread Patch in this message | | | From | Alexandre Chartre <> | Subject | [PATCH V3 5/9] objtool: Add return address unwind hints | Date | Tue, 14 Apr 2020 12:36:14 +0200 |
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Add the UNWIND_HINT_RADDR_DELETE and UNWIND_HINT_RADDR_ALTER unwind hint macros to flag instructions which remove or modify return addresses.
Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com> --- arch/x86/include/asm/orc_types.h | 2 + arch/x86/include/asm/unwind_hints.h | 23 +++++++++ tools/arch/x86/include/asm/orc_types.h | 2 + tools/objtool/check.c | 67 ++++++++++++++++++++++++++ 4 files changed, 94 insertions(+)
diff --git a/arch/x86/include/asm/orc_types.h b/arch/x86/include/asm/orc_types.h index 6e060907c163..5c1141175d51 100644 --- a/arch/x86/include/asm/orc_types.h +++ b/arch/x86/include/asm/orc_types.h @@ -60,6 +60,8 @@ #define ORC_TYPE_REGS_IRET 2 #define UNWIND_HINT_TYPE_SAVE 3 #define UNWIND_HINT_TYPE_RESTORE 4 +#define UNWIND_HINT_TYPE_RADDR_ALTER 6 +#define UNWIND_HINT_TYPE_RADDR_DELETE 7 #ifndef __ASSEMBLY__ /* diff --git a/arch/x86/include/asm/unwind_hints.h b/arch/x86/include/asm/unwind_hints.h index f5e2eb12cb71..5211d2c5b7a2 100644 --- a/arch/x86/include/asm/unwind_hints.h +++ b/arch/x86/include/asm/unwind_hints.h @@ -94,6 +94,23 @@ UNWIND_HINT type=UNWIND_HINT_TYPE_RESTORE .endm +/* + * RADDR_DELETE: Used on instructions (other than ret instruction) + * which remove a return address from the stack. count is the number + * of return address which are removed. + */ +.macro UNWIND_HINT_RADDR_DELETE count=1 + UNWIND_HINT type=UNWIND_HINT_TYPE_RADDR_DELETE sp_offset=\count +.endm + +/* + * RADDR_ALTER: Used on instructions which change a return address on + * the stack. count is the number of return address which are changed. + */ +.macro UNWIND_HINT_RADDR_ALTER count=1 + UNWIND_HINT type=UNWIND_HINT_TYPE_RADDR_ALTER sp_offset=\count +.endm + #else /* !__ASSEMBLY__ */ #define UNWIND_HINT(sp_reg, sp_offset, type, end) \ @@ -112,6 +129,12 @@ #define UNWIND_HINT_RESTORE UNWIND_HINT(0, 0, UNWIND_HINT_TYPE_RESTORE, 0) +#define UNWIND_HINT_RADDR_ALTER(count) \ + UNWIND_HINT(0, count, UNWIND_HINT_TYPE_RADDR_ALTER, 0) + +#define UNWIND_HINT_RADDR_DELETE(count) \ + UNWIND_HINT(0, count, UNWIND_HINT_TYPE_RADDR_DELETE, 0) + #endif /* __ASSEMBLY__ */ #endif /* _ASM_X86_UNWIND_HINTS_H */ diff --git a/tools/arch/x86/include/asm/orc_types.h b/tools/arch/x86/include/asm/orc_types.h index 6e060907c163..5c1141175d51 100644 --- a/tools/arch/x86/include/asm/orc_types.h +++ b/tools/arch/x86/include/asm/orc_types.h @@ -60,6 +60,8 @@ #define ORC_TYPE_REGS_IRET 2 #define UNWIND_HINT_TYPE_SAVE 3 #define UNWIND_HINT_TYPE_RESTORE 4 +#define UNWIND_HINT_TYPE_RADDR_ALTER 6 +#define UNWIND_HINT_TYPE_RADDR_DELETE 7 #ifndef __ASSEMBLY__ /* diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 8b1df659cd68..0574ce8e232d 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -66,6 +66,28 @@ static bool raddr_pop(struct instruction **insn) return true; } +static bool raddr_delete(int count) +{ + if (raddr_count < count) + return false; + + raddr_count -= count; + return true; +} + +static bool raddr_alter(int count) +{ + int i; + + if (raddr_count < count) + false; + + for (i = 0; i < count; i++) + raddr_list[raddr_count - 1 - i] = RADDR_ALTERED; + + return true; +} + static int validate_branch(struct objtool_file *file, struct symbol *func, struct instruction *from, struct instruction *first, struct insn_state state); @@ -1314,6 +1336,14 @@ static int read_unwind_hints(struct objtool_file *file) insn->restore = true; insn->hint = true; continue; + + } else if (hint->type == UNWIND_HINT_TYPE_RADDR_DELETE) { + insn->raddr_delete = hint->sp_offset; + continue; + + } else if (hint->type == UNWIND_HINT_TYPE_RADDR_ALTER) { + insn->raddr_alter = hint->sp_offset; + continue; } insn->hint = true; @@ -1526,6 +1556,13 @@ static bool has_modified_stack_frame(struct insn_state *state) state->drap) return true; + /* + * If the stack was altered then don't check registers because + * a callee-saved registers might have been pushed on the stack. + */ + if (state->stack_altered) + return false; + for (i = 0; i < CFI_NUM_REGS; i++) if (state->regs[i].base != initial_func_cfi.regs[i].base || state->regs[i].offset != initial_func_cfi.regs[i].offset) @@ -2103,6 +2140,15 @@ static int validate_return_address(struct objtool_file *file, if (!raddr_insn) break; + /* + * If this is a dynamic branch then we expect this + * branch to return or not, depending on the defined + * list of RA we have, so just continue the processing + * of the RA list. + */ + if (raddr_insn == RADDR_ALTERED) + continue; + /* * If we are branching to a defined address then * just do an unconditional jump there. @@ -2287,6 +2333,27 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, return 0; } + if (insn->raddr_delete) { + /* delete return address */ + if (!raddr_delete(insn->raddr_delete)) { + WARN_FUNC("fail to delete %d return address", + insn->sec, insn->offset, + insn->raddr_delete); + return 1; + } + state.stack_altered = true; + + } else if (insn->raddr_alter) { + /* alter return address */ + if (!raddr_alter(insn->raddr_alter)) { + WARN_FUNC("fail to alter %d return address", + insn->sec, insn->offset, + insn->raddr_alter); + return 1; + } + state.stack_altered = true; + } + switch (insn->type) { case INSN_RETURN: -- 2.18.2
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