From e25eea89bb8853763a22fa2547199cf96b571ba1 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 1 Apr 2020 16:38:19 +0200 Subject: objtool: Introduce HINT_RET_OFFSET Normally objtool ensures a function keeps the stack layout invariant. But there is a useful exception, it is possible to stuff the return stack in order to 'inject' a 'call': push $fun ret In this case the invariant mentioned above is violated. Add an objtool HINT to annotate this and allow a function exit with a modified stack frame. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Miroslav Benes Reviewed-by: Alexandre Chartre Acked-by: Josh Poimboeuf Link: https://lkml.kernel.org/r/20200416115118.690601403@infradead.org Signed-off-by: Ingo Molnar --- tools/arch/x86/include/asm/orc_types.h | 1 + 1 file changed, 1 insertion(+) (limited to 'tools/arch') diff --git a/tools/arch/x86/include/asm/orc_types.h b/tools/arch/x86/include/asm/orc_types.h index 6e060907c163..5f18ca7ac51a 100644 --- a/tools/arch/x86/include/asm/orc_types.h +++ b/tools/arch/x86/include/asm/orc_types.h @@ -60,6 +60,7 @@ #define ORC_TYPE_REGS_IRET 2 #define UNWIND_HINT_TYPE_SAVE 3 #define UNWIND_HINT_TYPE_RESTORE 4 +#define UNWIND_HINT_TYPE_RET_OFFSET 5 #ifndef __ASSEMBLY__ /* -- cgit v1.2.3 From c536ed2fffd5dbf81fe2dede8ef294e0cbb08f72 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 1 Apr 2020 16:54:26 +0200 Subject: objtool: Remove SAVE/RESTORE hints The SAVE/RESTORE hints are now unused; remove them. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Miroslav Benes Reviewed-by: Alexandre Chartre Acked-by: Josh Poimboeuf Link: https://lkml.kernel.org/r/20200416115118.926738768@infradead.org Signed-off-by: Ingo Molnar --- arch/x86/include/asm/orc_types.h | 4 +--- arch/x86/include/asm/unwind_hints.h | 27 ---------------------- tools/arch/x86/include/asm/orc_types.h | 4 +--- tools/objtool/check.c | 42 +++------------------------------- tools/objtool/check.h | 2 +- 5 files changed, 6 insertions(+), 73 deletions(-) (limited to 'tools/arch') diff --git a/arch/x86/include/asm/orc_types.h b/arch/x86/include/asm/orc_types.h index 5f18ca7ac51a..d25534940bde 100644 --- a/arch/x86/include/asm/orc_types.h +++ b/arch/x86/include/asm/orc_types.h @@ -58,9 +58,7 @@ #define ORC_TYPE_CALL 0 #define ORC_TYPE_REGS 1 #define ORC_TYPE_REGS_IRET 2 -#define UNWIND_HINT_TYPE_SAVE 3 -#define UNWIND_HINT_TYPE_RESTORE 4 -#define UNWIND_HINT_TYPE_RET_OFFSET 5 +#define UNWIND_HINT_TYPE_RET_OFFSET 3 #ifndef __ASSEMBLY__ /* diff --git a/arch/x86/include/asm/unwind_hints.h b/arch/x86/include/asm/unwind_hints.h index aabf7ace0476..7d903fdb3f43 100644 --- a/arch/x86/include/asm/unwind_hints.h +++ b/arch/x86/include/asm/unwind_hints.h @@ -86,15 +86,6 @@ UNWIND_HINT sp_offset=\sp_offset .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 - - /* * RET_OFFSET: Used on instructions that terminate a function; mostly RETURN * and sibling calls. On these, sp_offset denotes the expected offset from @@ -104,24 +95,6 @@ UNWIND_HINT type=UNWIND_HINT_TYPE_RET_OFFSET sp_offset=\sp_offset .endm -#else /* !__ASSEMBLY__ */ - -#define UNWIND_HINT(sp_reg, sp_offset, type, end) \ - "987: \n\t" \ - ".pushsection .discard.unwind_hints\n\t" \ - /* struct unwind_hint */ \ - ".long 987b - .\n\t" \ - ".short " __stringify(sp_offset) "\n\t" \ - ".byte " __stringify(sp_reg) "\n\t" \ - ".byte " __stringify(type) "\n\t" \ - ".byte " __stringify(end) "\n\t" \ - ".balign 4 \n\t" \ - ".popsection\n\t" - -#define UNWIND_HINT_SAVE UNWIND_HINT(0, 0, UNWIND_HINT_TYPE_SAVE, 0) - -#define UNWIND_HINT_RESTORE UNWIND_HINT(0, 0, UNWIND_HINT_TYPE_RESTORE, 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 5f18ca7ac51a..d25534940bde 100644 --- a/tools/arch/x86/include/asm/orc_types.h +++ b/tools/arch/x86/include/asm/orc_types.h @@ -58,9 +58,7 @@ #define ORC_TYPE_CALL 0 #define ORC_TYPE_REGS 1 #define ORC_TYPE_REGS_IRET 2 -#define UNWIND_HINT_TYPE_SAVE 3 -#define UNWIND_HINT_TYPE_RESTORE 4 -#define UNWIND_HINT_TYPE_RET_OFFSET 5 +#define UNWIND_HINT_TYPE_RET_OFFSET 3 #ifndef __ASSEMBLY__ /* diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 93c88ac51f0f..464f10c0a5ac 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -1254,15 +1254,7 @@ static int read_unwind_hints(struct objtool_file *file) cfa = &insn->state.cfa; - if (hint->type == UNWIND_HINT_TYPE_SAVE) { - insn->save = true; - continue; - - } else if (hint->type == UNWIND_HINT_TYPE_RESTORE) { - insn->restore = true; - insn->hint = true; - - } else if (hint->type == UNWIND_HINT_TYPE_RET_OFFSET) { + if (hint->type == UNWIND_HINT_TYPE_RET_OFFSET) { insn->ret_offset = hint->sp_offset; continue; } @@ -2113,37 +2105,9 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, return 0; } - 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->state = save_insn->state; - } - + if (insn->hint) state = insn->state; - - } else + else insn->state = state; insn->visited |= visited; diff --git a/tools/objtool/check.h b/tools/objtool/check.h index 81ce27e62c04..7c30760bee74 100644 --- a/tools/objtool/check.h +++ b/tools/objtool/check.h @@ -34,7 +34,7 @@ struct instruction { enum insn_type type; unsigned long immediate; bool alt_group, dead_end, ignore, ignore_alts; - bool hint, save, restore; + bool hint; bool retpoline_safe; u8 visited; u8 ret_offset; -- cgit v1.2.3