From: Peter Zijlstra peterz@infradead.org
stable inclusion from stable-v5.10.193 commit c6aecc29d29eeda6b963f1a5ea0adae2e9fd7c3d category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I7RQ67
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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commit 4ae68b26c3ab5a82aa271e6e9fc9b1a06e1d6b40 upstream.
Objtool --rethunk does two things:
- it collects all (tail) call's of __x86_return_thunk and places them into .return_sites. These are typically compiler generated, but RET also emits this same.
- it fudges the validation of the __x86_return_thunk symbol; because this symbol is inside another instruction, it can't actually find the instruction pointed to by the symbol offset and gets upset.
Because these two things pertained to the same symbol, there was no pressing need to separate these two separate things.
However, alas, along comes SRSO and more crazy things to deal with appeared.
The SRSO patch itself added the following symbol names to identify as rethunk:
'srso_untrain_ret', 'srso_safe_ret' and '__ret'
Where '__ret' is the old retbleed return thunk, 'srso_safe_ret' is a new similarly embedded return thunk, and 'srso_untrain_ret' is completely unrelated to anything the above does (and was only included because of that INT3 vs UD2 issue fixed previous).
Clear things up by adding a second category for the embedded instruction thing.
Fixes: fb3bd914b3ec ("x86/srso: Add a Speculative RAS Overflow mitigation") Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Signed-off-by: Borislav Petkov (AMD) bp@alien8.de Link: https://lore.kernel.org/r/20230814121148.704502245@infradead.org Signed-off-by: Josh Poimboeuf jpoimboe@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Jialin Zhang zhangjialin11@huawei.com --- tools/objtool/arch.h | 1 + tools/objtool/arch/x86/decode.c | 11 +++++++---- tools/objtool/check.c | 22 +++++++++++++++++++++- tools/objtool/elf.h | 1 + 4 files changed, 30 insertions(+), 5 deletions(-)
diff --git a/tools/objtool/arch.h b/tools/objtool/arch.h index 580ce1857585..75840291b393 100644 --- a/tools/objtool/arch.h +++ b/tools/objtool/arch.h @@ -90,6 +90,7 @@ int arch_decode_hint_reg(u8 sp_reg, int *base);
bool arch_is_retpoline(struct symbol *sym); bool arch_is_rethunk(struct symbol *sym); +bool arch_is_embedded_insn(struct symbol *sym);
int arch_rewrite_retpolines(struct objtool_file *file);
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c index 791263c4eea8..7e464a95ba55 100644 --- a/tools/objtool/arch/x86/decode.c +++ b/tools/objtool/arch/x86/decode.c @@ -661,8 +661,11 @@ bool arch_is_retpoline(struct symbol *sym)
bool arch_is_rethunk(struct symbol *sym) { - return !strcmp(sym->name, "__x86_return_thunk") || - !strcmp(sym->name, "srso_untrain_ret") || - !strcmp(sym->name, "srso_safe_ret") || - !strcmp(sym->name, "retbleed_return_thunk"); + return !strcmp(sym->name, "__x86_return_thunk"); +} + +bool arch_is_embedded_insn(struct symbol *sym) +{ + return !strcmp(sym->name, "retbleed_return_thunk") || + !strcmp(sym->name, "srso_safe_ret"); } diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 6d8cb8c76028..e473dc573c74 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -940,16 +940,33 @@ static int add_ignore_alternatives(struct objtool_file *file) return 0; }
+/* + * Symbols that replace INSN_CALL_DYNAMIC, every (tail) call to such a symbol + * will be added to the .retpoline_sites section. + */ __weak bool arch_is_retpoline(struct symbol *sym) { return false; }
+/* + * Symbols that replace INSN_RETURN, every (tail) call to such a symbol + * will be added to the .return_sites section. + */ __weak bool arch_is_rethunk(struct symbol *sym) { return false; }
+/* + * Symbols that are embedded inside other instructions, because sometimes crazy + * code exists. These are mostly ignored for validation purposes. + */ +__weak bool arch_is_embedded_insn(struct symbol *sym) +{ + return false; +} + #define NEGATIVE_RELOC ((void *)-1L)
static struct reloc *insn_reloc(struct objtool_file *file, struct instruction *insn) @@ -1166,7 +1183,7 @@ static int add_jump_destinations(struct objtool_file *file) * middle of another instruction. Objtool only * knows about the outer instruction. */ - if (sym && sym->return_thunk) { + if (sym && sym->embedded_insn) { add_return_call(file, insn, false); continue; } @@ -1965,6 +1982,9 @@ static int classify_symbols(struct objtool_file *file) if (arch_is_rethunk(func)) func->return_thunk = true;
+ if (arch_is_embedded_insn(func)) + func->embedded_insn = true; + if (!strcmp(func->name, "__fentry__")) func->fentry = true;
diff --git a/tools/objtool/elf.h b/tools/objtool/elf.h index a1863eb35fbb..19446d911244 100644 --- a/tools/objtool/elf.h +++ b/tools/objtool/elf.h @@ -61,6 +61,7 @@ struct symbol { u8 return_thunk : 1; u8 fentry : 1; u8 kcov : 1; + u8 embedded_insn : 1; };
struct reloc {