The following commit has been merged into the objtool/core branch of tip: Commit-ID: 45245f51f9a4b9a883a8c94468473c1de9b88153 Gitweb: https://git.kernel.org/tip/45245f51f9a4b9a883a8c94468473c1de9b88153 Author: Julien Thierry <[email protected]> AuthorDate: Fri, 04 Sep 2020 16:30:23 +01:00 Committer: Josh Poimboeuf <[email protected]> CommitterDate: Thu, 10 Sep 2020 10:43:13 -05:00
objtool: Make relocation in alternative handling arch dependent As pointed out by the comment in handle_group_alt(), support of relocation for instructions in an alternative group depends on whether arch specific kernel code handles it. So, let objtool arch specific code decide whether a relocation for the alternative section should be accepted. Reviewed-by: Miroslav Benes <[email protected]> Signed-off-by: Julien Thierry <[email protected]> Signed-off-by: Josh Poimboeuf <[email protected]> --- tools/objtool/arch/x86/special.c | 13 +++++++++++++ tools/objtool/check.c | 19 ++++++------------- tools/objtool/check.h | 6 ++++++ tools/objtool/special.h | 4 ++++ 4 files changed, 29 insertions(+), 13 deletions(-) diff --git a/tools/objtool/arch/x86/special.c b/tools/objtool/arch/x86/special.c index 823561e..34e0e16 100644 --- a/tools/objtool/arch/x86/special.c +++ b/tools/objtool/arch/x86/special.c @@ -35,3 +35,16 @@ void arch_handle_alternative(unsigned short feature, struct special_alt *alt) break; } } + +bool arch_support_alt_relocation(struct special_alt *special_alt, + struct instruction *insn, + struct reloc *reloc) +{ + /* + * The x86 alternatives code adjusts the offsets only when it + * encounters a branch instruction at the very beginning of the + * replacement group. + */ + return insn->offset == special_alt->new_off && + (insn->type == INSN_CALL || is_static_jump(insn)); +} diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 4afc2d5..1796a7c 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -110,12 +110,6 @@ static struct instruction *prev_insn_same_sym(struct objtool_file *file, for (insn = next_insn_same_sec(file, insn); insn; \ insn = next_insn_same_sec(file, insn)) -static bool is_static_jump(struct instruction *insn) -{ - return insn->type == INSN_JUMP_CONDITIONAL || - insn->type == INSN_JUMP_UNCONDITIONAL; -} - static bool is_sibling_call(struct instruction *insn) { /* An indirect jump is either a sibling call or a jump to a table. */ @@ -972,6 +966,8 @@ static int handle_group_alt(struct objtool_file *file, alt_group = alt_group_next_index++; insn = *new_insn; sec_for_each_insn_from(file, insn) { + struct reloc *alt_reloc; + if (insn->offset >= special_alt->new_off + special_alt->new_len) break; @@ -988,14 +984,11 @@ static int handle_group_alt(struct objtool_file *file, * .altinstr_replacement section, unless the arch's * alternatives code can adjust the relative offsets * accordingly. - * - * The x86 alternatives code adjusts the offsets only when it - * encounters a branch instruction at the very beginning of the - * replacement group. */ - if ((insn->offset != special_alt->new_off || - (insn->type != INSN_CALL && !is_static_jump(insn))) && - find_reloc_by_dest_range(file->elf, insn->sec, insn->offset, insn->len)) { + alt_reloc = find_reloc_by_dest_range(file->elf, insn->sec, + insn->offset, insn->len); + if (alt_reloc && + !arch_support_alt_relocation(special_alt, insn, alt_reloc)) { WARN_FUNC("unsupported relocation in alternatives section", insn->sec, insn->offset); diff --git a/tools/objtool/check.h b/tools/objtool/check.h index 6cac345..1de1188 100644 --- a/tools/objtool/check.h +++ b/tools/objtool/check.h @@ -48,6 +48,12 @@ struct instruction { #endif }; +static inline bool is_static_jump(struct instruction *insn) +{ + return insn->type == INSN_JUMP_CONDITIONAL || + insn->type == INSN_JUMP_UNCONDITIONAL; +} + struct instruction *find_insn(struct objtool_file *file, struct section *sec, unsigned long offset); diff --git a/tools/objtool/special.h b/tools/objtool/special.h index 44da89a..1dc1bb3 100644 --- a/tools/objtool/special.h +++ b/tools/objtool/special.h @@ -7,6 +7,7 @@ #define _SPECIAL_H #include <stdbool.h> +#include "check.h" #include "elf.h" struct special_alt { @@ -30,4 +31,7 @@ int special_get_alts(struct elf *elf, struct list_head *alts); void arch_handle_alternative(unsigned short feature, struct special_alt *alt); +bool arch_support_alt_relocation(struct special_alt *special_alt, + struct instruction *insn, + struct reloc *reloc); #endif /* _SPECIAL_H */
