From af3394d97a8c5187085c0eec5fb03e8da88db5fb Mon Sep 17 00:00:00 2001 From: Jan Beulich Date: Mon, 18 Nov 2024 11:36:57 +0100 Subject: [PATCH] ELF: SHF_STRINGS isn't really tied to SHF_MERGE It's not overly useful without it, but the spec doesn't name any dependency between the two. People may want to use it for purely informational purposes, for example. Adjust, in particular, entity size processing to be engaged if either flag is set, as mandated by the spec. --- bfd/elf.c | 10 ++++++++-- gas/config/obj-elf.c | 30 +++++++++++++++++------------- gas/doc/as.texi | 19 ++++++++++--------- gas/write.c | 2 +- 4 files changed, 36 insertions(+), 25 deletions(-) diff --git a/bfd/elf.c b/bfd/elf.c index 1a8618afbd2..bd9525959c1 100644 --- a/bfd/elf.c +++ b/bfd/elf.c @@ -846,7 +846,10 @@ _bfd_elf_make_section_from_shdr (bfd *abfd, newsect->entsize = hdr->sh_entsize; } if ((hdr->sh_flags & SHF_STRINGS) != 0) - flags |= SEC_STRINGS; + { + flags |= SEC_STRINGS; + newsect->entsize = hdr->sh_entsize; + } if ((hdr->sh_flags & SHF_TLS) != 0) flags |= SEC_THREAD_LOCAL; if ((hdr->sh_flags & SHF_EXCLUDE) != 0) @@ -3709,7 +3712,10 @@ elf_fake_sections (bfd *abfd, asection *asect, void *fsarg) this_hdr->sh_entsize = asect->entsize; } if ((asect->flags & SEC_STRINGS) != 0) - this_hdr->sh_flags |= SHF_STRINGS; + { + this_hdr->sh_flags |= SHF_STRINGS; + this_hdr->sh_entsize = asect->entsize; + } if ((asect->flags & SEC_GROUP) == 0 && elf_group_name (asect) != NULL) this_hdr->sh_flags |= SHF_GROUP; if ((asect->flags & SEC_THREAD_LOCAL) != 0) diff --git a/gas/config/obj-elf.c b/gas/config/obj-elf.c index deb902e5a55..7d6d1737446 100644 --- a/gas/config/obj-elf.c +++ b/gas/config/obj-elf.c @@ -809,7 +809,7 @@ change_section (const char *name, = match_p->linked_to_symbol_name; bfd_set_section_flags (sec, flags); - if (flags & SEC_MERGE) + if (flags & (SEC_MERGE | SEC_STRINGS)) sec->entsize = entsize; elf_group_name (sec) = match_p->group_name; @@ -864,7 +864,8 @@ change_section (const char *name, processor or application specific attribute as suspicious? */ elf_section_flags (sec) = attr; - if ((flags & SEC_MERGE) && old_sec->entsize != (unsigned) entsize) + if ((flags & (SEC_MERGE | SEC_STRINGS)) + && old_sec->entsize != (unsigned) entsize) as_bad (_("changed section entity size for %s"), name); } } @@ -1318,36 +1319,39 @@ obj_elf_section (int push) } SKIP_WHITESPACE (); - if ((attr & SHF_MERGE) != 0 && *input_line_pointer == ',') + if ((attr & (SHF_MERGE | SHF_STRINGS)) != 0 + && *input_line_pointer == ',') { ++input_line_pointer; SKIP_WHITESPACE (); if (inherit && *input_line_pointer == ',' - && (bfd_section_flags (now_seg) & SEC_MERGE) != 0) + && (bfd_section_flags (now_seg) + & (SEC_MERGE | SEC_STRINGS)) != 0) goto fetch_entsize; entsize = get_absolute_expression (); SKIP_WHITESPACE (); if (entsize <= 0) { - as_warn (_("invalid merge entity size")); - attr &= ~SHF_MERGE; + as_warn (_("invalid merge / string entity size")); + attr &= ~(SHF_MERGE | SHF_STRINGS); entsize = 0; } } - else if ((attr & SHF_MERGE) != 0 && inherit - && (bfd_section_flags (now_seg) & SEC_MERGE) != 0) + else if ((attr & (SHF_MERGE | SHF_STRINGS)) != 0 && inherit + && (bfd_section_flags (now_seg) + & (SEC_MERGE | SEC_STRINGS)) != 0) { fetch_entsize: entsize = now_seg->entsize; } - else if ((attr & SHF_MERGE) != 0) + else if ((attr & (SHF_MERGE | SHF_STRINGS)) != 0) { - as_warn (_("entity size for SHF_MERGE not specified")); - attr &= ~SHF_MERGE; + as_warn (_("entity size for SHF_MERGE / SHF_STRINGS not specified")); + attr &= ~(SHF_MERGE | SHF_STRINGS); } - if ((attr & SHF_MERGE) != 0 && type == SHT_NOBITS) - as_warn (_("bogus SHF_MERGE for SHT_NOBITS section")); + if ((attr & (SHF_MERGE | SHF_STRINGS)) != 0 && type == SHT_NOBITS) + as_warn (_("bogus SHF_MERGE / SHF_STRINGS for SHT_NOBITS section")); if ((attr & SHF_LINK_ORDER) != 0 && *input_line_pointer == ',') { diff --git a/gas/doc/as.texi b/gas/doc/as.texi index 4c7799acc50..a5535845e40 100644 --- a/gas/doc/as.texi +++ b/gas/doc/as.texi @@ -7001,17 +7001,18 @@ Note - some sections, eg @code{.text} and @code{.data} are considered to be special and have fixed types. Any attempt to declare them with a different type will generate an error from the assembler. -If @var{flags} contains the @code{M} symbol then the @var{type} argument must -be specified as well as an extra argument---@var{entsize}---like this: +If @var{flags} contains the @code{M} and/or @code{S} symbol then the @var{type} +argument must be specified as well as an extra argument---@var{entsize}---like +this: @smallexample .section @var{name} , "@var{flags}"M, @@@var{type}, @var{entsize} @end smallexample Sections with the @code{M} flag but not @code{S} flag must contain fixed size -constants, each @var{entsize} octets long. Sections with both @code{M} and -@code{S} must contain zero terminated strings where each character is -@var{entsize} bytes long. The linker may remove duplicates within sections with +constants, each @var{entsize} octets long. Sections with @code{S} must contain +zero terminated strings where each character is @var{entsize} bytes long. For +@code{M} sections the linker may remove duplicates within sections with the same name, same entity size and same flags. @var{entsize} must be an absolute expression. For sections with both @code{M} and @code{S}, a string which is a suffix of a larger string is considered a duplicate. Thus @@ -7031,8 +7032,8 @@ is not generally a good idea as section indices are rarely known at assembly time, but the facility is provided for testing purposes. An index of zero is allowed. It indicates that the linked-to section has already been discarded. -Note: If both the @var{M} and @var{o} flags are present, then the fields -for the Merge flag should come first, like this: +Note: If both one of @var{M} or @var{S} and @var{o} flags are present, then the +fields for the Merge/String flag should come first, like this: @smallexample .section @var{name},"@var{flags}"Mo,@@@var{type},@var{entsize},@var{SymbolName} @@ -7055,8 +7056,8 @@ indicates that only one copy of this section should be retained an alias for comdat @end table -Note: if both the @var{M} and @var{G} flags are present then the fields for -the Merge flag should come first, like this: +Note: Uf both one of @var{M} or @var{S} and @var{G} flags are present then the +fields for the Merge/String flag should come first, like this: @smallexample .section @var{name} , "@var{flags}"MG, @@@var{type}, @var{entsize}, @var{GroupName}[, @var{linkage}] diff --git a/gas/write.c b/gas/write.c index a9c53d70f7f..41888156db3 100644 --- a/gas/write.c +++ b/gas/write.c @@ -1891,7 +1891,7 @@ subsegs_finish_section (asection *s) do_not_pad_sections_to_alignment = 1; alignment = SUB_SEGMENT_ALIGN (now_seg, frchainP); - if ((bfd_section_flags (now_seg) & SEC_MERGE) + if ((bfd_section_flags (now_seg) & (SEC_MERGE | SEC_STRINGS)) && now_seg->entsize) { unsigned int entsize = now_seg->entsize;