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From a8c9f650b82109abf7aa730f298ea5182ed62613 Mon Sep 17 00:00:00 2001
From: Niklas Cassel <niklas.cassel@wdc.com>
Date: Tue, 9 Aug 2022 21:06:05 +0200
Subject: [PATCH] elf2flt: fix fatal error regression on m68k, xtensa, riscv64
Commit ba379d08bb78 ("elf2flt: fix for segfault on some ARM ELFs")
changed the condition of which input sections that should be included
in the .text output section from:
((a->flags & (SEC_DATA | SEC_READONLY)) == (SEC_DATA | SEC_READONLY))
to:
((a->flags & (SEC_DATA | SEC_READONLY | SEC_RELOC)) ==
(SEC_DATA | SEC_READONLY | SEC_RELOC))
On ARM, the .eh_frame input section does not have the SEC_RELOC flag set,
so on ARM, this change caused .eh_frame to move from .text to .data.
However, on e.g. m68k, xtensa and riscv64, the .eh_frame input section
does have the SEC_RELOC flag set, which means that the change in
commit ba379d08bb78 ("elf2flt: fix for segfault on some ARM ELFs")
caused .eh_frame to move in an opposite way, i.e. from .data to .text.
This resulted in a fatal error on m68k, xtensa and riscv64:
ERROR: text=0x3bab8 overlaps data=0x33f60 ?
This is because elf2flt cannot append to .text after .data has been
appended to.
Note that the binutils maintainer says that the correct thing is
to put read-only relocation data sections in .text:
https://sourceware.org/legacy-ml/binutils/2019-10/msg00132.html
So the proper fix is probably to rewrite elf2flt so that it can append
to .text after .data has been appended to (which will require elf2flt
to move/relocate everything that has already been appended to .data,
since the virtual addresses are contiguous).
However, for now, add an exception for input sections which have all
three flags SEC_DATA, SEC_READONLY, and SEC_RELOC set, and which have a
name equal to a problematic input section (.eh_frame, .gcc_except_table).
That way, we get the same behavior as older elf2flt releases for m68k,
xtensa and riscv64, where we put read-only relocation data in .data,
which was working perfectly fine.
This exception will not change any behavior on ARM, as the .eh_frame
input section does not have flag SEC_RELOC set.
Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
---
elf2flt.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/elf2flt.c b/elf2flt.c
index e0d7891..39d035f 100644
--- a/elf2flt.c
+++ b/elf2flt.c
@@ -341,8 +341,13 @@ compare_relocs (const void *pa, const void *pb)
static bool
ro_reloc_data_section_should_be_in_text(asection *s)
{
- return (s->flags & (SEC_DATA | SEC_READONLY | SEC_RELOC)) ==
- (SEC_DATA | SEC_READONLY | SEC_RELOC);
+ if ((s->flags & (SEC_DATA | SEC_READONLY | SEC_RELOC)) ==
+ (SEC_DATA | SEC_READONLY | SEC_RELOC)) {
+ if (!strcmp(".eh_frame", s->name) || !strcmp(".gcc_except_table", s->name))
+ return false;
+ return true;
+ }
+ return false;
}
static uint32_t *
--
2.39.0
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