* [binutils-gdb] BFD: Fix the bug of R_LARCH_AGLIN caused by discard section
@ 2024-03-31 6:21 liu & zhensong
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From: liu & zhensong @ 2024-03-31 6:21 UTC (permalink / raw)
To: binutils-cvs
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=daeda14191c1710ce967259a47ef4e0a3fb6eebf
commit daeda14191c1710ce967259a47ef4e0a3fb6eebf
Author: mengqinggang <mengqinggang@loongson.cn>
Date: Wed Jan 24 14:34:26 2024 +0800
BFD: Fix the bug of R_LARCH_AGLIN caused by discard section
To represent the first and third expression of .align, R_LARCH_ALIGN need to
associate with a symbol. We define a local symbol for R_LARCH_AGLIN.
But if the section of the local symbol is discarded, it may result in
a undefined symbol error.
Instead, we use the section name symbols, and this does not need to
add extra symbols.
During partial linking (ld -r), if the symbol associated with a relocation is
STT_SECTION type, the addend of relocation needs to add the section output
offset. We prevent it for R_LARCH_ALIGN.
The elf_backend_data.rela_normal only can set all relocations of a target to
rela_normal. Add a new function is_rela_normal to elf_backend_data, it can
set part of relocations to rela_normal.
Diff:
---
bfd/elf-bfd.h | 4 ++++
bfd/elflink.c | 5 ++++-
bfd/elfnn-loongarch.c | 16 ++++++++++++++++
bfd/elfxx-target.h | 5 +++++
gas/config/tc-loongarch.c | 5 +----
gas/testsuite/gas/loongarch/relax_align.d | 6 +++---
ld/testsuite/ld-loongarch-elf/relax-align-discard.lds | 4 ++++
ld/testsuite/ld-loongarch-elf/relax-align-discard.s | 17 +++++++++++++++++
ld/testsuite/ld-loongarch-elf/relax.exp | 12 ++++++++++++
9 files changed, 66 insertions(+), 8 deletions(-)
diff --git a/bfd/elf-bfd.h b/bfd/elf-bfd.h
index c5d325435b6..af507b93df5 100644
--- a/bfd/elf-bfd.h
+++ b/bfd/elf-bfd.h
@@ -1721,6 +1721,10 @@ struct elf_backend_data
backend relocate_section routine for relocatable linking. */
unsigned rela_normal : 1;
+ /* Whether a relocation is rela_normal. Compared with rela_normal,
+ is_rela_normal can set part of relocations to rela_normal. */
+ bool (*is_rela_normal) (Elf_Internal_Rela *);
+
/* Set if DT_REL/DT_RELA/DT_RELSZ/DT_RELASZ should not include PLT
relocations. */
unsigned dtrel_excludes_plt : 1;
diff --git a/bfd/elflink.c b/bfd/elflink.c
index 24eb30d1946..5d9b4092e48 100644
--- a/bfd/elflink.c
+++ b/bfd/elflink.c
@@ -11692,7 +11692,10 @@ elf_link_input_bfd (struct elf_final_link_info *flinfo, bfd *input_bfd)
{
rel_hash = PTR_ADD (esdo->rela.hashes, esdo->rela.count);
rela_hash_list = rel_hash;
- rela_normal = bed->rela_normal;
+ if (bed->is_rela_normal != NULL)
+ rela_normal = bed->is_rela_normal (irela);
+ else
+ rela_normal = bed->rela_normal;
}
irela->r_offset = _bfd_elf_section_offset (output_bfd,
diff --git a/bfd/elfnn-loongarch.c b/bfd/elfnn-loongarch.c
index c42052f9321..1679aa5da7d 100644
--- a/bfd/elfnn-loongarch.c
+++ b/bfd/elfnn-loongarch.c
@@ -5454,6 +5454,21 @@ elf_loongarch64_hash_symbol (struct elf_link_hash_entry *h)
return _bfd_elf_hash_symbol (h);
}
+/* If a relocation is rela_normal and the symbol associated with the
+ relocation is STT_SECTION type, the addend of the relocation would add
+ sec->output_offset when partial linking (ld -r).
+ See elf_backend_data.rela_normal and elf_link_input_bfd().
+ The addend of R_LARCH_ALIGN is used to represent the first and third
+ expression of .align, it should be a constant when linking. */
+
+static bool
+loongarch_elf_is_rela_normal (Elf_Internal_Rela *rel)
+{
+ if (R_LARCH_ALIGN == ELFNN_R_TYPE (rel->r_info))
+ return false;
+ return true;
+}
+
#define TARGET_LITTLE_SYM loongarch_elfNN_vec
#define TARGET_LITTLE_NAME "elfNN-loongarch"
#define ELF_ARCH bfd_arch_loongarch
@@ -5489,6 +5504,7 @@ elf_loongarch64_hash_symbol (struct elf_link_hash_entry *h)
#define elf_backend_grok_psinfo loongarch_elf_grok_psinfo
#define elf_backend_hash_symbol elf_loongarch64_hash_symbol
#define bfd_elfNN_bfd_relax_section loongarch_elf_relax_section
+#define elf_backend_is_rela_normal loongarch_elf_is_rela_normal
#define elf_backend_dtrel_excludes_plt 1
diff --git a/bfd/elfxx-target.h b/bfd/elfxx-target.h
index 1e6992b5793..6e2d948b69b 100644
--- a/bfd/elfxx-target.h
+++ b/bfd/elfxx-target.h
@@ -709,6 +709,10 @@
#define elf_backend_rela_normal 0
#endif
+#ifndef elf_backend_is_rela_normal
+#define elf_backend_is_rela_normal NULL
+#endif
+
#ifndef elf_backend_dtrel_excludes_plt
#define elf_backend_dtrel_excludes_plt 0
#endif
@@ -955,6 +959,7 @@ static const struct elf_backend_data elfNN_bed =
elf_backend_default_use_rela_p,
elf_backend_rela_plts_and_copies_p,
elf_backend_rela_normal,
+ elf_backend_is_rela_normal,
elf_backend_dtrel_excludes_plt,
elf_backend_sign_extend_vma,
elf_backend_want_got_plt,
diff --git a/gas/config/tc-loongarch.c b/gas/config/tc-loongarch.c
index 30aefce36fd..6b1a89738ef 100644
--- a/gas/config/tc-loongarch.c
+++ b/gas/config/tc-loongarch.c
@@ -1791,10 +1791,7 @@ loongarch_frag_align_code (int n, int max)
if (fragP->fr_subtype != 0 && offset > fragP->fr_subtype). */
if (max > 0 && (bfd_vma) max < worst_case_bytes)
{
- s = symbol_find (".Lla-relax-align");
- if (s == NULL)
- s = (symbolS *)local_symbol_make (".Lla-relax-align", now_seg,
- &zero_address_frag, 0);
+ s = symbol_find (now_seg->name);
ex.X_add_symbol = s;
ex.X_op = O_symbol;
ex.X_add_number = (max << 8) | n;
diff --git a/gas/testsuite/gas/loongarch/relax_align.d b/gas/testsuite/gas/loongarch/relax_align.d
index fc1fd032611..acd215a4abc 100644
--- a/gas/testsuite/gas/loongarch/relax_align.d
+++ b/gas/testsuite/gas/loongarch/relax_align.d
@@ -7,7 +7,7 @@
Disassembly of section .text:
-[ ]*0000000000000000 <.Lla-relax-align>:
+[ ]*0000000000000000 <.text>:
[ ]+0:[ ]+4c000020[ ]+ret
[ ]+4:[ ]+03400000[ ]+nop
[ ]+4: R_LARCH_ALIGN[ ]+\*ABS\*\+0xc
@@ -20,12 +20,12 @@ Disassembly of section .text:
[ ]+1c:[ ]+03400000[ ]+nop
[ ]+20:[ ]+4c000020[ ]+ret
[ ]+24:[ ]+03400000[ ]+nop
-[ ]+24: R_LARCH_ALIGN[ ]+.Lla-relax-align\+0x104
+[ ]+24: R_LARCH_ALIGN[ ]+.text\+0x104
[ ]+28:[ ]+03400000[ ]+nop
[ ]+2c:[ ]+03400000[ ]+nop
[ ]+30:[ ]+4c000020[ ]+ret
[ ]+34:[ ]+03400000[ ]+nop
-[ ]+34: R_LARCH_ALIGN[ ]+.Lla-relax-align\+0xb04
+[ ]+34: R_LARCH_ALIGN[ ]+.text\+0xb04
[ ]+38:[ ]+03400000[ ]+nop
[ ]+3c:[ ]+03400000[ ]+nop
[ ]+40:[ ]+4c000020[ ]+ret
diff --git a/ld/testsuite/ld-loongarch-elf/relax-align-discard.lds b/ld/testsuite/ld-loongarch-elf/relax-align-discard.lds
new file mode 100644
index 00000000000..4a81323d926
--- /dev/null
+++ b/ld/testsuite/ld-loongarch-elf/relax-align-discard.lds
@@ -0,0 +1,4 @@
+SECTIONS
+{
+ /DISCARD/ : { *(.another.*) }
+}
diff --git a/ld/testsuite/ld-loongarch-elf/relax-align-discard.s b/ld/testsuite/ld-loongarch-elf/relax-align-discard.s
new file mode 100644
index 00000000000..b65d63f370f
--- /dev/null
+++ b/ld/testsuite/ld-loongarch-elf/relax-align-discard.s
@@ -0,0 +1,17 @@
+# Use the section name symbol for R_LARCH_ALIGN to avoid discard section problem
+.section ".another.text", "ax"
+.cfi_startproc
+break 0
+.cfi_def_cfa_offset 16
+.p2align 5
+break 1
+.cfi_endproc
+
+.text
+.cfi_startproc
+break 0
+.cfi_def_cfa_offset 16
+.p2align 5
+break 1
+.cfi_endproc
+
diff --git a/ld/testsuite/ld-loongarch-elf/relax.exp b/ld/testsuite/ld-loongarch-elf/relax.exp
index 7d95a9ca41d..ed71fb45b46 100644
--- a/ld/testsuite/ld-loongarch-elf/relax.exp
+++ b/ld/testsuite/ld-loongarch-elf/relax.exp
@@ -295,6 +295,18 @@ if [istarget loongarch64-*-*] {
"relax-align" \
] \
]
+
+ run_ld_link_tests \
+ [list \
+ [list \
+ "loongarch relax align discard" \
+ "-e 0x0 -T relax-align-discard.lds -r" "" \
+ "" \
+ {relax-align-discard.s} \
+ {} \
+ "relax-align-discard" \
+ ] \
+ ]
}
set objdump_flags "-s -j .data"
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