[committed] MIPS/BFD: Fix RELA handling of borrow in the generic linker
Maciej W. Rozycki
macro@orcam.me.uk
Sun Jul 6 18:25:13 GMT 2025
Fix an issue with `_bfd_mips_elf_generic_reloc' not taking into account
any borrow from the lower part in the handling of relocations of the
HI/LO kind and resulting in incorrect calculations made for RELA targets
in the generic used for non-ELF output such as S-records. This doesn't
trigger for REL targets because they call `_bfd_mips_elf_generic_reloc'
indirectly from `_bfd_mips_elf_lo16_reloc' so as to obtain a complete
32-bit addend from relocation pairs and in calculating the addend the
latter function uses a hack to work around the lack of borrow handling
in the former function.
The MIPS/ELF linker is unaffected as it uses its own calculations.
Correct the calculation of the relevant partial relocations made in
`_bfd_mips_elf_generic_reloc' then to take the borrow into account and
remove the hack from `_bfd_mips_elf_lo16_reloc' as no longer needed.
Add generic linker test cases accordingly expecting the same disassembly
from srec output produced as from ELF output produced by the MIPS/ELF
linker.
---
bfd/elfxx-mips.c | 33 +++++++++++++++++----
ld/testsuite/ld-mips-elf/micromips-hilo-n64.d | 4 +-
ld/testsuite/ld-mips-elf/micromips-hilo-srec-n32.d | 8 +++++
ld/testsuite/ld-mips-elf/micromips-hilo-srec-n64.d | 8 +++++
ld/testsuite/ld-mips-elf/micromips-hilo-srec.d | 8 +++++
ld/testsuite/ld-mips-elf/micromips-hilo.d | 4 +-
ld/testsuite/ld-mips-elf/mips-elf.exp | 27 +++++++++++++++++
ld/testsuite/ld-mips-elf/mips-hilo-n64.d | 4 +-
ld/testsuite/ld-mips-elf/mips-hilo-srec-n32.d | 6 +++
ld/testsuite/ld-mips-elf/mips-hilo-srec-n64.d | 6 +++
ld/testsuite/ld-mips-elf/mips-hilo-srec.d | 6 +++
ld/testsuite/ld-mips-elf/mips-hilo.d | 4 +-
ld/testsuite/ld-mips-elf/mips16-hilo-srec-n32.d | 7 ++++
ld/testsuite/ld-mips-elf/mips16-hilo-srec.d | 7 ++++
ld/testsuite/ld-mips-elf/mips16-hilo.d | 4 +-
ld/testsuite/ld-mips-elf/mips16e2-hilo-srec-n32.d | 8 +++++
ld/testsuite/ld-mips-elf/mips16e2-hilo-srec.d | 8 +++++
ld/testsuite/ld-mips-elf/mips16e2-hilo.d | 4 +-
18 files changed, 138 insertions(+), 18 deletions(-)
binutils-mips-reloc-hipart-borrow.diff
Index: binutils-gdb/bfd/elfxx-mips.c
===================================================================
--- binutils-gdb.orig/bfd/elfxx-mips.c
+++ binutils-gdb/bfd/elfxx-mips.c
@@ -2599,15 +2599,13 @@ _bfd_mips_elf_lo16_reloc (bfd *abfd, are
addend is adjusted for the fact that the low part is sign
extended. For example, an addend of 0x38000 would have 0x0004 in
the high part and 0x8000 (=0xff..f8000) in the low part.
- To extract the actual addend, calculate (a)
+ To extract the actual addend, calculate
((hi & 0xffff) << 16) + ((lo & 0xffff) ^ 0x8000) - 0x8000.
We will be applying (symbol + addend) & 0xffff to the low insn,
- and we want to apply (b) (symbol + addend + 0x8000) >> 16 to the
+ and we want to apply (symbol + addend + 0x8000) >> 16 to the
high insn (the +0x8000 adjusting for when the applied low part is
- negative). Substituting (a) into (b) and recognising that
- (hi & 0xffff) is already in the high insn gives a high part
- addend adjustment of (lo & 0xffff) ^ 0x8000. */
- vallo = (bfd_get_32 (abfd, location) & 0xffff) ^ 0x8000;
+ negative). */
+ vallo = ((bfd_get_32 (abfd, location) & 0xffff) ^ 0x8000) - 0x8000;
_bfd_mips_elf_reloc_shuffle (abfd, reloc_entry->howto->type, false,
location);
@@ -2707,6 +2705,29 @@ _bfd_mips_elf_generic_reloc (bfd *abfd A
/* Add in the separate addend, if any. */
val += reloc_entry->addend;
+ /* The high 16 bits of the addend are stored in the high insn, the
+ low 16 bits in the low insn, but there is a catch: You can't
+ just concatenate the high and low parts. The high part of the
+ addend is adjusted for the fact that the low part is sign
+ extended. For example, an addend of 0x38000 would have 0x0004 in
+ the high part and 0x8000 (=0xff..f8000) in the low part.
+ We will be applying (symbol + addend) & 0xffff to the low insn,
+ and we want to apply (symbol + addend + 0x8000) >> 16 to the
+ high insn (the +0x8000 adjusting for when the applied low part is
+ negative). Analogously for the higher parts of a 64-bit addend. */
+ if (reloc_entry->howto->bitsize == 16
+ && reloc_entry->howto->rightshift % 16 == 0)
+#ifdef BFD64
+ val += 0x800080008000ULL >> (48 - reloc_entry->howto->rightshift);
+#else
+ {
+ if (reloc_entry->howto->rightshift <= 16)
+ val += 0x8000 >> (16 - reloc_entry->howto->rightshift);
+ else
+ abort ();
+ }
+#endif
+
/* Add VAL to the relocation field. */
_bfd_mips_elf_reloc_unshuffle (abfd, reloc_entry->howto->type, false,
location);
Index: binutils-gdb/ld/testsuite/ld-mips-elf/micromips-hilo-n64.d
===================================================================
--- binutils-gdb.orig/ld/testsuite/ld-mips-elf/micromips-hilo-n64.d
+++ binutils-gdb/ld/testsuite/ld-mips-elf/micromips-hilo-n64.d
@@ -6,9 +6,9 @@
#ld: -Tmips-hilo.ld -e 0x500000 -N
#notarget: mips*el-ps2-elf*
-.*: file format elf.*mips.*
+.*: file format (:?elf.*mips.*|srec)
-Disassembly of section \.text:
+Disassembly of section \.(:?text|sec1):
0*500000 <[^>]*>:
*500000: 41a1 0000 lui at,0x0
Index: binutils-gdb/ld/testsuite/ld-mips-elf/micromips-hilo-srec-n32.d
===================================================================
--- /dev/null
+++ binutils-gdb/ld/testsuite/ld-mips-elf/micromips-hilo-srec-n32.d
@@ -0,0 +1,8 @@
+#name: R_MICROMIPS_HI16 and R_MICROMIPS_LO16 relocs srec n32
+#source: ../../../gas/testsuite/gas/mips/mips-hilo.s
+#source: mips-hilo.s
+#as: -mmicromips -march=mips64r2
+#objdump: -m mips:micromips -j .sec1 -D
+#ld: --oformat=srec -Tmips-hilo.ld -e 0x500000 -N
+#notarget: mips*el-ps2-elf*
+#dump: micromips-hilo.d
Index: binutils-gdb/ld/testsuite/ld-mips-elf/micromips-hilo-srec-n64.d
===================================================================
--- /dev/null
+++ binutils-gdb/ld/testsuite/ld-mips-elf/micromips-hilo-srec-n64.d
@@ -0,0 +1,8 @@
+#name: R_MICROMIPS_HI16 and R_MICROMIPS_LO16 relocs srec n64
+#source: ../../../gas/testsuite/gas/mips/mips-hilo-n64.s
+#source: mips-hilo.s
+#as: -mmicromips -march=mips64r2
+#objdump: -m mips:micromips -j .sec1 -D
+#ld: --oformat=srec -Tmips-hilo.ld -e 0x500000 -N
+#notarget: mips*el-ps2-elf*
+#dump: micromips-hilo-n64.d
Index: binutils-gdb/ld/testsuite/ld-mips-elf/micromips-hilo-srec.d
===================================================================
--- /dev/null
+++ binutils-gdb/ld/testsuite/ld-mips-elf/micromips-hilo-srec.d
@@ -0,0 +1,8 @@
+#name: R_MICROMIPS_HI16 and R_MICROMIPS_LO16 relocs srec
+#source: ../../../gas/testsuite/gas/mips/mips-hilo.s
+#source: mips-hilo.s
+#as: -mmicromips -march=mips32r2
+#objdump: -m mips:micromips -j .sec1 -D
+#ld: --oformat=srec -Tmips-hilo.ld -e 0x500000 -N
+#notarget: mips*el-ps2-elf*
+#dump: micromips-hilo.d
Index: binutils-gdb/ld/testsuite/ld-mips-elf/micromips-hilo.d
===================================================================
--- binutils-gdb.orig/ld/testsuite/ld-mips-elf/micromips-hilo.d
+++ binutils-gdb/ld/testsuite/ld-mips-elf/micromips-hilo.d
@@ -6,9 +6,9 @@
#ld: -Tmips-hilo.ld -e 0x500000 -N
#notarget: mips*el-ps2-elf*
-.*: file format elf.*mips.*
+.*: file format (:?elf.*mips.*|srec)
-Disassembly of section \.text:
+Disassembly of section \.(:?text|sec1):
0*500000 <[^>]*>:
*500000: 41a4 0000 lui a0,0x0
Index: binutils-gdb/ld/testsuite/ld-mips-elf/mips-elf.exp
===================================================================
--- binutils-gdb.orig/ld/testsuite/ld-mips-elf/mips-elf.exp
+++ binutils-gdb/ld/testsuite/ld-mips-elf/mips-elf.exp
@@ -816,14 +816,41 @@ run_dump_test "mode-change-error-1"
run_dump_test_o32 "mips16-hilo" noarch
run_dump_test_n32 "mips16-hilo-n32" noarch
+run_dump_test_o32 "mips16-hilo-srec" \
+ [list noarch \
+ [list objdump [expr { [istarget *el-*-*] ? "-EL" : "-EB" }]]]
+run_dump_test_n32 "mips16-hilo-srec-n32" \
+ [list noarch \
+ [list objdump [expr { [istarget *el-*-*] ? "-EL" : "-EB" }]]]
run_dump_test_o32 "mips16e2-hilo" noarch
run_dump_test_n32 "mips16e2-hilo-n32" noarch
+run_dump_test_o32 "mips16e2-hilo-srec" \
+ [list noarch \
+ [list objdump [expr { [istarget *el-*-*] ? "-EL" : "-EB" }]]]
+run_dump_test_n32 "mips16e2-hilo-srec-n32" \
+ [list noarch \
+ [list objdump [expr { [istarget *el-*-*] ? "-EL" : "-EB" }]]]
run_dump_test_o32 "mips-hilo"
run_dump_test_n32 "mips-hilo-n32"
run_dump_test_n64 "mips-hilo-n64"
+run_dump_test_o32 "mips-hilo-srec" \
+ [list [list objdump [expr { [istarget *el-*-*] ? "-EL" : "-EB" }]]]
+run_dump_test_n32 "mips-hilo-srec-n32" \
+ [list [list objdump [expr { [istarget *el-*-*] ? "-EL" : "-EB" }]]]
+run_dump_test_n64 "mips-hilo-srec-n64" \
+ [list [list objdump [expr { [istarget *el-*-*] ? "-EL" : "-EB" }]]]
run_dump_test_o32 "micromips-hilo" noarch
run_dump_test_n32 "micromips-hilo-n32" noarch
run_dump_test_n64 "micromips-hilo-n64" noarch
+run_dump_test_o32 "micromips-hilo-srec" \
+ [list noarch \
+ [list objdump [expr { [istarget *el-*-*] ? "-EL" : "-EB" }]]]
+run_dump_test_n32 "micromips-hilo-srec-n32" \
+ [list noarch \
+ [list objdump [expr { [istarget *el-*-*] ? "-EL" : "-EB" }]]]
+run_dump_test_n64 "micromips-hilo-srec-n64" \
+ [list noarch \
+ [list objdump [expr { [istarget *el-*-*] ? "-EL" : "-EB" }]]]
if { $linux_gnu } {
run_dump_test_n32 "textrel-1"
Index: binutils-gdb/ld/testsuite/ld-mips-elf/mips-hilo-n64.d
===================================================================
--- binutils-gdb.orig/ld/testsuite/ld-mips-elf/mips-hilo-n64.d
+++ binutils-gdb/ld/testsuite/ld-mips-elf/mips-hilo-n64.d
@@ -4,9 +4,9 @@
#objdump: -d
#ld: -Tmips-hilo.ld -e 0x500000 -N
-.*: file format elf.*mips.*
+.*: file format (:?elf.*mips.*|srec)
-Disassembly of section \.text:
+Disassembly of section \.(:?text|sec1):
0*500000 <[^>]*>:
*500000: 3c010000 lui at,0x0
Index: binutils-gdb/ld/testsuite/ld-mips-elf/mips-hilo-srec-n32.d
===================================================================
--- /dev/null
+++ binutils-gdb/ld/testsuite/ld-mips-elf/mips-hilo-srec-n32.d
@@ -0,0 +1,6 @@
+#name: R_MIPS_HI16 and R_MIPS_LO16 relocs srec n32
+#source: ../../../gas/testsuite/gas/mips/mips-hilo.s
+#source: mips-hilo.s
+#objdump: -m mips:4000 -j .sec1 -D
+#ld: --oformat=srec -Tmips-hilo.ld -e 0x500000 -N
+#dump: mips-hilo.d
Index: binutils-gdb/ld/testsuite/ld-mips-elf/mips-hilo-srec-n64.d
===================================================================
--- /dev/null
+++ binutils-gdb/ld/testsuite/ld-mips-elf/mips-hilo-srec-n64.d
@@ -0,0 +1,6 @@
+#name: R_MIPS_HI16 and R_MIPS_LO16 relocs srec n64
+#source: ../../../gas/testsuite/gas/mips/mips-hilo-n64.s
+#source: mips-hilo.s
+#objdump: -m mips:4000 -j .sec1 -D
+#ld: --oformat=srec -Tmips-hilo.ld -e 0x500000 -N
+#dump: mips-hilo-n64.d
Index: binutils-gdb/ld/testsuite/ld-mips-elf/mips-hilo-srec.d
===================================================================
--- /dev/null
+++ binutils-gdb/ld/testsuite/ld-mips-elf/mips-hilo-srec.d
@@ -0,0 +1,6 @@
+#name: R_MIPS_HI16 and R_MIPS_LO16 relocs srec
+#source: ../../../gas/testsuite/gas/mips/mips-hilo.s
+#source: mips-hilo.s
+#objdump: -m mips:3000 -j .sec1 -D
+#ld: --oformat=srec -Tmips-hilo.ld -e 0x500000 -N
+#dump: mips-hilo.d
Index: binutils-gdb/ld/testsuite/ld-mips-elf/mips-hilo.d
===================================================================
--- binutils-gdb.orig/ld/testsuite/ld-mips-elf/mips-hilo.d
+++ binutils-gdb/ld/testsuite/ld-mips-elf/mips-hilo.d
@@ -4,9 +4,9 @@
#objdump: -d
#ld: -Tmips-hilo.ld -e 0x500000 -N
-.*: file format elf.*mips.*
+.*: file format (:?elf.*mips.*|srec)
-Disassembly of section \.text:
+Disassembly of section \.(:?text|sec1):
0*500000 <[^>]*>:
*500000: 3c040000 lui a0,0x0
Index: binutils-gdb/ld/testsuite/ld-mips-elf/mips16-hilo-srec-n32.d
===================================================================
--- /dev/null
+++ binutils-gdb/ld/testsuite/ld-mips-elf/mips16-hilo-srec-n32.d
@@ -0,0 +1,7 @@
+#name: R_MIPS16_HI16 and R_MIPS16_LO16 relocs srec n32
+#source: ../../../gas/testsuite/gas/mips/mips16-hilo.s
+#source: mips-hilo.s
+#as: -march=mips3
+#objdump: -mmips:16 -j .sec1 -D
+#ld: --oformat=srec -Tmips-hilo.ld -e 0x500000 -N
+#dump: mips16-hilo.d
Index: binutils-gdb/ld/testsuite/ld-mips-elf/mips16-hilo-srec.d
===================================================================
--- /dev/null
+++ binutils-gdb/ld/testsuite/ld-mips-elf/mips16-hilo-srec.d
@@ -0,0 +1,7 @@
+#name: R_MIPS16_HI16 and R_MIPS16_LO16 relocs srec
+#source: ../../../gas/testsuite/gas/mips/mips16-hilo.s
+#source: mips-hilo.s
+#as: -march=mips1
+#objdump: -mmips:16 -j .sec1 -D
+#ld: --oformat=srec -Tmips-hilo.ld -e 0x500000 -N
+#dump: mips16-hilo.d
Index: binutils-gdb/ld/testsuite/ld-mips-elf/mips16-hilo.d
===================================================================
--- binutils-gdb.orig/ld/testsuite/ld-mips-elf/mips16-hilo.d
+++ binutils-gdb/ld/testsuite/ld-mips-elf/mips16-hilo.d
@@ -5,9 +5,9 @@
#objdump: -mmips:16 -dr
#ld: -Tmips-hilo.ld -e 0x500000 -N
-.*: file format elf.*mips.*
+.*: file format (:?elf.*mips.*|srec)
-Disassembly of section .text:
+Disassembly of section \.(:?text|sec1):
0*500000 <[^>]*>:
*500000: 6c00 li a0,0
Index: binutils-gdb/ld/testsuite/ld-mips-elf/mips16e2-hilo-srec-n32.d
===================================================================
--- /dev/null
+++ binutils-gdb/ld/testsuite/ld-mips-elf/mips16e2-hilo-srec-n32.d
@@ -0,0 +1,8 @@
+#name: MIPS16e2 R_MIPS16_HI16 and R_MIPS16_LO16 relocs srec n32
+#source: ../../../gas/testsuite/gas/mips/mips-hilo.s
+#source: mips-hilo.s
+#as: -mips16 -mmips16e2 -march=mips64r2
+#objdump: -mmips:16 -j .sec1 -D
+#ld: --oformat=srec -Tmips-hilo.ld -e 0x500000 -N
+#notarget: mips*el-ps2-elf*
+#dump: mips16e2-hilo.d
Index: binutils-gdb/ld/testsuite/ld-mips-elf/mips16e2-hilo-srec.d
===================================================================
--- /dev/null
+++ binutils-gdb/ld/testsuite/ld-mips-elf/mips16e2-hilo-srec.d
@@ -0,0 +1,8 @@
+#name: MIPS16e2 R_MIPS16_HI16 and R_MIPS16_LO16 relocs srec
+#source: ../../../gas/testsuite/gas/mips/mips-hilo.s
+#source: mips-hilo.s
+#as: -mips16 -mmips16e2 -march=mips32r2
+#objdump: -mmips:16 -j .sec1 -D
+#ld: --oformat=srec -Tmips-hilo.ld -e 0x500000 -N
+#notarget: mips*el-ps2-elf*
+#dump: mips16e2-hilo.d
Index: binutils-gdb/ld/testsuite/ld-mips-elf/mips16e2-hilo.d
===================================================================
--- binutils-gdb.orig/ld/testsuite/ld-mips-elf/mips16e2-hilo.d
+++ binutils-gdb/ld/testsuite/ld-mips-elf/mips16e2-hilo.d
@@ -6,9 +6,9 @@
#ld: -Tmips-hilo.ld -e 0x500000 -N
#notarget: mips*el-ps2-elf*
-.*: file format elf.*mips.*
+.*: file format (:?elf.*mips.*|srec)
-Disassembly of section \.text:
+Disassembly of section \.(:?text|sec1):
0*500000 <[^>]*>:
*500000: f000 6c20 lui a0,0x0
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