[binutils-gdb] x86: Turn PLT32 to PC32 only for PC-relative relocations
H.J. Lu
hjl@sourceware.org
Sun Sep 22 19:54:28 GMT 2024
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=1b714c14e40f37ea8ea02a4998c4d95f25aff7f3
commit 1b714c14e40f37ea8ea02a4998c4d95f25aff7f3
Author: H.J. Lu <hjl.tools@gmail.com>
Date: Sun Sep 22 17:06:45 2024 +0800
x86: Turn PLT32 to PC32 only for PC-relative relocations
commit 292676c15a615b5a95bede9ee91004d3f7ee7dfd
Author: H.J. Lu <hjl.tools@gmail.com>
Date: Thu Feb 13 13:44:17 2020 -0800
x86: Resolve PLT32 reloc aganst local symbol to section
resolved PLT32 relocation against local symbol to section and
commit 2585b7a5ce5830e60a089aa2316a329558902f0c
Author: H.J. Lu <hjl.tools@gmail.com>
Date: Sun Jul 19 06:51:19 2020 -0700
x86: Change PLT32 reloc against section to PC32
turned PLT32 relocation against section into PC32 relocation. But these
transformations are valid only for PC-relative relocations. Add fx_pcrel
check for PC-relative relocations when performing these transformations
to keep PLT32 relocation in `movq $foo@PLT, %rax`.
gas/
PR gas/32196
* config/tc-i386.c (tc_i386_fix_adjustable): Return fixP->fx_pcrel
for PLT32 relocations.
(i386_validate_fix): Turn PLT32 relocation into PC32 relocation
only if fixp->fx_pcrel is set.
* testsuite/gas/i386/reloc32.d: Updated.
* testsuite/gas/i386/reloc64.d: Likewise.
* testsuite/gas/i386/reloc32.s: Add PR gas/32196 test.
* testsuite/gas/i386/reloc64.s: Likewise.
ld/
PR gas/32196
* testsuite/ld-x86-64/plt3.s: New file.
* testsuite/ld-x86-64/x86-64.exp: Run plt3.
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Diff:
---
gas/config/tc-i386.c | 11 ++++++++++-
gas/testsuite/gas/i386/reloc32.d | 1 +
gas/testsuite/gas/i386/reloc32.s | 7 +++++++
gas/testsuite/gas/i386/reloc64.d | 1 +
gas/testsuite/gas/i386/reloc64.s | 2 ++
ld/testsuite/ld-x86-64/plt3.s | 27 +++++++++++++++++++++++++++
ld/testsuite/ld-x86-64/x86-64.exp | 8 ++++++++
7 files changed, 56 insertions(+), 1 deletion(-)
diff --git a/gas/config/tc-i386.c b/gas/config/tc-i386.c
index 11565ac7cb0..864a38a9a20 100644
--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -3930,6 +3930,11 @@ tc_i386_fix_adjustable (fixS *fixP)
|| fixP->fx_r_type == BFD_RELOC_VTABLE_INHERIT
|| fixP->fx_r_type == BFD_RELOC_VTABLE_ENTRY)
return 0;
+ /* Resolve PLT32 relocation against local symbol to section only for
+ PC-relative relocations. */
+ if (fixP->fx_r_type == BFD_RELOC_386_PLT32
+ || fixP->fx_r_type == BFD_RELOC_X86_64_PLT32)
+ return fixP->fx_pcrel;
return 1;
}
#endif
@@ -17792,8 +17797,12 @@ i386_validate_fix (fixS *fixp)
{
/* NB: Commit 292676c1 resolved PLT32 reloc aganst local symbol
to section. Since PLT32 relocation must be against symbols,
- turn such PLT32 relocation into PC32 relocation. */
+ turn such PLT32 relocation into PC32 relocation. NB: We can
+ turn PLT32 relocation into PC32 relocation only for PC-relative
+ relocations since non-PC-relative relocations need PLT entries.
+ */
if (fixp->fx_addsy
+ && fixp->fx_pcrel
&& (fixp->fx_r_type == BFD_RELOC_386_PLT32
|| fixp->fx_r_type == BFD_RELOC_X86_64_PLT32)
&& symbol_section_p (fixp->fx_addsy))
diff --git a/gas/testsuite/gas/i386/reloc32.d b/gas/testsuite/gas/i386/reloc32.d
index 7d1b1ba2ae0..ebac545b200 100644
--- a/gas/testsuite/gas/i386/reloc32.d
+++ b/gas/testsuite/gas/i386/reloc32.d
@@ -43,6 +43,7 @@ Disassembly of section \.text:
.*[ ]+R_386_TLS_LE[ ]+xtrn
.*[ ]+R_386_TLS_LE_32[ ]+xtrn
.*[ ]+R_386_TLS_LE_32[ ]+xtrn
+.*[ ]+R_386_PLT32[ ]+ptr
Disassembly of section \.data:
#...
.*[ ]+R_386_32[ ]+xtrn
diff --git a/gas/testsuite/gas/i386/reloc32.s b/gas/testsuite/gas/i386/reloc32.s
index e766a3dcc25..5616cd57e3f 100644
--- a/gas/testsuite/gas/i386/reloc32.s
+++ b/gas/testsuite/gas/i386/reloc32.s
@@ -162,3 +162,10 @@ bad .byte xtrn@tpoff
.long xtrn@got + 4
.long xtrn@got - 4
bad .long xtrn@plt - .
+
+ .text
+ movl $ptr@PLT, %eax
+
+ .data
+ptr:
+ .dc.a 0
diff --git a/gas/testsuite/gas/i386/reloc64.d b/gas/testsuite/gas/i386/reloc64.d
index 665ede6f264..5fee029e56a 100644
--- a/gas/testsuite/gas/i386/reloc64.d
+++ b/gas/testsuite/gas/i386/reloc64.d
@@ -59,6 +59,7 @@ Disassembly of section \.text:
.*[ ]+R_X86_64_32[ ]+xtrn
.*[ ]+R_X86_64_GOT64[ ]+ptr
.*[ ]+R_X86_64_GOTOFF64[ ]+Ldst
+.*[ ]+R_X86_64_PLT32[ ]+ptr
Disassembly of section \.data:
#...
.*[ ]+R_X86_64_64[ ]+xtrn
diff --git a/gas/testsuite/gas/i386/reloc64.s b/gas/testsuite/gas/i386/reloc64.s
index 2293865df20..5c0f4136a09 100644
--- a/gas/testsuite/gas/i386/reloc64.s
+++ b/gas/testsuite/gas/i386/reloc64.s
@@ -229,6 +229,8 @@ bad .long xtrn@plt - .
.text
movabs $ptr@GOT, %rax
movabs $Ldst@GOTOFF, %rdx
+ movq $ptr@PLT, %rax
+
.data
ptr:
.quad 0
diff --git a/ld/testsuite/ld-x86-64/plt3.s b/ld/testsuite/ld-x86-64/plt3.s
new file mode 100644
index 00000000000..c3a29b5ca95
--- /dev/null
+++ b/ld/testsuite/ld-x86-64/plt3.s
@@ -0,0 +1,27 @@
+ .text
+ .global _start
+_start:
+ movq $foo@PLT, %rax
+ leaq -11(%rip), %rbx
+ leaq (%rbx, %rax), %rax
+ call *%rax
+
+ # Write out "PASS\n".
+ movl $5, %edx
+ movl $.LC0, %esi
+ movl $1, %edi
+ movl $1, %eax
+ syscall
+
+ # exit
+ movq $60, %rax
+ movq $0, %rdi
+ syscall
+
+foo:
+ ret
+
+ .section .rodata.str1.1,"aMS",@progbits,1
+.LC0:
+ .string "PASS\n"
+ .section .note.GNU-stack,"",@progbits
diff --git a/ld/testsuite/ld-x86-64/x86-64.exp b/ld/testsuite/ld-x86-64/x86-64.exp
index cf78fffe29f..1a6754dc31f 100644
--- a/ld/testsuite/ld-x86-64/x86-64.exp
+++ b/ld/testsuite/ld-x86-64/x86-64.exp
@@ -1929,6 +1929,14 @@ if { [isnative] && [check_compiler_available] } {
"pr32189" \
"pass.out" \
] \
+ [list \
+ "Run plt3" \
+ "$NOPIE_LDFLAGS -nostdlib -nostartfiles" \
+ "" \
+ { plt3.s } \
+ "plt3" \
+ "pass.out" \
+ ] \
]
# Run-time tests which require working ifunc attribute support.
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