From: "H.J. Lu" <hjl.tools@gmail.com>
To: binutils@sourceware.org
Subject: [PATCH] x86: Properly handle IFUNC function pointer reference
Date: Tue, 31 May 2022 15:47:34 -0700 [thread overview]
Message-ID: <20220531224734.634761-1-hjl.tools@gmail.com> (raw)
Update
commit 68c4956b1401de70173848a6bdf620cb42fa9358
Author: H.J. Lu <hjl.tools@gmail.com>
Date: Tue Apr 26 09:08:54 2022 -0700
x86: Properly handle function pointer reference
to properly handle IFUNC function pointer reference. Since IFUNC symbol
value is only known at run-time, set pointer_equality_needed for IFUNC
function pointer reference in PDE so that it will be resolved to its PLT
entry directly.
bfd/
PR ld/29216
* elf32-i386.c (elf_i386_scan_relocs): Set pointer_equality_needed
for IFUNC function pointer reference in PDE.
* elf64-x86-64.c (elf_x86_64_scan_relocs): Likewise.
ld/
PR ld/29216
* testsuite/ld-ifunc/ifunc.exp: Run PR ld/29216 test.
* testsuite/ld-ifunc/pr29216.c: New file.
---
bfd/elf32-i386.c | 8 ++++-
bfd/elf64-x86-64.c | 8 ++++-
ld/testsuite/ld-ifunc/ifunc.exp | 9 +++++
ld/testsuite/ld-ifunc/pr29216.c | 62 +++++++++++++++++++++++++++++++++
4 files changed, 85 insertions(+), 2 deletions(-)
create mode 100644 ld/testsuite/ld-ifunc/pr29216.c
diff --git a/bfd/elf32-i386.c b/bfd/elf32-i386.c
index b034154fb97..3bc710096aa 100644
--- a/bfd/elf32-i386.c
+++ b/bfd/elf32-i386.c
@@ -1778,7 +1778,13 @@ elf_i386_scan_relocs (bfd *abfd,
if (r_type == R_386_32
&& (sec->flags & SEC_READONLY) == 0)
func_pointer_ref = true;
- else
+
+ /* IFUNC symbol needs pointer equality in PDE so that
+ function pointer reference will be resolved to its
+ PLT entry directly. */
+ if (!func_pointer_ref
+ || (bfd_link_pde (info)
+ && h->type == STT_GNU_IFUNC))
h->pointer_equality_needed = 1;
}
diff --git a/bfd/elf64-x86-64.c b/bfd/elf64-x86-64.c
index 6d69d6141ee..eac5e83d7f1 100644
--- a/bfd/elf64-x86-64.c
+++ b/bfd/elf64-x86-64.c
@@ -2221,7 +2221,13 @@ elf_x86_64_scan_relocs (bfd *abfd, struct bfd_link_info *info,
&& (r_type == R_X86_64_32
|| r_type == R_X86_64_32S))))
func_pointer_ref = true;
- else
+
+ /* IFUNC symbol needs pointer equality in PDE so that
+ function pointer reference will be resolved to its
+ PLT entry directly. */
+ if (!func_pointer_ref
+ || (bfd_link_pde (info)
+ && h->type == STT_GNU_IFUNC))
h->pointer_equality_needed = 1;
}
diff --git a/ld/testsuite/ld-ifunc/ifunc.exp b/ld/testsuite/ld-ifunc/ifunc.exp
index 1cd8d388b26..fdb65d01f9f 100644
--- a/ld/testsuite/ld-ifunc/ifunc.exp
+++ b/ld/testsuite/ld-ifunc/ifunc.exp
@@ -714,6 +714,15 @@ run_ld_link_exec_tests [list \
"pr18841cn" \
"pr18841.out" \
] \
+ [list \
+ "Run pr29216" \
+ "$NOPIE_LDFLAGS" \
+ "" \
+ { pr29216.c } \
+ "pr29216" \
+ "pass.out" \
+ "-fPIC" \
+ ] \
]
# The pr23169 testcase is not valid. In general, you can't call ifunc
diff --git a/ld/testsuite/ld-ifunc/pr29216.c b/ld/testsuite/ld-ifunc/pr29216.c
new file mode 100644
index 00000000000..5019c723c2b
--- /dev/null
+++ b/ld/testsuite/ld-ifunc/pr29216.c
@@ -0,0 +1,62 @@
+#include <stdio.h>
+
+static int
+one (void)
+{
+ return -30;
+}
+
+int foo (void) __attribute__ ((ifunc ("resolve_foo")));
+
+void *
+resolve_foo (void)
+{
+ return (void *) one;
+}
+
+typedef int (*foo_p) (void);
+
+foo_p foo_ptr = foo;
+
+foo_p
+__attribute__ ((noinline))
+get_foo_p (void)
+{
+ return foo_ptr;
+}
+
+foo_p
+__attribute__ ((noinline))
+get_foo (void)
+{
+ return foo;
+}
+
+int
+main (void)
+{
+ foo_p p;
+
+ p = get_foo ();
+ if (p != foo)
+ __builtin_abort ();
+ if ((*p) () != -30)
+ __builtin_abort ();
+
+ p = get_foo_p ();
+ if (p != foo)
+ __builtin_abort ();
+ if ((*p) () != -30)
+ __builtin_abort ();
+
+ if (foo_ptr != foo)
+ __builtin_abort ();
+ if ((*foo_ptr) () != -30)
+ __builtin_abort ();
+ if (foo () != -30)
+ __builtin_abort ();
+
+ printf ("PASS\n");
+
+ return 0;
+}
--
2.36.1
next reply other threads:[~2022-05-31 22:47 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-31 22:47 H.J. Lu [this message]
2022-06-01 1:15 ` H.J. Lu
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