[PATCH v4] elf: Set image base address to the maximum page size

"H.J. Lu" <[email protected]>
Newsgroups gmane.comp.gnu.binutils
Message-ID <CAMe9rOoW4dnsHBBLqAbHS_6fTaDwmSbjw=Ah2M0SaZVWei7i4Q@mail.gmail.com> 
On Thu, Jun 25, 2026 at 11:46 PM H.J. Lu <[email protected]> wrote:
>
> On Thu, Jun 25, 2026 at 10:42 PM Nick Clifton <[email protected]> wrote:
> >
> > Hi H.J.
> >
> > >       PR ld/34184
> > >       * ldexp.c (fold_binary): Set text-segment address to the maximum
> > >       page size for ELF PDE output with -z max-page-size=SIZE.
> > >       * testsuite/ld-elf/elf.exp: Add ld/34184 test.
> > >       * testsuite/ld-elf/pr34184.c: New file.
> >
> > I like this patch, but I do have a couple of comments:
> >
> > > +      /* When generating Position Dependent Executable for ELF with the
> > > +      maximum page size set on command-line, if text-segment address
> > > +      is lower than the maximum page size, set text-segment address
> > > +      to the maximum page size.  */
> > > +      if ((bfd_get_flavour (link_info.output_bfd)
> > > +        == bfd_target_elf_flavour)
> > > +       && bfd_link_pde (&link_info)
> > > +       && link_info.maxpagesize_is_set
> > > +       && link_info.maxpagesize > value
> > > +       && strcmp (segment_name, "text-segment") == 0)
> > > +     value = link_info.maxpagesize;
> >
> > I think that it would be helpful to inform the user that the text
> > segment address is being changed - *if* they have tried to set it
> > using --image-base or --Ttext-segment.  Otherwise they may wonder
> > why their command line option is being ignored.
>
> Will do.

Fixed in the v4 patch.

> >
> > > +    [list \
> > > +     "Run pr34184" \
> > > +     "-Wl,-z,max-page-size=0x800000" \
> > > +     "" \
> > > +     {pr34184.c} \
> > > +     "pr34184" \
> > > +     "pass.out" \
> > > +    ] \
> >
> > As far as I can tell, this test does not actually check that
> > the text segment's address is now a multiple of the max page
> > size...
>
> This is a run-time test.  Without the fix, we get segfault:
>
> [hjl@gnu-tgl-3 tmp]$ cat x.c
> int
> main ()
> {
>   return 0;
> }
> [hjl@gnu-tgl-3 tmp]$ gcc -Wl,-z,max-page-size=0x800000 x.c
> [hjl@gnu-tgl-3 tmp]$ ./a.out
> Segmentation fault         ./a.out
> [hjl@gnu-tgl-3 tmp]$
>
>
> --
> H.J.

Here is the v4 patch.

-- 
H.J.
---
When generating Position Dependent Executable for ELF with the maximum
page size set on command-line, set the default image base address to the
maximum page size to avoid segfault if it is lower than the maximum page
size and issue an warning if the image base address set on command-line
is lower than the maximum page size.

PR ld/34184
* ldexp.c (fold_binary): Set the default image base address to
the maximum page size for ELF PDE output if it is lower than
the maximum page size set on command-line and issue an warning
if the image base address set on command-line is lower than the
maximum page size.
* testsuite/ld-elf/elf.exp: Add ld/34184 tests for PDE, PIE
static PDE and static PIE.
* testsuite/ld-elf/pr34184.c: New file.
* testsuite/ld-elf/textaddr3.d: Change -Ttext-segment adddress
to 0x200100 so that it > the maximum page size.
* testsuite/ld-elf/textaddr5.d: Likewise.
* testsuite/ld-elf/textaddr8.d: New test.
* testsuite/ld-elf/textaddr9.d: Likewise.
v4-0001-elf-Set-image-base-address-to-the-maximum-page-si.patch (text/x-patch, 7.3 KB) 
From 71b78427774b7a8e2971cef7eddfe84e84753d8e Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <[email protected]>
Date: Thu, 28 May 2026 10:47:37 +0800
Subject: [PATCH v4] elf: Set image base address to the maximum page size

When generating Position Dependent Executable for ELF with the maximum
page size set on command-line, set the default image base address to the
maximum page size to avoid segfault if it is lower than the maximum page
size and issue an warning if the image base address set on command-line
is lower than the maximum page size.

	PR ld/34184
	* ldexp.c (fold_binary): Set the default image base address to
	the maximum page size for ELF PDE output if it is lower than
	the maximum page size set on command-line and issue an warning
	if the image base address set on command-line is lower than the
	maximum page size.
	* testsuite/ld-elf/elf.exp: Add ld/34184 tests for PDE, PIE
	static PDE and static PIE.
	* testsuite/ld-elf/pr34184.c: New file.
	* testsuite/ld-elf/textaddr3.d: Change -Ttext-segment adddress
	to 0x200100 so that it > the maximum page size.
	* testsuite/ld-elf/textaddr5.d: Likewise.
	* testsuite/ld-elf/textaddr8.d: New test.
	* testsuite/ld-elf/textaddr9.d: Likewise.

Signed-off-by: H.J. Lu <[email protected]>
---
 ld/ldexp.c                      | 44 +++++++++++++++++++++++++++++----
 ld/testsuite/ld-elf/elf.exp     | 36 +++++++++++++++++++++++++++
 ld/testsuite/ld-elf/pr34184.c   |  8 ++++++
 ld/testsuite/ld-elf/textaddr3.d |  2 +-
 ld/testsuite/ld-elf/textaddr5.d |  2 +-
 ld/testsuite/ld-elf/textaddr8.d |  9 +++++++
 ld/testsuite/ld-elf/textaddr9.d |  9 +++++++
 7 files changed, 103 insertions(+), 7 deletions(-)
 create mode 100644 ld/testsuite/ld-elf/pr34184.c
 create mode 100644 ld/testsuite/ld-elf/textaddr8.d
 create mode 100644 ld/testsuite/ld-elf/textaddr9.d

diff --git a/ld/ldexp.c b/ld/ldexp.c
index 7bda6acc4c9..19542ad99c6 100644
--- a/ld/ldexp.c
+++ b/ld/ldexp.c
@@ -552,20 +552,54 @@ fold_binary (etree_type *tree)
       /* Check to see if the user has overridden the default
 	 value.  */
       segment_name = tree->binary.rhs->name.name;
+
+      bool update_image_base
+	= ((bfd_get_flavour (link_info.output_bfd)
+	    == bfd_target_elf_flavour)
+	   && bfd_link_pde (&link_info)
+	   && link_info.maxpagesize_is_set);
+
       for (seg = segments; seg; seg = seg->next)
 	if (strcmp (seg->name, segment_name) == 0)
 	  {
 	    if (!seg->used
 		&& config.magic_demand_paged
-		&& link_info.maxpagesize != 0
-		&& (seg->value % link_info.maxpagesize) != 0)
-	      einfo (_("%P: warning: address of `%s' "
-		       "isn't multiple of maximum page size\n"),
-		     segment_name);
+		&& link_info.maxpagesize != 0)
+	      {
+		if (seg->value < link_info.maxpagesize)
+		  {
+		    if (update_image_base)
+		      einfo (_("%P: warning: image base (0x%llx) < "
+			       "maximum page size (0x%llx)\n"),
+			     (unsigned long long) seg->value,
+			     (unsigned long long) link_info.maxpagesize);
+		  }
+		else if ((seg->value % link_info.maxpagesize) != 0)
+		  einfo (_("%P: warning: address of `%s' "
+			   "isn't multiple of maximum page size\n"),
+			 segment_name);
+
+		/* Don't override image base from command-line.  */
+		if (strcmp (segment_name, "text-segment") == 0)
+		  update_image_base = false;
+
+	      }
 	    seg->used = true;
 	    value = seg->value;
 	    break;
 	  }
+
+      /* When generating Position Dependent Executable for ELF with the
+	 maximum page size set on command-line, if image base address
+	 is lower than the maximum page size, set image base address
+	 to the maximum page size to avoid segfault.  NB: For ELF,
+	 -Ttext-segment=ADDR is an alias of --image-base=ADDR, which
+	 sets the base address of the ELF executable.  */
+      if (update_image_base
+	  && link_info.maxpagesize > value
+	  && strcmp (segment_name, "text-segment") == 0)
+	value = link_info.maxpagesize;
+
       new_rel_from_abs (value);
       return;
     }
diff --git a/ld/testsuite/ld-elf/elf.exp b/ld/testsuite/ld-elf/elf.exp
index 8fca30dbeeb..51b8c942648 100644
--- a/ld/testsuite/ld-elf/elf.exp
+++ b/ld/testsuite/ld-elf/elf.exp
@@ -535,6 +535,15 @@ if { [istarget *-*-linux*]
 		"pr14525.out" \
 		"-fPIE" \
 	    ] \
+	    [list \
+		"Run PR ld/34184 test (static PIE)" \
+		"-pie -Wl,-z,max-page-size=0x800000" \
+		"" \
+		{pr34184.c} \
+		"pr34184-static-pie" \
+		"pass.out" \
+		"-fPIE" \
+	    ] \
 	]
     }
 
@@ -580,6 +589,33 @@ if { [istarget *-*-linux*]
 	    {} \
 	    "-Wl,-R,tmpdir tmpdir/pr32690.so" \
 	] \
+	[list \
+	    "Run PR ld/34184 test (PDE)" \
+	    "$NOPIE_LDFLAGS -Wl,-z,max-page-size=0x800000" \
+	    "" \
+	    {pr34184.c} \
+	    "pr34184-pde" \
+	    "pass.out" \
+	    "$NOPIE_CFLAGS" \
+	] \
+	[list \
+	    "Run PR ld/34184 test (static PDE)" \
+	    "-static $NOPIE_LDFLAGS -Wl,-z,max-page-size=0x800000" \
+	    "" \
+	    {pr34184.c} \
+	    "pr34184-static-pde" \
+	    "pass.out" \
+	    "$NOPIE_CFLAGS" \
+	] \
+	[list \
+	    "Run PR ld/34184 test (PIE)" \
+	    "-pie -Wl,-z,max-page-size=0x800000" \
+	    "" \
+	    {pr34184.c} \
+	    "pr34184-pie" \
+	    "pass.out" \
+	    "-fPIE" \
+	] \
     ]
 }
 
diff --git a/ld/testsuite/ld-elf/pr34184.c b/ld/testsuite/ld-elf/pr34184.c
new file mode 100644
index 00000000000..8fb892c6aaa
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr34184.c
@@ -0,0 +1,8 @@
+#include <stdio.h>
+
+int
+main ()
+{
+  printf ("PASS\n");
+  return 0;
+}
diff --git a/ld/testsuite/ld-elf/textaddr3.d b/ld/testsuite/ld-elf/textaddr3.d
index 3796b7dcb98..284d5a47015 100644
--- a/ld/testsuite/ld-elf/textaddr3.d
+++ b/ld/testsuite/ld-elf/textaddr3.d
@@ -1,4 +1,4 @@
 #source: maxpage1.s
-#ld: -Ttext-segment 0x10000 -z max-page-size=0x200000
+#ld: -Ttext-segment 0x200100 -z max-page-size=0x200000
 #target: *-*-linux-gnu *-*-gnu* arm*-*-uclinuxfdpiceabi
 #warning: .*address of `text-segment' isn't multiple of maximum page size
diff --git a/ld/testsuite/ld-elf/textaddr5.d b/ld/testsuite/ld-elf/textaddr5.d
index ab1097f40cf..1f65c5136e0 100644
--- a/ld/testsuite/ld-elf/textaddr5.d
+++ b/ld/testsuite/ld-elf/textaddr5.d
@@ -1,5 +1,5 @@
 #source: maxpage1.s
-#ld: -shared -z max-page-size=0x200000 -Ttext-segment 0x10000
+#ld: -shared -z max-page-size=0x200000 -Ttext-segment 0x200100
 #target: *-*-linux-gnu *-*-gnu* arm*-*-uclinuxfdpiceabi
 #xfail: ![check_shared_lib_support]
 #warning: .*address of `text-segment' isn't multiple of maximum page size
diff --git a/ld/testsuite/ld-elf/textaddr8.d b/ld/testsuite/ld-elf/textaddr8.d
new file mode 100644
index 00000000000..df0bdc63f08
--- /dev/null
+++ b/ld/testsuite/ld-elf/textaddr8.d
@@ -0,0 +1,9 @@
+#source: maxpage1.s
+#ld: -z max-page-size=0x800000 --image-base 0x40000 -z separate-code
+#warning: image base \(0x40000\) < maximum page size \(0x800000\)
+#readelf: -l --wide
+#target: *-*-linux-gnu *-*-gnu* arm*-*-uclinuxfdpiceabi
+
+#...
+  LOAD +0x0* 0x0*800000 0x0*800000 0x[0-9a-f]+ 0x[0-9a-f]+ R E 0x800000
+#pass
diff --git a/ld/testsuite/ld-elf/textaddr9.d b/ld/testsuite/ld-elf/textaddr9.d
new file mode 100644
index 00000000000..147ee7967c2
--- /dev/null
+++ b/ld/testsuite/ld-elf/textaddr9.d
@@ -0,0 +1,9 @@
+#source: maxpage1.s
+#ld: -shared -z max-page-size=0x800000 --image-base 0x40000 -z separate-code
+#readelf: -l --wide
+#target: *-*-linux-gnu *-*-gnu* arm*-*-uclinuxfdpiceabi
+#xfail: ![check_shared_lib_support]
+
+#...
+  LOAD +0x800000 0x0*800000 0x0*800000 0x[0-9a-f]+ 0x[0-9a-f]+ R E 0x800000
+#pass
-- 
2.54.0
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