Re: toolchain/52427 (VAX text relocations)

[Rin Okuyama <rokuyama.rk%gmail.com@localhost>]

-------- Forwarded Message --------
Subject: [PATCH] 1/2: toolchain/52427: VAX text relocations
Date: Mon, 31 Jul 2023 14:29:13 +1000
From: Kalvis Duckmanton <kalvisd%gmail.com@localhost>
To: tech-toolchain%netbsd.org@localhost

Hi all,

I'd like to submit the following change to the GNU assembler in NetBSD
10.99.6 for consideration.  This alters the behaviour of
tc-vax.c:md_create_long_jump() to emit a jump to a offset from the PC
instead of a jump to an absolute address.

md_create_long_jump() is used, as far as I can tell, as part of the GNU
assembler's handling of displacements to branch targets where the
displacement won't fit in a 16 bit word.

Using an absolute address works but in a shared library ld.elf_so will
complain about relocations in the text segment.

I think that this should address PR toolchain/52427
(https://mail-index.netbsd.org/netbsd-bugs/2017/07/25/msg052924.html)

Tested on my machine by compiling Perl for VAX from source and using it.

many thanks

kalvis

---
 external/gpl3/binutils/dist/gas/config/tc-vax.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/external/gpl3/binutils/dist/gas/config/tc-vax.c
b/external/gpl3/binutils/dist/gas/config/tc-vax.c
index 88548bf72096..30a12c705fed 100644
--- a/external/gpl3/binutils/dist/gas/config/tc-vax.c
+++ b/external/gpl3/binutils/dist/gas/config/tc-vax.c
@@ -2330,18 +2330,19 @@ md_create_short_jump (char *ptr,

 void
 md_create_long_jump (char *ptr,
-                    addressT from_addr ATTRIBUTE_UNUSED,
-                    addressT to_addr,
-                    fragS *frag,
-                    symbolS *to_symbol)
+                     addressT from_addr,
+                     addressT to_addr,
+                     fragS *frag ATTRIBUTE_UNUSED,
+                     symbolS *to_symbol ATTRIBUTE_UNUSED)
 {
   valueT offset;

-  offset = to_addr - S_GET_VALUE (to_symbol);
-  *ptr++ = VAX_JMP;            /* Arbitrary jump.  */
-  *ptr++ = VAX_ABSOLUTE_MODE;
+  /* account for 1 byte instruction, 1 byte of address specifier and
+     4 bytes of offset from PC */
+  offset = to_addr - (from_addr + 1 + 1 + 4);
+  *ptr++ = VAX_JMP;             /* long jump */
+  *ptr++ = VAX_PC_RELATIVE_MODE;
   md_number_to_chars (ptr, offset, 4);
-  fix_new (frag, ptr - frag->fr_literal, 4, to_symbol, (long) 0, 0,
NO_RELOC);
 }
 ^L
 #ifdef OBJ_VMS
--
2.20.1