From 0eeb2d97112c0deaf8c7741564316068f923b40d Mon Sep 17 00:00:00 2001
From: kettenis <kettenis@openbsd.org>
Date: Thu, 7 Dec 2023 21:57:34 +0000
Subject: [PATCH] Collect .openbsd.syscalls sections into a new
 PT_OPENBSD_SYSCALLS segment. This will be used soon to pin system calls to
 designated call sites.

ok deraadt@
---
 gnu/usr.bin/binutils-2.17/bfd/elf.c           | 37 +++++++++++++++++++
 gnu/usr.bin/binutils-2.17/binutils/readelf.c  |  2 +
 .../binutils-2.17/include/elf/common.h        |  1 +
 gnu/usr.bin/binutils-2.17/ld/ldgram.y         |  2 +
 4 files changed, 42 insertions(+)

diff --git a/gnu/usr.bin/binutils-2.17/bfd/elf.c b/gnu/usr.bin/binutils-2.17/bfd/elf.c
index 01d3b3445b3..b23e3a66e97 100644
--- a/gnu/usr.bin/binutils-2.17/bfd/elf.c
+++ b/gnu/usr.bin/binutils-2.17/bfd/elf.c
@@ -1105,6 +1105,7 @@ get_segment_type (unsigned int p_type)
     case PT_OPENBSD_NOBTCFI: pt = "OPENBSD_NOBTCFI"; break;
     case PT_OPENBSD_BOOTDATA: pt = "OPENBSD_BOOTDATA"; break;
     case PT_OPENBSD_MUTABLE: pt = "OPENBSD_MUTABLE"; break;
+    case PT_OPENBSD_SYSCALLS: pt = "OPENBSD_SYSCALLS"; break;
     default: pt = NULL; break;
     }
   return pt;
@@ -2654,6 +2655,11 @@ bfd_section_from_phdr (bfd *abfd, Elf_Internal_Phdr *hdr, int index)
     case PT_OPENBSD_MUTABLE:
       return _bfd_elf_make_section_from_phdr (abfd, hdr, index,
 					      "openbsd_mutable");
+
+    case PT_OPENBSD_SYSCALLS:
+      return _bfd_elf_make_section_from_phdr (abfd, hdr, index,
+					      "openbsd_syscalls");
+
     default:
       /* Check for any processor-specific program segment types.  */
       bed = get_elf_backend_data (abfd);
@@ -3659,6 +3665,7 @@ map_sections_to_segments (bfd *abfd)
   int tls_count = 0;
   asection *first_tls = NULL;
   asection *dynsec, *eh_frame_hdr, *randomdata, *mutabledata;
+  asection *syscalls;
   bfd_size_type amt;
 
   if (elf_tdata (abfd)->segment_map != NULL)
@@ -4044,6 +4051,24 @@ map_sections_to_segments (bfd *abfd)
       pm = &m->next;
     }
 
+  /* If there is a .openbsd.syscalls section, throw in a PT_OPENBSD_SYSCALLS
+     segment.  */
+  syscalls = bfd_get_section_by_name (abfd, ".openbsd.syscalls");
+  if (syscalls != NULL && (syscalls->flags & SEC_LOAD) == 0)
+    {
+      amt = sizeof (struct elf_segment_map);
+      m = bfd_zalloc (abfd, amt);
+      if (m == NULL)
+	goto error_return;
+      m->next = NULL;
+      m->p_type = PT_OPENBSD_SYSCALLS;
+      m->count = 1;
+      m->sections[0] = syscalls->output_section;
+
+      *pm = m;
+      pm = &m->next;
+    }
+
   if (elf_tdata (abfd)->relro)
     {
       amt = sizeof (struct elf_segment_map);
@@ -4594,6 +4619,12 @@ assign_file_positions_for_segments (bfd *abfd, struct bfd_link_info *link_info)
 	      else if (p->p_type == PT_NOTE
 		  && (flags & SEC_HAS_CONTENTS) != 0)
 		p->p_filesz += sec->size;
+	      else if (p->p_type == PT_OPENBSD_SYSCALLS)
+	        {
+		  sec->filepos = off;
+		  off += sec->size;
+		  p->p_filesz += sec->size;
+		}
 
 	      /* .tbss is special.  It doesn't contribute to p_memsz of
 		 normal segments.  */
@@ -4796,6 +4827,12 @@ get_program_header_size (bfd *abfd)
       ++segs;
     }
 
+  if (bfd_get_section_by_name (abfd, ".openbsd.syscalls") != NULL)
+    {
+      /* We need a PT_OPENBSD_SYSCALLS segment.  */
+      ++segs;
+    }
+
   if (elf_tdata (abfd)->eh_frame_hdr)
     {
       /* We need a PT_GNU_EH_FRAME segment.  */
diff --git a/gnu/usr.bin/binutils-2.17/binutils/readelf.c b/gnu/usr.bin/binutils-2.17/binutils/readelf.c
index 262a0b3967c..eacb32ff28c 100644
--- a/gnu/usr.bin/binutils-2.17/binutils/readelf.c
+++ b/gnu/usr.bin/binutils-2.17/binutils/readelf.c
@@ -2713,6 +2713,8 @@ get_segment_type (unsigned long p_type)
 			return "OPENBSD_MUTABLE";
     case PT_OPENBSD_NOBTCFI:
 			return "OPENBSD_NOBTCFI";
+    case PT_OPENBSD_SYSCALLS:
+			return "OPENBSD_SYSCALLS";
 
     default:
       if ((p_type >= PT_LOPROC) && (p_type <= PT_HIPROC))
diff --git a/gnu/usr.bin/binutils-2.17/include/elf/common.h b/gnu/usr.bin/binutils-2.17/include/elf/common.h
index a494372473a..1fe2ce9ae17 100644
--- a/gnu/usr.bin/binutils-2.17/include/elf/common.h
+++ b/gnu/usr.bin/binutils-2.17/include/elf/common.h
@@ -315,6 +315,7 @@
 #define PT_OPENBSD_NOBTCFI	0x65a3dbe8 /* no branch target CFI */
 #define PT_OPENBSD_BOOTDATA	0x65a41be6 /* Section for boot arguments */
 #define PT_OPENBSD_MUTABLE	0x65a3dbe5 /* Like bss, but not immutable */
+#define PT_OPENBSD_SYSCALLS	0x65a3dbe9 /* System call sites */
 
 /* Program segment permissions, in program header p_flags field.  */
 
diff --git a/gnu/usr.bin/binutils-2.17/ld/ldgram.y b/gnu/usr.bin/binutils-2.17/ld/ldgram.y
index 5ed2a5fc752..60097ab1323 100644
--- a/gnu/usr.bin/binutils-2.17/ld/ldgram.y
+++ b/gnu/usr.bin/binutils-2.17/ld/ldgram.y
@@ -1101,6 +1101,8 @@ phdr_type:
 			    $$ = exp_intop (0x65a41be6);
 			  else if (strcmp (s, "PT_OPENBSD_MUTABLE") == 0)
 			    $$ = exp_intop (0x65a3dbe5);
+			  else if (strcmp (s, "PT_OPENBSD_SYSCALLS") == 0)
+			    $$ = exp_intop (0x65a3dbe9);
 			  else
 			    {
 			      einfo (_("\
-- 
2.20.1