From e91b9bcc275f9a7b5297bed7fd0403699123304d Mon Sep 17 00:00:00 2001
From: ad <ad@NetBSD.org>
Date: Fri, 5 Dec 2008 21:38:10 +0000
Subject: [PATCH] Make the fake ELF object work with gdb.

- Output a .bss section and make all the symbols relative to it, instead
  of making them absolute.
- Output a single load section, no need for two.

'gdb /dev/ksyms' still doesn't work because ksyms doesn't do mmap yet.
---
 sys/kern/kern_ksyms.c | 29 ++++++++++++++++++-----------
 sys/sys/ksyms.h       |  7 ++++---
 2 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/sys/kern/kern_ksyms.c b/sys/kern/kern_ksyms.c
index 38e5fbcd7edd..147c7226be5a 100644
--- a/sys/kern/kern_ksyms.c
+++ b/sys/kern/kern_ksyms.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: kern_ksyms.c,v 1.47 2008/11/30 18:21:36 martin Exp $	*/
+/*	$NetBSD: kern_ksyms.c,v 1.48 2008/12/05 21:38:10 ad Exp $	*/
 
 /*-
  * Copyright (c) 2008 The NetBSD Foundation, Inc.
@@ -71,7 +71,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_ksyms.c,v 1.47 2008/11/30 18:21:36 martin Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_ksyms.c,v 1.48 2008/12/05 21:38:10 ad Exp $");
 
 #ifdef _KERNEL
 #include "opt_ddb.h"
@@ -90,6 +90,8 @@ __KERNEL_RCSID(0, "$NetBSD: kern_ksyms.c,v 1.47 2008/11/30 18:21:36 martin Exp $
 #include <sys/atomic.h>
 #include <sys/ksyms.h>
 
+#include <uvm/uvm_extern.h>
+
 #ifdef DDB
 #include <ddb/db_output.h>
 #endif
@@ -302,7 +304,7 @@ addsymtab(const char *name, void *symstart, size_t symsize,
 
 		/* Save symbol. Set it as an absolute offset */
 		nsym[n] = sym[i];
-		nsym[n].st_shndx = SHN_ABS;
+		nsym[n].st_shndx = SHBSS;
 		j = strlen(nsym[n].st_name + str) + 1;
 		if (j > ksyms_maxlen)
 			ksyms_maxlen = j;
@@ -680,17 +682,12 @@ ksyms_hdr_init(void *hdraddr)
 	ksyms_hdr.kh_ehdr.e_shoff = offsetof(struct ksyms_hdr, kh_shdr[0]);
 	ksyms_hdr.kh_ehdr.e_shentsize = sizeof(Elf_Shdr);
 	ksyms_hdr.kh_ehdr.e_shnum = NSECHDR;
-	ksyms_hdr.kh_ehdr.e_shstrndx = NSECHDR - 1; /* Last section */
+	ksyms_hdr.kh_ehdr.e_shstrndx = SHSTRTAB;
 
-	/* Text */
+	/* Text/data - fake */
 	ksyms_hdr.kh_phdr[0].p_type = PT_LOAD;
 	ksyms_hdr.kh_phdr[0].p_memsz = (unsigned long)-1L;
-	ksyms_hdr.kh_phdr[0].p_flags = PF_R | PF_X;
-
-	/* Data */
-	ksyms_hdr.kh_phdr[1].p_type = PT_LOAD;
-	ksyms_hdr.kh_phdr[1].p_memsz = (unsigned long)-1L;
-	ksyms_hdr.kh_phdr[1].p_flags = PF_R | PF_W | PF_X;
+	ksyms_hdr.kh_phdr[0].p_flags = PF_R | PF_X | PF_W;
 
 	/* First section is null */
 
@@ -718,6 +715,14 @@ ksyms_hdr_init(void *hdraddr)
 	ksyms_hdr.kh_shdr[SHSTRTAB].sh_size = SHSTRSIZ;
 	ksyms_hdr.kh_shdr[SHSTRTAB].sh_addralign = sizeof(char);
 
+	/* Fifth section, ".bss". All symbols reside here. */
+	ksyms_hdr.kh_shdr[SHBSS].sh_name = 27; /* This section name offset */
+	ksyms_hdr.kh_shdr[SHBSS].sh_type = SHT_NOBITS;
+	ksyms_hdr.kh_shdr[SHBSS].sh_offset = 0;
+	ksyms_hdr.kh_shdr[SHBSS].sh_size = (unsigned long)-1L;
+	ksyms_hdr.kh_shdr[SHBSS].sh_addralign = PAGE_SIZE;
+	ksyms_hdr.kh_shdr[SHBSS].sh_flags = SHF_ALLOC | SHF_EXECINSTR;
+
 	/* Set section names */
 	strlcpy(&ksyms_hdr.kh_strtab[1], ".symtab",
 	    sizeof(ksyms_hdr.kh_strtab) - 1);
@@ -725,6 +730,8 @@ ksyms_hdr_init(void *hdraddr)
 	    sizeof(ksyms_hdr.kh_strtab) - 9);
 	strlcpy(&ksyms_hdr.kh_strtab[17], ".shstrtab",
 	    sizeof(ksyms_hdr.kh_strtab) - 17);
+	strlcpy(&ksyms_hdr.kh_strtab[27], ".bss",
+	    sizeof(ksyms_hdr.kh_strtab) - 27);
 }
 
 static int
diff --git a/sys/sys/ksyms.h b/sys/sys/ksyms.h
index c240859344ed..d16f4832d205 100644
--- a/sys/sys/ksyms.h
+++ b/sys/sys/ksyms.h
@@ -1,4 +1,4 @@
-/*	$NetBSD: ksyms.h,v 1.21 2008/11/30 18:21:36 martin Exp $	*/
+/*	$NetBSD: ksyms.h,v 1.22 2008/12/05 21:38:10 ad Exp $	*/
 
 /*
  * Copyright (c) 2001, 2003 Anders Magnusson (ragge@ludd.luth.se).
@@ -56,9 +56,10 @@ struct ksyms_symtab {
 #define	SYMTAB		1
 #define	STRTAB		2
 #define	SHSTRTAB	3
-#define NSECHDR		4
+#define	SHBSS		4
+#define NSECHDR		5
 
-#define	NPRGHDR		2
+#define	NPRGHDR		1
 #define	SHSTRSIZ	32
 
 struct ksyms_hdr {