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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.
This commit is contained in:
ad 2008-12-05 21:38:10 +00:00
parent 7f4672798d
commit e91b9bcc27
2 changed files with 22 additions and 14 deletions
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29
sys/kern/kern_ksyms.c
View File

@ -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. * Copyright (c) 2008 The NetBSD Foundation, Inc.
@ -71,7 +71,7 @@
*/ */
#include <sys/cdefs.h> #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 $");
#ifdef _KERNEL #ifdef _KERNEL
#include "opt_ddb.h" #include "opt_ddb.h"
@ -90,6 +90,8 @@ __KERNEL_RCSID(0, "$NetBSD: kern_ksyms.c,v 1.47 2008/11/30 18:21:36 martin Exp $
#include <sys/atomic.h> #include <sys/atomic.h>
#include <sys/ksyms.h> #include <sys/ksyms.h>
#include <uvm/uvm_extern.h>
#ifdef DDB #ifdef DDB
#include <ddb/db_output.h> #include <ddb/db_output.h>
#endif #endif
@ -302,7 +304,7 @@ addsymtab(const char *name, void *symstart, size_t symsize,
/* Save symbol. Set it as an absolute offset */ /* Save symbol. Set it as an absolute offset */
nsym[n] = sym[i]; nsym[n] = sym[i];
nsym[n].st_shndx = SHN_ABS; nsym[n].st_shndx = SHBSS;
j = strlen(nsym[n].st_name + str) + 1; j = strlen(nsym[n].st_name + str) + 1;
if (j > ksyms_maxlen) if (j > ksyms_maxlen)
ksyms_maxlen = j; 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_shoff = offsetof(struct ksyms_hdr, kh_shdr[0]);
ksyms_hdr.kh_ehdr.e_shentsize = sizeof(Elf_Shdr); ksyms_hdr.kh_ehdr.e_shentsize = sizeof(Elf_Shdr);
ksyms_hdr.kh_ehdr.e_shnum = NSECHDR; 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_type = PT_LOAD;
ksyms_hdr.kh_phdr[0].p_memsz = (unsigned long)-1L; ksyms_hdr.kh_phdr[0].p_memsz = (unsigned long)-1L;
ksyms_hdr.kh_phdr[0].p_flags = PF_R | PF_X; ksyms_hdr.kh_phdr[0].p_flags = PF_R | PF_X | PF_W;
/* 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;
/* First section is null */ /* 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_size = SHSTRSIZ;
ksyms_hdr.kh_shdr[SHSTRTAB].sh_addralign = sizeof(char); 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 */ /* Set section names */
strlcpy(&ksyms_hdr.kh_strtab[1], ".symtab", strlcpy(&ksyms_hdr.kh_strtab[1], ".symtab",
sizeof(ksyms_hdr.kh_strtab) - 1); sizeof(ksyms_hdr.kh_strtab) - 1);
@ -725,6 +730,8 @@ ksyms_hdr_init(void *hdraddr)
sizeof(ksyms_hdr.kh_strtab) - 9); sizeof(ksyms_hdr.kh_strtab) - 9);
strlcpy(&ksyms_hdr.kh_strtab[17], ".shstrtab", strlcpy(&ksyms_hdr.kh_strtab[17], ".shstrtab",
sizeof(ksyms_hdr.kh_strtab) - 17); sizeof(ksyms_hdr.kh_strtab) - 17);
strlcpy(&ksyms_hdr.kh_strtab[27], ".bss",
sizeof(ksyms_hdr.kh_strtab) - 27);
} }
static int static int

7
sys/sys/ksyms.h
View File

@ -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). * Copyright (c) 2001, 2003 Anders Magnusson (ragge@ludd.luth.se).
@ -56,9 +56,10 @@ struct ksyms_symtab {
#define SYMTAB 1 #define SYMTAB 1
#define STRTAB 2 #define STRTAB 2
#define SHSTRTAB 3 #define SHSTRTAB 3
#define NSECHDR 4 #define SHBSS 4
#define NSECHDR 5
#define NPRGHDR 2 #define NPRGHDR 1
#define SHSTRSIZ 32 #define SHSTRSIZ 32
struct ksyms_hdr { struct ksyms_hdr {