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freebsd-nq/gnu/usr.bin/gdb/kgdb/trgt_i386.c
John Baldwin 3461a0f244 Rework how kgdb manages kernel and vmcore files to be a bit more gdb-ish 
so that kgdb can be used more like a normal gdb:
- Load the kernel via the standard 'exec' target and allow it to be changed
  via the 'file' command.
  - Instead of explicitly loading the kernel file as the mail symbol file
    during startup, just pass it to gdb_main() as the executable file.
  - Change the kld support (via shared libraries) to cache the address of
    the linker_files and linker_kernel_file variables in addition to the
    offsets of various members in 'struct linker_file'.
  - When a new symbol file is loaded, recompute the addresses and offsets
    used by the kld support code.
  - When a new symbol file is loaded, recalculate the ofs_fix variable to
    account for the different ways a trapframe can be passed to trap
    frame handlers in i386.  This is done by adding a MD
    kgdb_trgt_new_objfile() hook that is empty on all but i386.
  - Don't use the directory name of the kernel specified on the command
    line to find kernel modules in the kld support code.  Instead,
    extract the filename of the current executable via exec_bfd.  Now
    the 'kernel' variable is private to main.c again.
  - Make the 'add-kld' command explicitly fail if no executable is loaded.
- Make the support for vmcores a real core-dump target that opens the
  kernel and vmcore on open and closes the kvm connection when closed, etc.
  - The 'core' command can now be used to select a vmcore to use, either
    a crash dump file or /dev/mem for live debugging.
  - The 'detach' command can be used to detach from a vmcore w/o attaching
    to a new one.
  - kgdb no longer explicitly opens a core dump during startup and no longer
    has to use an atexit() hook to close the kvm connection on shutdown.
  - Symbols for kld's are automatically loaded anytime a core is opened.
    Also, the unread portion of dmesg is dumped just as it was done on kgdb
    startup previously.
- Don't require either a remote target or core dump if a kernel is specified.
  You can now just run 'kgdb kernel' similar to running gdb on an executable
  and later connect to a remote target or core dump.
- Use a more relaxed way to verify remote targets specified via -r.
  Instead of explicitly allowing a few non-file target specifications,
  just assume that if stat() on the arg and on "/dev/" + arg both fail
  that is some non-file target and pass it to gdb.
- Don't use a custom interpreter.  The existing kgdb_init() hook and the
  target_new_objfile() hook give us sufficient hooks during startup to
  setup kgdb-specific behavior now.
- Always add the 'proc', 'tid', and 'add-kld' commands on startup and not
  just if we have a core dump.  Currently the 'proc' and 'tid' commands do
  not work for remote targets (I will fix at least 'tid' in the next round
  of changes though).  However, the 'add-kld' command works fine for
  loading symbols for a kernel module on a remote target.
- Always setup the 'kld' shared library target operations instead of just
  if we have a core dump.  Although symbols for kernel modules are not
  automatically loaded when connecting to a remote target, you can do
  'info sharedlibrary' after connecting to the remote target and kgdb will
  find all the modules.  You can then use the 'sharedlibrary' command to
  load symbols from the module files.
- Change kthr_init() to free the existing list of kthr objects before
  generating a new one.  This allows it to be invoked multiple times
  w/o leaking memory.

MFC after:	1 week
2008-04-29 20:32:45 +00:00

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/*
* Copyright (c) 2004 Marcel Moolenaar
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/proc.h>
#include <machine/pcb.h>
#include <machine/frame.h>
#include <machine/segments.h>
#include <machine/tss.h>
#include <err.h>
#include <kvm.h>
#include <string.h>
#include <defs.h>
#include <target.h>
#include <gdbthread.h>
#include <inferior.h>
#include <objfiles.h>
#include <regcache.h>
#include <frame-unwind.h>
#include <i386-tdep.h>
#include "kgdb.h"
static int ofs_fix;
void
kgdb_trgt_fetch_registers(int regno __unused)
{
struct kthr *kt;
struct pcb pcb;
kt = kgdb_thr_lookup_tid(ptid_get_tid(inferior_ptid));
if (kt == NULL)
return;
if (kvm_read(kvm, kt->pcb, &pcb, sizeof(pcb)) != sizeof(pcb)) {
warnx("kvm_read: %s", kvm_geterr(kvm));
memset(&pcb, 0, sizeof(pcb));
}
supply_register(I386_EBX_REGNUM, (char *)&pcb.pcb_ebx);
supply_register(I386_ESP_REGNUM, (char *)&pcb.pcb_esp);
supply_register(I386_EBP_REGNUM, (char *)&pcb.pcb_ebp);
supply_register(I386_ESI_REGNUM, (char *)&pcb.pcb_esi);
supply_register(I386_EDI_REGNUM, (char *)&pcb.pcb_edi);
supply_register(I386_EIP_REGNUM, (char *)&pcb.pcb_eip);
}
void
kgdb_trgt_store_registers(int regno __unused)
{
fprintf_unfiltered(gdb_stderr, "XXX: %s\n", __func__);
}
void
kgdb_trgt_new_objfile(struct objfile *objfile)
{
/*
* In revision 1.117 of i386/i386/exception.S trap handlers
* were changed to pass trapframes by reference rather than
* by value. Detect this by seeing if the first instruction
* at the 'calltrap' label is a "push %esp" which has the
* opcode 0x54.
*/
if (kgdb_parse("((char *)calltrap)[0]") == 0x54)
ofs_fix = 4;
else
ofs_fix = 0;
}
struct kgdb_tss_cache {
CORE_ADDR pc;
CORE_ADDR sp;
CORE_ADDR tss;
};
static int kgdb_trgt_tss_offset[15] = {
offsetof(struct i386tss, tss_eax),
offsetof(struct i386tss, tss_ecx),
offsetof(struct i386tss, tss_edx),
offsetof(struct i386tss, tss_ebx),
offsetof(struct i386tss, tss_esp),
offsetof(struct i386tss, tss_ebp),
offsetof(struct i386tss, tss_esi),
offsetof(struct i386tss, tss_edi),
offsetof(struct i386tss, tss_eip),
offsetof(struct i386tss, tss_eflags),
offsetof(struct i386tss, tss_cs),
offsetof(struct i386tss, tss_ss),
offsetof(struct i386tss, tss_ds),
offsetof(struct i386tss, tss_es),
offsetof(struct i386tss, tss_fs)
};
/*
* If the current thread is executing on a CPU, fetch the common_tss
* for that CPU.
*
* This is painful because 'struct pcpu' is variant sized, so we can't
* use it. Instead, we lookup the GDT selector for this CPU and
* extract the base of the TSS from there.
*/
static CORE_ADDR
kgdb_trgt_fetch_tss(void)
{
struct kthr *kt;
struct segment_descriptor sd;
uintptr_t addr, cpu0prvpage, tss;
kt = kgdb_thr_lookup_tid(ptid_get_tid(inferior_ptid));
if (kt == NULL || kt->cpu == NOCPU)
return (0);
addr = kgdb_lookup("_gdt");
if (addr == 0)
return (0);
addr += (kt->cpu * NGDT + GPROC0_SEL) * sizeof(sd);
if (kvm_read(kvm, addr, &sd, sizeof(sd)) != sizeof(sd)) {
warnx("kvm_read: %s", kvm_geterr(kvm));
return (0);
}
if (sd.sd_type != SDT_SYS386BSY) {
warnx("descriptor is not a busy TSS");
return (0);
}
tss = sd.sd_hibase << 24 | sd.sd_lobase;
/*
* In SMP kernels, the TSS is stored as part of the per-CPU
* data. On older kernels, the CPU0's private page
* is stored at an address that isn't mapped in minidumps.
* However, the data is mapped at the alternate cpu0prvpage
* address. Thus, if the TSS is at the invalid address,
* change it to be relative to cpu0prvpage instead.
*/
if (trunc_page(tss) == 0xffc00000) {
addr = kgdb_lookup("_cpu0prvpage");
if (addr == 0) {
warnx("kvm_nlist(_cpu0prvpage): %s", kvm_geterr(kvm));
return (0);
}
if (kvm_read(kvm, addr, &cpu0prvpage, sizeof(cpu0prvpage)) !=
sizeof(cpu0prvpage)) {
warnx("kvm_read: %s", kvm_geterr(kvm));
return (0);
}
tss = cpu0prvpage + (tss & PAGE_MASK);
}
return ((CORE_ADDR)tss);
}
static struct kgdb_tss_cache *
kgdb_trgt_tss_cache(struct frame_info *next_frame, void **this_cache)
{
char buf[MAX_REGISTER_SIZE];
struct kgdb_tss_cache *cache;
cache = *this_cache;
if (cache == NULL) {
cache = FRAME_OBSTACK_ZALLOC(struct kgdb_tss_cache);
*this_cache = cache;
cache->pc = frame_func_unwind(next_frame);
frame_unwind_register(next_frame, SP_REGNUM, buf);
cache->sp = extract_unsigned_integer(buf,
register_size(current_gdbarch, SP_REGNUM));
cache->tss = kgdb_trgt_fetch_tss();
}
return (cache);
}
static void
kgdb_trgt_dblfault_this_id(struct frame_info *next_frame, void **this_cache,
struct frame_id *this_id)
{
struct kgdb_tss_cache *cache;
cache = kgdb_trgt_tss_cache(next_frame, this_cache);
*this_id = frame_id_build(cache->sp, cache->pc);
}
static void
kgdb_trgt_dblfault_prev_register(struct frame_info *next_frame,
void **this_cache, int regnum, int *optimizedp, enum lval_type *lvalp,
CORE_ADDR *addrp, int *realnump, void *valuep)
{
char dummy_valuep[MAX_REGISTER_SIZE];
struct kgdb_tss_cache *cache;
int ofs, regsz;
regsz = register_size(current_gdbarch, regnum);
if (valuep == NULL)
valuep = dummy_valuep;
memset(valuep, 0, regsz);
*optimizedp = 0;
*addrp = 0;
*lvalp = not_lval;
*realnump = -1;
ofs = (regnum >= I386_EAX_REGNUM && regnum <= I386_FS_REGNUM)
? kgdb_trgt_tss_offset[regnum] : -1;
if (ofs == -1)
return;
cache = kgdb_trgt_tss_cache(next_frame, this_cache);
if (cache->tss == 0)
return;
*addrp = cache->tss + ofs;
*lvalp = lval_memory;
target_read_memory(*addrp, valuep, regsz);
}
static const struct frame_unwind kgdb_trgt_dblfault_unwind = {
UNKNOWN_FRAME,
&kgdb_trgt_dblfault_this_id,
&kgdb_trgt_dblfault_prev_register
};
struct kgdb_frame_cache {
int intrframe;
CORE_ADDR pc;
CORE_ADDR sp;
};
static int kgdb_trgt_frame_offset[15] = {
offsetof(struct trapframe, tf_eax),
offsetof(struct trapframe, tf_ecx),
offsetof(struct trapframe, tf_edx),
offsetof(struct trapframe, tf_ebx),
offsetof(struct trapframe, tf_esp),
offsetof(struct trapframe, tf_ebp),
offsetof(struct trapframe, tf_esi),
offsetof(struct trapframe, tf_edi),
offsetof(struct trapframe, tf_eip),
offsetof(struct trapframe, tf_eflags),
offsetof(struct trapframe, tf_cs),
offsetof(struct trapframe, tf_ss),
offsetof(struct trapframe, tf_ds),
offsetof(struct trapframe, tf_es),
offsetof(struct trapframe, tf_fs)
};
static struct kgdb_frame_cache *
kgdb_trgt_frame_cache(struct frame_info *next_frame, void **this_cache)
{
char buf[MAX_REGISTER_SIZE];
struct kgdb_frame_cache *cache;
char *pname;
cache = *this_cache;
if (cache == NULL) {
cache = FRAME_OBSTACK_ZALLOC(struct kgdb_frame_cache);
*this_cache = cache;
cache->pc = frame_func_unwind(next_frame);
find_pc_partial_function(cache->pc, &pname, NULL, NULL);
cache->intrframe = (pname[0] == 'X') ? 1 : 0;
frame_unwind_register(next_frame, SP_REGNUM, buf);
cache->sp = extract_unsigned_integer(buf,
register_size(current_gdbarch, SP_REGNUM));
}
return (cache);
}
static void
kgdb_trgt_trapframe_this_id(struct frame_info *next_frame, void **this_cache,
struct frame_id *this_id)
{
struct kgdb_frame_cache *cache;
cache = kgdb_trgt_frame_cache(next_frame, this_cache);
*this_id = frame_id_build(cache->sp, cache->pc);
}
static void
kgdb_trgt_trapframe_prev_register(struct frame_info *next_frame,
void **this_cache, int regnum, int *optimizedp, enum lval_type *lvalp,
CORE_ADDR *addrp, int *realnump, void *valuep)
{
char dummy_valuep[MAX_REGISTER_SIZE];
struct kgdb_frame_cache *cache;
int ofs, regsz;
regsz = register_size(current_gdbarch, regnum);
if (valuep == NULL)
valuep = dummy_valuep;
memset(valuep, 0, regsz);
*optimizedp = 0;
*addrp = 0;
*lvalp = not_lval;
*realnump = -1;
ofs = (regnum >= I386_EAX_REGNUM && regnum <= I386_FS_REGNUM)
? kgdb_trgt_frame_offset[regnum] + ofs_fix : -1;
if (ofs == -1)
return;
cache = kgdb_trgt_frame_cache(next_frame, this_cache);
*addrp = cache->sp + ofs + (cache->intrframe ? 4 : 0);
*lvalp = lval_memory;
target_read_memory(*addrp, valuep, regsz);
}
static const struct frame_unwind kgdb_trgt_trapframe_unwind = {
UNKNOWN_FRAME,
&kgdb_trgt_trapframe_this_id,
&kgdb_trgt_trapframe_prev_register
};
const struct frame_unwind *
kgdb_trgt_trapframe_sniffer(struct frame_info *next_frame)
{
char *pname;
CORE_ADDR pc;
pc = frame_pc_unwind(next_frame);
pname = NULL;
find_pc_partial_function(pc, &pname, NULL, NULL);
if (pname == NULL)
return (NULL);
if (strcmp(pname, "dblfault_handler") == 0)
return (&kgdb_trgt_dblfault_unwind);
if (strcmp(pname, "calltrap") == 0 ||
(pname[0] == 'X' && pname[1] != '_'))
return (&kgdb_trgt_trapframe_unwind);
/* printf("%s: %llx =%s\n", __func__, pc, pname); */
return (NULL);
}
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