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Update FreeBSD native build for multi-target-v2.
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For the bsd-kvm target (which I do not use and is not tested), I moved
several globals into the target and then changed the global kvm
commands to fetch the current process target and use a new public
method to alter the PCB address of that target.  In theory this should
permit multiple KVM targets and the commands just affect the current
inferior.

While here I cleaned up a few places to use CORE_ADDR instead of raw
pointers.  The bsd-kvm.c code is still not really ready for
cross-debugging, but this makes it slightly less terrible.

For the fbsd-nat target, I just had to sprinkle some target pointers
in various places.  There are a couple of static methods that I
added explicit target pointers as the first argument.  Alternatively
they could become private members of the class instead and just use
this.
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@bsdjhb
bsdjhb committed Oct 18, 2019
1 parent b1a5a5e commit e58a36e
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Showing 2 changed files with 94 additions and 68 deletions.
129 changes: 77 additions & 52 deletions gdb/bsd-kvm.c
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Original file line number Diff line number Diff line change
Expand Up @@ -45,15 +45,6 @@

#include "bsd-kvm.h"

/* Kernel memory device file. */
static const char *bsd_kvm_corefile;

/* Kernel memory interface descriptor. */
static kvm_t *core_kd;

/* Address of process control block. */
static struct pcb *bsd_kvm_paddr;

/* Pointer to architecture-specific function that reconstructs the
register state from PCB and supplies it to REGCACHE. */
static int (*bsd_kvm_supply_pcb)(struct regcache *regcache, struct pcb *pcb);
Expand All @@ -75,7 +66,8 @@ Optionally specify the filename of a core dump.")
class bsd_kvm_target final : public process_stratum_target
{
public:
bsd_kvm_target () = default;
bsd_kvm_target (const char *corefile, kvm_t *kd) :
corefile (corefile), kd (kd) {}

const target_info &info () const override
{ return bsd_kvm_target_info; }
Expand All @@ -97,10 +89,19 @@ class bsd_kvm_target final : public process_stratum_target
bool has_memory () override { return true; }
bool has_stack () override { return true; }
bool has_registers () override { return true; }
};

/* Target ops for libkvm interface. */
static bsd_kvm_target bsd_kvm_ops;
void set_pcb_addr (CORE_ADDR addr) { pcb_addr = addr; }

private:
/* Kernel memory device file. */
const char *corefile;

/* Kernel memory interface descriptor. */
kvm_t *kd;

/* Address of process control block. */
CORE_ADDR pcb_addr;
};

static void
bsd_kvm_target_open (const char *arg, int from_tty)
Expand Down Expand Up @@ -131,12 +132,13 @@ bsd_kvm_target_open (const char *arg, int from_tty)
if (temp_kd == NULL)
error (("%s"), errbuf);

bsd_kvm_corefile = filename;
unpush_target (&bsd_kvm_ops);
core_kd = temp_kd;
push_target (&bsd_kvm_ops);
/* XXX: Need a way to close existing KVM target if it exists. */

bsd_kvm_target *target = new bsd_kvm_target (filename, temp_kd);

push_target (target);

add_thread_silent (bsd_kvm_ptid);
add_thread_silent (target, bsd_kvm_ptid);
inferior_ptid = bsd_kvm_ptid;

target_fetch_registers (get_current_regcache (), -1);
Expand All @@ -148,19 +150,20 @@ bsd_kvm_target_open (const char *arg, int from_tty)
void
bsd_kvm_target::close ()
{
if (core_kd)
if (kd)
{
if (kvm_close (core_kd) == -1)
warning (("%s"), kvm_geterr(core_kd));
core_kd = NULL;
inferior_ptid = null_ptid;
exit_inferior_silent (current_inferior ());

if (kvm_close (kd) == -1)
warning (("%s"), kvm_geterr(kd));
}

inferior_ptid = null_ptid;
discard_all_inferiors ();
delete this;
}

static LONGEST
bsd_kvm_xfer_memory (CORE_ADDR addr, ULONGEST len,
bsd_kvm_xfer_memory (kvm_t *core_kd, CORE_ADDR addr, ULONGEST len,
gdb_byte *readbuf, const gdb_byte *writebuf)
{
ssize_t nbytes = len;
Expand All @@ -182,7 +185,7 @@ bsd_kvm_target::xfer_partial (enum target_object object,
{
case TARGET_OBJECT_MEMORY:
{
LONGEST ret = bsd_kvm_xfer_memory (offset, len, readbuf, writebuf);
LONGEST ret = bsd_kvm_xfer_memory (kd, offset, len, readbuf, writebuf);

if (ret < 0)
return TARGET_XFER_E_IO;
Expand All @@ -203,21 +206,21 @@ bsd_kvm_target::xfer_partial (enum target_object object,
void
bsd_kvm_target::files_info ()
{
if (bsd_kvm_corefile && strcmp (bsd_kvm_corefile, _PATH_MEM) != 0)
if (corefile && strcmp (corefile, _PATH_MEM) != 0)
printf_filtered (_("\tUsing the kernel crash dump %s.\n"),
bsd_kvm_corefile);
corefile);
else
printf_filtered (_("\tUsing the currently running kernel.\n"));
}

/* Fetch process control block at address PADDR. */

static int
bsd_kvm_fetch_pcb (struct regcache *regcache, struct pcb *paddr)
bsd_kvm_fetch_pcb (kvm_t *core_kd, struct regcache *regcache, CORE_ADDR paddr)
{
struct pcb pcb;

if (kvm_read (core_kd, (unsigned long) paddr, &pcb, sizeof pcb) == -1)
if (kvm_read (core_kd, paddr, &pcb, sizeof pcb) == -1)
error (("%s"), kvm_geterr (core_kd));

gdb_assert (bsd_kvm_supply_pcb);
Expand All @@ -229,9 +232,9 @@ bsd_kvm_target::fetch_registers (struct regcache *regcache, int regnum)
{
struct nlist nl[2];

if (bsd_kvm_paddr)
if (pcb_addr != 0)
{
bsd_kvm_fetch_pcb (regcache, bsd_kvm_paddr);
bsd_kvm_fetch_pcb (kd, regcache, pcb_addr);
return;
}

Expand All @@ -240,14 +243,14 @@ bsd_kvm_target::fetch_registers (struct regcache *regcache, int regnum)
memset (nl, 0, sizeof nl);
nl[0].n_name = "_dumppcb";

if (kvm_nlist (core_kd, nl) == -1)
error (("%s"), kvm_geterr (core_kd));
if (kvm_nlist (kd, nl) == -1)
error (("%s"), kvm_geterr (kd));

if (nl[0].n_value != 0)
{
/* Found dumppcb. If it contains a valid context, return
immediately. */
if (bsd_kvm_fetch_pcb (regcache, (struct pcb *) nl[0].n_value))
if (bsd_kvm_fetch_pcb (kd, regcache, nl[0].n_value))
return;
}

Expand All @@ -258,18 +261,18 @@ bsd_kvm_target::fetch_registers (struct regcache *regcache, int regnum)
memset (nl, 0, sizeof nl);
nl[0].n_name = "_proc0paddr";

if (kvm_nlist (core_kd, nl) == -1)
error (("%s"), kvm_geterr (core_kd));
if (kvm_nlist (kd, nl) == -1)
error (("%s"), kvm_geterr (kd));

if (nl[0].n_value != 0)
{
struct pcb *paddr;
uintptr_t paddr;

/* Found proc0paddr. */
if (kvm_read (core_kd, nl[0].n_value, &paddr, sizeof paddr) == -1)
error (("%s"), kvm_geterr (core_kd));
if (kvm_read (kd, nl[0].n_value, &paddr, sizeof paddr) == -1)
error (("%s"), kvm_geterr (kd));

bsd_kvm_fetch_pcb (regcache, paddr);
bsd_kvm_fetch_pcb (kd, regcache, paddr);
return;
}

Expand All @@ -282,19 +285,19 @@ bsd_kvm_target::fetch_registers (struct regcache *regcache, int regnum)
memset (nl, 0, sizeof nl);
nl[0].n_name = "_thread0";

if (kvm_nlist (core_kd, nl) == -1)
error (("%s"), kvm_geterr (core_kd));
if (kvm_nlist (kd, nl) == -1)
error (("%s"), kvm_geterr (kd));

if (nl[0].n_value != 0)
{
struct pcb *paddr;
uintptr_t paddr;

/* Found thread0. */
nl[0].n_value += offsetof (struct thread, td_pcb);
if (kvm_read (core_kd, nl[0].n_value, &paddr, sizeof paddr) == -1)
error (("%s"), kvm_geterr (core_kd));
if (kvm_read (kd, nl[0].n_value, &paddr, sizeof paddr) == -1)
error (("%s"), kvm_geterr (kd));

bsd_kvm_fetch_pcb (regcache, paddr);
bsd_kvm_fetch_pcb (kd, regcache, paddr);
return;
}
#endif
Expand All @@ -313,6 +316,20 @@ bsd_kvm_cmd (const char *arg, int fromtty)
/* ??? Should this become an alias for "target kvm"? */
}

static bsd_kvm_target *
current_bsd_kvm_target ()
{
inferior *inferior = current_inferior ();
if (inferior == NULL)
return NULL;

struct process_stratum_target *target = inferior->process_target ();
if (target == NULL)
return NULL;

return dynamic_cast<bsd_kvm_target *> (target);
}

#ifndef HAVE_STRUCT_THREAD_TD_PCB

static void
Expand All @@ -323,7 +340,8 @@ bsd_kvm_proc_cmd (const char *arg, int fromtty)
if (arg == NULL)
error_no_arg (_("proc address"));

if (core_kd == NULL)
bsd_kvm_target *target = current_bsd_kvm_target ();
if (target == NULL)
error (_("No kernel memory image."));

addr = parse_and_eval_address (arg);
Expand All @@ -333,8 +351,14 @@ bsd_kvm_proc_cmd (const char *arg, int fromtty)
addr += offsetof (struct proc, p_addr);
#endif

if (kvm_read (core_kd, addr, &bsd_kvm_paddr, sizeof bsd_kvm_paddr) == -1)
error (("%s"), kvm_geterr (core_kd));
gdbarch *gdbarch = current_gdbarch ();
gdb_byte ptr[gdbarch_ptr_bit (gdbarch) / TARGET_CHAR_BIT];
if (target_read_memory (addr, ptr, sizeof ptr) != 0)
error (_("Failed to read PCB address"));
addr = gdbarch_pointer_to_address (gdbarch,
builtin_type (gdbarch)->builtin_data_ptr,
buf);
target->set_pcb_addr (addr);

target_fetch_registers (get_current_regcache (), -1);

Expand All @@ -351,10 +375,11 @@ bsd_kvm_pcb_cmd (const char *arg, int fromtty)
/* i18n: PCB == "Process Control Block". */
error_no_arg (_("pcb address"));

if (core_kd == NULL)
bsd_kvm_target *target = current_bsd_kvm_target ();
if (target == NULL)
error (_("No kernel memory image."));

bsd_kvm_paddr = (struct pcb *)(u_long) parse_and_eval_address (arg);
target->set_pcb_addr (parse_and_eval_address (arg));

target_fetch_registers (get_current_regcache (), -1);

Expand Down

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