[v5] Implement "info proc mappings" for NetBSD

Message ID 20200412000907.2137-1-n54@gmx.com
State New
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  • [v5] Implement "info proc mappings" for NetBSD
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Commit Message

Kamil Rytarowski April 12, 2020, 12:09 a.m.
Define nbsd_nat_target::find_memory_regions and
nbsd_nat_target::info_proc. info_proc handles as of now only
the "mappings" command.

Define a local static function kinfo_get_vmmap() that reads
the process memory layout of a specified process.
kinfo_get_vmmap() wraps the sysctl(3) call.

nbsd-tdep.c defines now utility functions for printing the
process memory layout:
 * nbsd_info_proc_mappings_header()
 * nbsd_vm_map_entry_flags()
 * nbsd_info_proc_mappings_entry()

gdb/ChangeLog:

	* nbsd-nat.c; Include "nbsd-tdep.h" and "gdbarch.h".
	* nbsd-nat.c (nbsd_nat_target::find_memory_regions)
	(nbsd_nat_target::info_proc): New functions.
	* nbsd-nat.c (kinfo_get_vmmap): New function.
	* nbsd-nat.c (nbsd_nat_target::info_proc) Use
	nbsd_info_proc_mappings_header and nbsd_info_proc_mappings_entry.
	* nbsd-tdep.c (nbsd_info_proc_mappings_header)
	(nbsd_info_proc_mappings_entry, nbsd_vm_map_entry_flags): New
	functions.
	* nbsd-tdep.c (KINFO_VME_PROT_READ, KINFO_VME_PROT_WRITE)
	(KINFO_VME_PROT_EXEC, KINFO_VME_FLAG_COW)
	(KINFO_VME_FLAG_NEEDS_COPY, KINFO_VME_FLAG_NOCOREDUMP)
	(KINFO_VME_FLAG_PAGEABLE, KINFO_VME_FLAG_GROWS_UP)
	(KINFO_VME_FLAG_GROWS_DOWN): New.
---
 gdb/ChangeLog   |  17 ++++++
 gdb/nbsd-nat.c  | 149 ++++++++++++++++++++++++++++++++++++++++++++++++
 gdb/nbsd-nat.h  |   3 +
 gdb/nbsd-tdep.c |  89 +++++++++++++++++++++++++++++
 gdb/nbsd-tdep.h |  18 ++++++
 5 files changed, 276 insertions(+)

--
2.25.0

Comments

Simon Marchi April 12, 2020, 12:56 a.m. | #1
On 2020-04-11 8:09 p.m., Kamil Rytarowski wrote:
> +  /* Prereserve more space.  The length argument is volatile and can change

> +     between the sysctl(3) calls as this function can be called against a

> +     running process.  */

> +  length = length * 5 / 3;


I was also wondering why such a "precise" factor, and why not simply times two, for example.

In any case, the patch v5 is ok to push.

Simon
Kamil Rytarowski April 12, 2020, 10:17 a.m. | #2
On 12.04.2020 02:56, Simon Marchi wrote:
> On 2020-04-11 8:09 p.m., Kamil Rytarowski wrote:

>> +  /* Prereserve more space.  The length argument is volatile and can change

>> +     between the sysctl(3) calls as this function can be called against a

>> +     running process.  */

>> +  length = length * 5 / 3;

>

> I was also wondering why such a "precise" factor, and why not simply times two, for example.

>


It's just guessing and there are races... actually a kernel can return a
similar result too for various sysctl(3) calls, adding some more room
for users that forgot to enlarge the buffer.

In almost 100% cases this code will be good enough, and when it won't be
good enough we might have bigger problems in the system.

For a traced process there are no races as the process is stopped.

> In any case, the patch v5 is ok to push.

>


OK!

> Simon

>

Patch

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 81102ee569b..336bd497413 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,20 @@ 
+2020-04-11  Kamil Rytarowski  <n54@gmx.com>
+
+	* nbsd-nat.c; Include "nbsd-tdep.h" and "gdbarch.h".
+	* nbsd-nat.c (nbsd_nat_target::find_memory_regions)
+	(nbsd_nat_target::info_proc): New functions.
+	* nbsd-nat.c (kinfo_get_vmmap): New function.
+	* nbsd-nat.c (nbsd_nat_target::info_proc) Use
+	nbsd_info_proc_mappings_header and nbsd_info_proc_mappings_entry.
+	* nbsd-tdep.c (nbsd_info_proc_mappings_header)
+	(nbsd_info_proc_mappings_entry, nbsd_vm_map_entry_flags): New
+	functions.
+	* nbsd-tdep.c (KINFO_VME_PROT_READ, KINFO_VME_PROT_WRITE)
+	(KINFO_VME_PROT_EXEC, KINFO_VME_FLAG_COW)
+	(KINFO_VME_FLAG_NEEDS_COPY, KINFO_VME_FLAG_NOCOREDUMP)
+	(KINFO_VME_FLAG_PAGEABLE, KINFO_VME_FLAG_GROWS_UP)
+	(KINFO_VME_FLAG_GROWS_DOWN): New.
+
 2020-04-10  Artur Shepilko  <nomadbyte@gmail.com>

 	* utils.c (copy_bitwise): Use unsigned 0 constant as operand of
diff --git a/gdb/nbsd-nat.c b/gdb/nbsd-nat.c
index 4423e19428d..2420153c7bc 100644
--- a/gdb/nbsd-nat.c
+++ b/gdb/nbsd-nat.c
@@ -21,7 +21,9 @@ 

 #include "nbsd-nat.h"
 #include "gdbthread.h"
+#include "nbsd-tdep.h"
 #include "inferior.h"
+#include "gdbarch.h"

 #include <sys/types.h>
 #include <sys/ptrace.h>
@@ -199,3 +201,150 @@  nbsd_nat_target::pid_to_str (ptid_t ptid)

   return normal_pid_to_str (ptid);
 }
+
+/* Retrieve all the memory regions in the specified process.  */
+
+static gdb::unique_xmalloc_ptr<struct kinfo_vmentry[]>
+nbsd_kinfo_get_vmmap (pid_t pid, size_t *size)
+{
+  int mib[5] = {CTL_VM, VM_PROC, VM_PROC_MAP, pid,
+		sizeof (struct kinfo_vmentry)};
+
+  size_t length = 0;
+  if (sysctl (mib, ARRAY_SIZE (mib), NULL, &length, NULL, 0))
+    {
+      *size = 0;
+      return NULL;
+    }
+
+  /* Prereserve more space.  The length argument is volatile and can change
+     between the sysctl(3) calls as this function can be called against a
+     running process.  */
+  length = length * 5 / 3;
+
+  gdb::unique_xmalloc_ptr<struct kinfo_vmentry[]> kiv
+    (XNEWVAR (kinfo_vmentry, length));
+
+  if (sysctl (mib, ARRAY_SIZE (mib), kiv.get (), &length, NULL, 0))
+    {
+      *size = 0;
+      return NULL;
+    }
+
+  *size = length / sizeof (struct kinfo_vmentry);
+  return kiv;
+}
+
+/* Iterate over all the memory regions in the current inferior,
+   calling FUNC for each memory region.  OBFD is passed as the last
+   argument to FUNC.  */
+
+int
+nbsd_nat_target::find_memory_regions (find_memory_region_ftype func,
+				      void *data)
+{
+  pid_t pid = inferior_ptid.pid ();
+
+  size_t nitems;
+  gdb::unique_xmalloc_ptr<struct kinfo_vmentry[]> vmentl
+    = nbsd_kinfo_get_vmmap (pid, &nitems);
+  if (vmentl == NULL)
+    perror_with_name (_("Couldn't fetch VM map entries."));
+
+  for (size_t i = 0; i < nitems; i++)
+    {
+      struct kinfo_vmentry *kve = &vmentl[i];
+
+      /* Skip unreadable segments and those where MAP_NOCORE has been set.  */
+      if (!(kve->kve_protection & KVME_PROT_READ)
+	  || kve->kve_flags & KVME_FLAG_NOCOREDUMP)
+	continue;
+
+      /* Skip segments with an invalid type.  */
+      switch (kve->kve_type)
+	{
+	case KVME_TYPE_VNODE:
+	case KVME_TYPE_ANON:
+	case KVME_TYPE_SUBMAP:
+	case KVME_TYPE_OBJECT:
+	  break;
+	default:
+	  continue;
+	}
+
+      size_t size = kve->kve_end - kve->kve_start;
+      if (info_verbose)
+	{
+	  fprintf_filtered (gdb_stdout,
+			    "Save segment, %ld bytes at %s (%c%c%c)\n",
+			    (long) size,
+			    paddress (target_gdbarch (), kve->kve_start),
+			    kve->kve_protection & KVME_PROT_READ ? 'r' : '-',
+			    kve->kve_protection & KVME_PROT_WRITE ? 'w' : '-',
+			    kve->kve_protection & KVME_PROT_EXEC ? 'x' : '-');
+	}
+
+      /* Invoke the callback function to create the corefile segment.
+	 Pass MODIFIED as true, we do not know the real modification state.  */
+      func (kve->kve_start, size, kve->kve_protection & KVME_PROT_READ,
+	    kve->kve_protection & KVME_PROT_WRITE,
+	    kve->kve_protection & KVME_PROT_EXEC, 1, data);
+    }
+  return 0;
+}
+
+/* Implement the "info_proc" target_ops method.  */
+
+bool
+nbsd_nat_target::info_proc (const char *args, enum info_proc_what what)
+{
+  pid_t pid;
+  bool do_mappings = false;
+
+  switch (what)
+    {
+    case IP_MAPPINGS:
+      do_mappings = true;
+      break;
+    default:
+      error (_("Not supported on this target."));
+    }
+
+  gdb_argv built_argv (args);
+  if (built_argv.count () == 0)
+    {
+      pid = inferior_ptid.pid ();
+      if (pid == 0)
+        error (_("No current process: you must name one."));
+    }
+  else if (built_argv.count () == 1 && isdigit (built_argv[0][0]))
+    pid = strtol (built_argv[0], NULL, 10);
+  else
+    error (_("Invalid arguments."));
+
+  printf_filtered (_("process %d\n"), pid);
+
+  if (do_mappings)
+    {
+      size_t nvment;
+      gdb::unique_xmalloc_ptr<struct kinfo_vmentry[]> vmentl
+	= nbsd_kinfo_get_vmmap (pid, &nvment);
+
+      if (vmentl != nullptr)
+	{
+	  int addr_bit = TARGET_CHAR_BIT * sizeof (void *);
+	  nbsd_info_proc_mappings_header (addr_bit);
+
+	  struct kinfo_vmentry *kve = vmentl.get ();
+	  for (int i = 0; i < nvment; i++, kve++)
+	    nbsd_info_proc_mappings_entry (addr_bit, kve->kve_start,
+					   kve->kve_end, kve->kve_offset,
+					   kve->kve_flags, kve->kve_protection,
+					   kve->kve_path);
+	}
+      else
+	warning (_("unable to fetch virtual memory map"));
+    }
+
+  return true;
+}
diff --git a/gdb/nbsd-nat.h b/gdb/nbsd-nat.h
index 3606048cd07..256db4b9017 100644
--- a/gdb/nbsd-nat.h
+++ b/gdb/nbsd-nat.h
@@ -35,6 +35,9 @@  struct nbsd_nat_target : public inf_ptrace_target
   void post_attach (int pid) override;
   void update_thread_list () override;
   std::string pid_to_str (ptid_t ptid) override;
+
+  int find_memory_regions (find_memory_region_ftype func, void *data) override;
+  bool info_proc (const char *, enum info_proc_what) override;
 };

 #endif /* nbsd-nat.h */
diff --git a/gdb/nbsd-tdep.c b/gdb/nbsd-tdep.c
index 158a43bebaa..52e0640e35c 100644
--- a/gdb/nbsd-tdep.c
+++ b/gdb/nbsd-tdep.c
@@ -26,6 +26,23 @@ 
 #include "gdbarch.h"
 #include "objfiles.h"

+/* Flags in the 'kve_protection' field in struct kinfo_vmentry.  These
+   match the KVME_PROT_* constants in <sys/sysctl.h>.  */
+
+#define	KINFO_VME_PROT_READ	0x00000001
+#define	KINFO_VME_PROT_WRITE	0x00000002
+#define	KINFO_VME_PROT_EXEC	0x00000004
+
+/* Flags in the 'kve_flags' field in struct kinfo_vmentry.  These
+   match the KVME_FLAG_* constants in <sys/sysctl.h>.  */
+
+#define	KINFO_VME_FLAG_COW		0x00000001
+#define	KINFO_VME_FLAG_NEEDS_COPY	0x00000002
+#define	KINFO_VME_FLAG_NOCOREDUMP	0x00000004
+#define	KINFO_VME_FLAG_PAGEABLE		0x00000008
+#define	KINFO_VME_FLAG_GROWS_UP		0x00000010
+#define	KINFO_VME_FLAG_GROWS_DOWN	0x00000020
+
 /* FIXME: kettenis/20060115: We should really eliminate the next two
    functions completely.  */

@@ -357,6 +374,78 @@  nbsd_skip_solib_resolver (struct gdbarch *gdbarch, CORE_ADDR pc)

 /* See nbsd-tdep.h.  */

+void
+nbsd_info_proc_mappings_header (int addr_bit)
+{
+  printf_filtered (_("Mapped address spaces:\n\n"));
+  if (addr_bit == 64)
+    {
+      printf_filtered ("  %18s %18s %10s %10s %9s %s\n",
+		       "Start Addr",
+		       "  End Addr",
+		       "      Size", "    Offset", "Flags  ", "File");
+    }
+  else
+    {
+      printf_filtered ("\t%10s %10s %10s %10s %9s %s\n",
+		       "Start Addr",
+		       "  End Addr",
+		       "      Size", "    Offset", "Flags  ", "File");
+    }
+}
+
+/* Helper function to generate mappings flags for a single VM map
+   entry in 'info proc mappings'.  */
+
+static const char *
+nbsd_vm_map_entry_flags (int kve_flags, int kve_protection)
+{
+  static char vm_flags[9];
+
+  vm_flags[0] = (kve_protection & KINFO_VME_PROT_READ) ? 'r' : '-';
+  vm_flags[1] = (kve_protection & KINFO_VME_PROT_WRITE) ? 'w' : '-';
+  vm_flags[2] = (kve_protection & KINFO_VME_PROT_EXEC) ? 'x' : '-';
+  vm_flags[3] = ' ';
+  vm_flags[4] = (kve_flags & KINFO_VME_FLAG_COW) ? 'C' : '-';
+  vm_flags[5] = (kve_flags & KINFO_VME_FLAG_NEEDS_COPY) ? 'N' : '-';
+  vm_flags[6] = (kve_flags & KINFO_VME_FLAG_PAGEABLE) ? 'P' : '-';
+  vm_flags[7] = (kve_flags & KINFO_VME_FLAG_GROWS_UP) ? 'U'
+    : (kve_flags & KINFO_VME_FLAG_GROWS_DOWN) ? 'D' : '-';
+  vm_flags[8] = '\0';
+
+  return vm_flags;
+}
+
+void
+nbsd_info_proc_mappings_entry (int addr_bit, ULONGEST kve_start,
+			       ULONGEST kve_end, ULONGEST kve_offset,
+			       int kve_flags, int kve_protection,
+			       const char *kve_path)
+{
+  if (addr_bit == 64)
+    {
+      printf_filtered ("  %18s %18s %10s %10s %9s %s\n",
+		       hex_string (kve_start),
+		       hex_string (kve_end),
+		       hex_string (kve_end - kve_start),
+		       hex_string (kve_offset),
+		       nbsd_vm_map_entry_flags (kve_flags, kve_protection),
+		       kve_path);
+    }
+  else
+    {
+      printf_filtered ("\t%10s %10s %10s %10s %9s %s\n",
+		       hex_string (kve_start),
+		       hex_string (kve_end),
+		       hex_string (kve_end - kve_start),
+		       hex_string (kve_offset),
+		       nbsd_vm_map_entry_flags (kve_flags, kve_protection),
+		       kve_path);
+    }
+}
+
+/* See nbsd-tdep.h.  */
+
 void
 nbsd_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
 {
diff --git a/gdb/nbsd-tdep.h b/gdb/nbsd-tdep.h
index 4b06c13f87b..a6e3a8f0f3f 100644
--- a/gdb/nbsd-tdep.h
+++ b/gdb/nbsd-tdep.h
@@ -29,4 +29,22 @@  int nbsd_pc_in_sigtramp (CORE_ADDR, const char *);

 void nbsd_init_abi (struct gdbarch_info, struct gdbarch *);

+/* Output the header for "info proc mappings".  ADDR_BIT is the size
+   of a virtual address in bits.  */
+
+extern void nbsd_info_proc_mappings_header (int addr_bit);
+
+/* Output description of a single memory range for "info proc
+   mappings".  ADDR_BIT is the size of a virtual address in bits.  The
+   KVE_START, KVE_END, KVE_OFFSET, KVE_FLAGS, and KVE_PROTECTION
+   parameters should contain the value of the corresponding fields in
+   a 'struct kinfo_vmentry'.  The KVE_PATH parameter should contain a
+   pointer to the 'kve_path' field in a 'struct kinfo_vmentry'. */
+
+extern void nbsd_info_proc_mappings_entry (int addr_bit, ULONGEST kve_start,
+					   ULONGEST kve_end,
+					   ULONGEST kve_offset,
+					   int kve_flags, int kve_protection,
+					   const char *kve_path);
+
 #endif /* NBSD_TDEP_H */