Remove unused ps_lgetLDT etc. on Solaris/x86 [PR25981]

Message ID yddzha5h4pc.fsf@CeBiTec.Uni-Bielefeld.DE
State New
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  • Remove unused ps_lgetLDT etc. on Solaris/x86 [PR25981]
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Commit Message

Rainer Orth May 18, 2020, 11:18 a.m.
As reported in PR build/25981, a future Solaris 11.4 update will soon
remove the short i386 register names like SS etc. from <sys/regset.h>.
They could leak into user code (e.g. via <signa.h> -> <sys/signal.h> ->
<sys/ucontext.h>) and pollute the user namespace.  Affected code would
have a hard time avoiding the issue: LLVM is one of those.

While the short names are required to be present by the i386 psABI, that
document only demands that they exist in <ucontext.h>, which is what the
upcoming update assures.

With this change, in a 64-bit-default configuration, procfs.c fails to
compile on Solaris/x86:

/vol/src/gnu/gdb/hg/master/git/gdb/procfs.c: In function 'ssd* procfs_find_LDT_entry(ptid_t)':
/vol/src/gnu/gdb/hg/master/git/gdb/procfs.c:1643:18: error: 'GS' was not declared in this scope
 1643 |   key = (*gregs)[GS] & 0xffff;
      |                  ^~
make[2]: *** [Makefile:1607: procfs.o] Error 1

Initially I meant to provide a definition using the planned replacement
macro, but closer inspection revealed a better way.
procfs_find_LDT_entry and its helper proc_get_LDT_entry are only used to
implement ps_lgetLDT, one of the callback functions required by
libthread_db.so.1 (cf. <proc_service.h>).  While that function is still
documented as being required even in Solaris 11.4, I found that it had
been removed long ago in Solaris 9, so just removing the three functions
above of them is the easiest fix.

The following patch does just that.  It compiled successfully on
amd64-pc-solaris2.11, however, as reported in PR gdb/25939, master is
completely broken on Solaris since the multi-target patch.  The patch
applies cleanly to the gdb-9 branch and there I could test it
successfully.

I'm going to apply it to master soon.  Also ok for the gdb-9 branch?  It
would be nice to have a compiling and working gdb on Solaris/x86
somehow.

Thanks.
	Rainer

-- 
-----------------------------------------------------------------------------
Rainer Orth, Center for Biotechnology, Bielefeld University


2020-05-13  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>

	PR build/25981
	* procfs.c [(__i386__ || __x86_64__) && sun] (proc_get_LDT_entry,
	procfs_find_LDT_entry): Remove.
	* procfs.h [(__i386__ || __x86_64__) && sun] (struct ssd,
	procfs_find_LDT_entry): Remove.
	* sol-thread.c [(__i386__ || __x86_64__) && sun] (ps_lgetLDT):
	Remove.

Comments

Joel Brobecker May 18, 2020, 2:14 p.m. | #1
Hi Rainer,

> I'm going to apply it to master soon.  Also ok for the gdb-9 branch?  It

> would be nice to have a compiling and working gdb on Solaris/x86

> somehow.

[...]
> 2020-05-13  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>

> 

> 	PR build/25981

> 	* procfs.c [(__i386__ || __x86_64__) && sun] (proc_get_LDT_entry,

> 	procfs_find_LDT_entry): Remove.

> 	* procfs.h [(__i386__ || __x86_64__) && sun] (struct ssd,

> 	procfs_find_LDT_entry): Remove.

> 	* sol-thread.c [(__i386__ || __x86_64__) && sun] (ps_lgetLDT):

> 	Remove.


OK for gdb-9-branch as well.

I've adjusted the PR's "target milestone" accordingly.

Thanks for the patch!
-- 
Joel

Patch

# HG changeset patch
# Parent  252276819bb73ea3314465ae8ed49307aecaddc0
Remove unused ps_lgetLDT etc. on Solaris/x86 [PR25981]

diff --git a/gdb/procfs.c b/gdb/procfs.c
--- a/gdb/procfs.c
+++ b/gdb/procfs.c
@@ -1569,85 +1569,6 @@  proc_set_watchpoint (procinfo *pi, CORE_
   return (write (pi->ctl_fd, &arg, sizeof (arg)) == sizeof (arg));
 }
 
-#if (defined(__i386__) || defined(__x86_64__)) && defined (sun)
-
-#include <sys/sysi86.h>
-
-/* The KEY is actually the value of the lower 16 bits of the GS
-   register for the LWP that we're interested in.  Returns the
-   matching ssh struct (LDT entry).  */
-
-static struct ssd *
-proc_get_LDT_entry (procinfo *pi, int key)	/* ARI: editCase function */
-{
-  static struct ssd *ldt_entry = NULL;
-  char pathname[MAX_PROC_NAME_SIZE];
-
-  /* Allocate space for one LDT entry.
-     This alloc must persist, because we return a pointer to it.  */
-  if (ldt_entry == NULL)
-    ldt_entry = XNEW (struct ssd);
-
-  /* Open the file descriptor for the LDT table.  */
-  xsnprintf (pathname, sizeof (pathname), "/proc/%d/ldt", pi->pid);
-  scoped_fd fd (open_with_retry (pathname, O_RDONLY));
-  if (fd.get () < 0)
-    {
-      proc_warn (pi, "proc_get_LDT_entry (open)", __LINE__);
-      return NULL;
-    }
-
-  /* Now 'read' thru the table, find a match and return it.  */
-  while (read (fd.get (), ldt_entry, sizeof (struct ssd))
-	 == sizeof (struct ssd))
-    {
-      if (ldt_entry->sel == 0
-	  && ldt_entry->bo  == 0
-	  && ldt_entry->acc1 == 0
-	  && ldt_entry->acc2 == 0)
-	break;	/* end of table */
-      /* If key matches, return this entry.  */
-      if (ldt_entry->sel == key)
-	return ldt_entry;
-    }
-  /* Loop ended, match not found.  */
-  return NULL;
-}
-
-/* Returns the pointer to the LDT entry of PTID.  */
-
-struct ssd *
-procfs_find_LDT_entry (ptid_t ptid)	/* ARI: editCase function */
-{
-  gdb_gregset_t *gregs;
-  int            key;
-  procinfo      *pi;
-
-  /* Find procinfo for the lwp.  */
-  pi = find_procinfo (ptid.pid (), ptid.lwp ());
-  if (pi == NULL)
-    {
-      warning (_("procfs_find_LDT_entry: could not find procinfo for %d:%ld."),
-	       ptid.pid (), ptid.lwp ());
-      return NULL;
-    }
-  /* get its general registers.  */
-  gregs = proc_get_gregs (pi);
-  if (gregs == NULL)
-    {
-      warning (_("procfs_find_LDT_entry: could not read gregs for %d:%ld."),
-	       ptid.pid (), ptid.lwp ());
-      return NULL;
-    }
-  /* Now extract the GS register's lower 16 bits.  */
-  key = (*gregs)[GS] & 0xffff;
-
-  /* Find the matching entry and return it.  */
-  return proc_get_LDT_entry (pi, key);
-}
-
-#endif
-
 /* =============== END, non-thread part of /proc  "MODULE" =============== */
 
 /* =================== Thread "MODULE" =================== */
diff --git a/gdb/procfs.h b/gdb/procfs.h
--- a/gdb/procfs.h
+++ b/gdb/procfs.h
@@ -25,10 +25,4 @@ 
 
 extern ptid_t procfs_first_available (void);
 
-#if (defined (__i386__) || defined (__x86_64__)) && defined (sun)
-struct ssd;
-
-extern struct ssd *procfs_find_LDT_entry (ptid_t);
-#endif
-
 #endif /* PROCFS_H */
diff --git a/gdb/sol-thread.c b/gdb/sol-thread.c
--- a/gdb/sol-thread.c
+++ b/gdb/sol-thread.c
@@ -969,38 +969,6 @@  ps_pdmodel (struct ps_prochandle *ph, in
 
   return PS_OK;
 }
-
-#if (defined(__i386__) || defined(__x86_64__)) && defined (sun)
-
-/* Reads the local descriptor table of a LWP.
-
-   This function is necessary on x86-solaris only.  Without it, the loading
-   of libthread_db would fail because of ps_lgetLDT being undefined.  */
-
-ps_err_e
-ps_lgetLDT (struct ps_prochandle *ph, lwpid_t lwpid, struct ssd *pldt)	/* ARI: editCase function */
-{
-  /* NOTE: only used on Solaris, therefore OK to refer to procfs.c.  */
-  struct ssd *ret;
-
-  /* FIXME: can't I get the process ID from the prochandle or
-     something?  */
-
-  if (inferior_ptid.pid () <= 0 || lwpid <= 0)
-    return PS_BADLID;
-
-  ret = procfs_find_LDT_entry (ptid_t (inferior_ptid.pid (),
-			       lwpid, 0));
-  if (ret)
-    {
-      memcpy (pldt, ret, sizeof (struct ssd));
-      return PS_OK;
-    }
-  else
-    /* LDT not found.  */
-    return PS_ERR;
-}
-#endif
 
 
 /* Convert PTID to printable form.  */