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

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

[Rainer Orth]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=7f2043399809c0ba5c4819172214371ed820e8c6

commit 7f2043399809c0ba5c4819172214371ed820e8c6
Author: Rainer Orth <ro@CeBiTec.Uni-Bielefeld.DE>
Date:   Mon May 18 17:56:00 2020 +0200

    Remove unused ps_lgetLDT etc. on Solaris/x86 [PR25981]
    
    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 <signal.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 calls to it had been removed
    long ago in Solaris 9, so just removing the three functions above 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.
    
            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.

Diff:
---
 gdb/ChangeLog    | 10 +++++++
 gdb/procfs.c     | 79 --------------------------------------------------------
 gdb/procfs.h     |  6 -----
 gdb/sol-thread.c | 32 -----------------------
 4 files changed, 10 insertions(+), 117 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 1c2ddcecb7e..cba0464770c 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,13 @@
+2020-05-18  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.
+
 2020-05-17  Pedro Alves  <palves@redhat.com>
 	    Andrew Burgess  <andrew.burgess@embecosm.com>
 	    Keno Fischer  <keno@juliacomputing.com>
diff --git a/gdb/procfs.c b/gdb/procfs.c
index 09a036f90b9..f6c6b0e71c1 100644
--- a/gdb/procfs.c
+++ b/gdb/procfs.c
@@ -1569,85 +1569,6 @@ proc_set_watchpoint (procinfo *pi, CORE_ADDR addr, int len, int wflags)
   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
index 5bba4672b57..46835fdf820 100644
--- 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
index 333fb961931..9addf8de3ab 100644
--- a/gdb/sol-thread.c
+++ b/gdb/sol-thread.c
@@ -969,38 +969,6 @@ ps_pdmodel (struct ps_prochandle *ph, int *data_model)
 
   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
 \f
 
 /* Convert PTID to printable form.  */