From: Julian Seward <jseward@acm.org>
Date: Wed, 6 Oct 2010 15:24:39 +0000 (+0000)
Subject: Make client sys_shmat work properly on arm-linux by taking into
X-Git-Tag: svn/VALGRIND_3_6_0~58
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=566a25cf7e93d704890988797ebef05544dbbf66;p=thirdparty%2Fvalgrind.git

Make client sys_shmat work properly on arm-linux by taking into
account rounding requirements to SHMLBA.  Modified version of a patch
by Kirill Batuzov, batuzovk@ispras.ru.  This fixes the main bug in
#222545.  Temporarily breaks the build on all other platforms though.



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@11399
---

diff --git a/coregrind/m_syswrap/syswrap-arm-linux.c b/coregrind/m_syswrap/syswrap-arm-linux.c
index 159a011183..3d1f3b514b 100644
--- a/coregrind/m_syswrap/syswrap-arm-linux.c
+++ b/coregrind/m_syswrap/syswrap-arm-linux.c
@@ -831,6 +831,12 @@ PRE(wrap_sys_shmat)
    PRINT("wrap_sys_shmat ( %ld, %#lx, %ld )",ARG1,ARG2,ARG3);
    PRE_REG_READ3(long, "shmat",
                  int, shmid, const void *, shmaddr, int, shmflg);
+   /* Round the attach address down to an VKI_SHMLBA boundary if the
+      client requested rounding.  See #222545.  This is necessary only
+      on arm-linux because VKI_SHMLBA is 4 * VKI_PAGE size; on all
+      other linux targets it is the same as the page size. */
+   if (ARG3 & VKI_SHM_RND)
+      ARG2 = VG_ROUNDDN(ARG2, VKI_SHMLBA);
    arg2tmp = ML_(generic_PRE_sys_shmat)(tid, ARG1,ARG2,ARG3);
    if (arg2tmp == 0)
       SET_STATUS_Failure( VKI_EINVAL );
diff --git a/coregrind/m_syswrap/syswrap-generic.c b/coregrind/m_syswrap/syswrap-generic.c
index 9c00c57852..22eae2891b 100644
--- a/coregrind/m_syswrap/syswrap-generic.c
+++ b/coregrind/m_syswrap/syswrap-generic.c
@@ -1741,9 +1741,26 @@ ML_(generic_PRE_sys_shmat) ( ThreadId tid,
    UWord tmp;
    Bool  ok;
    if (arg1 == 0) {
+      /* arm-linux only: work around the fact that
+         VG_(am_get_advisory_client_simple) produces something that is
+         VKI_PAGE_SIZE aligned, whereas what we want is something
+         VKI_SHMLBA aligned, and VKI_SHMLBA >= VKI_PAGE_SIZE.  Hence
+         increase the request size by VKI_SHMLBA - VKI_PAGE_SIZE and
+         then round the result up to the next VKI_SHMLBA boundary.
+         See bug 222545 comment 15.  So far, arm-linux is the only
+         platform where this is known to be necessary. */
+      vg_assert(VKI_SHMLBA >= VKI_PAGE_SIZE);
+      if (VKI_SHMLBA > VKI_PAGE_SIZE) {
+         segmentSize += VKI_SHMLBA - VKI_PAGE_SIZE;
+      }
       tmp = VG_(am_get_advisory_client_simple)(0, segmentSize, &ok);
-      if (ok)
-         arg1 = tmp;
+      if (ok) {
+         if (VKI_SHMLBA > VKI_PAGE_SIZE) {
+            arg1 = VG_ROUNDUP(tmp, VKI_SHMLBA);
+         } else {
+            arg1 = tmp;
+         }
+      }
    }
    else if (!ML_(valid_client_addr)(arg1, segmentSize, tid, "shmat"))
       arg1 = 0;
diff --git a/include/vki/vki-arm-linux.h b/include/vki/vki-arm-linux.h
index 9e6ff1ea72..508be43791 100644
--- a/include/vki/vki-arm-linux.h
+++ b/include/vki/vki-arm-linux.h
@@ -731,6 +731,8 @@ struct vki_ipc_kludge {
 #define VKI_SHMGET		23
 #define VKI_SHMCTL		24
 
+#define VKI_SHMLBA  (4 * VKI_PAGE_SIZE)
+
 
 //----------------------------------------------------------------------
 // From linux-2.6.8.1/include/asm-i386/shmbuf.h
diff --git a/include/vki/vki-linux.h b/include/vki/vki-linux.h
index 6b676e6aeb..537f0e09dd 100644
--- a/include/vki/vki-linux.h
+++ b/include/vki/vki-linux.h
@@ -1451,6 +1451,7 @@ struct vki_shmid_ds {
 };
 
 #define VKI_SHM_RDONLY  010000  /* read-only access */
+#define VKI_SHM_RND     020000  /* round attach address to SHMLBA boundary */
 
 #define VKI_SHM_STAT 	13
 #define VKI_SHM_INFO 	14