[OE-core] [PATCH] Fix X server on PowerPC when using GCC 4.7.x
Gary Thomas
gary at mlbassoc.com
Wed May 16 13:30:40 UTC 2012
On 2012-05-16 07:23, Martin Jansa wrote:
> On Wed, May 16, 2012 at 3:09 PM, Gary Thomas<gary at mlbassoc.com> wrote:
>> The function XaceHook() was trying to do something like this:
>> void *ptr;
>> switch(XX) {
>> case a:
>> define_some_structure A;
>> ptr =&A;
>> break;
>> case b:
>> define_some_structure B;
>> ptr =&B;
>> break;
>> }
>> call_some_function(ptr);
>>
>> Clearly this is not even legal - the scope of the variables A& B
>> is not well defined outside of the switch cases. This code pattern
>> stopped working on PowerPC with GCC>= 4.7.1 (it has worked forever
>> up to& including 4.6.3). Replace this sequence with legal code:
>> switch(XX) {
>> case a:
>> define_some_structure A;
>> call_some_function(&A);
>> break;
>> case b:
>> define_some_structure B;
>> call_some_function(&B);
>> break;
>> }
>> ---
>> .../fix-bogus-stack-variables.patch | 130 ++++++++++++++++++++
>> .../xorg-xserver/xserver-kdrive_1.7.99.2.bb | 3 +-
>> 2 files changed, 132 insertions(+), 1 deletions(-)
>> create mode 100644 meta/recipes-graphics/xorg-xserver/xserver-kdrive-1.7.99.2/fix-bogus-stack-variables.patch
>>
>> diff --git a/meta/recipes-graphics/xorg-xserver/xserver-kdrive-1.7.99.2/fix-bogus-stack-variables.patch b/meta/recipes-graphics/xorg-xserver/xserver-kdrive-1.7.99.2/fix-bogus-stack-variables.patch
>> new file mode 100644
>> index 0000000..0946dfb
>> --- /dev/null
>> +++ b/meta/recipes-graphics/xorg-xserver/xserver-kdrive-1.7.99.2/fix-bogus-stack-variables.patch
>> @@ -0,0 +1,130 @@
>> +Index: xorg-server-1.7.99.2/Xext/xace.c
>> +===================================================================
>> +--- xorg-server-1.7.99.2.orig/Xext/xace.c
>> ++++ xorg-server-1.7.99.2/Xext/xace.c
>> +@@ -87,8 +87,7 @@ void XaceHookAuditEnd(ClientPtr ptr, int
>> + */
>> + int XaceHook(int hook, ...)
>> + {
>> +- pointer calldata; /* data passed to callback */
>> +- int *prv = NULL; /* points to return value from callback */
>> ++ int res = Success;
>> + va_list ap; /* argument list */
>> + va_start(ap, hook);
>> +
>> +@@ -109,8 +108,8 @@ int XaceHook(int hook, ...)
>> + rec.parent = va_arg(ap, pointer);
>> + rec.access_mode = va_arg(ap, Mask);
>> + rec.status = Success; /* default allow */
>> +- calldata =&rec;
>> +- prv =&rec.status;
>> ++ CallCallbacks(&XaceHooks[hook],&rec);
>> ++ res = rec.status;
>> + break;
>> + }
>> + case XACE_DEVICE_ACCESS: {
>> +@@ -119,8 +118,8 @@ int XaceHook(int hook, ...)
>> + rec.dev = va_arg(ap, DeviceIntPtr);
>> + rec.access_mode = va_arg(ap, Mask);
>> + rec.status = Success; /* default allow */
>> +- calldata =&rec;
>> +- prv =&rec.status;
>> ++ CallCallbacks(&XaceHooks[hook],&rec);
>> ++ res = rec.status;
>> + break;
>> + }
>> + case XACE_SEND_ACCESS: {
>> +@@ -131,8 +130,8 @@ int XaceHook(int hook, ...)
>> + rec.events = va_arg(ap, xEventPtr);
>> + rec.count = va_arg(ap, int);
>> + rec.status = Success; /* default allow */
>> +- calldata =&rec;
>> +- prv =&rec.status;
>> ++ CallCallbacks(&XaceHooks[hook],&rec);
>> ++ res = rec.status;
>> + break;
>> + }
>> + case XACE_RECEIVE_ACCESS: {
>> +@@ -142,8 +141,8 @@ int XaceHook(int hook, ...)
>> + rec.events = va_arg(ap, xEventPtr);
>> + rec.count = va_arg(ap, int);
>> + rec.status = Success; /* default allow */
>> +- calldata =&rec;
>> +- prv =&rec.status;
>> ++ CallCallbacks(&XaceHooks[hook],&rec);
>> ++ res = rec.status;
>> + break;
>> + }
>> + case XACE_CLIENT_ACCESS: {
>> +@@ -152,8 +151,8 @@ int XaceHook(int hook, ...)
>> + rec.target = va_arg(ap, ClientPtr);
>> + rec.access_mode = va_arg(ap, Mask);
>> + rec.status = Success; /* default allow */
>> +- calldata =&rec;
>> +- prv =&rec.status;
>> ++ CallCallbacks(&XaceHooks[hook],&rec);
>> ++ res = rec.status;
>> + break;
>> + }
>> + case XACE_EXT_ACCESS: {
>> +@@ -162,8 +161,8 @@ int XaceHook(int hook, ...)
>> + rec.ext = va_arg(ap, ExtensionEntry*);
>> + rec.access_mode = DixGetAttrAccess;
>> + rec.status = Success; /* default allow */
>> +- calldata =&rec;
>> +- prv =&rec.status;
>> ++ CallCallbacks(&XaceHooks[hook],&rec);
>> ++ res = rec.status;
>> + break;
>> + }
>> + case XACE_SERVER_ACCESS: {
>> +@@ -171,8 +170,8 @@ int XaceHook(int hook, ...)
>> + rec.client = va_arg(ap, ClientPtr);
>> + rec.access_mode = va_arg(ap, Mask);
>> + rec.status = Success; /* default allow */
>> +- calldata =&rec;
>> +- prv =&rec.status;
>> ++ CallCallbacks(&XaceHooks[hook],&rec);
>> ++ res = rec.status;
>> + break;
>> + }
>> + case XACE_SCREEN_ACCESS:
>> +@@ -182,15 +181,15 @@ int XaceHook(int hook, ...)
>> + rec.screen = va_arg(ap, ScreenPtr);
>> + rec.access_mode = va_arg(ap, Mask);
>> + rec.status = Success; /* default allow */
>> +- calldata =&rec;
>> +- prv =&rec.status;
>> ++ CallCallbacks(&XaceHooks[hook],&rec);
>> ++ res = rec.status;
>> + break;
>> + }
>> + case XACE_AUTH_AVAIL: {
>> + XaceAuthAvailRec rec;
>> + rec.client = va_arg(ap, ClientPtr);
>> + rec.authId = va_arg(ap, XID);
>> +- calldata =&rec;
>> ++ CallCallbacks(&XaceHooks[hook],&rec);
>> + break;
>> + }
>> + case XACE_KEY_AVAIL: {
>> +@@ -198,7 +197,7 @@ int XaceHook(int hook, ...)
>> + rec.event = va_arg(ap, xEventPtr);
>> + rec.keybd = va_arg(ap, DeviceIntPtr);
>> + rec.count = va_arg(ap, int);
>> +- calldata =&rec;
>> ++ CallCallbacks(&XaceHooks[hook],&rec);
>> + break;
>> + }
>> + default: {
>> +@@ -208,9 +207,7 @@ int XaceHook(int hook, ...)
>> + }
>> + va_end(ap);
>> +
>> +- /* call callbacks and return result, if any. */
>> +- CallCallbacks(&XaceHooks[hook], calldata);
>> +- return prv ? *prv : Success;
>> ++ return res;
>> + }
>> +
>> + /* XaceCensorImage
>> diff --git a/meta/recipes-graphics/xorg-xserver/xserver-kdrive_1.7.99.2.bb b/meta/recipes-graphics/xorg-xserver/xserver-kdrive_1.7.99.2.bb
>> index 360a0f3..dc17e2b 100644
>> --- a/meta/recipes-graphics/xorg-xserver/xserver-kdrive_1.7.99.2.bb
>> +++ b/meta/recipes-graphics/xorg-xserver/xserver-kdrive_1.7.99.2.bb
>> @@ -7,7 +7,7 @@ RDEPENDS_${PN} += "xkeyboard-config"
>> EXTRA_OECONF += "--disable-glx"
>>
>> PE = "1"
>> -PR = "r29"
>> +PR = "r30"
>>
>> SRC_URI = "${XORG_MIRROR}/individual/xserver/xorg-server-${PV}.tar.bz2 \
>> file://extra-kmodes.patch \
>> @@ -21,6 +21,7 @@ SRC_URI = "${XORG_MIRROR}/individual/xserver/xorg-server-${PV}.tar.bz2 \
>> file://crosscompile.patch \
>> file://error-address-work-around.patch \
>> file://nodolt.patch"
>> + file://fix-bogus-stack-variables.patch \
>> # file://kdrive-evdev.patch
>> # file://kdrive-use-evdev.patch
>> # file://enable-builtin-fonts.patch
>> --
>> 1.7.7.6
>>
>>
>> _______________________________________________
>> Openembedded-core mailing list
>> Openembedded-core at lists.openembedded.org
>> http://lists.linuxtogo.org/cgi-bin/mailman/listinfo/openembedded-core
>
> Isn't this better fix?
> http://cgit.freedesktop.org/xorg/xserver/commit/Xext/xace.c?id=6dae7f3792611aace1df0cca63bf50c50d93de43
Either way - they are pretty much the same (I had actually done it the
freedesktop.org way before but I thought it obfuscated what was happening).
I'm sure the person that wrote this was being clever, trying to have only
one function call, but a smart compiler will unwind this anyway and writing
it out explicitly is easier to read...
All I care is that it gets fixed and my X server starts working again :-)
--
------------------------------------------------------------
Gary Thomas | Consulting for the
MLB Associates | Embedded world
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