This bug report was migrated from our old Bugzilla tracker.

These attachments are available in the static archive:

• no-exec-stack (libsdl-no-exec-stack.patch, text/plain, 2006-01-03 12:03:57 +0000, 1146 bytes)
• hermes-call-dont-jump (libsdl-PIC-hermes-call-dont-jump., text/plain, 2006-01-03 12:04:18 +0000, 4868 bytes)
• hermes-cpuid (libsdl-PIC-hermes-cpuid.patch, text/plain, 2006-01-03 12:04:33 +0000, 405 bytes)
• load-mmx-masks-from-stack (libsdl-PIC-load-mmx-masks-from-st, text/plain, 2006-01-03 12:05:00 +0000, 1803 bytes)
• SDL_stretch-PIC (libsdl-SDL_stretch-PIC.patch, text/plain, 2006-01-03 12:07:14 +0000, 639 bytes)
• libsdl-1.2.9-PIC-load-mmx-masks-from-stack.patch (libsdl-1.2.9-PIC-load-mmx-masks-f, text/plain, 2006-01-05 09:35:35 +0000, 3901 bytes)

Reported in version: don't know
Reported for operating system, platform: Other, x86

Comments on the original bug report:

On 2006-01-03 12:03:28 +0000, Ryan C. Gordon wrote:

From: Mike Frysinger vapier@gentoo.org
To: sdl@libsdl.org
Date: Thu, 29 Sep 2005 05:57:04 -0400
Subject: [SDL] clean up some of the PIC issues in libSDL asm

the assembly used in some parts of libSDL arent very PIC friendly thus causing
some ugly TEXTREL's in the final library ... the PaX team has put together a
bunch of fixes which i'm forwarding (along with some test cases to show that
the code is sane) ... there may be a little conflict between these patches,
but hopefully not

• libsdl-SDL_stretch-PIC.patch
  ignoring the general fact of how SDL_stretch relies on executing dynamic code,
  the inline asm should let gcc handle the a details for getting the actual
  address for _copy_row as it will do the right thing
  test case: http://dev.gentoo.org/~vapier/libsdl/sdl-stretch.tar.bz2

• libsdl-no-exec-stack.patch
  this makes sure that the nasm code declares itself as not needing executable
  stacks. if GNU stack is not found in assembly files, binutils assumes that
  it requires a read/write/executable stack. before the patch, running readelf -l libSDL.so would show a GNU_STACK program header marked as RWE ... after
  the patch, the GNU_STACK should be marked as just RW.

• libsdl-PIC-hermes-cpuid.patch
  rewrites the code in _Hermes_X86_CPU so that it doesnt require the local
  cpu_flags memory variable, it just uses registers.
  test case: http://dev.gentoo.org/~vapier/libsdl/hermes-cpuid-test.tar.bz2

• libsdl-PIC-hermes-call-dont-jump.patch
  call, dont jmp, with _mmxreturn and _x86return labels. if you try to jmp to
  them, nasm will generate relocations which ld is unable to resolve while
  linking, so the resulting library will contain a ton of TEXTREL's (one per
  jmp pretty much). simply calling and returning in a normal function fashion
  resolves this. no test case as i'm not well versed enough in SDL to put
  together a comprehensive one ... but it does compile and my games dont
  segfault :)

• libsdl-PIC-load-mmx-masks-from-stack.patch
  this one may be a little controversial ... the fix here is again that you cant
  reference the memory addresses like this to load into a mmx register, so the
  way to do it is to push two 32bit words onto the stack, load the 64bit value
  off of the stack into the mmx register, and then adjust the stack so that
  it's back to normal.
  -mike

On 2006-01-03 12:03:57 +0000, Ryan C. Gordon wrote:

Created attachment 10
no-exec-stack

On 2006-01-03 12:04:18 +0000, Ryan C. Gordon wrote:

Created attachment 11
hermes-call-dont-jump

On 2006-01-03 12:04:33 +0000, Ryan C. Gordon wrote:

Created attachment 12
hermes-cpuid

On 2006-01-03 12:05:00 +0000, Ryan C. Gordon wrote:

Created attachment 13
load-mmx-masks-from-stack

On 2006-01-03 12:05:57 +0000, Ryan C. Gordon wrote:

Please note that some (or all?) of these might have been applied to CVS, and some (or all?) might have been declared broken by Mike later on. Please follow up with Mike before committing!

--ryan.

On 2006-01-03 12:07:14 +0000, Ryan C. Gordon wrote:

Created attachment 14
SDL_stretch-PIC

On 2006-01-04 22:17:43 +0000, Mike Frysinger wrote:

Comment on attachment 10
no-exec-stack

this has been committed

On 2006-01-04 22:19:02 +0000, Mike Frysinger wrote:

Comment on attachment 12
hermes-cpuid

this hermes-cpuid patch is still applicable

On 2006-01-04 22:19:23 +0000, Mike Frysinger wrote:

Comment on attachment 14
SDL_stretch-PIC

this SDL_stretch change is safe and still applicable

On 2006-01-04 22:19:46 +0000, Mike Frysinger wrote:

Comment on attachment 13
load-mmx-masks-from-stack

this load mmx masks is safe and still applicable

On 2006-01-04 22:20:24 +0000, Mike Frysinger wrote:

Comment on attachment 11
hermes-call-dont-jump

i would put this on hold as it can be solved with just a few lines of code once ELF visibility is added to nasm, so i wouldnt bother changing it now

On 2006-01-05 02:09:36 +0000, Ryan C. Gordon wrote:

hermes-cpuid is in CVS.

--ryan.

On 2006-01-05 02:13:17 +0000, Ryan C. Gordon wrote:

Comment on attachment 12
hermes-cpuid

(Tagging cpuid patch as obsolete so I know it's done with.)

--ryan.

On 2006-01-05 02:20:37 +0000, Ryan C. Gordon wrote:

Comment on attachment 14
SDL_stretch-PIC

SDL_stretch patch is in CVS now.

--ryan.

On 2006-01-05 02:26:09 +0000, Ryan C. Gordon wrote:

Mike,

In the mmx-masks-from-stack patch:

Why was this a problem:
movq mm6, qword [mmx32_rgb888_mask]

But this one in _ConvertMMXpII32_16RGB555 wasn't:
movq mm7,qword [mmx32_rgb555_mul]

(and a few others)

--ryan.

On 2006-01-05 09:35:35 +0000, Mike Frysinger wrote:

Created attachment 17
libsdl-1.2.9-PIC-load-mmx-masks-from-stack.patch

hrm, it looks like in my original e-mail i attached two patches named the samething ... the first one was incomplete and is the one you see here

here is the "full" version :)

On 2006-01-05 10:25:48 +0000, Ryan C. Gordon wrote:

Comment on attachment 17
libsdl-1.2.9-PIC-load-mmx-masks-from-stack.patch

MMX patch is in CVS now.

--ryan.

On 2006-01-05 10:26:17 +0000, Ryan C. Gordon wrote:

Look at that, we're out of patches! :)

I'm resolving this bug now.

Thanks, Mike!

--ryan.

On 2006-01-05 10:54:34 +0000, Mike Frysinger wrote:

awesome ... i'll file a new bug for the other issue once i can get the nasm guys to wake up

On 2006-01-27 11:23:03 +0000, Ryan C. Gordon wrote:

Setting Sam as "QA Contact" on all bugs (even resolved ones) so he'll definitely be in the loop to any further discussion here about SDL.

--ryan.

On 2007-03-19 15:19:55 +0000, Ryan C. Gordon wrote:

*** Bug 418 has been marked as a duplicate of this bug. ***