* [PATCH] make gcc -O1 in fs/reiserfs optional @ 2005-04-26 21:10 Olaf Hering 2005-04-26 21:46 ` Jeff Mahoney 2005-04-27 13:40 ` Hans Reiser 0 siblings, 2 replies; 8+ messages in thread From: Olaf Hering @ 2005-04-26 21:10 UTC (permalink / raw) To: Jeff Mahoney; +Cc: linuxppc-dev, reiserfs-dev Jeff, you added this EXTRA_CFLAGS= during 2.4 development, I think the broken compiler was gcc 3.2 on SLES8. Can we turn this -O1 into a .config option? Signed-off-by: Olaf Hering <olh@suse.de> Index: linux-2.6.12-rc3-olh/fs/reiserfs/Makefile =================================================================== --- linux-2.6.12-rc3-olh.orig/fs/reiserfs/Makefile +++ linux-2.6.12-rc3-olh/fs/reiserfs/Makefile @@ -21,13 +21,7 @@ ifeq ($(CONFIG_REISERFS_FS_POSIX_ACL),y) reiserfs-objs += xattr_acl.o endif -# gcc -O2 (the kernel default) is overaggressive on ppc32 when many inline -# functions are used. This causes the compiler to advance the stack -# pointer out of the available stack space, corrupting kernel space, -# and causing a panic. Since this behavior only affects ppc32, this ifeq -# will work around it. If any other architecture displays this behavior, -# add it here. -ifeq ($(CONFIG_PPC32),y) +ifeq ($(CONFIG_REISERFS_CC_REDUCE_OPTIMZE),y) EXTRA_CFLAGS := -O1 endif Index: linux-2.6.12-rc3-olh/fs/Kconfig =================================================================== --- linux-2.6.12-rc3-olh.orig/fs/Kconfig +++ linux-2.6.12-rc3-olh/fs/Kconfig @@ -186,6 +186,18 @@ config REISERFS_FS If you like it, you can pay us to add new features to it that you need, buy a support contract, or pay us to port it to another OS. +config REISERFS_CC_REDUCE_OPTIMZE + bool "Reduce CC optimization level to workaround compiler bugs" + depends on PPC32 + default n + help + gcc -O2 (the kernel default) is overaggressive on ppc32 when many inline + functions are used. This causes the compiler to advance the stack + pointer out of the available stack space, corrupting kernel space, + and causing a panic. Since this behavior only affects ppc32, this ifeq + will work around it. If any other architecture displays this behavior, + add it here. + config REISERFS_CHECK bool "Enable reiserfs debug mode" depends on REISERFS_FS ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] make gcc -O1 in fs/reiserfs optional 2005-04-26 21:10 [PATCH] make gcc -O1 in fs/reiserfs optional Olaf Hering @ 2005-04-26 21:46 ` Jeff Mahoney 2005-04-27 13:40 ` Hans Reiser 1 sibling, 0 replies; 8+ messages in thread From: Jeff Mahoney @ 2005-04-26 21:46 UTC (permalink / raw) To: Olaf Hering; +Cc: linuxppc-dev, reiserfs-dev Olaf Hering wrote: > Jeff, > > you added this EXTRA_CFLAGS= during 2.4 development, I think the broken > compiler was gcc 3.2 on SLES8. Can we turn this -O1 into a .config > option? Hi Olaf - Yeah, the initial problem was that the anti aliasing[*] code when -O2 was enabled was being way too cautious and ended up allocating something like 6k on the stack in do_balance(). It was observable elsewhere, but not so problematic. My ppc box isn't booting right now. If you've verified that newer versions of the compiler don't blow the stack in do_balance(), I'm not opposed to it. -Jeff [*]: I think that's the right term - I'm not a compiler developer :) -- Jeff Mahoney SuSE Labs ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] make gcc -O1 in fs/reiserfs optional 2005-04-26 21:10 [PATCH] make gcc -O1 in fs/reiserfs optional Olaf Hering 2005-04-26 21:46 ` Jeff Mahoney @ 2005-04-27 13:40 ` Hans Reiser 2005-10-11 19:01 ` Olaf Hering 1 sibling, 1 reply; 8+ messages in thread From: Hans Reiser @ 2005-04-27 13:40 UTC (permalink / raw) To: Olaf Hering; +Cc: linuxppc-dev, reiserfs-dev, Jeff Mahoney Olaf Hering wrote: >Jeff, > >you added this EXTRA_CFLAGS= during 2.4 development, I think the broken >compiler was gcc 3.2 on SLES8. Can we turn this -O1 into a .config >option? > > >Signed-off-by: Olaf Hering <olh@suse.de> > >Index: linux-2.6.12-rc3-olh/fs/reiserfs/Makefile >=================================================================== >--- linux-2.6.12-rc3-olh.orig/fs/reiserfs/Makefile >+++ linux-2.6.12-rc3-olh/fs/reiserfs/Makefile >@@ -21,13 +21,7 @@ ifeq ($(CONFIG_REISERFS_FS_POSIX_ACL),y) > reiserfs-objs += xattr_acl.o > endif > >-# gcc -O2 (the kernel default) is overaggressive on ppc32 when many inline >-# functions are used. This causes the compiler to advance the stack >-# pointer out of the available stack space, corrupting kernel space, >-# and causing a panic. Since this behavior only affects ppc32, this ifeq >-# will work around it. If any other architecture displays this behavior, >-# add it here. >-ifeq ($(CONFIG_PPC32),y) >+ifeq ($(CONFIG_REISERFS_CC_REDUCE_OPTIMZE),y) > EXTRA_CFLAGS := -O1 > endif > >Index: linux-2.6.12-rc3-olh/fs/Kconfig >=================================================================== >--- linux-2.6.12-rc3-olh.orig/fs/Kconfig >+++ linux-2.6.12-rc3-olh/fs/Kconfig >@@ -186,6 +186,18 @@ config REISERFS_FS > If you like it, you can pay us to add new features to it that you > need, buy a support contract, or pay us to port it to another OS. > >+config REISERFS_CC_REDUCE_OPTIMZE >+ bool "Reduce CC optimization level to workaround compiler bugs" >+ depends on PPC32 >+ default n >+ help >+ gcc -O2 (the kernel default) is overaggressive on ppc32 when many inline >+ functions are used. This causes the compiler to advance the stack >+ pointer out of the available stack space, corrupting kernel space, >+ and causing a panic. Since this behavior only affects ppc32, this ifeq >+ will work around it. If any other architecture displays this behavior, >+ add it here. >+ > config REISERFS_CHECK > bool "Enable reiserfs debug mode" > depends on REISERFS_FS > > > > Sounds reasonable. ^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH] make gcc -O1 in fs/reiserfs optional 2005-04-27 13:40 ` Hans Reiser @ 2005-10-11 19:01 ` Olaf Hering 2005-10-11 20:04 ` Hans Reiser ` (2 more replies) 0 siblings, 3 replies; 8+ messages in thread From: Olaf Hering @ 2005-10-11 19:01 UTC (permalink / raw) To: Hans Reiser, Andrew Morton; +Cc: linuxppc-dev, reiserfs-dev, Jeff Mahoney On Wed, Apr 27, Hans Reiser wrote: > Olaf Hering wrote: > > >Jeff, > > > >you added this EXTRA_CFLAGS= during 2.4 development, I think the broken > >compiler was gcc 3.2 on SLES8. Can we turn this -O1 into a .config > >option? > Sounds reasonable. only compile with -O1 if the (very old) compiler is broken We use reiserfs alot in SLES9 on ppc64, and it was never seen with gcc33. Signed-off-by: Olaf Hering <olh@suse.de> Index: linux-2.6.12-rc3-olh/fs/reiserfs/Makefile =================================================================== --- linux-2.6.12-rc3-olh.orig/fs/reiserfs/Makefile +++ linux-2.6.12-rc3-olh/fs/reiserfs/Makefile @@ -21,13 +21,7 @@ ifeq ($(CONFIG_REISERFS_FS_POSIX_ACL),y) reiserfs-objs += xattr_acl.o endif -# gcc -O2 (the kernel default) is overaggressive on ppc32 when many inline -# functions are used. This causes the compiler to advance the stack -# pointer out of the available stack space, corrupting kernel space, -# and causing a panic. Since this behavior only affects ppc32, this ifeq -# will work around it. If any other architecture displays this behavior, -# add it here. -ifeq ($(CONFIG_PPC32),y) +ifeq ($(CONFIG_REISERFS_CC_REDUCE_OPTIMZE),y) EXTRA_CFLAGS := -O1 endif Index: linux-2.6.12-rc3-olh/fs/Kconfig =================================================================== --- linux-2.6.12-rc3-olh.orig/fs/Kconfig +++ linux-2.6.12-rc3-olh/fs/Kconfig @@ -186,6 +186,18 @@ config REISERFS_FS If you like it, you can pay us to add new features to it that you need, buy a support contract, or pay us to port it to another OS. +config REISERFS_CC_REDUCE_OPTIMZE + bool "Reduce CC optimization level to workaround compiler bugs" + depends on PPC32 + default n + help + gcc -O2 (the kernel default) is overaggressive on ppc32 when many inline + functions are used. This causes the compiler to advance the stack + pointer out of the available stack space, corrupting kernel space, + and causing a panic. Since this behavior only affects ppc32, this ifeq + will work around it. If any other architecture displays this behavior, + add it here. + config REISERFS_CHECK bool "Enable reiserfs debug mode" depends on REISERFS_FS -- short story of a lazy sysadmin: alias appserv=wotan ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] make gcc -O1 in fs/reiserfs optional 2005-10-11 19:01 ` Olaf Hering @ 2005-10-11 20:04 ` Hans Reiser 2005-10-13 23:27 ` Andrew Morton 2006-07-24 6:52 ` [PATCH] use gcc -O1 in fs/reiserfs only for ancient gcc versions Olaf Hering 2 siblings, 0 replies; 8+ messages in thread From: Hans Reiser @ 2005-10-11 20:04 UTC (permalink / raw) To: Olaf Hering; +Cc: Andrew Morton, linuxppc-dev, reiserfs-dev, Jeff Mahoney Sounds good to me. Thanks Olaf! Hans Olaf Hering wrote: > On Wed, Apr 27, Hans Reiser wrote: > > > >>Olaf Hering wrote: >> >> >> >>>Jeff, >>> >>>you added this EXTRA_CFLAGS= during 2.4 development, I think the broken >>>compiler was gcc 3.2 on SLES8. Can we turn this -O1 into a .config >>>option? >>> >>> > > > >>Sounds reasonable. >> >> > > only compile with -O1 if the (very old) compiler is broken > We use reiserfs alot in SLES9 on ppc64, and it was never seen > with gcc33. > >Signed-off-by: Olaf Hering <olh@suse.de> > >Index: linux-2.6.12-rc3-olh/fs/reiserfs/Makefile >=================================================================== >--- linux-2.6.12-rc3-olh.orig/fs/reiserfs/Makefile >+++ linux-2.6.12-rc3-olh/fs/reiserfs/Makefile >@@ -21,13 +21,7 @@ ifeq ($(CONFIG_REISERFS_FS_POSIX_ACL),y) > reiserfs-objs += xattr_acl.o > endif > >-# gcc -O2 (the kernel default) is overaggressive on ppc32 when many inline >-# functions are used. This causes the compiler to advance the stack >-# pointer out of the available stack space, corrupting kernel space, >-# and causing a panic. Since this behavior only affects ppc32, this ifeq >-# will work around it. If any other architecture displays this behavior, >-# add it here. >-ifeq ($(CONFIG_PPC32),y) >+ifeq ($(CONFIG_REISERFS_CC_REDUCE_OPTIMZE),y) > EXTRA_CFLAGS := -O1 > endif > >Index: linux-2.6.12-rc3-olh/fs/Kconfig >=================================================================== >--- linux-2.6.12-rc3-olh.orig/fs/Kconfig >+++ linux-2.6.12-rc3-olh/fs/Kconfig >@@ -186,6 +186,18 @@ config REISERFS_FS > If you like it, you can pay us to add new features to it that you > need, buy a support contract, or pay us to port it to another OS. > >+config REISERFS_CC_REDUCE_OPTIMZE >+ bool "Reduce CC optimization level to workaround compiler bugs" >+ depends on PPC32 >+ default n >+ help >+ gcc -O2 (the kernel default) is overaggressive on ppc32 when many inline >+ functions are used. This causes the compiler to advance the stack >+ pointer out of the available stack space, corrupting kernel space, >+ and causing a panic. Since this behavior only affects ppc32, this ifeq >+ will work around it. If any other architecture displays this behavior, >+ add it here. >+ > config REISERFS_CHECK > bool "Enable reiserfs debug mode" > depends on REISERFS_FS > > ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] make gcc -O1 in fs/reiserfs optional 2005-10-11 19:01 ` Olaf Hering 2005-10-11 20:04 ` Hans Reiser @ 2005-10-13 23:27 ` Andrew Morton 2005-10-14 1:17 ` Jeff Mahoney 2006-07-24 6:52 ` [PATCH] use gcc -O1 in fs/reiserfs only for ancient gcc versions Olaf Hering 2 siblings, 1 reply; 8+ messages in thread From: Andrew Morton @ 2005-10-13 23:27 UTC (permalink / raw) To: Olaf Hering; +Cc: linuxppc-dev, reiserfs-dev, reiser, jeffm Olaf Hering <olh@suse.de> wrote: > > On Wed, Apr 27, Hans Reiser wrote: > > > Olaf Hering wrote: > > > > >Jeff, > > > > > >you added this EXTRA_CFLAGS= during 2.4 development, I think the broken > > >compiler was gcc 3.2 on SLES8. Can we turn this -O1 into a .config > > >option? > > > Sounds reasonable. > > only compile with -O1 if the (very old) compiler is broken > We use reiserfs alot in SLES9 on ppc64, and it was never seen > with gcc33. > I dunno about this. > > Index: linux-2.6.12-rc3-olh/fs/reiserfs/Makefile > =================================================================== > --- linux-2.6.12-rc3-olh.orig/fs/reiserfs/Makefile > +++ linux-2.6.12-rc3-olh/fs/reiserfs/Makefile > @@ -21,13 +21,7 @@ ifeq ($(CONFIG_REISERFS_FS_POSIX_ACL),y) > reiserfs-objs += xattr_acl.o > endif > > -# gcc -O2 (the kernel default) is overaggressive on ppc32 when many inline > -# functions are used. This causes the compiler to advance the stack > -# pointer out of the available stack space, corrupting kernel space, > -# and causing a panic. Since this behavior only affects ppc32, this ifeq > -# will work around it. If any other architecture displays this behavior, > -# add it here. > -ifeq ($(CONFIG_PPC32),y) > +ifeq ($(CONFIG_REISERFS_CC_REDUCE_OPTIMZE),y) > EXTRA_CFLAGS := -O1 > endif > > Index: linux-2.6.12-rc3-olh/fs/Kconfig > =================================================================== > --- linux-2.6.12-rc3-olh.orig/fs/Kconfig > +++ linux-2.6.12-rc3-olh/fs/Kconfig > @@ -186,6 +186,18 @@ config REISERFS_FS > If you like it, you can pay us to add new features to it that you > need, buy a support contract, or pay us to port it to another OS. > > +config REISERFS_CC_REDUCE_OPTIMZE > + bool "Reduce CC optimization level to workaround compiler bugs" > + depends on PPC32 > + default n > + help > + gcc -O2 (the kernel default) is overaggressive on ppc32 when many inline > + functions are used. This causes the compiler to advance the stack > + pointer out of the available stack space, corrupting kernel space, > + and causing a panic. Since this behavior only affects ppc32, this ifeq > + will work around it. If any other architecture displays this behavior, > + add it here. > + Are you sure it's due to inline functions? I thought the problem was that certain versions of gcc did automatic inlining of non-inlined functions and we get excessive stack windup due to that. And iirc we put in global compiler options to defeat that behaviour. Andi would recall. Furthermore, we do have infrastructure for detecting the gcc version at build time. It would be better to use that for disabling `-O2', rather than a config option. ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] make gcc -O1 in fs/reiserfs optional 2005-10-13 23:27 ` Andrew Morton @ 2005-10-14 1:17 ` Jeff Mahoney 0 siblings, 0 replies; 8+ messages in thread From: Jeff Mahoney @ 2005-10-14 1:17 UTC (permalink / raw) To: Andrew Morton; +Cc: linuxppc-dev, reiserfs-dev, reiser, Olaf Hering Andrew Morton wrote: > Are you sure it's due to inline functions? I thought the problem was that > certain versions of gcc did automatic inlining of non-inlined functions and > we get excessive stack windup due to that. And iirc we put in global > compiler options to defeat that behaviour. Andi would recall. > > Furthermore, we do have infrastructure for detecting the gcc version at > build time. It would be better to use that for disabling `-O2', rather > than a config option. Andrew - This "fix" has been in the kernel since I developed the endian safe patches for ReiserFS in the 2.4 days; This patch just makes it optional rather than required. You could be correct regarding the behavior. I noticed it was related to inline functions and stack usage. Since this was quite a few years ago now, I don't recall the exact details, just that -O1 worked around it. I was content blaming gcc and moving on with development. I seem to recall thinking that was overaggressive aliasing avoidance between temporary variables in static inline functions. The endian safe code frequently uses static inlines for conversion of disk order bitfields (like key type and offset). balance_leaf() is a beast of a function at around 1400 lines or so. When compiled with -O2, it wanted to allocate 6k of stack space. With -O1, it ended up allocating about 230 bytes. It seemed to be the only function really affected by the bug, but I wanted to be certain. I do agree that using the kbuild infrastructure to determine the need for this option would work quite a bit better. -Jeff -- Jeff Mahoney SUSE Labs ^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH] use gcc -O1 in fs/reiserfs only for ancient gcc versions 2005-10-11 19:01 ` Olaf Hering 2005-10-11 20:04 ` Hans Reiser 2005-10-13 23:27 ` Andrew Morton @ 2006-07-24 6:52 ` Olaf Hering 2 siblings, 0 replies; 8+ messages in thread From: Olaf Hering @ 2006-07-24 6:52 UTC (permalink / raw) To: Andrew Morton; +Cc: linuxppc-dev, reiserfs-dev only compile with -O1 if the (very old) compiler is broken. We use reiserfs alot since SLES9 on ppc64, and it was never seen with gcc33. Assume the broken gcc is gcc-3.4 or older. Signed-off-by: Olaf Hering <olh@suse.de> --- fs/reiserfs/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) Index: linux-2.6.18-rc2/fs/reiserfs/Makefile =================================================================== --- linux-2.6.18-rc2.orig/fs/reiserfs/Makefile +++ linux-2.6.18-rc2/fs/reiserfs/Makefile @@ -28,7 +28,7 @@ endif # will work around it. If any other architecture displays this behavior, # add it here. ifeq ($(CONFIG_PPC32),y) -EXTRA_CFLAGS := -O1 +EXTRA_CFLAGS := $(call cc-ifversion, -lt, 0400, -O1) endif TAGS: ^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2006-07-24 6:52 UTC | newest] Thread overview: 8+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2005-04-26 21:10 [PATCH] make gcc -O1 in fs/reiserfs optional Olaf Hering 2005-04-26 21:46 ` Jeff Mahoney 2005-04-27 13:40 ` Hans Reiser 2005-10-11 19:01 ` Olaf Hering 2005-10-11 20:04 ` Hans Reiser 2005-10-13 23:27 ` Andrew Morton 2005-10-14 1:17 ` Jeff Mahoney 2006-07-24 6:52 ` [PATCH] use gcc -O1 in fs/reiserfs only for ancient gcc versions Olaf Hering
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