linux/include/asm-powerpc/current.h, branch v2.6.19

[POWERPC] Make current preempt-safe

2006-11-01T03:52:48Z

Repeated -j20 kernel builds on a G5 Quad running an SMP PREEMPT kernel would often collapse within a day, some exec failing with "Bad address". In each case examined, load_elf_binary was doing a kernel_read, but generic_file_aio_read's access_ok saw current->thread.fs.seg as USER_DS instead of KERNEL_DS. objdump of filemap.o shows gcc 4.1.0 emitting "mr r5,r13 ... ld r9,416(r5)" here for get_paca()->__current, instead of the expected and much more usual "ld r9,416(r13)"; I've seen other gcc4s do the same, but perhaps not gcc3s. So, if the task is preempted and rescheduled on a different cpu in between the mr and the ld, r5 will be looking at a different paca_struct from the one it's now on, pick up the wrong __current, and perhaps the wrong seg. Presumably much worse could happen elsewhere, though that split is rare. Other architectures appear to be safe (x86_64's read_pda is more limiting than get_paca), but ppc64 needs to force "current" into one instruction. Signed-off-by: Hugh Dickins Signed-off-by: Paul Mackerras

[PATCH] powerpc: sanitize header files for user space includes

2006-01-09T04:13:08Z

include/asm-ppc/ had #ifdef __KERNEL__ in all header files that are not meant for use by user space, include/asm-powerpc does not have this yet. This patch gets us a lot closer there. There are a few cases where I was not sure, so I left them out. I have verified that no CONFIG_* symbols are used outside of __KERNEL__ any more and that there are no obvious compile errors when including any of the headers in user space libraries. Signed-off-by: Arnd Bergmann Signed-off-by: Paul Mackerras

[PATCH] powerpc: Merge current.h

2005-11-10T00:23:53Z

This patch merges current.h. This is a one-big-ifdef merge, but both versions are so tiny, I think we can live with it. While we're at it, we get rid of the fairly pointless redirection through get_current() in the ppc64 version. Built and booted on POWER5 LPAR (ARCH=powerpc & ARCH=ppc64). Built for 32-bit pmac (ARCH=powerpc & ARCH=ppc). Signed-off-by: David Gibson Signed-off-by: Paul Mackerras