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2008-04-24[POWERPC] Fix kernel stack allocation alignmentBenjamin Herrenschmidt
The powerpc kernel stacks need to be naturally aligned, as they contain the thread info at the bottom, which is obtained by clearing the low bits of the stack pointer. However, when using 64K pages, the stack is smaller than a page, so we use kmalloc to allocate it, but that doesn't provide the alignment guarantee we need. It appeared to work so far... until one enables SLUB debugging which then returns unaligned pointers. Ooops... This fixes it by using a slab cache with enforced alignment. It relies on my previous patch that adds a thread_info_cache_init() callback. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Acked-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Paul Mackerras <paulus@samba.org>
2007-07-31remove unused TIF_NOTIFY_RESUME flagStephane Eranian
Remove unused TIF_NOTIFY_RESUME flag for all processor architectures. The flag was not used excecpt on IA-64 where the patch replaces it with TIF_PERFMON_WORK. Signed-off-by: stephane eranian <eranian@hpl.hp.com> Cc: <linux-arch@vger.kernel.org> Cc: "Luck, Tony" <tony.luck@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-06-14[POWERPC] Reserve threadinfo flags for perfmon2Anton Blanchard
Reserve two TIF flags for perfmon2 and shift them into the low 16 bits so we can use single assembly instructions to create constants based off them. Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-12-13[PATCH] PM: Fix SMP races in the freezerRafael J. Wysocki
Currently, to tell a task that it should go to the refrigerator, we set the PF_FREEZE flag for it and send a fake signal to it. Unfortunately there are two SMP-related problems with this approach. First, a task running on another CPU may be updating its flags while the freezer attempts to set PF_FREEZE for it and this may leave the task's flags in an inconsistent state. Second, there is a potential race between freeze_process() and refrigerator() in which freeze_process() running on one CPU is reading a task's PF_FREEZE flag while refrigerator() running on another CPU has just set PF_FROZEN for the same task and attempts to reset PF_FREEZE for it. If the refrigerator wins the race, freeze_process() will state that PF_FREEZE hasn't been set for the task and will set it unnecessarily, so the task will go to the refrigerator once again after it's been thawed. To solve first of these problems we need to stop using PF_FREEZE to tell tasks that they should go to the refrigerator. Instead, we can introduce a special TIF_*** flag and use it for this purpose, since it is allowed to change the other tasks' TIF_*** flags and there are special calls for it. To avoid the freeze_process()-refrigerator() race we can make freeze_process() to always check the task's PF_FROZEN flag after it's read its "freeze" flag. We should also make sure that refrigerator() will always reset the task's "freeze" flag after it's set PF_FROZEN for it. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Acked-by: Pavel Machek <pavel@ucw.cz> Cc: Russell King <rmk@arm.linux.org.uk> Cc: David Howells <dhowells@redhat.com> Cc: Andi Kleen <ak@muc.de> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Mundt <lethal@linux-sh.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-04-26Don't include linux/config.h from anywhere else in include/David Woodhouse
Signed-off-by: David Woodhouse <dwmw2@infradead.org>
2006-04-18powerpc: Use correct sequence for putting CPU into nap modePaul Mackerras
We weren't using the recommended sequence for putting the CPU into nap mode. When I changed the idle loop, for some reason 7447A cpus started hanging when we put them into nap mode. Changing to the recommended sequence fixes that. The complexity here is that the recommended sequence is a loop that keeps putting the cpu back into nap mode. Clearly we need some way to break out of the loop when an interrupt (external interrupt, decrementer, performance monitor) occurs. Here we use a bit in the thread_info struct to indicate that we need this, and the exception entry code notices this and arranges for the exception to return to the value in the link register, thus breaking out of the loop. We use a new `local_flags' field in the thread_info which we can alter without needing to use an atomic update sequence. The PPC970 has the same recommended sequence, so we do the same thing there too. This also fixes a bug in the kernel stack overflow handling code on 32-bit, since it was causing a value that we needed in a register to get trashed. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-03-08powerpc: Fix various syscall/signal/swapcontext bugsPaul Mackerras
A careful reading of the recent changes to the system call entry/exit paths revealed several problems, plus some things that could be simplified and improved: * 32-bit wasn't testing the _TIF_NOERROR bit in the syscall fast exit path, so it was only doing anything with it once it saw some other bit being set. In other words, the noerror behaviour would apply to the next system call where we had to reschedule or deliver a signal, which is not necessarily the current system call. * 32-bit wasn't doing the call to ptrace_notify in the syscall exit path when the _TIF_SINGLESTEP bit was set. * _TIF_RESTOREALL was in both _TIF_USER_WORK_MASK and _TIF_PERSYSCALL_MASK, which is odd since _TIF_RESTOREALL is only set by system calls. I took it out of _TIF_USER_WORK_MASK. * On 64-bit, _TIF_RESTOREALL wasn't causing the non-volatile registers to be restored (unless perhaps a signal was delivered or the syscall was traced or single-stepped). Thus the non-volatile registers weren't restored on exit from a signal handler. We probably got away with it mostly because signal handlers written in C wouldn't alter the non-volatile registers. * On 32-bit I simplified the code and made it more like 64-bit by making the syscall exit path jump to ret_from_except to handle preemption and signal delivery. * 32-bit was calling do_signal unnecessarily when _TIF_RESTOREALL was set - but I think because of that 32-bit was actually restoring the non-volatile registers on exit from a signal handler. * I changed the order of enabling interrupts and saving the non-volatile registers before calling do_syscall_trace_leave; now we enable interrupts first. Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-02-24[PATCH] powerpc: Fix runlatch performance issuesAnton Blanchard
The runlatch SPR can take a lot of time to write. My original runlatch code would set it on every exception entry even though most of the time this was not required. It would also continually set it in the idle loop, which is an issue on an SMT capable processor. Now we cache the runlatch value in a threadinfo bit, and only check for it in decrementer and hardware interrupt exceptions as well as the idle loop. Boot on POWER3, POWER5 and iseries, and compile tested on pmac32. Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Paul Mackerras <paulus@samba.org>
2006-02-08[PATCH] __user annotations in powerpc thread_infoAl Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2006-01-18[PATCH] TIF_RESTORE_SIGMASK support for arch/powerpcDavid Woodhouse
Implement the TIF_RESTORE_SIGMASK flag in the new arch/powerpc kernel, for both 32-bit and 64-bit system call paths. Signed-off-by: David Woodhouse <dwmw2@infradead.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-12[PATCH] death of get_thread_info/put_thread_infoAl Viro
{get,put}_thread_info() were introduced in 2.5.4 and never had been called by anything in the tree. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-09[PATCH] syscall entry/exit revampDavid Woodhouse
This cleanup patch speeds up the null syscall path on ppc64 by about 3%, and brings the ppc32 and ppc64 code slightly closer together. The ppc64 code was checking current_thread_info()->flags twice in the syscall exit path; once for TIF_SYSCALL_T_OR_A before disabling interrupts, and then again for TIF_SIGPENDING|TIF_NEED_RESCHED etc after disabling interrupts. Now we do the same as ppc32 -- check the flags only once in the fast path, and re-enable interrupts if necessary in the ptrace case. The patch abolishes the 'syscall_noerror' member of struct thread_info and replaces it with a TIF_NOERROR bit in the flags, which is handled in the slow path. This shortens the syscall entry code, which no longer needs to clear syscall_noerror. The patch adds a TIF_SAVE_NVGPRS flag which causes the syscall exit slow path to save the non-volatile GPRs into a signal frame. This removes the need for the assembly wrappers around sys_sigsuspend(), sys_rt_sigsuspend(), et al which existed solely to save those registers in advance. It also means I don't have to add new wrappers for ppoll() and pselect(), which is what I was supposed to be doing when I got distracted into this... Finally, it unifies the ppc64 and ppc32 methods of handling syscall exit directly into a signal handler (as required by sigsuspend et al) by introducing a TIF_RESTOREALL flag which causes _all_ the registers to be reloaded from the pt_regs by taking the ret_from_exception path, instead of the normal syscall exit path which stomps on the callee-saved GPRs. It appears to pass an LTP test run on ppc64, and passes basic testing on ppc32 too. Brief tests of ptrace functionality with strace and gdb also appear OK. I wouldn't send it to Linus for 2.6.15 just yet though :) Signed-off-by: David Woodhouse <dwmw2@infradead.org> Signed-off-by: Paul Mackerras <paulus@samba.org>
2005-11-06[PATCH] ppc64: support 64k pagesBenjamin Herrenschmidt
Adds a new CONFIG_PPC_64K_PAGES which, when enabled, changes the kernel base page size to 64K. The resulting kernel still boots on any hardware. On current machines with 4K pages support only, the kernel will maintain 16 "subpages" for each 64K page transparently. Note that while real 64K capable HW has been tested, the current patch will not enable it yet as such hardware is not released yet, and I'm still verifying with the firmware architects the proper to get the information from the newer hypervisors. Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-27[PATCH] powerpc: Don't use kmalloc() for kernel stacksDavid Gibson
In readiness for 64k pages, when THREAD_SIZE will be less than PAGE_SIZE, ppc64 uses kmalloc() rather than __get_free_pages() to allocate kernel stacks, and since thread_info.h was merged, so does ppc32. However that adds some overhead which we don't really want when PAGE_SIZE <= THREAD_SIZE (including all ppc32 machines), so this patch avoids it. Signed-off-by: David Gibson <dwg@au1.ibm.com> Signed-off-by: Paul Mackerras <paulus@samba.org>
2005-10-21[PATCH] powerpc: Merge thread_info.hDavid Gibson
Merge ppc32 and ppc64 versions of thread_info.h. They were pretty similar already, the chief changes are: - Instead of inline asm to implement current_thread_info(), which needs to be different for ppc32 and ppc64, we use C with an asm("r1") register variable. gcc turns it into the same asm as we used to have for both platforms. - We replace ppc32's 'local_flags' with the ppc64 'syscall_noerror' field. The noerror flag was in fact the only thing in the local_flags field anyway, so the ppc64 approach is simpler, and means we only need a load-immediate/store instead of load/mask/store when clearing the flag. - In readiness for 64k pages, when THREAD_SIZE will be less than a page, ppc64 used kmalloc() rather than get_free_pages() to allocate the kernel stack. With this patch we do the same for ppc32, since there's no strong reason not to. - For ppc64, we no longer export THREAD_SHIFT and THREAD_SIZE via asm-offsets, thread_info.h can now be safely included in asm, as on ppc32. Built and booted on G4 Powerbook (ARCH=ppc and ARCH=powerpc) and Power5 (ARCH=ppc64 and ARCH=powerpc). Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Paul Mackerras <paulus@samba.org>