kernel.git/arch/x86/kernel/process_32.c, branch linux-2.6.30.y

Simplify copy_thread()

2009-04-03T02:04:51Z

First argument unused since 2.3.11. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Alexey Dobriyan Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

x86: unify chunks of kernel/process*.c

2009-03-02T11:07:48Z

With x86-32 and -64 using the same mechanism for managing the tss io permissions bitmap, large chunks of process*.c are trivially unifyable, including: - exit_thread - flush_thread - __switch_to_xtra (along with tsc enable/disable) and as bonus pickups: - sys_fork - sys_vfork (Note: asmlinkage expands to empty on x86-64) Signed-off-by: Jeremy Fitzhardinge Signed-off-by: Ingo Molnar

x86-32: use non-lazy io bitmap context switching

2009-03-02T11:07:48Z

Impact: remove 32-bit optimization to prepare unification x86-32 and -64 differ in the way they context-switch tasks with io permission bitmaps. x86-64 simply copies the next tasks io bitmap into place (if any) on context switch. x86-32 invalidates the bitmap on context switch, so that the next IO instruction will fault; at that point it installs the appropriate IO bitmap. This makes context switching IO-bitmap-using tasks a bit more less expensive, at the cost of making the next IO instruction slower due to the extra fault. This tradeoff only makes sense if IO-bitmap-using processes are relatively common, but they don't actually use IO instructions very often. However, in a typical desktop system, the only process likely to be using IO bitmaps is the X server, and nothing at all on a server. Therefore the lazy context switch doesn't really win all that much, and its just a gratuitious difference from 64-bit code. This patch removes the lazy context switch, with a view to unifying this code in a later change. Signed-off-by: Jeremy Fitzhardinge Signed-off-by: Ingo Molnar

Merge branch 'linus' into x86/apic

2009-02-22T19:05:19Z

Conflicts: arch/x86/mach-default/setup.c Semantic conflict resolution: arch/x86/kernel/setup.c Signed-off-by: Ingo Molnar

x86, rcu: fix strange load average and ksoftirqd behavior

2009-02-17T21:47:45Z

Damien Wyart reported high ksoftirqd CPU usage (20%) on an otherwise idle system. The function-graph trace Damien provided: > 799.521187 | 1) -0 | | rcu_check_callbacks() { > 799.521371 | 1) -0 | | rcu_check_callbacks() { > 799.521555 | 1) -0 | | rcu_check_callbacks() { > 799.521738 | 1) -0 | | rcu_check_callbacks() { > 799.521934 | 1) -0 | | rcu_check_callbacks() { > 799.522068 | 1) ksoftir-2324 | | rcu_check_callbacks() { > 799.522208 | 1) -0 | | rcu_check_callbacks() { > 799.522392 | 1) -0 | | rcu_check_callbacks() { > 799.522575 | 1) -0 | | rcu_check_callbacks() { > 799.522759 | 1) -0 | | rcu_check_callbacks() { > 799.522956 | 1) -0 | | rcu_check_callbacks() { > 799.523074 | 1) ksoftir-2324 | | rcu_check_callbacks() { > 799.523214 | 1) -0 | | rcu_check_callbacks() { > 799.523397 | 1) -0 | | rcu_check_callbacks() { > 799.523579 | 1) -0 | | rcu_check_callbacks() { > 799.523762 | 1) -0 | | rcu_check_callbacks() { > 799.523960 | 1) -0 | | rcu_check_callbacks() { > 799.524079 | 1) ksoftir-2324 | | rcu_check_callbacks() { > 799.524220 | 1) -0 | | rcu_check_callbacks() { > 799.524403 | 1) -0 | | rcu_check_callbacks() { > 799.524587 | 1) -0 | | rcu_check_callbacks() { > 799.524770 | 1) -0 | | rcu_check_callbacks() { > [ . . . ] Shows rcu_check_callbacks() being invoked way too often. It should be called once per jiffy, and here it is called no less than 22 times in about 3.5 milliseconds, meaning one call every 160 microseconds or so. Why do we need to call rcu_pending() and rcu_check_callbacks() from the idle loop of 32-bit x86, especially given that no other architecture does this? The following patch removes the call to rcu_pending() and rcu_check_callbacks() from the x86 32-bit idle loop in order to reduce the softirq load on idle systems. Reported-by: Damien Wyart Signed-off-by: Paul E. McKenney Signed-off-by: Ingo Molnar

x86: use regparm(3) for passed-in pt_regs pointer

2009-02-11T22:00:56Z

Some syscalls need to access the pt_regs structure, either to copy user register state or to modifiy it. This patch adds stubs to load the address of the pt_regs struct into the %eax register, and changes the syscalls to take the pointer as an argument instead of relying on the assumption that the pt_regs structure overlaps the function arguments. Drop the use of regparm(1) due to concern about gcc bugs, and to move in the direction of the eventual removal of regparm(0) for asmlinkage. Signed-off-by: Brian Gerst Signed-off-by: H. Peter Anvin

x86: pass in pt_regs pointer for syscalls that need it

2009-02-11T11:40:45Z

Some syscalls need to access the pt_regs structure, either to copy user register state or to modifiy it. This patch adds stubs to load the address of the pt_regs struct into the %eax register, and changes the syscalls to regparm(1) to receive the pt_regs pointer as the first argument. Signed-off-by: Brian Gerst Acked-by: Tejun Heo Signed-off-by: Ingo Molnar

x86: fix x86_32 stack protector bugs

2009-02-11T10:33:49Z

Impact: fix x86_32 stack protector Brian Gerst found out that %gs was being initialized to stack_canary instead of stack_canary - 20, which basically gave the same canary value for all threads. Fixing this also exposed the following bugs. * cpu_idle() didn't call boot_init_stack_canary() * stack canary switching in switch_to() was being done too late making the initial run of a new thread use the old stack canary value. Fix all of them and while at it update comment in cpu_idle() about calling boot_init_stack_canary(). Reported-by: Brian Gerst Signed-off-by: Tejun Heo Signed-off-by: Ingo Molnar

x86: implement x86_32 stack protector

2009-02-09T23:42:01Z

Impact: stack protector for x86_32 Implement stack protector for x86_32. GDT entry 28 is used for it. It's set to point to stack_canary-20 and have the length of 24 bytes. CONFIG_CC_STACKPROTECTOR turns off CONFIG_X86_32_LAZY_GS and sets %gs to the stack canary segment on entry. As %gs is otherwise unused by the kernel, the canary can be anywhere. It's defined as a percpu variable. x86_32 exception handlers take register frame on stack directly as struct pt_regs. With -fstack-protector turned on, gcc copies the whole structure after the stack canary and (of course) doesn't copy back on return thus losing all changed. For now, -fno-stack-protector is added to all files which contain those functions. We definitely need something better. Signed-off-by: Tejun Heo Signed-off-by: Ingo Molnar

x86: make lazy %gs optional on x86_32

2009-02-09T23:42:00Z

Impact: pt_regs changed, lazy gs handling made optional, add slight overhead to SAVE_ALL, simplifies error_code path a bit On x86_32, %gs hasn't been used by kernel and handled lazily. pt_regs doesn't have place for it and gs is saved/loaded only when necessary. In preparation for stack protector support, this patch makes lazy %gs handling optional by doing the followings. * Add CONFIG_X86_32_LAZY_GS and place for gs in pt_regs. * Save and restore %gs along with other registers in entry_32.S unless LAZY_GS. Note that this unfortunately adds "pushl $0" on SAVE_ALL even when LAZY_GS. However, it adds no overhead to common exit path and simplifies entry path with error code. * Define different user_gs accessors depending on LAZY_GS and add lazy_save_gs() and lazy_load_gs() which are noop if !LAZY_GS. The lazy_*_gs() ops are used to save, load and clear %gs lazily. * Define ELF_CORE_COPY_KERNEL_REGS() which always read %gs directly. xen and lguest changes need to be verified. Signed-off-by: Tejun Heo Cc: Jeremy Fitzhardinge Cc: Rusty Russell Signed-off-by: Ingo Molnar