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2008-04-17x86, tracing: add notrace to asm-x86/linkage.hIngo Molnar
notrace signals that a function should not be traced. Most of the time this is used by tracers to annotate code that cannot be traced - it's in a volatile state (such as in user vdso context or NMI context) or it's in the tracer internals. Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-04-10Add commentary about the new "asmlinkage_protect()" macroLinus Torvalds
It's really a pretty ugly thing to need, and some day it will hopefully be obviated by teaching gcc about the magic calling conventions for the low-level system call code, but in the meantime we can at least add big honking comments about why we need these insane and strange macros. I took my comments from my version of the macro, but I ended up deciding to just pick Roland's version of the actual code instead (with his prettier syntax that uses vararg macros). Thus the previous two commits that actually implement it. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-10asmlinkage_protect replaces prevent_tail_callRoland McGrath
The prevent_tail_call() macro works around the problem of the compiler clobbering argument words on the stack, which for asmlinkage functions is the caller's (user's) struct pt_regs. The tail/sibling-call optimization is not the only way that the compiler can decide to use stack argument words as scratch space, which we have to prevent. Other optimizations can do it too. Until we have new compiler support to make "asmlinkage" binding on the compiler's own use of the stack argument frame, we have work around all the manifestations of this issue that crop up. More cases seem to be prevented by also keeping the incoming argument variables live at the end of the function. This makes their original stack slots attractive places to leave those variables, so the compiler tends not clobber them for something else. It's still no guarantee, but it handles some observed cases that prevent_tail_call() did not. Signed-off-by: Roland McGrath <roland@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-01-30x86: fix UML and -regparm=3Ingo Molnar
introduce the "asmregparm" calling convention: for functions implemented in assembly with a fixed regparm input parameters calling convention. mark the semaphore and rwsem slowpath functions with that. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30x86: unify include/asm-x86/linkage_[32|64].hHarvey Harrison
Remove definitions of FASTCALL/fastcall from linkage_32 as compiled with -regparm=3 by default since 2.6.20 and should no longer be needed. CONFIG X86_64 and CONFIG_X86_ALIGNMENT_16 are mutually exclusive as found in Kconfig.cpu so it should be fine to test them separately. Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2007-10-11i386/x86_64: move headers to include/asm-x86Thomas Gleixner
Move the headers to include/asm-x86 and fixup the header install make rules Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>