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* asmlinkage_protect replaces prevent_tail_callRoland McGrath2008-04-10
| | | | | | | | | | | | | | | | | | | | | | 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>
* x86: tls prevent_tail_callRoland McGrath2008-02-29
| | | | | | | | | | | | | | Fix a kernel bug (vmware boot problem) reported by Tomasz Grobelny, which occurs with certain .config variants and gccs. The x86 TLS cleanup in commit efd1ca52d04d2f6df337a3332cee56cd60e6d4c4 made the sys_set_thread_area and sys_get_thread_area functions ripe for tail call optimization. If the compiler chooses to use it for them, it can clobber the user trap frame because these are asmlinkage functions. Reported-by: Tomasz Grobelny <tomasz@grobelny.oswiecenia.net> Signed-off-by: Roland McGrath <roland@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* x86: x86 user_regset TLSRoland McGrath2008-01-30
| | | | | | | | This adds accessor functions in the user_regset style for the TLS data. Signed-off-by: Roland McGrath <roland@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* x86: x86 TLS desc_struct cleanupRoland McGrath2008-01-30
| | | | | | | | | This cleans up the TLS code to use struct desc_struct and to separate the encoding and installation magic from the interface wrappers. Signed-off-by: Roland McGrath <roland@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* x86: modify get_desc_baseGlauber de Oliveira Costa2008-01-30
| | | | | | | | | | | This patch makes get_desc_base() receive a struct desc_struct, and then uses its internal fields to compute the base address. This is done at both i386 and x86_64, and then it is moved to common header Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* x86: introduce fill_ldtGlauber de Oliveira Costa2008-01-30
| | | | | | | | | | This patch introduces fill_ldt(), which populates a ldt descriptor from a user_desc in once, instead of relying in the LDT_entry_a and LDT_entry_b macros Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* x86: TLS cleanupRoland McGrath2008-01-30
| | | | | | | | | | | | | This consolidates the four different places that implemented the same encoding magic for the GDT-slot 32-bit TLS support. The old tls32.c was renamed and is now only slightly modified to be the shared implementation. Signed-off-by: Roland McGrath <roland@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Zachary Amsden <zach@vmware.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
* x86: tls32 movedRoland McGrath2008-01-30
This renames arch/x86/ia32/tls32.c to arch/x86/kernel/tls.c, which does nothing now but paves the way to consolidate this code for 32-bit too. Signed-off-by: Roland McGrath <roland@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Zachary Amsden <zach@vmware.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>