similar to: [PATCH 6/12] early-clobber-tss

Use an early clobber on addr to avoid the extra rorl instruction at the end of _set_tssldt_desc. Also, get some C type checking on the descriptor struct here. Patch-base: 2.6.13-rc5-mm1 Patch-keys: i386 desc cleanup optimize Signed-off-by: Zachary Amsden <zach@vmware.com> Index: linux-2.6.13/include/asm-i386/desc.h =================================================================== ---

Use an early clobber on addr to avoid the extra rorl instruction at the end of _set_tssldt_desc. Also, get some C type checking on the descriptor struct here. Patch-base: 2.6.13-rc5-mm1 Patch-keys: i386 desc cleanup optimize Signed-off-by: Zachary Amsden <zach@vmware.com> Index: linux-2.6.13/include/asm-i386/desc.h =================================================================== ---

Ancient inline assembler that manipulates descriptor tables is unreadable and has no type checking. Doing this in C actually generates better code, saves code space, and improves readability. The fact that you must cast descriptors to (char *) for the inline assembler to work properly caused me no end of grief working on these patches. Note that GCC does not generate rotations to utilize

Ancient inline assembler that manipulates descriptor tables is unreadable and has no type checking. Doing this in C actually generates better code, saves code space, and improves readability. The fact that you must cast descriptors to (char *) for the inline assembler to work properly caused me no end of grief working on these patches. Note that GCC does not generate rotations to utilize

Stop using extra underscores on asm and volatiles, that is just silly. Also, make lgdt/lidt/sgdt/sldt explicitly "l". Index: linux-2.6.13/include/asm-i386/desc.h =================================================================== --- linux-2.6.13.orig/include/asm-i386/desc.h 2005-08-08 17:10:49.000000000 -0700 +++ linux-2.6.13/include/asm-i386/desc.h 2005-08-08 17:15:46.000000000 -0700

Stop using extra underscores on asm and volatiles, that is just silly. Also, make lgdt/lidt/sgdt/sldt explicitly "l". Index: linux-2.6.13/include/asm-i386/desc.h =================================================================== --- linux-2.6.13.orig/include/asm-i386/desc.h 2005-08-08 17:10:49.000000000 -0700 +++ linux-2.6.13/include/asm-i386/desc.h 2005-08-08 17:15:46.000000000 -0700

Descriptor and trap table cleanups. Add cleanly written accessors for IDT and GDT gates so the subarch may override them. Note that this allows the hypervisor to transparently tweak the DPL of the descriptors as well as the RPL of segments in those descriptors, with no unnecessary kernel code modification. It also allows the hypervisor implementation of the VMI to tweak the gates, allowing for

Descriptor and trap table cleanups. Add cleanly written accessors for IDT and GDT gates so the subarch may override them. Note that this allows the hypervisor to transparently tweak the DPL of the descriptors as well as the RPL of segments in those descriptors, with no unnecessary kernel code modification. It also allows the hypervisor implementation of the VMI to tweak the gates, allowing for

Move base / limit accessors into desc.h, where they properly belong. Signed-off-by: Zachary Amsden <zach@vmware.com> Index: linux-2.6.13/include/asm-i386/system.h =================================================================== --- linux-2.6.13.orig/include/asm-i386/system.h 2005-08-08 17:58:03.000000000 -0700 +++ linux-2.6.13/include/asm-i386/system.h 2005-08-08 18:01:31.000000000 -0700

Move base / limit accessors into desc.h, where they properly belong. Signed-off-by: Zachary Amsden <zach@vmware.com> Index: linux-2.6.13/include/asm-i386/system.h =================================================================== --- linux-2.6.13.orig/include/asm-i386/system.h 2005-08-08 17:58:03.000000000 -0700 +++ linux-2.6.13/include/asm-i386/system.h 2005-08-08 18:01:31.000000000 -0700

Move base / limit accessors into desc.h, where they properly belong. Patch-base: 2.6.13-rc5-mm1 Patch-keys: i386 desc cleanup Signed-off-by: Zachary Amsden <zach@vmware.com> Index: linux-2.6.13/include/asm-i386/system.h =================================================================== --- linux-2.6.13.orig/include/asm-i386/system.h 2005-08-09 20:17:26.000000000 -0700 +++

Move base / limit accessors into desc.h, where they properly belong. Patch-base: 2.6.13-rc5-mm1 Patch-keys: i386 desc cleanup Signed-off-by: Zachary Amsden <zach@vmware.com> Index: linux-2.6.13/include/asm-i386/system.h =================================================================== --- linux-2.6.13.orig/include/asm-i386/system.h 2005-08-09 20:17:26.000000000 -0700 +++

Found some stray descriptor table accessors that had non-optimal assembler constraints. Use "q" to get word, high and low byte access without forcing a specific register constraint. Add desc as a memory output operand. Also, get_base was completely unused. Deprecate it. The function get_limit is also unused, but I did not deprecate it; it could be used in arch/i386/mm/fault.c.

Found some stray descriptor table accessors that had non-optimal assembler constraints. Use "q" to get word, high and low byte access without forcing a specific register constraint. Add desc as a memory output operand. Also, get_base was completely unused. Deprecate it. The function get_limit is also unused, but I did not deprecate it; it could be used in arch/i386/mm/fault.c.

Found some stray descriptor table accessors that had non-optimal assembler constraints. Use "q" to get word, high and low byte access without forcing a specific register constraint. Add desc as a memory output operand. Also, get_base was completely unused. Deprecate it. The function get_limit is also unused, but I did not deprecate it; it could be used in arch/i386/mm/fault.c.

Found some stray descriptor table accessors that had non-optimal assembler constraints. Use "q" to get word, high and low byte access without forcing a specific register constraint. Add desc as a memory output operand. Also, get_base was completely unused. Deprecate it. The function get_limit is also unused, but I did not deprecate it; it could be used in arch/i386/mm/fault.c.

Add an accessor function for getting the per-CPU gdt. Callee must already have the CPU. Signed-off-by: Zachary Amsden <zach@vmware.com> Index: linux-2.6.14-rc1/include/asm-i386/desc.h =================================================================== --- linux-2.6.14-rc1.orig/include/asm-i386/desc.h 2005-09-20 14:49:10.000000000 -0700 +++ linux-2.6.14-rc1/include/asm-i386/desc.h

Add an accessor function for getting the per-CPU gdt. Callee must already have the CPU. Signed-off-by: Zachary Amsden <zach@vmware.com> Index: linux-2.6.14-rc1/include/asm-i386/desc.h =================================================================== --- linux-2.6.14-rc1.orig/include/asm-i386/desc.h 2005-09-20 14:49:10.000000000 -0700 +++ linux-2.6.14-rc1/include/asm-i386/desc.h

I can get clang/llvm to emit a rotate instruction on x86-64 when compiling C by just using -Os and the rotate from Hacker's Delight i.e., ====== #include <stdlib.h> #include <stdint.h> uint32_t ror(uint32_t input, size_t rot_bits) { return (input >> rot_bits) | (input << ((sizeof(input) << 3) - rot_bits)); } ====== Then compile with (assuming you are on OS

Nice! Clever compiler.. On 07/28/2012 08:55 PM, Michael Gottesman wrote: > I can get clang/llvm to emit a rotate instruction on x86-64 when compiling C by just using -Os and the rotate from Hacker's Delight i.e., > > ====== > #include<stdlib.h> > #include<stdint.h> > > uint32_t ror(uint32_t input, size_t rot_bits) > { > return (input>>