]> git.proxmox.com Git - mirror_ubuntu-eoan-kernel.git/commit
x86/asm/entry: Get rid of KERNEL_STACK_OFFSET
authorDenys Vlasenko <dvlasenk@redhat.com>
Thu, 19 Mar 2015 17:17:46 +0000 (18:17 +0100)
committerIngo Molnar <mingo@kernel.org>
Tue, 24 Mar 2015 18:42:38 +0000 (19:42 +0100)
commitef593260f0cae2699874f098fb5b19fb46502cb3
tree68b114f2e6ad9413dc030a0e0960e6fd934f9942
parentb3fe8ba320ace38cee6859b4c015d81627254ddb
x86/asm/entry: Get rid of KERNEL_STACK_OFFSET

PER_CPU_VAR(kernel_stack) was set up in a way where it points
five stack slots below the top of stack.

Presumably, it was done to avoid one "sub $5*8,%rsp"
in syscall/sysenter code paths, where iret frame needs to be
created by hand.

Ironically, none of them benefits from this optimization,
since all of them need to allocate additional data on stack
(struct pt_regs), so they still have to perform subtraction.

This patch eliminates KERNEL_STACK_OFFSET.

PER_CPU_VAR(kernel_stack) now points directly to top of stack.
pt_regs allocations are adjusted to allocate iret frame as well.
Hopefully we can merge it later with 32-bit specific
PER_CPU_VAR(cpu_current_top_of_stack) variable...

Net result in generated code is that constants in several insns
are changed.

This change is necessary for changing struct pt_regs creation
in SYSCALL64 code path from MOV to PUSH instructions.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
Acked-by: Borislav Petkov <bp@suse.de>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: Alexei Starovoitov <ast@plumgrid.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Will Drewry <wad@chromium.org>
Link: http://lkml.kernel.org/r/1426785469-15125-2-git-send-email-dvlasenk@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
arch/x86/ia32/ia32entry.S
arch/x86/include/asm/thread_info.h
arch/x86/kernel/cpu/common.c
arch/x86/kernel/entry_64.S
arch/x86/kernel/process_32.c
arch/x86/kernel/process_64.c
arch/x86/kernel/smpboot.c
arch/x86/xen/smp.c