* Re: [tip:x86/asm] x86/asm/entry/64: Rename 'old_rsp' to 'rsp_scratch'
[not found] <tip-c38e503804b0402c510f82437069f7769fa0cea9@git.kernel.org>
@ 2015-03-17 17:49 ` Andy Lutomirski
2015-03-17 17:57 ` Denys Vlasenko
1 sibling, 0 replies; 3+ messages in thread
From: Andy Lutomirski @ 2015-03-17 17:49 UTC (permalink / raw)
To: Thomas Gleixner, Frédéric Weisbecker, Ingo Molnar,
Alexei Starovoitov, Oleg Nesterov, Andy Lutomirski, Kees Cook,
H. Peter Anvin, Denys Vlasenko, Borislav Petkov, Linus Torvalds,
Steven Rostedt, linux-kernel@vger.kernel.org, Will Drewry
Cc: linux-tip-commits@vger.kernel.org
On Tue, Mar 17, 2015 at 9:43 AM, tip-bot for Ingo Molnar
<tipbot@zytor.com> wrote:
> Commit-ID: c38e503804b0402c510f82437069f7769fa0cea9
> Gitweb: http://git.kernel.org/tip/c38e503804b0402c510f82437069f7769fa0cea9
> Author: Ingo Molnar <mingo@kernel.org>
> AuthorDate: Tue, 17 Mar 2015 14:42:59 +0100
> Committer: Ingo Molnar <mingo@kernel.org>
> CommitDate: Tue, 17 Mar 2015 16:01:42 +0100
>
> x86/asm/entry/64: Rename 'old_rsp' to 'rsp_scratch'
>
> Make clear that the usage of PER_CPU(old_rsp) is purely temporary,
> by renaming it to 'rsp_scratch'.
Thanks. This is much better.
--Andy
>
> Cc: Alexei Starovoitov <ast@plumgrid.com>
> Cc: Andy Lutomirski <luto@amacapital.net>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: Denys Vlasenko <dvlasenk@redhat.com>
> 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>
> Signed-off-by: Ingo Molnar <mingo@kernel.org>
> ---
> arch/x86/kernel/entry_64.S | 10 +++++-----
> arch/x86/kernel/process_64.c | 2 +-
> arch/x86/xen/xen-asm_64.S | 8 ++++----
> 3 files changed, 10 insertions(+), 10 deletions(-)
>
> diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
> index d287f78..0c91256 100644
> --- a/arch/x86/kernel/entry_64.S
> +++ b/arch/x86/kernel/entry_64.S
> @@ -237,16 +237,16 @@ ENTRY(system_call)
> GLOBAL(system_call_after_swapgs)
>
> /*
> - * We use 'old_rsp' as a scratch register, hence this block must execute
> + * We use 'rsp_scratch' as a scratch register, hence this block must execute
> * atomically in the face of possible interrupt-driven task preemption,
> - * so we can enable interrupts only after we're done with using old_rsp:
> + * so we can enable interrupts only after we're done with using rsp_scratch:
> */
> - movq %rsp,PER_CPU_VAR(old_rsp)
> + movq %rsp,PER_CPU_VAR(rsp_scratch)
> /* kernel_stack is set so that 5 slots (iret frame) are preallocated */
> movq PER_CPU_VAR(kernel_stack),%rsp
> ALLOC_PT_GPREGS_ON_STACK 8 /* +8: space for orig_ax */
> movq %rcx,RIP(%rsp)
> - movq PER_CPU_VAR(old_rsp),%rcx
> + movq PER_CPU_VAR(rsp_scratch),%rcx
> movq %r11,EFLAGS(%rsp)
> movq %rcx,RSP(%rsp)
> /*
> @@ -657,7 +657,7 @@ common_interrupt:
> ASM_CLAC
> addq $-0x80,(%rsp) /* Adjust vector to [-256,-1] range */
> interrupt do_IRQ
> - /* 0(%rsp): old_rsp */
> + /* 0(%rsp): rsp_scratch */
> ret_from_intr:
> DISABLE_INTERRUPTS(CLBR_NONE)
> TRACE_IRQS_OFF
> diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
> index 14df2be..97f5658 100644
> --- a/arch/x86/kernel/process_64.c
> +++ b/arch/x86/kernel/process_64.c
> @@ -52,7 +52,7 @@
>
> asmlinkage extern void ret_from_fork(void);
>
> -__visible DEFINE_PER_CPU(unsigned long, old_rsp);
> +__visible DEFINE_PER_CPU(unsigned long, rsp_scratch);
>
> /* Prints also some state that isn't saved in the pt_regs */
> void __show_regs(struct pt_regs *regs, int all)
> diff --git a/arch/x86/xen/xen-asm_64.S b/arch/x86/xen/xen-asm_64.S
> index 53adefd..985fc3e 100644
> --- a/arch/x86/xen/xen-asm_64.S
> +++ b/arch/x86/xen/xen-asm_64.S
> @@ -68,11 +68,11 @@ ENTRY(xen_sysret64)
> * We're already on the usermode stack at this point, but
> * still with the kernel gs, so we can easily switch back
> */
> - movq %rsp, PER_CPU_VAR(old_rsp)
> + movq %rsp, PER_CPU_VAR(rsp_scratch)
> movq PER_CPU_VAR(kernel_stack), %rsp
>
> pushq $__USER_DS
> - pushq PER_CPU_VAR(old_rsp)
> + pushq PER_CPU_VAR(rsp_scratch)
> pushq %r11
> pushq $__USER_CS
> pushq %rcx
> @@ -87,11 +87,11 @@ ENTRY(xen_sysret32)
> * We're already on the usermode stack at this point, but
> * still with the kernel gs, so we can easily switch back
> */
> - movq %rsp, PER_CPU_VAR(old_rsp)
> + movq %rsp, PER_CPU_VAR(rsp_scratch)
> movq PER_CPU_VAR(kernel_stack), %rsp
>
> pushq $__USER32_DS
> - pushq PER_CPU_VAR(old_rsp)
> + pushq PER_CPU_VAR(rsp_scratch)
> pushq %r11
> pushq $__USER32_CS
> pushq %rcx
--
Andy Lutomirski
AMA Capital Management, LLC
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [tip:x86/asm] x86/asm/entry/64: Rename 'old_rsp' to 'rsp_scratch'
[not found] <tip-c38e503804b0402c510f82437069f7769fa0cea9@git.kernel.org>
2015-03-17 17:49 ` [tip:x86/asm] x86/asm/entry/64: Rename 'old_rsp' to 'rsp_scratch' Andy Lutomirski
@ 2015-03-17 17:57 ` Denys Vlasenko
2015-03-23 13:58 ` Ingo Molnar
1 sibling, 1 reply; 3+ messages in thread
From: Denys Vlasenko @ 2015-03-17 17:57 UTC (permalink / raw)
To: tglx, fweisbec, mingo, ast, oleg, luto, keescook, hpa, bp,
torvalds, rostedt, linux-kernel, wad, linux-tip-commits
On 03/17/2015 05:43 PM, tip-bot for Ingo Molnar wrote:
> Commit-ID: c38e503804b0402c510f82437069f7769fa0cea9
> Gitweb: http://git.kernel.org/tip/c38e503804b0402c510f82437069f7769fa0cea9
> Author: Ingo Molnar <mingo@kernel.org>
> AuthorDate: Tue, 17 Mar 2015 14:42:59 +0100
> Committer: Ingo Molnar <mingo@kernel.org>
> CommitDate: Tue, 17 Mar 2015 16:01:42 +0100
>
> x86/asm/entry/64: Rename 'old_rsp' to 'rsp_scratch'
>
> Make clear that the usage of PER_CPU(old_rsp) is purely temporary,
> by renaming it to 'rsp_scratch'.
...
> @@ -657,7 +657,7 @@ common_interrupt:
> ASM_CLAC
> addq $-0x80,(%rsp) /* Adjust vector to [-256,-1] range */
> interrupt do_IRQ
> - /* 0(%rsp): old_rsp */
> + /* 0(%rsp): rsp_scratch */
> ret_from_intr:
Here the "old_rsp" word in comment did not refer to old_rsp variable.
Rather, it literally means "old %rsp register value (before we possibly
switched to per-CPU interrupt stack)".
The stack switch is hidden in "interrupt do_IRQ" macro invocation.
I think here "old_rsp" needs to be replaced by "old rsp" or "old %rsp".
^ permalink raw reply [flat|nested] 3+ messages in thread