2015-04-01 14:51:08

by Denys Vlasenko

[permalink] [raw]
Subject: [PATCH] x86/asm/entry/64: fold test_in_nmi macro into its only user

No code changes.

Signed-off-by: Denys Vlasenko <[email protected]>
Acked-by: Borislav Petkov <[email protected]>
CC: Linus Torvalds <[email protected]>
CC: Steven Rostedt <[email protected]>
CC: Ingo Molnar <[email protected]>
CC: Borislav Petkov <[email protected]>
CC: "H. Peter Anvin" <[email protected]>
CC: Andy Lutomirski <[email protected]>
CC: Oleg Nesterov <[email protected]>
CC: Frederic Weisbecker <[email protected]>
CC: Alexei Starovoitov <[email protected]>
CC: Will Drewry <[email protected]>
CC: Kees Cook <[email protected]>
CC: [email protected]
CC: [email protected]
---

Changes since v1: added comments as requested by Steven Rostedt

arch/x86/kernel/entry_64.S | 28 +++++++++++++---------------
1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index e498542..175393d 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -1355,19 +1355,7 @@ ENTRY(error_exit)
CFI_ENDPROC
END(error_exit)

-/*
- * Test if a given stack is an NMI stack or not.
- */
- .macro test_in_nmi reg stack nmi_ret normal_ret
- cmpq %\reg, \stack
- ja \normal_ret
- subq $EXCEPTION_STKSZ, %\reg
- cmpq %\reg, \stack
- jb \normal_ret
- jmp \nmi_ret
- .endm
-
- /* runs on exception stack */
+/* Runs on exception stack */
ENTRY(nmi)
INTR_FRAME
PARAVIRT_ADJUST_EXCEPTION_FRAME
@@ -1428,8 +1416,18 @@ ENTRY(nmi)
* We check the variable because the first NMI could be in a
* breakpoint routine using a breakpoint stack.
*/
- lea 6*8(%rsp), %rdx
- test_in_nmi rdx, 4*8(%rsp), nested_nmi, first_nmi
+ lea 6*8(%rsp), %rdx
+ /* Compare the NMI stack (rdx) with the stack we came from (4*8(%rsp)) */
+ cmpq %rdx, 4*8(%rsp)
+ /* If the stack pointer is above the NMI stack, this is a normal NMI */
+ ja first_nmi
+ subq $EXCEPTION_STKSZ, %rdx
+ cmpq %rdx, 4*8(%rsp)
+ /* If it is below the NMI stack, it is a normal NMI */
+ jb first_nmi
+ /* Ah, it is within the NMI stack, treat it as nested */
+ jmp nested_nmi
+
CFI_REMEMBER_STATE

nested_nmi:
--
1.8.1.4


2015-04-01 14:51:11

by Denys Vlasenko

[permalink] [raw]
Subject: [PATCH] x86/asm/head/64: Use __BOOT_TSS instead of literal 0x20

No code changes.

Signed-off-by: Denys Vlasenko <[email protected]>
CC: Linus Torvalds <[email protected]>
CC: Steven Rostedt <[email protected]>
CC: Ingo Molnar <[email protected]>
CC: Borislav Petkov <[email protected]>
CC: "H. Peter Anvin" <[email protected]>
CC: Andy Lutomirski <[email protected]>
CC: Oleg Nesterov <[email protected]>
CC: Frederic Weisbecker <[email protected]>
CC: Alexei Starovoitov <[email protected]>
CC: Will Drewry <[email protected]>
CC: Kees Cook <[email protected]>
CC: [email protected]
CC: [email protected]
---
arch/x86/boot/compressed/head_64.S | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index 90c1521..b0c0d16 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -165,7 +165,7 @@ ENTRY(startup_32)
/* After gdt is loaded */
xorl %eax, %eax
lldt %ax
- movl $0x20, %eax
+ movl $__BOOT_TSS, %eax
ltr %ax

/*
--
1.8.1.4

2015-04-01 15:45:54

by Steven Rostedt

[permalink] [raw]
Subject: Re: [PATCH] x86/asm/entry/64: fold test_in_nmi macro into its only user

On Wed, 1 Apr 2015 16:50:57 +0200
Denys Vlasenko <[email protected]> wrote:

> - /* runs on exception stack */
> +/* Runs on exception stack */
> ENTRY(nmi)
> INTR_FRAME
> PARAVIRT_ADJUST_EXCEPTION_FRAME
> @@ -1428,8 +1416,18 @@ ENTRY(nmi)
> * We check the variable because the first NMI could be in a
> * breakpoint routine using a breakpoint stack.
> */
> - lea 6*8(%rsp), %rdx
> - test_in_nmi rdx, 4*8(%rsp), nested_nmi, first_nmi
> + lea 6*8(%rsp), %rdx
> + /* Compare the NMI stack (rdx) with the stack we came from (4*8(%rsp)) */
> + cmpq %rdx, 4*8(%rsp)
> + /* If the stack pointer is above the NMI stack, this is a normal NMI */
> + ja first_nmi
> + subq $EXCEPTION_STKSZ, %rdx
> + cmpq %rdx, 4*8(%rsp)
> + /* If it is below the NMI stack, it is a normal NMI */
> + jb first_nmi
> + /* Ah, it is within the NMI stack, treat it as nested */
> + jmp nested_nmi

I guess we can get rid of the jmp nested_nmi, as it just jumps to the
next instruction. Although, I would keep the comment.

-- Steve

> +
> CFI_REMEMBER_STATE
>
> nested_nmi:

2015-04-01 16:48:15

by Borislav Petkov

[permalink] [raw]
Subject: Re: [PATCH] x86/asm/head/64: Use __BOOT_TSS instead of literal 0x20

On Wed, Apr 01, 2015 at 04:50:58PM +0200, Denys Vlasenko wrote:
> No code changes.
>
> Signed-off-by: Denys Vlasenko <[email protected]>
> CC: Linus Torvalds <[email protected]>
> CC: Steven Rostedt <[email protected]>
> CC: Ingo Molnar <[email protected]>
> CC: Borislav Petkov <[email protected]>
> CC: "H. Peter Anvin" <[email protected]>
> CC: Andy Lutomirski <[email protected]>
> CC: Oleg Nesterov <[email protected]>
> CC: Frederic Weisbecker <[email protected]>
> CC: Alexei Starovoitov <[email protected]>
> CC: Will Drewry <[email protected]>
> CC: Kees Cook <[email protected]>
> CC: [email protected]
> CC: [email protected]
> ---
> arch/x86/boot/compressed/head_64.S | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
> index 90c1521..b0c0d16 100644
> --- a/arch/x86/boot/compressed/head_64.S
> +++ b/arch/x86/boot/compressed/head_64.S
> @@ -165,7 +165,7 @@ ENTRY(startup_32)
> /* After gdt is loaded */
> xorl %eax, %eax
> lldt %ax
> - movl $0x20, %eax
> + movl $__BOOT_TSS, %eax
> ltr %ax

Acked-by: Borislav Petkov <[email protected]>

--
Regards/Gruss,
Boris.

ECO tip #101: Trim your mails when you reply.
--

2015-04-01 17:01:46

by Steven Rostedt

[permalink] [raw]
Subject: Re: [PATCH] x86/asm/head/64: Use __BOOT_TSS instead of literal 0x20

On Wed, 1 Apr 2015 16:50:58 +0200
Denys Vlasenko <[email protected]> wrote:

> No code changes.
>


> diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
> index 90c1521..b0c0d16 100644
> --- a/arch/x86/boot/compressed/head_64.S
> +++ b/arch/x86/boot/compressed/head_64.S
> @@ -165,7 +165,7 @@ ENTRY(startup_32)
> /* After gdt is loaded */
> xorl %eax, %eax
> lldt %ax
> - movl $0x20, %eax
> + movl $__BOOT_TSS, %eax

__BOOT_TSS = (GDT_ENTRY_BOOT_TSS * 8)
GDT_ENTRY_BOOT_TSS = (GDT_ENTRY_BOOT_CS + 2)
GDT_ENTRY_BOOT_CS = 2

(2 + 2) * 8 = 4 * 8 = 32 = 0x20

Reviewed-by: Steven Rostedt <[email protected]>

-- Steve

> ltr %ax
>
> /*

Subject: [tip:x86/asm] x86/asm/entry/64: Fold the 'test_in_nmi' macro into its only user

Commit-ID: 0784b36448a2a85b95b6eb21a69b9045c896c065
Gitweb: http://git.kernel.org/tip/0784b36448a2a85b95b6eb21a69b9045c896c065
Author: Denys Vlasenko <[email protected]>
AuthorDate: Wed, 1 Apr 2015 16:50:57 +0200
Committer: Ingo Molnar <[email protected]>
CommitDate: Thu, 2 Apr 2015 12:00:10 +0200

x86/asm/entry/64: Fold the 'test_in_nmi' macro into its only user

No code changes.

Signed-off-by: Denys Vlasenko <[email protected]>
Acked-by: Borislav Petkov <[email protected]>
Cc: Alexei Starovoitov <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Will Drewry <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
arch/x86/kernel/entry_64.S | 28 +++++++++++++---------------
1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 03c52e2..386375d 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -1355,19 +1355,7 @@ ENTRY(error_exit)
CFI_ENDPROC
END(error_exit)

-/*
- * Test if a given stack is an NMI stack or not.
- */
- .macro test_in_nmi reg stack nmi_ret normal_ret
- cmpq %\reg, \stack
- ja \normal_ret
- subq $EXCEPTION_STKSZ, %\reg
- cmpq %\reg, \stack
- jb \normal_ret
- jmp \nmi_ret
- .endm
-
- /* runs on exception stack */
+/* Runs on exception stack */
ENTRY(nmi)
INTR_FRAME
PARAVIRT_ADJUST_EXCEPTION_FRAME
@@ -1428,8 +1416,18 @@ ENTRY(nmi)
* We check the variable because the first NMI could be in a
* breakpoint routine using a breakpoint stack.
*/
- lea 6*8(%rsp), %rdx
- test_in_nmi rdx, 4*8(%rsp), nested_nmi, first_nmi
+ lea 6*8(%rsp), %rdx
+ /* Compare the NMI stack (rdx) with the stack we came from (4*8(%rsp)) */
+ cmpq %rdx, 4*8(%rsp)
+ /* If the stack pointer is above the NMI stack, this is a normal NMI */
+ ja first_nmi
+ subq $EXCEPTION_STKSZ, %rdx
+ cmpq %rdx, 4*8(%rsp)
+ /* If it is below the NMI stack, it is a normal NMI */
+ jb first_nmi
+ /* Ah, it is within the NMI stack, treat it as nested */
+ jmp nested_nmi
+
CFI_REMEMBER_STATE

nested_nmi:

Subject: [tip:x86/asm] x86/asm/boot/64: Use __BOOT_TSS instead of literal $0x20

Commit-ID: 40e4f2d177f748a83e7639554ea7d11568a9fa1f
Gitweb: http://git.kernel.org/tip/40e4f2d177f748a83e7639554ea7d11568a9fa1f
Author: Denys Vlasenko <[email protected]>
AuthorDate: Wed, 1 Apr 2015 16:50:58 +0200
Committer: Ingo Molnar <[email protected]>
CommitDate: Thu, 2 Apr 2015 12:00:20 +0200

x86/asm/boot/64: Use __BOOT_TSS instead of literal $0x20

__BOOT_TSS = (GDT_ENTRY_BOOT_TSS * 8)
GDT_ENTRY_BOOT_TSS = (GDT_ENTRY_BOOT_CS + 2)
GDT_ENTRY_BOOT_CS = 2

(2 + 2) * 8 = 4 * 8 = 32 = 0x20

No code changes.

Signed-off-by: Denys Vlasenko <[email protected]>
Reviewed-by: Steven Rostedt <[email protected]>
Acked-by: Borislav Petkov <[email protected]>
Cc: Alexei Starovoitov <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Will Drewry <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
arch/x86/boot/compressed/head_64.S | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index 90c1521..b0c0d16 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -165,7 +165,7 @@ ENTRY(startup_32)
/* After gdt is loaded */
xorl %eax, %eax
lldt %ax
- movl $0x20, %eax
+ movl $__BOOT_TSS, %eax
ltr %ax

/*