| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <tip-626109130267713cac020515504ec341e47c96f9@git.kernel.org>
Date: Tue, 28 Feb 2012 02:37:06 -0800
From: tip-bot for Jan Beulich <JBeulich@...e.com>
To: linux-tip-commits@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...hat.com,
rostedt@...dmis.org, jbeulich@...e.com, JBeulich@...e.com,
tglx@...utronix.de
Subject: [tip:x86/asm] x86-64: Fix CFI annotations for NMI nesting code
Commit-ID: 626109130267713cac020515504ec341e47c96f9
Gitweb: http://git.kernel.org/tip/626109130267713cac020515504ec341e47c96f9
Author: Jan Beulich <JBeulich@...e.com>
AuthorDate: Fri, 24 Feb 2012 14:54:37 +0000
Committer: Steven Rostedt <rostedt@...dmis.org>
CommitDate: Fri, 24 Feb 2012 14:05:14 -0500
x86-64: Fix CFI annotations for NMI nesting code
The saving and restoring of %rdx wasn't annotated at all, and the
jumping over sections where state gets partly restored wasn't handled
either.
Further, by folding the pushing of the previous frame in repeat_nmi
into that which so far was immediately preceding restart_nmi (after
moving the restore of %rdx ahead of that, since it doesn't get used
anymore when pushing prior frames), annotations of the replicated
frame creations can be made consistent too.
v2: Fully fold repeat_nmi into the normal code flow (adding a single
redundant instruction to the "normal" code path), thus retaining
the special protection of all instructions between repeat_nmi and
end_repeat_nmi.
Link: http://lkml.kernel.org/r/4F478B630200007800074A31@nat28.tlf.novell.com
Signed-off-by: Jan Beulich <jbeulich@...e.com>
Signed-off-by: Steven Rostedt <rostedt@...dmis.org>
---
arch/x86/kernel/entry_64.S | 52 +++++++++++++++++++++++--------------------
1 files changed, 28 insertions(+), 24 deletions(-)
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 1333d98..e0eca00 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -1530,6 +1530,7 @@ ENTRY(nmi)
/* Use %rdx as out temp variable throughout */
pushq_cfi %rdx
+ CFI_REL_OFFSET rdx, 0
/*
* If %cs was not the kernel segment, then the NMI triggered in user
@@ -1554,6 +1555,7 @@ ENTRY(nmi)
*/
lea 6*8(%rsp), %rdx
test_in_nmi rdx, 4*8(%rsp), nested_nmi, first_nmi
+ CFI_REMEMBER_STATE
nested_nmi:
/*
@@ -1585,10 +1587,12 @@ nested_nmi:
nested_nmi_out:
popq_cfi %rdx
+ CFI_RESTORE rdx
/* No need to check faults here */
INTERRUPT_RETURN
+ CFI_RESTORE_STATE
first_nmi:
/*
* Because nested NMIs will use the pushed location that we
@@ -1624,6 +1628,10 @@ first_nmi:
* NMI may zero out. The original stack frame and the temp storage
* is also used by nested NMIs and can not be trusted on exit.
*/
+ /* Do not pop rdx, nested NMIs will corrupt it */
+ movq (%rsp), %rdx
+ CFI_RESTORE rdx
+
/* Set the NMI executing variable on the stack. */
pushq_cfi $1
@@ -1631,14 +1639,31 @@ first_nmi:
.rept 5
pushq_cfi 6*8(%rsp)
.endr
+ CFI_DEF_CFA_OFFSET SS+8-RIP
+
+ /*
+ * If there was a nested NMI, the first NMI's iret will return
+ * here. But NMIs are still enabled and we can take another
+ * nested NMI. The nested NMI checks the interrupted RIP to see
+ * if it is between repeat_nmi and end_repeat_nmi, and if so
+ * it will just return, as we are about to repeat an NMI anyway.
+ * This makes it safe to copy to the stack frame that a nested
+ * NMI will update.
+ */
+repeat_nmi:
+ /*
+ * Update the stack variable to say we are still in NMI (the update
+ * is benign for the non-repeat case, where 1 was pushed just above
+ * to this very stack slot).
+ */
+ movq $1, 5*8(%rsp)
/* Make another copy, this one may be modified by nested NMIs */
.rept 5
pushq_cfi 4*8(%rsp)
.endr
-
- /* Do not pop rdx, nested NMIs will corrupt it */
- movq 11*8(%rsp), %rdx
+ CFI_DEF_CFA_OFFSET SS+8-RIP
+end_repeat_nmi:
/*
* Everything below this point can be preempted by a nested
@@ -1646,7 +1671,6 @@ first_nmi:
* caused by an exception and nested NMI will start here, and
* can still be preempted by another NMI.
*/
-restart_nmi:
pushq_cfi $-1 /* ORIG_RAX: no syscall to restart */
subq $ORIG_RAX-R15, %rsp
CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
@@ -1675,26 +1699,6 @@ nmi_restore:
CFI_ENDPROC
END(nmi)
- /*
- * If an NMI hit an iret because of an exception or breakpoint,
- * it can lose its NMI context, and a nested NMI may come in.
- * In that case, the nested NMI will change the preempted NMI's
- * stack to jump to here when it does the final iret.
- */
-repeat_nmi:
- INTR_FRAME
- /* Update the stack variable to say we are still in NMI */
- movq $1, 5*8(%rsp)
-
- /* copy the saved stack back to copy stack */
- .rept 5
- pushq_cfi 4*8(%rsp)
- .endr
-
- jmp restart_nmi
- CFI_ENDPROC
-end_repeat_nmi:
-
ENTRY(ignore_sysret)
CFI_STARTPROC
mov $-ENOSYS,%eax
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists