From: tip-bot for Joerg Roedel <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: dvlasenk@redhat.com, mingo@kernel.org, will.deacon@arm.com,
jgross@suse.com, tglx@linutronix.de, eduval@amazon.com,
torvalds@linux-foundation.org, dhgutteridge@sympatico.ca,
dave.hansen@intel.com, peterz@infradead.org, hpa@zytor.com,
brgerst@gmail.com, jpoimboe@redhat.com, luto@kernel.org,
boris.ostrovsky@oracle.com, David.Laight@aculab.com,
bp@alien8.de, aarcange@redhat.com, llong@redhat.com,
linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org,
jroedel@suse.de, jkosina@suse.cz, pavel@ucw.cz
Subject: [tip:x86/pti] x86/entry/32: Leave the kernel via trampoline stack
Date: Thu, 19 Jul 2018 16:22:32 -0700 [thread overview]
Message-ID: <tip-e5862d0515ad970ccec6208ecf5bb0cffe291ea3@git.kernel.org> (raw)
In-Reply-To: <1531906876-13451-9-git-send-email-joro@8bytes.org>
Commit-ID: e5862d0515ad970ccec6208ecf5bb0cffe291ea3
Gitweb: https://git.kernel.org/tip/e5862d0515ad970ccec6208ecf5bb0cffe291ea3
Author: Joerg Roedel <jroedel@suse.de>
AuthorDate: Wed, 18 Jul 2018 11:40:45 +0200
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Fri, 20 Jul 2018 01:11:37 +0200
x86/entry/32: Leave the kernel via trampoline stack
Switch back to the trampoline stack before returning to userspace.
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Pavel Machek <pavel@ucw.cz>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: linux-mm@kvack.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eduardo Valentin <eduval@amazon.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: keescook@google.com
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Waiman Long <llong@redhat.com>
Cc: "David H . Gutteridge" <dhgutteridge@sympatico.ca>
Cc: joro@8bytes.org
Link: https://lkml.kernel.org/r/1531906876-13451-9-git-send-email-joro@8bytes.org
---
arch/x86/entry/entry_32.S | 79 +++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 77 insertions(+), 2 deletions(-)
diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index fea49ec345ba..a905e6215ea9 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -342,6 +342,60 @@
.Lend_\@:
.endm
+/*
+ * Switch back from the kernel stack to the entry stack.
+ *
+ * The %esp register must point to pt_regs on the task stack. It will
+ * first calculate the size of the stack-frame to copy, depending on
+ * whether we return to VM86 mode or not. With that it uses 'rep movsl'
+ * to copy the contents of the stack over to the entry stack.
+ *
+ * We must be very careful here, as we can't trust the contents of the
+ * task-stack once we switched to the entry-stack. When an NMI happens
+ * while on the entry-stack, the NMI handler will switch back to the top
+ * of the task stack, overwriting our stack-frame we are about to copy.
+ * Therefore we switch the stack only after everything is copied over.
+ */
+.macro SWITCH_TO_ENTRY_STACK
+
+ ALTERNATIVE "", "jmp .Lend_\@", X86_FEATURE_XENPV
+
+ /* Bytes to copy */
+ movl $PTREGS_SIZE, %ecx
+
+#ifdef CONFIG_VM86
+ testl $(X86_EFLAGS_VM), PT_EFLAGS(%esp)
+ jz .Lcopy_pt_regs_\@
+
+ /* Additional 4 registers to copy when returning to VM86 mode */
+ addl $(4 * 4), %ecx
+
+.Lcopy_pt_regs_\@:
+#endif
+
+ /* Initialize source and destination for movsl */
+ movl PER_CPU_VAR(cpu_tss_rw + TSS_sp0), %edi
+ subl %ecx, %edi
+ movl %esp, %esi
+
+ /* Save future stack pointer in %ebx */
+ movl %edi, %ebx
+
+ /* Copy over the stack-frame */
+ shrl $2, %ecx
+ cld
+ rep movsl
+
+ /*
+ * Switch to entry-stack - needs to happen after everything is
+ * copied because the NMI handler will overwrite the task-stack
+ * when on entry-stack
+ */
+ movl %ebx, %esp
+
+.Lend_\@:
+.endm
+
/*
* %eax: prev task
* %edx: next task
@@ -581,25 +635,45 @@ ENTRY(entry_SYSENTER_32)
/* Opportunistic SYSEXIT */
TRACE_IRQS_ON /* User mode traces as IRQs on. */
+
+ /*
+ * Setup entry stack - we keep the pointer in %eax and do the
+ * switch after almost all user-state is restored.
+ */
+
+ /* Load entry stack pointer and allocate frame for eflags/eax */
+ movl PER_CPU_VAR(cpu_tss_rw + TSS_sp0), %eax
+ subl $(2*4), %eax
+
+ /* Copy eflags and eax to entry stack */
+ movl PT_EFLAGS(%esp), %edi
+ movl PT_EAX(%esp), %esi
+ movl %edi, (%eax)
+ movl %esi, 4(%eax)
+
+ /* Restore user registers and segments */
movl PT_EIP(%esp), %edx /* pt_regs->ip */
movl PT_OLDESP(%esp), %ecx /* pt_regs->sp */
1: mov PT_FS(%esp), %fs
PTGS_TO_GS
+
popl %ebx /* pt_regs->bx */
addl $2*4, %esp /* skip pt_regs->cx and pt_regs->dx */
popl %esi /* pt_regs->si */
popl %edi /* pt_regs->di */
popl %ebp /* pt_regs->bp */
- popl %eax /* pt_regs->ax */
+
+ /* Switch to entry stack */
+ movl %eax, %esp
/*
* Restore all flags except IF. (We restore IF separately because
* STI gives a one-instruction window in which we won't be interrupted,
* whereas POPF does not.)
*/
- addl $PT_EFLAGS-PT_DS, %esp /* point esp at pt_regs->flags */
btrl $X86_EFLAGS_IF_BIT, (%esp)
popfl
+ popl %eax
/*
* Return back to the vDSO, which will pop ecx and edx.
@@ -668,6 +742,7 @@ ENTRY(entry_INT80_32)
restore_all:
TRACE_IRQS_IRET
+ SWITCH_TO_ENTRY_STACK
.Lrestore_all_notrace:
CHECK_AND_APPLY_ESPFIX
.Lrestore_nocheck:
next prev parent reply other threads:[~2018-07-19 23:23 UTC|newest]
Thread overview: 96+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-18 9:40 [PATCH 00/39 v8] PTI support for x86-32 Joerg Roedel
2018-07-18 9:40 ` [PATCH 01/39] x86/asm-offsets: Move TSS_sp0 and TSS_sp1 to asm-offsets.c Joerg Roedel
2018-07-19 23:18 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:40 ` [PATCH 02/39] x86/entry/32: Rename TSS_sysenter_sp0 to TSS_entry2task_stack Joerg Roedel
2018-07-19 23:19 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:40 ` [PATCH 03/39] x86/entry/32: Load task stack from x86_tss.sp1 in SYSENTER handler Joerg Roedel
2018-07-19 23:19 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:40 ` [PATCH 04/39] x86/entry/32: Put ESPFIX code into a macro Joerg Roedel
2018-07-19 23:20 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:40 ` [PATCH 05/39] x86/entry/32: Unshare NMI return path Joerg Roedel
2018-07-19 23:21 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:40 ` [PATCH 06/39] x86/entry/32: Split off return-to-kernel path Joerg Roedel
2018-07-19 23:21 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:40 ` [PATCH 07/39] x86/entry/32: Enter the kernel via trampoline stack Joerg Roedel
2018-07-18 18:09 ` Brian Gerst
2018-07-19 20:52 ` Thomas Gleixner
2018-07-19 23:22 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:40 ` [PATCH 08/39] x86/entry/32: Leave " Joerg Roedel
2018-07-19 23:22 ` tip-bot for Joerg Roedel [this message]
2018-07-18 9:40 ` [PATCH 09/39] x86/entry/32: Introduce SAVE_ALL_NMI and RESTORE_ALL_NMI Joerg Roedel
2018-07-19 23:23 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:40 ` [PATCH 10/39] x86/entry/32: Handle Entry from Kernel-Mode on Entry-Stack Joerg Roedel
2018-07-19 23:23 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-10-12 18:29 ` [PATCH 10/39] " Jan Kiszka
2018-10-13 9:54 ` [PATCH] x86/entry/32: Fix setup of CS high bits Jan Kiszka
2018-10-13 15:12 ` Andy Lutomirski
2018-10-15 13:08 ` Jan Kiszka
2018-10-15 13:14 ` David Laight
2018-10-15 13:18 ` Jan Kiszka
2018-10-15 13:29 ` David Laight
2018-10-15 9:10 ` Joerg Roedel
2018-10-15 14:09 ` [PATCH v2] " Jan Kiszka
2018-10-15 15:09 ` [tip:x86/urgent] x86/entry/32: Clear the " tip-bot for Jan Kiszka
2018-10-18 6:21 ` tip-bot for Jan Kiszka
2018-07-18 9:40 ` [PATCH 11/39] x86/entry/32: Simplify debug entry point Joerg Roedel
2018-07-19 23:24 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:40 ` [PATCH 12/39] x86/entry/32: Add PTI cr3 switch to non-NMI entry/exit points Joerg Roedel
2018-07-19 23:24 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:40 ` [PATCH 13/39] x86/entry/32: Add PTI cr3 switches to NMI handler code Joerg Roedel
2018-07-19 23:25 ` [tip:x86/pti] x86/entry/32: Add PTI CR3 " tip-bot for Joerg Roedel
2018-07-18 9:40 ` [PATCH 14/39] x86/entry: Rename update_sp0 to update_task_stack Joerg Roedel
2018-07-19 23:25 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:40 ` [PATCH 15/39] x86/pgtable: Rename pti_set_user_pgd to pti_set_user_pgtbl Joerg Roedel
2018-07-19 23:26 ` [tip:x86/pti] x86/pgtable: Rename pti_set_user_pgd() to pti_set_user_pgtbl() tip-bot for Joerg Roedel
2018-07-18 9:40 ` [PATCH 16/39] x86/pgtable/pae: Unshare kernel PMDs when PTI is enabled Joerg Roedel
2018-07-19 23:26 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:40 ` [PATCH 17/39] x86/pgtable/32: Allocate 8k page-tables " Joerg Roedel
2018-07-19 23:27 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:40 ` [PATCH 18/39] x86/pgtable: Move pgdp kernel/user conversion functions to pgtable.h Joerg Roedel
2018-07-19 23:27 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:40 ` [PATCH 19/39] x86/pgtable: Move pti_set_user_pgtbl() " Joerg Roedel
2018-07-19 23:28 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:40 ` [PATCH 20/39] x86/pgtable: Move two more functions from pgtable_64.h " Joerg Roedel
2018-07-19 23:28 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:40 ` [PATCH 21/39] x86/mm/pae: Populate valid user PGD entries Joerg Roedel
2018-07-19 23:29 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:40 ` [PATCH 22/39] x86/mm/pae: Populate the user page-table with user pgd's Joerg Roedel
2018-07-19 23:30 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:41 ` [PATCH 23/39] x86/mm/legacy: " Joerg Roedel
2018-07-19 23:30 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:41 ` [PATCH 24/39] x86/mm/pti: Add an overflow check to pti_clone_pmds() Joerg Roedel
2018-07-19 23:31 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:41 ` [PATCH 25/39] x86/mm/pti: Define X86_CR3_PTI_PCID_USER_BIT on x86_32 Joerg Roedel
2018-07-19 23:31 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:41 ` [PATCH 26/39] x86/mm/pti: Clone CPU_ENTRY_AREA on PMD level " Joerg Roedel
2018-07-19 23:32 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:41 ` [PATCH 27/39] x86/mm/pti: Make pti_clone_kernel_text() compile on 32 bit Joerg Roedel
2018-07-19 23:32 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:41 ` [PATCH 28/39] x86/mm/pti: Keep permissions when cloning kernel text in pti_clone_kernel_text() Joerg Roedel
2018-07-19 23:33 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:41 ` [PATCH 29/39] x86/mm/pti: Introduce pti_finalize() Joerg Roedel
2018-07-19 23:33 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:41 ` [PATCH 30/39] x86/mm/pti: Clone entry-text again in pti_finalize() Joerg Roedel
2018-07-19 23:34 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:41 ` [PATCH 31/39] x86/mm/dump_pagetables: Define INIT_PGD Joerg Roedel
2018-07-19 23:34 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:41 ` [PATCH 32/39] x86/pgtable/pae: Use separate kernel PMDs for user page-table Joerg Roedel
2018-07-19 23:35 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-10-05 14:06 ` [PATCH 32/39] " Arnd Bergmann
2018-07-18 9:41 ` [PATCH 33/39] x86/ldt: Reserve address-space range on 32 bit for the LDT Joerg Roedel
2018-07-19 23:35 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:41 ` [PATCH 34/39] x86/ldt: Define LDT_END_ADDR Joerg Roedel
2018-07-19 23:36 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:41 ` [PATCH 35/39] x86/ldt: Split out sanity check in map_ldt_struct() Joerg Roedel
2018-07-19 23:36 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:41 ` [PATCH 36/39] x86/ldt: Enable LDT user-mapping for PAE Joerg Roedel
2018-07-19 23:37 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:41 ` [PATCH 37/39] x86/pti: Allow CONFIG_PAGE_TABLE_ISOLATION for x86_32 Joerg Roedel
2018-07-19 23:37 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:41 ` [PATCH 38/39] x86/mm/pti: Add Warning when booting on a PCID capable CPU Joerg Roedel
2018-07-19 23:38 ` [tip:x86/pti] " tip-bot for Joerg Roedel
2018-07-18 9:41 ` [PATCH 39/39] x86/entry/32: Add debug code to check entry/exit cr3 Joerg Roedel
2018-07-19 23:38 ` [tip:x86/pti] x86/entry/32: Add debug code to check entry/exit CR3 tip-bot for Joerg Roedel
2018-07-18 11:59 ` [PATCH 00/39 v8] PTI support for x86-32 Pavel Machek
2018-07-19 23:21 ` Thomas Gleixner
2018-07-20 7:59 ` Joerg Roedel
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