Re: [PATCH 00/43] x86 entry-stack and Kaiser series, 2017/11/24 version
From: Ingo Molnar
Date: Fri Nov 24 2017 - 08:55:40 EST
* Ingo Molnar <mingo@xxxxxxxxxx> wrote:
> This is a linear series of patches of the latest entry-stack plus Kaiser
> bits from Andy Lutomirski (v3 series from today) and Dave Hansen
> (kaiser-414-tipwip-20171123 version), on top of latest tip:x86/urgent (12a78d43de76),
> plus fixes - for easier review.
>
> The code should be the latest posted by Andy and Dave.
>
> Any bugs caused by mis-merges, mis-backmerges or mis-fixes are mine.
There were some mis-merges in the assembly code, crashing the kernel on bootup
with Kaiser enabled. Thomas helped find & fix them.
I've pushed out the latest to tip:WIP.x86/mm, the interdiff between the posted and
the Git version can be found below.
Thanks,
Ingo
===============>
arch/x86/entry/entry_64.S | 12 ++----------
arch/x86/entry/entry_64_compat.S | 8 --------
arch/x86/events/intel/ds.c | 2 +-
3 files changed, 3 insertions(+), 19 deletions(-)
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 20be5e89a36a..4ac952080869 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -201,7 +201,6 @@ ENTRY(entry_SYSCALL_64)
swapgs
movq %rsp, PER_CPU_VAR(rsp_scratch)
-
/*
* The kernel CR3 is needed to map the process stack, but we
* need a scratch register to be able to load CR3. %rsp is
@@ -209,7 +208,6 @@ ENTRY(entry_SYSCALL_64)
* %rsp will be look crazy here for a couple instructions.
*/
SWITCH_TO_KERNEL_CR3 scratch_reg=%rsp
-
movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp
/* Construct struct pt_regs on stack */
@@ -259,9 +257,6 @@ GLOBAL(entry_SYSCALL_64_after_hwframe)
ja 1f /* return -ENOSYS (already in pt_regs->ax) */
movq %r10, %rcx
- /* Must wait until we have the kernel CR3 to call C functions: */
- TRACE_IRQS_OFF
-
/*
* This call instruction is handled specially in stub_ptregs_64.
* It might end up jumping to the slow path. If it jumps, RAX
@@ -647,7 +642,6 @@ END(irq_entries_start)
testb $3, CS-ORIG_RAX(%rsp)
jz 1f
SWAPGS
- SWITCH_TO_KERNEL_CR3 scratch_reg=%rax
call switch_to_thread_stack
1:
@@ -956,10 +950,9 @@ apicinterrupt IRQ_WORK_VECTOR irq_work_interrupt smp_irq_work_interrupt
ENTRY(switch_to_thread_stack)
UNWIND_HINT_FUNC
+ pushq %rdi
/* Need to switch before accessing the thread stack. */
SWITCH_TO_KERNEL_CR3 scratch_reg=%rdi
-
- pushq %rdi
movq %rsp, %rdi
movq PER_CPU_VAR(cpu_current_top_of_stack), %rsp
UNWIND_HINT sp_offset=16 sp_reg=ORC_REG_DI
@@ -1315,7 +1308,6 @@ ENTRY(error_entry)
* from user mode due to an IRET fault.
*/
SWAPGS
-
/* We have user CR3. Change to kernel CR3. */
SWITCH_TO_KERNEL_CR3 scratch_reg=%rax
@@ -1377,8 +1369,8 @@ ENTRY(error_entry)
* We came from an IRET to user mode, so we have user
* gsbase and CR3. Switch to kernel gsbase and CR3:
*/
- SWITCH_TO_KERNEL_CR3 scratch_reg=%rax
SWAPGS
+ SWITCH_TO_KERNEL_CR3 scratch_reg=%rax
/*
* Pretend that the exception came from user mode: set up pt_regs
diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index 57cd353c0667..05238b29895e 100644
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -319,14 +319,6 @@ ENTRY(entry_INT80_compat)
ASM_CLAC /* Do this early to minimize exposure */
SWAPGS
- /*
- * Must switch CR3 before thread stack is used. %r8 itself
- * is not saved into pt_regs and is not preserved across
- * function calls (like TRACE_IRQS_OFF calls), thus should
- * be safe to use.
- */
- SWITCH_TO_KERNEL_CR3 scratch_reg=%r8
-
/*
* User tracing code (ptrace or signal handlers) might assume that
* the saved RAX contains a 32-bit number when we're invoking a 32-bit
diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c
index 61388b01962d..b5cf473e443a 100644
--- a/arch/x86/events/intel/ds.c
+++ b/arch/x86/events/intel/ds.c
@@ -1,9 +1,9 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/bitops.h>
#include <linux/types.h>
+#include <linux/kaiser.h>
#include <linux/slab.h>
-#include <linux/kaiser.h>
#include <asm/perf_event.h>
#include <asm/insn.h>