This is a note to let you know that I've just added the patch titled
kaiser: use ALTERNATIVE instead of x86_cr3_pcid_noflush
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kaiser-use-alternative-instead-of-x86_cr3_pcid_noflush.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Wed Jan 3 18:58:12 CET 2018
From: Hugh Dickins <hughd@xxxxxxxxxx>
Date: Tue, 3 Oct 2017 20:49:04 -0700
Subject: kaiser: use ALTERNATIVE instead of x86_cr3_pcid_noflush
From: Hugh Dickins <hughd@xxxxxxxxxx>
Now that we're playing the ALTERNATIVE game, use that more efficient
method: instead of user-mapping an extra page, and reading an extra
cacheline each time for x86_cr3_pcid_noflush.
Neel has found that __stringify(bts $X86_CR3_PCID_NOFLUSH_BIT, %rax)
is a working substitute for the "bts $63, %rax" in these ALTERNATIVEs;
but the one line with $63 in looks clearer, so let's stick with that.
Worried about what happens with an ALTERNATIVE between the jump and
jump label in another ALTERNATIVE? I was, but have checked the
combinations in SWITCH_KERNEL_CR3_NO_STACK at entry_SYSCALL_64,
and it does a good job.
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
Acked-by: Jiri Kosina <jkosina@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/entry/entry_64.S | 7 ++++---
arch/x86/include/asm/kaiser.h | 6 +++---
arch/x86/mm/kaiser.c | 11 +----------
3 files changed, 8 insertions(+), 16 deletions(-)
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1056,7 +1056,8 @@ ENTRY(paranoid_entry)
jz 2f
orl $2, %ebx
andq $(~(X86_CR3_PCID_ASID_MASK | KAISER_SHADOW_PGD_OFFSET)), %rax
- orq x86_cr3_pcid_noflush, %rax
+ /* If PCID enabled, set X86_CR3_PCID_NOFLUSH_BIT */
+ ALTERNATIVE "", "bts $63, %rax", X86_FEATURE_PCID
movq %rax, %cr3
2:
#endif
@@ -1318,7 +1319,7 @@ ENTRY(nmi)
/* %rax is saved above, so OK to clobber here */
ALTERNATIVE "jmp 2f", "movq %cr3, %rax", X86_FEATURE_KAISER
/* If PCID enabled, NOFLUSH now and NOFLUSH on return */
- orq x86_cr3_pcid_noflush, %rax
+ ALTERNATIVE "", "bts $63, %rax", X86_FEATURE_PCID
pushq %rax
/* mask off "user" bit of pgd address and 12 PCID bits: */
andq $(~(X86_CR3_PCID_ASID_MASK | KAISER_SHADOW_PGD_OFFSET)), %rax
@@ -1562,7 +1563,7 @@ end_repeat_nmi:
/* %rax is saved above, so OK to clobber here */
ALTERNATIVE "jmp 2f", "movq %cr3, %rax", X86_FEATURE_KAISER
/* If PCID enabled, NOFLUSH now and NOFLUSH on return */
- orq x86_cr3_pcid_noflush, %rax
+ ALTERNATIVE "", "bts $63, %rax", X86_FEATURE_PCID
pushq %rax
/* mask off "user" bit of pgd address and 12 PCID bits: */
andq $(~(X86_CR3_PCID_ASID_MASK | KAISER_SHADOW_PGD_OFFSET)), %rax
--- a/arch/x86/include/asm/kaiser.h
+++ b/arch/x86/include/asm/kaiser.h
@@ -25,7 +25,8 @@
.macro _SWITCH_TO_KERNEL_CR3 reg
movq %cr3, \reg
andq $(~(X86_CR3_PCID_ASID_MASK | KAISER_SHADOW_PGD_OFFSET)), \reg
-orq x86_cr3_pcid_noflush, \reg
+/* If PCID enabled, set X86_CR3_PCID_NOFLUSH_BIT */
+ALTERNATIVE "", "bts $63, \reg", X86_FEATURE_PCID
movq \reg, %cr3
.endm
@@ -39,7 +40,7 @@ movq \reg, %cr3
movq %cr3, \reg
orq PER_CPU_VAR(x86_cr3_pcid_user), \reg
js 9f
-/* FLUSH this time, reset to NOFLUSH for next time (if PCID enabled) */
+/* If PCID enabled, FLUSH this time, reset to NOFLUSH for next time */
movb \regb, PER_CPU_VAR(x86_cr3_pcid_user+7)
9:
movq \reg, %cr3
@@ -90,7 +91,6 @@ movq PER_CPU_VAR(unsafe_stack_register_b
*/
DECLARE_PER_CPU_USER_MAPPED(unsigned long, unsafe_stack_register_backup);
-extern unsigned long x86_cr3_pcid_noflush;
DECLARE_PER_CPU(unsigned long, x86_cr3_pcid_user);
extern char __per_cpu_user_mapped_start[], __per_cpu_user_mapped_end[];
--- a/arch/x86/mm/kaiser.c
+++ b/arch/x86/mm/kaiser.c
@@ -32,7 +32,6 @@ DEFINE_PER_CPU_USER_MAPPED(unsigned long
* This is also handy because systems that do not support PCIDs
* just end up or'ing a 0 into their CR3, which does no harm.
*/
-unsigned long x86_cr3_pcid_noflush __read_mostly;
DEFINE_PER_CPU(unsigned long, x86_cr3_pcid_user);
/*
@@ -357,10 +356,6 @@ void __init kaiser_init(void)
kaiser_add_user_map_early(&debug_idt_table,
sizeof(gate_desc) * NR_VECTORS,
__PAGE_KERNEL);
-
- kaiser_add_user_map_early(&x86_cr3_pcid_noflush,
- sizeof(x86_cr3_pcid_noflush),
- __PAGE_KERNEL);
}
/* Add a mapping to the shadow mapping, and synchronize the mappings */
@@ -434,18 +429,14 @@ pgd_t kaiser_set_shadow_pgd(pgd_t *pgdp,
void kaiser_setup_pcid(void)
{
- unsigned long kern_cr3 = 0;
unsigned long user_cr3 = KAISER_SHADOW_PGD_OFFSET;
- if (this_cpu_has(X86_FEATURE_PCID)) {
- kern_cr3 |= X86_CR3_PCID_KERN_NOFLUSH;
+ if (this_cpu_has(X86_FEATURE_PCID))
user_cr3 |= X86_CR3_PCID_USER_NOFLUSH;
- }
/*
* These variables are used by the entry/exit
* code to change PCID and pgd and TLB flushing.
*/
- x86_cr3_pcid_noflush = kern_cr3;
this_cpu_write(x86_cr3_pcid_user, user_cr3);
}
Patches currently in stable-queue which might be from hughd@xxxxxxxxxx are
queue-4.4/kaiser-vmstat-show-nr_kaisertable-as-nr_overhead.patch
queue-4.4/kaiser-add-nokaiser-boot-option-using-alternative.patch
queue-4.4/kaiser-fix-unlikely-error-in-alloc_ldt_struct.patch
queue-4.4/kaiser-_pgd_alloc-without-__gfp_repeat-to-avoid-stalls.patch
queue-4.4/kaiser-kaiser_flush_tlb_on_return_to_user-check-pcid.patch
queue-4.4/x86-paravirt-dont-patch-flush_tlb_single.patch
queue-4.4/kaiser-merged-update.patch
queue-4.4/kaiser-delete-kaiser_real_switch-option.patch
queue-4.4/kaiser-kaiser_remove_mapping-move-along-the-pgd.patch
queue-4.4/kaiser-fix-perf-crashes.patch
queue-4.4/kaiser-drop-is_atomic-arg-to-kaiser_pagetable_walk.patch
queue-4.4/kaiser-load_new_mm_cr3-let-switch_user_cr3-flush-user.patch
queue-4.4/kaiser-enhanced-by-kernel-and-user-pcids.patch
queue-4.4/kaiser-x86_cr3_pcid_noflush-and-x86_cr3_pcid_user.patch
queue-4.4/kaiser-use-alternative-instead-of-x86_cr3_pcid_noflush.patch
queue-4.4/kaiser-stack-map-page_size-at-thread_size-page_size.patch
queue-4.4/kaiser-name-that-0x1000-kaiser_shadow_pgd_offset.patch
queue-4.4/kaiser-fix-regs-to-do_nmi-ifndef-config_kaiser.patch
queue-4.4/kaiser-do-not-set-_page_nx-on-pgd_none.patch
queue-4.4/kaiser-tidied-up-asm-kaiser.h-somewhat.patch
queue-4.4/kaiser-cleanups-while-trying-for-gold-link.patch
queue-4.4/kaiser-tidied-up-kaiser_add-remove_mapping-slightly.patch
queue-4.4/kaiser-fix-build-and-fixme-in-alloc_ldt_struct.patch
queue-4.4/kaiser-kernel-address-isolation.patch
queue-4.4/kaiser-enomem-if-kaiser_pagetable_walk-null.patch
queue-4.4/kaiser-asm-tlbflush.h-handle-nopge-at-lower-level.patch
queue-4.4/kaiser-paranoid_entry-pass-cr3-need-to-paranoid_exit.patch
queue-4.4/kaiser-kaiser-depends-on-smp.patch
queue-4.4/kaiser-pcid-0-for-kernel-and-128-for-user.patch