From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, Linus Torvalds <torvalds@linux-foundation.org>,
Andy Lutomirsky <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Dave Hansen <dave.hansen@intel.com>,
Borislav Petkov <bpetkov@suse.de>,
Greg KH <gregkh@linuxfoundation.org>,
keescook@google.com, hughd@google.com,
Brian Gerst <brgerst@gmail.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Denys Vlasenko <dvlasenk@redhat.com>,
Rik van Riel <riel@redhat.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Juergen Gross <jgross@suse.com>,
David Laight <David.Laight@aculab.com>,
Eduardo Valentin <eduval@amazon.com>,
aliguori@amazon.com, Will Deacon <will.deacon@arm.com>,
daniel.gruss@iaik.tugraz.at, Ingo Molnar <mingo@kernel.org>,
Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
linux-mm@kvack.org
Subject: [patch V149 45/50] x86/mm: Clarify the whole ASID/kernel PCID/user PCID naming
Date: Sat, 16 Dec 2017 22:24:39 +0100 [thread overview]
Message-ID: <20171216213140.137090325@linutronix.de> (raw)
In-Reply-To: 20171216212354.120930222@linutronix.de
[-- Attachment #1: 0068-x86-mm-Clarify-the-whole-ASID-kernel-PCID-user-PCID-.patch --]
[-- Type: text/plain, Size: 4284 bytes --]
From: Peter Zijlstra <peterz@infradead.org>
Ideally we'd also use sparse to enforce this separation so it becomes much
more difficult to mess up.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.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: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.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: linux-mm@kvack.org
---
arch/x86/include/asm/tlbflush.h | 55 +++++++++++++++++++++++++++++++---------
1 file changed, 43 insertions(+), 12 deletions(-)
--- a/arch/x86/include/asm/tlbflush.h
+++ b/arch/x86/include/asm/tlbflush.h
@@ -13,16 +13,33 @@
#include <asm/pti.h>
#include <asm/processor-flags.h>
-static inline u64 inc_mm_tlb_gen(struct mm_struct *mm)
-{
- /*
- * Bump the generation count. This also serves as a full barrier
- * that synchronizes with switch_mm(): callers are required to order
- * their read of mm_cpumask after their writes to the paging
- * structures.
- */
- return atomic64_inc_return(&mm->context.tlb_gen);
-}
+/*
+ * The x86 feature is called PCID (Process Context IDentifier). It is similar
+ * to what is traditionally called ASID on the RISC processors.
+ *
+ * We don't use the traditional ASID implementation, where each process/mm gets
+ * its own ASID and flush/restart when we run out of ASID space.
+ *
+ * Instead we have a small per-cpu array of ASIDs and cache the last few mm's
+ * that came by on this CPU, allowing cheaper switch_mm between processes on
+ * this CPU.
+ *
+ * We end up with different spaces for different things. To avoid confusion we
+ * use different names for each of them:
+ *
+ * ASID - [0, TLB_NR_DYN_ASIDS-1]
+ * the canonical identifier for an mm
+ *
+ * kPCID - [1, TLB_NR_DYN_ASIDS]
+ * the value we write into the PCID part of CR3; corresponds to the
+ * ASID+1, because PCID 0 is special.
+ *
+ * uPCID - [2048 + 1, 2048 + TLB_NR_DYN_ASIDS]
+ * for KPTI each mm has two address spaces and thus needs two
+ * PCID values, but we can still do with a single ASID denomination
+ * for each mm. Corresponds to kPCID + 2048.
+ *
+ */
/* There are 12 bits of space for ASIDS in CR3 */
#define CR3_HW_ASID_BITS 12
@@ -41,7 +58,7 @@ static inline u64 inc_mm_tlb_gen(struct
/*
* ASIDs are zero-based: 0->MAX_AVAIL_ASID are valid. -1 below to account
- * for them being zero-based. Another -1 is because ASID 0 is reserved for
+ * for them being zero-based. Another -1 is because PCID 0 is reserved for
* use by non-PCID-aware users.
*/
#define MAX_ASID_AVAILABLE ((1 << CR3_AVAIL_PCID_BITS) - 2)
@@ -52,6 +69,9 @@ static inline u64 inc_mm_tlb_gen(struct
*/
#define TLB_NR_DYN_ASIDS 6
+/*
+ * Given @asid, compute kPCID
+ */
static inline u16 kern_pcid(u16 asid)
{
VM_WARN_ON_ONCE(asid > MAX_ASID_AVAILABLE);
@@ -86,7 +106,7 @@ static inline u16 kern_pcid(u16 asid)
}
/*
- * The user PCID is just the kernel one, plus the "switch bit".
+ * Given @asid, compute uPCID
*/
static inline u16 user_pcid(u16 asid)
{
@@ -487,6 +507,17 @@ static inline void flush_tlb_page(struct
void native_flush_tlb_others(const struct cpumask *cpumask,
const struct flush_tlb_info *info);
+static inline u64 inc_mm_tlb_gen(struct mm_struct *mm)
+{
+ /*
+ * Bump the generation count. This also serves as a full barrier
+ * that synchronizes with switch_mm(): callers are required to order
+ * their read of mm_cpumask after their writes to the paging
+ * structures.
+ */
+ return atomic64_inc_return(&mm->context.tlb_gen);
+}
+
static inline void arch_tlbbatch_add_mm(struct arch_tlbflush_unmap_batch *batch,
struct mm_struct *mm)
{
next prev parent reply other threads:[~2017-12-16 21:40 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-16 21:23 [patch V149 00/50] x86/pti: Updated and reshuffled patch queue Thomas Gleixner
2017-12-16 21:23 ` [patch V149 01/50] x86/mm/dump_pagetables: Check PAGE_PRESENT for real Thomas Gleixner
2017-12-16 21:23 ` [patch V149 02/50] x86/vsyscall/64: Explicitly set _PAGE_USER in the pagetable hierarchy Thomas Gleixner
2017-12-16 21:23 ` [patch V149 03/50] x86/vsyscall/64: Warn and fail vsyscall emulation in NATIVE mode Thomas Gleixner
2017-12-16 21:23 ` [patch V149 04/50] arch: Allow arch_dup_mmap() to fail Thomas Gleixner
2017-12-16 21:23 ` [patch V149 05/50] x86/ldt: Rework locking Thomas Gleixner
2017-12-16 21:24 ` [patch V149 06/50] x86/ldt: Prevent ldt inheritance on exec Thomas Gleixner
2017-12-16 21:24 ` [patch V149 07/50] x86/mm/64: Improve the memory map documentation Thomas Gleixner
2017-12-16 21:24 ` [patch V149 08/50] x86/doc: Remove obvious weirdness Thomas Gleixner
2017-12-16 21:24 ` [patch V149 09/50] x86/entry: Remove SYSENTER_stack naming Thomas Gleixner
2017-12-16 21:24 ` [patch V149 10/50] x86/uv: Use the right tlbflush API Thomas Gleixner
2017-12-16 21:24 ` [patch V149 11/50] x86/microcode: Dont abuse the tlbflush interface Thomas Gleixner
2017-12-16 21:24 ` [patch V149 12/50] x86/mm: Use __flush_tlb_one() for kernel memory Thomas Gleixner
2017-12-16 21:24 ` [patch V149 13/50] x86/mm: Remove superfluous barriers Thomas Gleixner
2017-12-16 21:24 ` [patch V149 14/50] x86/mm: Clarify which functions are supposed to flush what Thomas Gleixner
2017-12-16 21:24 ` [patch V149 15/50] x86/mm: Move the CR3 construction functions to tlbflush.h Thomas Gleixner
2017-12-16 21:24 ` [patch V149 16/50] x86/mm: Remove hard-coded ASID limit checks Thomas Gleixner
2017-12-16 21:24 ` [patch V149 17/50] x86/mm: Put MMU to hardware ASID translation in one place Thomas Gleixner
2017-12-16 21:24 ` [patch V149 18/50] x86/mm: Create asm/invpcid.h Thomas Gleixner
2017-12-16 21:24 ` [patch V149 19/50] x86/cpufeatures: Add X86_BUG_CPU_INSECURE Thomas Gleixner
2017-12-16 21:24 ` [patch V149 20/50] x86/mm/pti: Disable global pages if PAGE_TABLE_ISOLATION=y Thomas Gleixner
2017-12-16 21:24 ` [patch V149 21/50] x86/mm/pti: Prepare the x86/entry assembly code for entry/exit CR3 switching Thomas Gleixner
2017-12-16 21:24 ` [patch V149 22/50] x86/mm/pti: Add infrastructure for page table isolation Thomas Gleixner
2017-12-16 21:24 ` [patch V149 23/50] x86/mm/pti: Add mapping helper functions Thomas Gleixner
2017-12-16 21:24 ` [patch V149 24/50] x86/mm/pti: Allow NX poison to be set in p4d/pgd Thomas Gleixner
2017-12-16 21:24 ` [patch V149 25/50] x86/mm/pti: Allocate a separate user PGD Thomas Gleixner
2017-12-16 21:24 ` [patch V149 26/50] x86/mm/pti: Populate " Thomas Gleixner
2017-12-16 21:24 ` [patch V149 27/50] x86/mm/pti: Add functions to clone kernel PMDs Thomas Gleixner
2017-12-16 21:24 ` [patch V149 28/50] x86/mm/pti: Force entry through trampoline when PTI active Thomas Gleixner
2017-12-16 21:24 ` [patch V149 29/50] x86/fixmap: Move the CPU entry area into a separate PMD Thomas Gleixner
2017-12-16 21:24 ` [patch V149 30/50] x86/mm/pti: Share cpu_entry_area PMDs Thomas Gleixner
2017-12-16 21:24 ` [patch V149 31/50] x86/entry: Align entry text section to PMD boundary Thomas Gleixner
2017-12-16 21:24 ` [patch V149 32/50] x86/mm/pti: Share entry text PMD Thomas Gleixner
2017-12-16 21:24 ` [patch V149 33/50] x86/mm/pti: Map ESPFIX into user space Thomas Gleixner
2017-12-16 21:24 ` [patch V149 34/50] x86/fixmap: Move IDT fixmap into the cpu_entry_area range Thomas Gleixner
2017-12-16 21:24 ` [patch V149 35/50] x86/fixmap: Add debugstore entries to cpu_entry_area Thomas Gleixner
2017-12-16 21:24 ` [patch V149 36/50] x86/events/intel/ds: Map debug buffers in fixmap Thomas Gleixner
2017-12-16 21:24 ` [patch V149 37/50] x86/mm/64: Make a full PGD-entry size hole in the memory map Thomas Gleixner
2017-12-17 11:07 ` Kirill A. Shutemov
2017-12-16 21:24 ` [patch V149 38/50] x86/pti: Put the LDT in its own PGD if PTI is on Thomas Gleixner
2017-12-17 11:09 ` Kirill A. Shutemov
2017-12-16 21:24 ` [patch V149 39/50] x86/pti: Map the vsyscall page if needed Thomas Gleixner
2017-12-16 21:24 ` [patch V149 40/50] x86/mm: Allow flushing for future ASID switches Thomas Gleixner
2017-12-16 21:24 ` [patch V149 41/50] x86/mm: Abstract switching CR3 Thomas Gleixner
2017-12-16 21:24 ` [patch V149 42/50] x86/mm: Use/Fix PCID to optimize user/kernel switches Thomas Gleixner
2017-12-16 21:24 ` [patch V149 43/50] x86/mm: Optimize RESTORE_CR3 Thomas Gleixner
2017-12-16 21:24 ` [patch V149 44/50] x86/mm: Use INVPCID for __native_flush_tlb_single() Thomas Gleixner
2017-12-16 21:24 ` Thomas Gleixner [this message]
2017-12-16 21:24 ` [patch V149 46/50] x86/mm/pti: Add Kconfig Thomas Gleixner
2017-12-16 21:24 ` [patch V149 47/50] x86/mm/dump_pagetables: Add page table directory Thomas Gleixner
2017-12-16 21:24 ` [patch V149 48/50] x86/mm/dump_pagetables: Check user space page table for WX pages Thomas Gleixner
2017-12-16 21:24 ` [patch V149 49/50] x86/mm/dump_pagetables: Allow dumping current pagetables Thomas Gleixner
2017-12-16 21:24 ` [patch V149 50/50] x86/ldt: Make the LDT mapping RO Thomas Gleixner
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