From: Borislav Petkov <bp@suse.de>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
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>,
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,
Dave Hansen <dave.hansen@linux.intel.com>
Subject: Re: [patch 31/60] x86/mm/kpti: Add mapping helper functions
Date: Tue, 5 Dec 2017 17:01:34 +0100 [thread overview]
Message-ID: <20171205160134.dhrc5oata2hqln3a@pd.tnic> (raw)
In-Reply-To: <20171204150607.391576490@linutronix.de>
On Mon, Dec 04, 2017 at 03:07:37PM +0100, Thomas Gleixner wrote:
> From: Dave Hansen <dave.hansen@linux.intel.com>
>
> Add the pagetable helper functions do manage the separate user space page
> tables.
>
> [ tglx: Split out from the big combo kaiser patch ]
>
> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
>
> ---
> arch/x86/include/asm/pgtable_64.h | 139 ++++++++++++++++++++++++++++++++++++++
> 1 file changed, 139 insertions(+)
...
> +/*
> + * Take a PGD location (pgdp) and a pgd value that needs to be set there.
> + * Populates the user and returns the resulting PGD that must be set in
> + * the kernel copy of the page tables.
> + */
> +static inline pgd_t kpti_set_user_pgd(pgd_t *pgdp, pgd_t pgd)
> +{
Btw, do we want to inline a relatively big function like that? I see at
least 20-ish callsites of set_pgd() only.
> +#ifdef CONFIG_KERNEL_PAGE_TABLE_ISOLATION
> + if (!static_cpu_has_bug(X86_BUG_CPU_SECURE_MODE_KPTI))
> + return pgd;
> +
> + if (pgd_userspace_access(pgd)) {
> + if (pgdp_maps_userspace(pgdp)) {
> + /*
> + * The user page tables get the full PGD,
> + * accessible from userspace:
> + */
> + kernel_to_user_pgdp(pgdp)->pgd = pgd.pgd;
> + /*
> + * For the copy of the pgd that the kernel uses,
> + * make it unusable to userspace. This ensures on
> + * in case that a return to userspace with the
> + * kernel CR3 value, userspace will crash instead
> + * of running.
> + *
> + * Note: NX might be not available or disabled.
> + */
> + if (__supported_pte_mask & _PAGE_NX)
> + pgd.pgd |= _PAGE_NX;
> + }
> + } else if (pgd_userspace_access(*pgdp)) {
> + /*
> + * We are clearing a _PAGE_USER PGD for which we presumably
> + * populated the user PGD. We must now clear the user PGD
> + * entry.
> + */
> + if (pgdp_maps_userspace(pgdp)) {
> + kernel_to_user_pgdp(pgdp)->pgd = pgd.pgd;
> + } else {
> + /*
> + * Attempted to clear a _PAGE_USER PGD which is in
> + * the kernel porttion of the address space. PGDs
"portion"
> + * are pre-populated and we never clear them.
> + */
> + WARN_ON_ONCE(1);
> + }
> + } else {
> + /*
> + * _PAGE_USER was not set in either the PGD being set or
> + * cleared. All kernel PGDs should be pre-populated so
> + * this should never happen after boot.
> + */
> + WARN_ON_ONCE(system_state == SYSTEM_RUNNING);
> + }
Btw, we could keep the warning and have a separate path kernel users
like kernel_ident_mapping_init() (i.e., kexec, hibernation, et al) call
to bypass the warning vs all the remaining users which call the default
set_pgd().
> +#endif
> + /* return the copy of the PGD we want the kernel to use: */
> + return pgd;
> +}
> +
> +
> static inline void native_set_p4d(p4d_t *p4dp, p4d_t p4d)
> {
> +#if defined(CONFIG_KERNEL_PAGE_TABLE_ISOLATION) && !defined(CONFIG_X86_5LEVEL)
> + p4dp->pgd = kpti_set_user_pgd(&p4dp->pgd, p4d.pgd);
> +#else
> *p4dp = p4d;
> +#endif
> }
>
> static inline void native_p4d_clear(p4d_t *p4d)
> @@ -147,7 +282,11 @@ static inline void native_p4d_clear(p4d_
>
> static inline void native_set_pgd(pgd_t *pgdp, pgd_t pgd)
> {
> +#ifdef CONFIG_KERNEL_PAGE_TABLE_ISOLATION
> + *pgdp = kpti_set_user_pgd(pgdp, pgd);
> +#else
> *pgdp = pgd;
> +#endif
I guess that ifdef is not needed as kpti_set_user_pgd() already has it
so we can do simply:
static inline void native_set_pgd(pgd_t *pgdp, pgd_t pgd)
{
*pgdp = kpti_set_user_pgd(pgdp, pgd);
}
AFAICT.
--
Regards/Gruss,
Boris.
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--
next prev parent reply other threads:[~2017-12-05 16:01 UTC|newest]
Thread overview: 118+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-04 14:07 [patch 00/60] x86/kpti: Kernel Page Table Isolation (was KAISER) Thomas Gleixner
2017-12-04 14:07 ` [patch 01/60] x86/entry/64/paravirt: Use paravirt-safe macro to access eflags Thomas Gleixner
2017-12-05 12:17 ` Juergen Gross
2017-12-04 14:07 ` [patch 02/60] x86/unwinder/orc: Dont bail on stack overflow Thomas Gleixner
2017-12-04 20:31 ` Andy Lutomirski
2017-12-04 21:31 ` Thomas Gleixner
2017-12-04 14:07 ` [patch 03/60] x86/unwinder: Handle stack overflows more gracefully Thomas Gleixner
2017-12-04 14:07 ` [patch 04/60] x86/irq: Remove an old outdated comment about context tracking races Thomas Gleixner
2017-12-04 14:07 ` [patch 05/60] x86/irq/64: Print the offending IP in the stack overflow warning Thomas Gleixner
2017-12-04 14:07 ` [patch 06/60] x86/entry/64: Allocate and enable the SYSENTER stack Thomas Gleixner
2017-12-04 14:07 ` [patch 07/60] x86/dumpstack: Add get_stack_info() support for " Thomas Gleixner
2017-12-04 14:07 ` [patch 08/60] x86/entry/gdt: Put per-CPU GDT remaps in ascending order Thomas Gleixner
2017-12-04 14:07 ` [patch 09/60] x86/mm/fixmap: Generalize the GDT fixmap mechanism, introduce struct cpu_entry_area Thomas Gleixner
2017-12-04 14:07 ` [patch 10/60] x86/kasan/64: Teach KASAN about the cpu_entry_area Thomas Gleixner
2017-12-04 14:07 ` [patch 11/60] x86/entry: Fix assumptions that the HW TSS is at the beginning of cpu_tss Thomas Gleixner
2017-12-04 14:07 ` [patch 12/60] x86/dumpstack: Handle stack overflow on all stacks Thomas Gleixner
2017-12-04 14:07 ` [patch 13/60] x86/entry: Move SYSENTER_stack to the beginning of struct tss_struct Thomas Gleixner
2017-12-04 14:07 ` [patch 14/60] x86/entry: Remap the TSS into the CPU entry area Thomas Gleixner
2017-12-04 18:20 ` Borislav Petkov
2017-12-04 14:07 ` [patch 15/60] x86/entry/64: Separate cpu_current_top_of_stack from TSS.sp0 Thomas Gleixner
2017-12-04 14:07 ` [patch 16/60] x86/espfix/64: Stop assuming that pt_regs is on the entry stack Thomas Gleixner
2017-12-04 14:07 ` [patch 17/60] x86/entry/64: Use a per-CPU trampoline stack for IDT entries Thomas Gleixner
2017-12-04 14:07 ` [patch 18/60] x86/entry/64: Return to userspace from the trampoline stack Thomas Gleixner
2017-12-04 14:07 ` [patch 19/60] x86/entry/64: Create a per-CPU SYSCALL entry trampoline Thomas Gleixner
2017-12-04 22:30 ` Andy Lutomirski
2017-12-04 14:07 ` [patch 20/60] x86/entry/64: Move the IST stacks into struct cpu_entry_area Thomas Gleixner
2017-12-04 14:07 ` [patch 21/60] x86/entry/64: Remove the SYSENTER stack canary Thomas Gleixner
2017-12-04 14:07 ` [patch 22/60] x86/entry: Clean up the SYSENTER_stack code Thomas Gleixner
2017-12-04 19:41 ` Borislav Petkov
2017-12-04 14:07 ` [patch 23/60] x86/entry/64: Make cpu_entry_area.tss read-only Thomas Gleixner
2017-12-04 20:25 ` Borislav Petkov
2017-12-04 14:07 ` [patch 24/60] x86/paravirt: Dont patch flush_tlb_single Thomas Gleixner
2017-12-05 12:18 ` Juergen Gross
2017-12-04 14:07 ` [patch 25/60] x86/paravirt: Provide a way to check for hypervisors Thomas Gleixner
2017-12-05 12:19 ` Juergen Gross
2017-12-04 14:07 ` [patch 26/60] x86/cpufeature: Make cpu bugs sticky Thomas Gleixner
2017-12-04 22:39 ` Borislav Petkov
2017-12-04 14:07 ` [patch 27/60] x86/cpufeatures: Add X86_BUG_CPU_INSECURE Thomas Gleixner
2017-12-04 23:18 ` Borislav Petkov
2017-12-04 14:07 ` [patch 28/60] x86/mm/kpti: Disable global pages if KERNEL_PAGE_TABLE_ISOLATION=y Thomas Gleixner
2017-12-05 14:34 ` Borislav Petkov
2017-12-04 14:07 ` [patch 29/60] x86/mm/kpti: Prepare the x86/entry assembly code for entry/exit CR3 switching Thomas Gleixner
2017-12-04 14:07 ` [patch 30/60] x86/mm/kpti: Add infrastructure for page table isolation Thomas Gleixner
2017-12-05 15:20 ` Borislav Petkov
2017-12-04 14:07 ` [patch 31/60] x86/mm/kpti: Add mapping helper functions Thomas Gleixner
2017-12-04 22:27 ` Andy Lutomirski
2017-12-05 16:01 ` Borislav Petkov [this message]
2017-12-07 8:33 ` Borislav Petkov
2017-12-04 14:07 ` [patch 32/60] x86/mm/kpti: Allow NX poison to be set in p4d/pgd Thomas Gleixner
2017-12-05 17:09 ` Borislav Petkov
2017-12-04 14:07 ` [patch 33/60] x86/mm/kpti: Allocate a separate user PGD Thomas Gleixner
2017-12-05 18:33 ` Borislav Petkov
2017-12-06 20:56 ` Ingo Molnar
2017-12-04 14:07 ` [patch 34/60] x86/mm/kpti: Populate " Thomas Gleixner
2017-12-05 19:17 ` Borislav Petkov
2017-12-04 14:07 ` [patch 35/60] x86/espfix: Ensure that ESPFIX is visible in " Thomas Gleixner
2017-12-04 22:28 ` Andy Lutomirski
2017-12-04 14:07 ` [patch 36/60] x86/mm/kpti: Add functions to clone kernel PMDs Thomas Gleixner
2017-12-06 15:39 ` Borislav Petkov
2017-12-04 14:07 ` [patch 37/60] x86mm//kpti: Force entry through trampoline when KPTI active Thomas Gleixner
2017-12-06 16:01 ` Borislav Petkov
2017-12-04 14:07 ` [patch 38/60] x86/fixmap: Move cpu entry area into a separate PMD Thomas Gleixner
2017-12-06 18:57 ` Borislav Petkov
2017-12-04 14:07 ` [patch 39/60] x86/mm/kpti: Share cpu_entry_area PMDs Thomas Gleixner
2017-12-06 21:18 ` Borislav Petkov
2017-12-04 14:07 ` [patch 40/60] x86: PMD align entry text Thomas Gleixner
2017-12-07 8:07 ` Borislav Petkov
2017-12-04 14:07 ` [patch 41/60] x86/mm/kpti: Share entry text PMD Thomas Gleixner
2017-12-07 8:24 ` Borislav Petkov
2017-12-04 14:07 ` [patch 42/60] x86/fixmap: Move IDT fixmap into the cpu_entry_area range Thomas Gleixner
2017-12-04 14:07 ` [patch 43/60] x86/fixmap: Add debugstore entries to cpu_entry_area Thomas Gleixner
2017-12-07 9:55 ` Borislav Petkov
2017-12-04 14:07 ` [patch 44/60] x86/events/intel/ds: Map debug buffers in fixmap Thomas Gleixner
2017-12-04 14:07 ` [patch 45/60] x86/fixmap: Add ldt entries to user shared fixmap Thomas Gleixner
2017-12-04 14:07 ` [patch 46/60] x86/ldt: Rename ldt_struct->entries member Thomas Gleixner
2017-12-04 14:07 ` [patch 47/60] x86/ldt: Map LDT entries into fixmap Thomas Gleixner
2017-12-04 22:33 ` Andy Lutomirski
2017-12-04 22:51 ` Thomas Gleixner
2017-12-04 14:07 ` [patch 48/60] x86/mm: Move the CR3 construction functions to tlbflush.h Thomas Gleixner
2017-12-04 14:07 ` [patch 49/60] x86/mm: Remove hard-coded ASID limit checks Thomas Gleixner
2017-12-04 14:07 ` [patch 50/60] x86/mm: Put MMU to hardware ASID translation in one place Thomas Gleixner
2017-12-04 14:07 ` [patch 51/60] x86/mm: Allow flushing for future ASID switches Thomas Gleixner
2017-12-04 22:22 ` Andy Lutomirski
2017-12-04 22:34 ` Dave Hansen
2017-12-04 22:36 ` Andy Lutomirski
2017-12-04 22:47 ` Peter Zijlstra
2017-12-04 22:54 ` Andy Lutomirski
2017-12-04 23:06 ` Peter Zijlstra
2017-12-04 14:07 ` [patch 52/60] x86/mm: Abstract switching CR3 Thomas Gleixner
2017-12-04 14:07 ` [patch 53/60] x86/mm: Use/Fix PCID to optimize user/kernel switches Thomas Gleixner
2017-12-05 21:46 ` Andy Lutomirski
2017-12-05 22:05 ` Peter Zijlstra
2017-12-05 22:08 ` Dave Hansen
2017-12-04 14:08 ` [patch 54/60] x86/mm: Optimize RESTORE_CR3 Thomas Gleixner
2017-12-04 14:08 ` [patch 55/60] x86/mm: Use INVPCID for __native_flush_tlb_single() Thomas Gleixner
2017-12-04 22:25 ` Andy Lutomirski
2017-12-04 22:51 ` Peter Zijlstra
2017-12-05 13:51 ` Dave Hansen
2017-12-05 14:08 ` Peter Zijlstra
2017-12-04 14:08 ` [patch 56/60] x86/mm/kpti: Disable native VSYSCALL Thomas Gleixner
2017-12-04 22:33 ` Andy Lutomirski
2017-12-04 14:08 ` [patch 57/60] x86/mm/kpti: Add Kconfig Thomas Gleixner
2017-12-04 16:54 ` Andy Lutomirski
2017-12-04 16:57 ` Thomas Gleixner
2017-12-05 9:34 ` Thomas Gleixner
2017-12-04 14:08 ` [patch 58/60] x86/mm/debug_pagetables: Add page table directory Thomas Gleixner
2017-12-04 14:08 ` [patch 59/60] x86/mm/dump_pagetables: Check user space page table for WX pages Thomas Gleixner
2017-12-04 14:08 ` [patch 60/60] x86/mm/debug_pagetables: Allow dumping current pagetables Thomas Gleixner
2017-12-04 18:02 ` [patch 00/60] x86/kpti: Kernel Page Table Isolation (was KAISER) Linus Torvalds
2017-12-04 18:18 ` Thomas Gleixner
2017-12-04 18:21 ` Boris Ostrovsky
2017-12-04 18:28 ` Linus Torvalds
2017-12-05 21:49 ` Andy Lutomirski
2017-12-05 21:57 ` Dave Hansen
2017-12-05 23:19 ` Andy Lutomirski
2018-01-19 20:56 ` Andrew Morton
2018-01-19 21:06 ` Dave Hansen
2018-01-20 19:59 ` Thomas Gleixner
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