From: Borislav Petkov <bp@suse.de>
To: Andy Lutomirski <luto@kernel.org>
Cc: X86 ML <x86@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Brian Gerst <brgerst@gmail.com>,
Dave Hansen <dave.hansen@intel.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Josh Poimboeuf <jpoimboe@redhat.com>
Subject: Re: [PATCH v2 05/18] x86/fixmap: Generalize the GDT fixmap mechanism
Date: Wed, 22 Nov 2017 16:33:38 +0100 [thread overview]
Message-ID: <20171122153327.fyxn4zspgdrjs45s@pd.tnic> (raw)
In-Reply-To: <7d11626f17da123a741dc54b61edec5d868c3987.1511325444.git.luto@kernel.org>
On Tue, Nov 21, 2017 at 08:44:00PM -0800, Andy Lutomirski wrote:
> Currently, the GDT is an ad-hoc array of pages, one per CPU, in the
> fixmap. Generalize it to be an array of a new struct cpu_entry_area
> so that we can cleanly add new things to it.
>
> Signed-off-by: Andy Lutomirski <luto@kernel.org>
> ---
> arch/x86/include/asm/desc.h | 9 +--------
> arch/x86/include/asm/fixmap.h | 36 ++++++++++++++++++++++++++++++++++--
> arch/x86/kernel/cpu/common.c | 14 +++++++-------
> arch/x86/xen/mmu_pv.c | 2 +-
> 4 files changed, 43 insertions(+), 18 deletions(-)
>
> diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h
> index 95cd95eb7285..194ffab00ebe 100644
> --- a/arch/x86/include/asm/desc.h
> +++ b/arch/x86/include/asm/desc.h
> @@ -60,17 +60,10 @@ static inline struct desc_struct *get_current_gdt_rw(void)
> return this_cpu_ptr(&gdt_page)->gdt;
> }
>
> -/* Get the fixmap index for a specific processor */
> -static inline unsigned int get_cpu_gdt_ro_index(int cpu)
> -{
> - return FIX_GDT_REMAP_END - cpu;
> -}
> -
> /* Provide the fixmap address of the remapped GDT */
> static inline struct desc_struct *get_cpu_gdt_ro(int cpu)
> {
> - unsigned int idx = get_cpu_gdt_ro_index(cpu);
> - return (struct desc_struct *)__fix_to_virt(idx);
> + return (struct desc_struct *)&get_cpu_entry_area(cpu)->gdt;
> }
>
> /* Provide the current read-only GDT */
> diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h
> index b0c505fe9a95..038b8474c7f8 100644
> --- a/arch/x86/include/asm/fixmap.h
> +++ b/arch/x86/include/asm/fixmap.h
Btw, the whole cpu_entry_area machinery looks like it should belong more
in asm/processor.h and not in fixmap.h
> @@ -44,6 +44,17 @@ extern unsigned long __FIXADDR_TOP;
> PAGE_SIZE)
> #endif
>
> +/*
> + * cpu_entry_area is a percpu region in the fixmap that contains things
> + * needed by the CPU and early entry/exit code. Real types aren't used
> + * for all fields here to about circular header dependencies.
s/about/avoid/
> + */
> +struct cpu_entry_area
> +{
ERROR: open brace '{' following struct go on the same line
#67: FILE: arch/x86/include/asm/fixmap.h:53:
+struct cpu_entry_area
+{
> + char gdt[PAGE_SIZE];
> +};
> +
> +#define CPU_ENTRY_AREA_PAGES (sizeof(struct cpu_entry_area) / PAGE_SIZE)
>
> /*
> * Here we define all the compile-time 'special' virtual
> @@ -101,8 +112,8 @@ enum fixed_addresses {
> FIX_LNW_VRTC,
> #endif
> /* Fixmap entries to remap the GDTs, one per processor. */
> - FIX_GDT_REMAP_BEGIN,
> - FIX_GDT_REMAP_END = FIX_GDT_REMAP_BEGIN + NR_CPUS - 1,
> + FIX_CPU_ENTRY_AREA_TOP,
> + FIX_CPU_ENTRY_AREA_BOTTOM = FIX_CPU_ENTRY_AREA_TOP + (CPU_ENTRY_AREA_PAGES * NR_CPUS) - 1,
>
> #ifdef CONFIG_ACPI_APEI_GHES
> /* Used for GHES mapping from assorted contexts */
> @@ -191,5 +202,26 @@ void __init *early_memremap_decrypted_wp(resource_size_t phys_addr,
> void __early_set_fixmap(enum fixed_addresses idx,
> phys_addr_t phys, pgprot_t flags);
>
> +static inline unsigned int __get_cpu_entry_area_page_index(int cpu, int page)
> +{
> + BUILD_BUG_ON(sizeof(struct cpu_entry_area) % PAGE_SIZE != 0);
BUILD_BUG_ON(sizeof(struct cpu_entry_area) % PAGE_SIZE);
> +
> + return FIX_CPU_ENTRY_AREA_BOTTOM - cpu*CPU_ENTRY_AREA_PAGES - page;
> +}
> +
> +#define __get_cpu_entry_area_offset_index(cpu, offset) ({ \
> + BUILD_BUG_ON(offset % PAGE_SIZE != 0); \
BUILD_BUG_ON(offset % PAGE_SIZE);
> + __get_cpu_entry_area_page_index(cpu, offset / PAGE_SIZE); \
> + })
> +
> +#define get_cpu_entry_area_index(cpu, field) \
> + __get_cpu_entry_area_offset_index((cpu), offsetof(struct cpu_entry_area, field))
> +
> +static inline struct cpu_entry_area *get_cpu_entry_area(int cpu)
> +{
> + return (struct cpu_entry_area *)
> + __fix_to_virt(__get_cpu_entry_area_page_index(cpu, 0));
Just let it stick out.
--
Regards/Gruss,
Boris.
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--
next prev parent reply other threads:[~2017-11-22 15:33 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-22 4:43 [PATCH v2 00/18] Entry stack switching Andy Lutomirski
2017-11-22 4:43 ` [PATCH v2 01/18] x86/entry/64: Fix entry_SYSCALL_64_after_hwframe IRQ tracing Andy Lutomirski
2017-11-22 5:35 ` Ingo Molnar
2017-11-22 7:45 ` [tip:x86/urgent] x86/entry/64: Fix entry_SYSCALL_64_after_hwframe() " tip-bot for Andy Lutomirski
2017-11-22 4:43 ` [PATCH v2 02/18] x86/asm/64: Allocate and enable the SYSENTER stack Andy Lutomirski
2017-11-22 4:43 ` [PATCH v2 03/18] x86/dumpstack: Add get_stack_info() support for " Andy Lutomirski
2017-11-22 12:10 ` Borislav Petkov
2017-11-22 4:43 ` [PATCH v2 04/18] x86/gdt: Put per-cpu GDT remaps in ascending order Andy Lutomirski
2017-11-22 11:05 ` Borislav Petkov
2017-11-22 15:26 ` Andy Lutomirski
2017-11-22 4:44 ` [PATCH v2 05/18] x86/fixmap: Generalize the GDT fixmap mechanism Andy Lutomirski
2017-11-22 15:33 ` Borislav Petkov [this message]
2017-11-22 17:16 ` Andy Lutomirski
2017-11-22 17:32 ` Borislav Petkov
2017-11-23 15:24 ` Andy Lutomirski
2017-11-23 19:24 ` Thomas Gleixner
2017-11-22 4:44 ` [PATCH v2 06/18] x86/kasan/64: Teach KASAN about the cpu_entry_area Andy Lutomirski
2017-11-22 6:19 ` Ingo Molnar
2017-11-22 9:05 ` Andrey Ryabinin
2017-11-22 15:22 ` Andy Lutomirski
2017-11-23 10:08 ` Andrey Ryabinin
2017-11-23 15:22 ` Andy Lutomirski
2017-11-22 4:44 ` [PATCH v2 07/18] x86/asm: Fix assumptions that the HW TSS is at the beginning of cpu_tss Andy Lutomirski
2017-11-22 19:06 ` Borislav Petkov
2017-11-22 4:44 ` [PATCH v2 08/18] x86/dumpstack: Handle stack overflow on all stacks Andy Lutomirski
2017-11-23 11:19 ` Borislav Petkov
2017-11-22 4:44 ` [PATCH v2 09/18] x86/asm: Move SYSENTER_stack to the beginning of struct tss_struct Andy Lutomirski
2017-11-23 12:00 ` Borislav Petkov
2017-11-23 13:16 ` Denys Vlasenko
2017-11-23 15:02 ` Andy Lutomirski
2017-11-23 19:30 ` Thomas Gleixner
2017-11-22 4:44 ` [PATCH v2 10/18] x86/asm: Remap the TSS into the cpu entry area Andy Lutomirski
2017-11-23 19:32 ` Thomas Gleixner
2017-11-23 19:55 ` Borislav Petkov
2017-11-23 20:15 ` Andy Lutomirski
2017-11-23 20:37 ` Borislav Petkov
2017-11-24 2:40 ` Andy Lutomirski
2017-11-24 4:17 ` Andy Lutomirski
2017-11-22 4:44 ` [PATCH v2 11/18] x86/asm/64: Separate cpu_current_top_of_stack from TSS.sp0 Andy Lutomirski
2017-11-23 19:34 ` Thomas Gleixner
2017-11-22 4:44 ` [PATCH v2 12/18] x86/espfix/64: Stop assuming that pt_regs is on the entry stack Andy Lutomirski
2017-11-23 19:36 ` Thomas Gleixner
2017-11-22 4:44 ` [PATCH v2 13/18] x86/asm/64: Use a percpu trampoline stack for IDT entries Andy Lutomirski
2017-11-23 23:44 ` Thomas Gleixner
2017-11-24 4:14 ` Andy Lutomirski
2017-11-22 4:44 ` [PATCH v2 14/18] x86/asm/64: Return to userspace from the trampoline stack Andy Lutomirski
2017-11-22 4:44 ` [PATCH v2 15/18] x86/entry/64: Create a percpu SYSCALL entry trampoline Andy Lutomirski
2017-11-22 4:44 ` [PATCH v2 16/18] x86/irq: Remove an old outdated comment about context tracking races Andy Lutomirski
2017-11-22 4:44 ` [PATCH v2 17/18] x86/irq/64: In the stack overflow warning, print the offending IP Andy Lutomirski
2017-11-22 4:44 ` [PATCH v2 18/18] x86/entry/64: Move the IST stacks into cpu_entry_area Andy Lutomirski
2017-11-22 6:22 ` [PATCH v2 00/18] Entry stack switching Ingo Molnar
2017-11-22 6:36 ` Ingo Molnar
2017-11-22 16:23 ` Andy Lutomirski
2017-11-23 6:21 ` Ingo Molnar
2017-11-23 6:44 ` Ingo Molnar
2017-11-23 6:58 ` Ingo Molnar
2017-11-23 15:29 ` Andy Lutomirski
2017-11-23 16:41 ` Thomas Gleixner
2017-11-22 7:39 ` WARNING: can't dereference registers at ffffc90004dfff60 for ip error_entry+0x7d/0xd0 (Re: [PATCH v2 00/18] Entry stack switching) Ingo Molnar
2017-11-22 7:43 ` Ingo Molnar
2017-11-22 13:55 ` Josh Poimboeuf
2017-11-22 15:19 ` Andy Lutomirski
2017-11-22 15:56 ` Ingo Molnar
2017-11-22 16:35 ` Andy Lutomirski
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