From: Andy Lutomirski <luto@kernel.org>
To: X86 ML <x86@kernel.org>
Cc: Borislav Petkov <bpetkov@suse.de>,
"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>,
Andy Lutomirski <luto@kernel.org>
Subject: [PATCH v2 05/18] x86/fixmap: Generalize the GDT fixmap mechanism
Date: Tue, 21 Nov 2017 20:44:00 -0800 [thread overview]
Message-ID: <7d11626f17da123a741dc54b61edec5d868c3987.1511325444.git.luto@kernel.org> (raw)
In-Reply-To: <cover.1511325444.git.luto@kernel.org>
In-Reply-To: <cover.1511325444.git.luto@kernel.org>
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
@@ -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.
+ */
+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);
+
+ 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); \
+ __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));
+}
+
#endif /* !__ASSEMBLY__ */
#endif /* _ASM_X86_FIXMAP_H */
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 1243f732810b..1e0843d15e64 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -488,12 +488,12 @@ void load_percpu_segment(int cpu)
load_stack_canary_segment();
}
-/* Setup the fixmap mapping only once per-processor */
-static inline void setup_fixmap_gdt(int cpu)
+/* Setup the fixmap mappings only once per-processor */
+static inline void setup_cpu_entry_area(int cpu)
{
#ifdef CONFIG_X86_64
/* On 64-bit systems, we use a read-only fixmap GDT. */
- pgprot_t prot = PAGE_KERNEL_RO;
+ pgprot_t gdt_prot = PAGE_KERNEL_RO;
#else
/*
* On native 32-bit systems, the GDT cannot be read-only because
@@ -504,11 +504,11 @@ static inline void setup_fixmap_gdt(int cpu)
* On Xen PV, the GDT must be read-only because the hypervisor requires
* it.
*/
- pgprot_t prot = boot_cpu_has(X86_FEATURE_XENPV) ?
+ pgprot_t gdt_prot = boot_cpu_has(X86_FEATURE_XENPV) ?
PAGE_KERNEL_RO : PAGE_KERNEL;
#endif
- __set_fixmap(get_cpu_gdt_ro_index(cpu), get_cpu_gdt_paddr(cpu), prot);
+ __set_fixmap(get_cpu_entry_area_index(cpu, gdt), get_cpu_gdt_paddr(cpu), gdt_prot);
}
/* Load the original GDT from the per-cpu structure */
@@ -1612,7 +1612,7 @@ void cpu_init(void)
if (is_uv_system())
uv_cpu_init();
- setup_fixmap_gdt(cpu);
+ setup_cpu_entry_area(cpu);
load_fixmap_gdt(cpu);
}
@@ -1674,7 +1674,7 @@ void cpu_init(void)
fpu__init_cpu();
- setup_fixmap_gdt(cpu);
+ setup_cpu_entry_area(cpu);
load_fixmap_gdt(cpu);
}
#endif
diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c
index fc048ec686e7..6cf801ca1142 100644
--- a/arch/x86/xen/mmu_pv.c
+++ b/arch/x86/xen/mmu_pv.c
@@ -2272,7 +2272,7 @@ static void xen_set_fixmap(unsigned idx, phys_addr_t phys, pgprot_t prot)
#endif
case FIX_TEXT_POKE0:
case FIX_TEXT_POKE1:
- case FIX_GDT_REMAP_BEGIN ... FIX_GDT_REMAP_END:
+ case FIX_CPU_ENTRY_AREA_TOP ... FIX_CPU_ENTRY_AREA_BOTTOM:
/* All local page mappings */
pte = pfn_pte(phys, prot);
break;
--
2.13.6
next prev parent reply other threads:[~2017-11-22 4:44 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 ` Andy Lutomirski [this message]
2017-11-22 15:33 ` [PATCH v2 05/18] x86/fixmap: Generalize the GDT fixmap mechanism Borislav Petkov
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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