* [PATCH v2] x86/boot/64: Load kernel GDT in early boot
@ 2024-02-26 22:05 Brian Gerst
2024-02-27 14:57 ` Ard Biesheuvel
2024-02-28 10:11 ` [tip: x86/boot] x86/boot/64: Load the final kernel GDT during early boot directly, remove startup_gdt[] tip-bot2 for Brian Gerst
0 siblings, 2 replies; 3+ messages in thread
From: Brian Gerst @ 2024-02-26 22:05 UTC (permalink / raw)
To: linux-kernel, x86
Cc: Ingo Molnar, Thomas Gleixner, Borislav Petkov, H . Peter Anvin,
Peter Zijlstra, Ard Biesheuvel, Brian Gerst
Instead of loading a duplicate GDT just for early boot, load the kernel
GDT from its physical address.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
---
v2: Updated to latest tip tree
arch/x86/include/asm/desc.h | 1 +
arch/x86/kernel/head64.c | 13 ++-----------
2 files changed, 3 insertions(+), 11 deletions(-)
diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h
index ec95fe44fa3a..62dc9f59ea76 100644
--- a/arch/x86/include/asm/desc.h
+++ b/arch/x86/include/asm/desc.h
@@ -46,6 +46,7 @@ struct gdt_page {
} __attribute__((aligned(PAGE_SIZE)));
DECLARE_PER_CPU_PAGE_ALIGNED(struct gdt_page, gdt_page);
+DECLARE_INIT_PER_CPU(gdt_page);
/* Provide the original GDT */
static inline struct desc_struct *get_cpu_gdt_rw(unsigned int cpu)
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 72351c3121a6..fd77a266f29d 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -68,15 +68,6 @@ unsigned long vmemmap_base __ro_after_init = __VMEMMAP_BASE_L4;
EXPORT_SYMBOL(vmemmap_base);
#endif
-/*
- * GDT used on the boot CPU before switching to virtual addresses.
- */
-static struct desc_struct startup_gdt[GDT_ENTRIES] __initdata = {
- [GDT_ENTRY_KERNEL32_CS] = GDT_ENTRY_INIT(DESC_CODE32, 0, 0xfffff),
- [GDT_ENTRY_KERNEL_CS] = GDT_ENTRY_INIT(DESC_CODE64, 0, 0xfffff),
- [GDT_ENTRY_KERNEL_DS] = GDT_ENTRY_INIT(DESC_DATA64, 0, 0xfffff),
-};
-
#ifdef CONFIG_X86_5LEVEL
static void __head *fixup_pointer(void *ptr, unsigned long physaddr)
{
@@ -589,8 +580,8 @@ void __head startup_64_setup_gdt_idt(void)
void *handler = NULL;
struct desc_ptr startup_gdt_descr = {
- .address = (unsigned long)&RIP_REL_REF(startup_gdt),
- .size = sizeof(startup_gdt) - 1,
+ .address = (unsigned long)&RIP_REL_REF(init_per_cpu_var(gdt_page.gdt)),
+ .size = GDT_SIZE - 1,
};
/* Load GDT */
base-commit: afb9cce6ad6e808cf659f43925941be96f61b9c9
--
2.43.2
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v2] x86/boot/64: Load kernel GDT in early boot
2024-02-26 22:05 [PATCH v2] x86/boot/64: Load kernel GDT in early boot Brian Gerst
@ 2024-02-27 14:57 ` Ard Biesheuvel
2024-02-28 10:11 ` [tip: x86/boot] x86/boot/64: Load the final kernel GDT during early boot directly, remove startup_gdt[] tip-bot2 for Brian Gerst
1 sibling, 0 replies; 3+ messages in thread
From: Ard Biesheuvel @ 2024-02-27 14:57 UTC (permalink / raw)
To: Brian Gerst
Cc: linux-kernel, x86, Ingo Molnar, Thomas Gleixner, Borislav Petkov,
H . Peter Anvin, Peter Zijlstra
On Mon, 26 Feb 2024 at 23:05, Brian Gerst <brgerst@gmail.com> wrote:
>
> Instead of loading a duplicate GDT just for early boot, load the kernel
> GDT from its physical address.
>
> Signed-off-by: Brian Gerst <brgerst@gmail.com>
> ---
> v2: Updated to latest tip tree
>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
> arch/x86/include/asm/desc.h | 1 +
> arch/x86/kernel/head64.c | 13 ++-----------
> 2 files changed, 3 insertions(+), 11 deletions(-)
>
> diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h
> index ec95fe44fa3a..62dc9f59ea76 100644
> --- a/arch/x86/include/asm/desc.h
> +++ b/arch/x86/include/asm/desc.h
> @@ -46,6 +46,7 @@ struct gdt_page {
> } __attribute__((aligned(PAGE_SIZE)));
>
> DECLARE_PER_CPU_PAGE_ALIGNED(struct gdt_page, gdt_page);
> +DECLARE_INIT_PER_CPU(gdt_page);
>
> /* Provide the original GDT */
> static inline struct desc_struct *get_cpu_gdt_rw(unsigned int cpu)
> diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
> index 72351c3121a6..fd77a266f29d 100644
> --- a/arch/x86/kernel/head64.c
> +++ b/arch/x86/kernel/head64.c
> @@ -68,15 +68,6 @@ unsigned long vmemmap_base __ro_after_init = __VMEMMAP_BASE_L4;
> EXPORT_SYMBOL(vmemmap_base);
> #endif
>
> -/*
> - * GDT used on the boot CPU before switching to virtual addresses.
> - */
> -static struct desc_struct startup_gdt[GDT_ENTRIES] __initdata = {
> - [GDT_ENTRY_KERNEL32_CS] = GDT_ENTRY_INIT(DESC_CODE32, 0, 0xfffff),
> - [GDT_ENTRY_KERNEL_CS] = GDT_ENTRY_INIT(DESC_CODE64, 0, 0xfffff),
> - [GDT_ENTRY_KERNEL_DS] = GDT_ENTRY_INIT(DESC_DATA64, 0, 0xfffff),
> -};
> -
> #ifdef CONFIG_X86_5LEVEL
> static void __head *fixup_pointer(void *ptr, unsigned long physaddr)
> {
> @@ -589,8 +580,8 @@ void __head startup_64_setup_gdt_idt(void)
> void *handler = NULL;
>
> struct desc_ptr startup_gdt_descr = {
> - .address = (unsigned long)&RIP_REL_REF(startup_gdt),
> - .size = sizeof(startup_gdt) - 1,
> + .address = (unsigned long)&RIP_REL_REF(init_per_cpu_var(gdt_page.gdt)),
> + .size = GDT_SIZE - 1,
> };
>
> /* Load GDT */
>
> base-commit: afb9cce6ad6e808cf659f43925941be96f61b9c9
> --
> 2.43.2
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* [tip: x86/boot] x86/boot/64: Load the final kernel GDT during early boot directly, remove startup_gdt[]
2024-02-26 22:05 [PATCH v2] x86/boot/64: Load kernel GDT in early boot Brian Gerst
2024-02-27 14:57 ` Ard Biesheuvel
@ 2024-02-28 10:11 ` tip-bot2 for Brian Gerst
1 sibling, 0 replies; 3+ messages in thread
From: tip-bot2 for Brian Gerst @ 2024-02-28 10:11 UTC (permalink / raw)
To: linux-tip-commits
Cc: Brian Gerst, Ingo Molnar, Ard Biesheuvel, Kees Cook,
Andy Lutomirski, Linus Torvalds, H. Peter Anvin, Josh Poimboeuf,
x86, linux-kernel
The following commit has been merged into the x86/boot branch of tip:
Commit-ID: 11e36b0f7c2150a6453872b79555767b43c846d0
Gitweb: https://git.kernel.org/tip/11e36b0f7c2150a6453872b79555767b43c846d0
Author: Brian Gerst <brgerst@gmail.com>
AuthorDate: Mon, 26 Feb 2024 17:05:44 -05:00
Committer: Ingo Molnar <mingo@kernel.org>
CommitterDate: Wed, 28 Feb 2024 11:02:16 +01:00
x86/boot/64: Load the final kernel GDT during early boot directly, remove startup_gdt[]
Instead of loading a duplicate GDT just for early boot, load the kernel
GDT from its physical address.
Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20240226220544.70769-1-brgerst@gmail.com
---
arch/x86/include/asm/desc.h | 1 +
arch/x86/kernel/head64.c | 13 ++-----------
2 files changed, 3 insertions(+), 11 deletions(-)
diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h
index ab97b22..52c0150 100644
--- a/arch/x86/include/asm/desc.h
+++ b/arch/x86/include/asm/desc.h
@@ -46,6 +46,7 @@ struct gdt_page {
} __attribute__((aligned(PAGE_SIZE)));
DECLARE_PER_CPU_PAGE_ALIGNED(struct gdt_page, gdt_page);
+DECLARE_INIT_PER_CPU(gdt_page);
/* Provide the original GDT */
static inline struct desc_struct *get_cpu_gdt_rw(unsigned int cpu)
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 72351c3..fd77a26 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -68,15 +68,6 @@ unsigned long vmemmap_base __ro_after_init = __VMEMMAP_BASE_L4;
EXPORT_SYMBOL(vmemmap_base);
#endif
-/*
- * GDT used on the boot CPU before switching to virtual addresses.
- */
-static struct desc_struct startup_gdt[GDT_ENTRIES] __initdata = {
- [GDT_ENTRY_KERNEL32_CS] = GDT_ENTRY_INIT(DESC_CODE32, 0, 0xfffff),
- [GDT_ENTRY_KERNEL_CS] = GDT_ENTRY_INIT(DESC_CODE64, 0, 0xfffff),
- [GDT_ENTRY_KERNEL_DS] = GDT_ENTRY_INIT(DESC_DATA64, 0, 0xfffff),
-};
-
#ifdef CONFIG_X86_5LEVEL
static void __head *fixup_pointer(void *ptr, unsigned long physaddr)
{
@@ -589,8 +580,8 @@ void __head startup_64_setup_gdt_idt(void)
void *handler = NULL;
struct desc_ptr startup_gdt_descr = {
- .address = (unsigned long)&RIP_REL_REF(startup_gdt),
- .size = sizeof(startup_gdt) - 1,
+ .address = (unsigned long)&RIP_REL_REF(init_per_cpu_var(gdt_page.gdt)),
+ .size = GDT_SIZE - 1,
};
/* Load GDT */
^ permalink raw reply related [flat|nested] 3+ messages in thread
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2024-02-26 22:05 [PATCH v2] x86/boot/64: Load kernel GDT in early boot Brian Gerst
2024-02-27 14:57 ` Ard Biesheuvel
2024-02-28 10:11 ` [tip: x86/boot] x86/boot/64: Load the final kernel GDT during early boot directly, remove startup_gdt[] tip-bot2 for Brian Gerst
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