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Subject[tip: x86/entry] x86/idt: Consolidate idt functionality
The following commit has been merged into the x86/entry branch of tip:

Commit-ID: 5980d208e5ef28455e9e8b08f6250b443a2f0893
Gitweb: https://git.kernel.org/tip/5980d208e5ef28455e9e8b08f6250b443a2f0893
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Thu, 28 May 2020 16:53:20 +02:00
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Sat, 30 May 2020 11:50:13 +02:00

x86/idt: Consolidate idt functionality

- Move load_current_idt() out of line and replace the hideous comment with
a lockdep assert. This allows to make idt_table and idt_descr static.

- Mark idt_table read only after the IDT initialization is complete.

- Shuffle code around to consolidate the #ifdef sections into one.

- Adapt the F00F bug code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200528145523.084915381@linutronix.de

---
arch/x86/include/asm/desc.h | 17 +---------
arch/x86/kernel/idt.c | 63 +++++++++++++++++++++---------------
arch/x86/mm/fault.c | 16 ++-------
3 files changed, 44 insertions(+), 52 deletions(-)

diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h
index 07632f3..1ced11d 100644
--- a/arch/x86/include/asm/desc.h
+++ b/arch/x86/include/asm/desc.h
@@ -40,9 +40,6 @@ static inline void fill_ldt(struct desc_struct *desc, const struct user_desc *in
desc->l = 0;
}

-extern struct desc_ptr idt_descr;
-extern gate_desc idt_table[];
-
struct gdt_page {
struct desc_struct gdt[GDT_ENTRIES];
} __attribute__((aligned(PAGE_SIZE)));
@@ -388,22 +385,12 @@ void alloc_intr_gate(unsigned int n, const void *addr);

extern unsigned long system_vectors[];

-/*
- * The load_current_idt() must be called with interrupts disabled
- * to avoid races. That way the IDT will always be set back to the expected
- * descriptor. It's also called when a CPU is being initialized, and
- * that doesn't need to disable interrupts, as nothing should be
- * bothering the CPU then.
- */
-static __always_inline void load_current_idt(void)
-{
- load_idt((const struct desc_ptr *)&idt_descr);
-}
-
+extern void load_current_idt(void);
extern void idt_setup_early_handler(void);
extern void idt_setup_early_traps(void);
extern void idt_setup_traps(void);
extern void idt_setup_apic_and_irq_gates(void);
+extern bool idt_is_f00f_address(unsigned long address);

#ifdef CONFIG_X86_64
extern void idt_setup_early_pf(void);
diff --git a/arch/x86/kernel/idt.c b/arch/x86/kernel/idt.c
index 902cdd0..85e3e22 100644
--- a/arch/x86/kernel/idt.c
+++ b/arch/x86/kernel/idt.c
@@ -5,6 +5,7 @@
#include <linux/interrupt.h>

#include <asm/cpu_entry_area.h>
+#include <asm/set_memory.h>
#include <asm/traps.h>
#include <asm/proto.h>
#include <asm/desc.h>
@@ -156,37 +157,25 @@ static const __initconst struct idt_data apic_idts[] = {
#endif
};

-#ifdef CONFIG_X86_64
-/*
- * Early traps running on the DEFAULT_STACK because the other interrupt
- * stacks work only after cpu_init().
- */
-static const __initconst struct idt_data early_pf_idts[] = {
- INTG(X86_TRAP_PF, asm_exc_page_fault),
-};
-#endif
-
-/* Must be page-aligned because the real IDT is used in a fixmap. */
-gate_desc idt_table[IDT_ENTRIES] __page_aligned_bss;
+/* Must be page-aligned because the real IDT is used in the cpu entry area */
+static gate_desc idt_table[IDT_ENTRIES] __page_aligned_bss;

struct desc_ptr idt_descr __ro_after_init = {
.size = IDT_TABLE_SIZE - 1,
.address = (unsigned long) idt_table,
};

-#ifdef CONFIG_X86_64
-/*
- * The exceptions which use Interrupt stacks. They are setup after
- * cpu_init() when the TSS has been initialized.
- */
-static const __initconst struct idt_data ist_idts[] = {
- ISTG(X86_TRAP_DB, asm_exc_debug, IST_INDEX_DB),
- ISTG(X86_TRAP_NMI, asm_exc_nmi, IST_INDEX_NMI),
- ISTG(X86_TRAP_DF, asm_exc_double_fault, IST_INDEX_DF),
-#ifdef CONFIG_X86_MCE
- ISTG(X86_TRAP_MC, asm_exc_machine_check, IST_INDEX_MCE),
-#endif
-};
+void load_current_idt(void)
+{
+ lockdep_assert_irqs_disabled();
+ load_idt(&idt_descr);
+}
+
+#ifdef CONFIG_X86_F00F_BUG
+bool idt_is_f00f_address(unsigned long address)
+{
+ return (address - idt_descr.address) >> 3) == 6;
+}
#endif

static inline void idt_init_desc(gate_desc *gate, const struct idt_data *d)
@@ -255,6 +244,27 @@ void __init idt_setup_traps(void)
}

#ifdef CONFIG_X86_64
+/*
+ * Early traps running on the DEFAULT_STACK because the other interrupt
+ * stacks work only after cpu_init().
+ */
+static const __initconst struct idt_data early_pf_idts[] = {
+ INTG(X86_TRAP_PF, asm_exc_page_fault),
+};
+
+/*
+ * The exceptions which use Interrupt stacks. They are setup after
+ * cpu_init() when the TSS has been initialized.
+ */
+static const __initconst struct idt_data ist_idts[] = {
+ ISTG(X86_TRAP_DB, asm_exc_debug, IST_INDEX_DB),
+ ISTG(X86_TRAP_NMI, asm_exc_nmi, IST_INDEX_NMI),
+ ISTG(X86_TRAP_DF, asm_exc_double_fault, IST_INDEX_DF),
+#ifdef CONFIG_X86_MCE
+ ISTG(X86_TRAP_MC, asm_exc_machine_check, IST_INDEX_MCE),
+#endif
+};
+
/**
* idt_setup_early_pf - Initialize the idt table with early pagefault handler
*
@@ -325,6 +335,9 @@ void __init idt_setup_apic_and_irq_gates(void)
idt_map_in_cea();
load_idt(&idt_descr);

+ /* Make the IDT table read only */
+ set_memory_ro((unsigned long)&idt_table, 1);
+
idt_setup_done = true;
}

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 9c57fb8..e4625f4 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -555,21 +555,13 @@ static int is_errata100(struct pt_regs *regs, unsigned long address)
return 0;
}

+/* Pentium F0 0F C7 C8 bug workaround: */
static int is_f00f_bug(struct pt_regs *regs, unsigned long address)
{
#ifdef CONFIG_X86_F00F_BUG
- unsigned long nr;
-
- /*
- * Pentium F0 0F C7 C8 bug workaround:
- */
- if (boot_cpu_has_bug(X86_BUG_F00F)) {
- nr = (address - idt_descr.address) >> 3;
-
- if (nr == 6) {
- handle_invalid_op(regs);
- return 1;
- }
+ if (boot_cpu_has_bug(X86_BUG_F00F) && idt_is_f00f_address(address)) {
+ handle_invalid_op(regs);
+ return 1;
}
#endif
return 0;
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