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-rw-r--r--arch/x86/entry/entry_64.S39
-rw-r--r--arch/x86/include/asm/irq_stack.h53
2 files changed, 92 insertions, 0 deletions
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index d983a0d4bc73..159737062611 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1106,6 +1106,45 @@ SYM_CODE_START_LOCAL_NOALIGN(.Lbad_gs)
SYM_CODE_END(.Lbad_gs)
.previous
+/*
+ * rdi: New stack pointer points to the top word of the stack
+ * rsi: Function pointer
+ * rdx: Function argument (can be NULL if none)
+ */
+SYM_FUNC_START(asm_call_on_stack)
+ /*
+ * Save the frame pointer unconditionally. This allows the ORC
+ * unwinder to handle the stack switch.
+ */
+ pushq %rbp
+ mov %rsp, %rbp
+
+ /*
+ * The unwinder relies on the word at the top of the new stack
+ * page linking back to the previous RSP.
+ */
+ mov %rsp, (%rdi)
+ mov %rdi, %rsp
+ /* Move the argument to the right place */
+ mov %rdx, %rdi
+
+1:
+ .pushsection .discard.instr_begin
+ .long 1b - .
+ .popsection
+
+ CALL_NOSPEC rsi
+
+2:
+ .pushsection .discard.instr_end
+ .long 2b - .
+ .popsection
+
+ /* Restore the previous stack pointer from RBP. */
+ leaveq
+ ret
+SYM_FUNC_END(asm_call_on_stack)
+
/* Call softirq on interrupt stack. Interrupts are off. */
.pushsection .text, "ax"
SYM_FUNC_START(do_softirq_own_stack)
diff --git a/arch/x86/include/asm/irq_stack.h b/arch/x86/include/asm/irq_stack.h
new file mode 100644
index 000000000000..4ae66f097101
--- /dev/null
+++ b/arch/x86/include/asm/irq_stack.h
@@ -0,0 +1,53 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_X86_IRQ_STACK_H
+#define _ASM_X86_IRQ_STACK_H
+
+#include <linux/ptrace.h>
+
+#include <asm/processor.h>
+
+#ifdef CONFIG_X86_64
+static __always_inline bool irqstack_active(void)
+{
+ return __this_cpu_read(irq_count) != -1;
+}
+
+void asm_call_on_stack(void *sp, void *func, void *arg);
+
+static __always_inline void __run_on_irqstack(void *func, void *arg)
+{
+ void *tos = __this_cpu_read(hardirq_stack_ptr);
+
+ __this_cpu_add(irq_count, 1);
+ asm_call_on_stack(tos - 8, func, arg);
+ __this_cpu_sub(irq_count, 1);
+}
+
+#else /* CONFIG_X86_64 */
+static inline bool irqstack_active(void) { return false; }
+static inline void __run_on_irqstack(void *func, void *arg) { }
+#endif /* !CONFIG_X86_64 */
+
+static __always_inline bool irq_needs_irq_stack(struct pt_regs *regs)
+{
+ if (IS_ENABLED(CONFIG_X86_32))
+ return false;
+ if (!regs)
+ return !irqstack_active();
+ return !user_mode(regs) && !irqstack_active();
+}
+
+static __always_inline void run_on_irqstack_cond(void *func, void *arg,
+ struct pt_regs *regs)
+{
+ void (*__func)(void *arg) = func;
+
+ lockdep_assert_irqs_disabled();
+
+ if (irq_needs_irq_stack(regs))
+ __run_on_irqstack(__func, arg);
+ else
+ __func(arg);
+}
+
+#endif