[patch V4 part 5 14/31] x86/irq/64: Provide handle_irq()

Thomas Gleixner
2020-05-05T14:18:32Z

To consolidate the interrupt entry/exit code vs. the other exceptions
provide handle_irq() (similar to 32bit) to move the interrupt stack
switching to C code. That allows to consolidate the entry exit handling by
reusing the idtentry machinery both in ASM and C.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
arch/x86/kernel/irq_64.c | 42 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 42 insertions(+)

--- a/arch/x86/kernel/irq_64.c
+++ b/arch/x86/kernel/irq_64.c
@@ -72,6 +72,48 @@ int irq_init_percpu_irqstack(unsigned in
return map_irq_stack(cpu);
}

+static noinstr void handle_irq_on_irqstack(struct irq_desc *desc)
+{
+ unsigned long tos;
+
+ tos = (unsigned long) __this_cpu_read(hardirq_stack_ptr);
+ tos -= 8;
+ /*
+ * The unwinder requires that the top of the IRQ stack links back
+ * to the previous stack and RBP is set up.
+ */
+ asm volatile(
+ "pushq %%rbp \n"
+ "movq %%rsp, %%rbp \n"
+ "movq %%rsp, (%[ts]) \n"
+ "movq %[ts], %%rsp \n"
+ "1: \n"
+ " .pushsection .discard.instr_begin \n"
+ " .long 1b - . \n"
+ " .popsection \n"
+ CALL_NOSPEC
+ "2: \n"
+ " .pushsection .discard.instr_end \n"
+ " .long 2b - . \n"
+ " .popsection \n"
+ "popq %%rsp \n"
+ "leaveq \n"
+ :
+ : [ts] "r" (tos),
+ [thunk_target] "r" (desc->handle_irq),
+ "D" (desc)
+ : "memory"
+ );
+}
+
+void handle_irq(struct irq_desc *desc, struct pt_regs *regs)
+{
+ if (!irq_needs_irq_stack(regs))
+ generic_handle_irq_desc(desc);
+ else
+ handle_irq_on_irqstack(desc);
+}
+
noinstr void do_softirq_own_stack(void)
{
if (irqstack_active()) {