/* SPDX-License-Identifier: GPL-2.0 */ #ifndef _ASM_X86_IRQ_STACK_H #define _ASM_X86_IRQ_STACK_H #include <linux/ptrace.h> #include <linux/objtool.h> #include <asm/processor.h> #ifdef CONFIG_X86_64 /* * Macro to inline switching to an interrupt stack and invoking function * calls from there. The following rules apply: * * - Ordering: * * 1. Write the stack pointer into the top most place of the irq * stack. This ensures that the various unwinders can link back to the * original stack. * * 2. Switch the stack pointer to the top of the irq stack. * * 3. Invoke whatever needs to be done (@asm_call argument) * * 4. Pop the original stack pointer from the top of the irq stack * which brings it back to the original stack where it left off. * * - Function invocation: * * To allow flexible usage of the macro, the actual function code including * the store of the arguments in the call ABI registers is handed in via * the @asm_call argument. * * - Local variables: * * @tos: * The @tos variable holds a pointer to the top of the irq stack and * _must_ be allocated in a non-callee saved register as this is a * restriction coming from objtool. * * Note, that (tos) is both in input and output constraints to ensure * that the compiler does not assume that R11 is left untouched in * case this macro is used in some place where the per cpu interrupt * stack pointer is used again afterwards * * - Function arguments: * The function argument(s), if any, have to be defined in register * variables at the place where this is invoked. Storing the * argument(s) in the proper register(s) is part of the @asm_call * * - Constraints: * * The constraints have to be done very carefully because the compiler * does not know about the assembly call. * * output: * As documented already above the @tos variable is required to be in * the output constraints to make the compiler aware that R11 cannot be * reused after the asm() statement. * * For builds with CONFIG_UNWINDER_FRAME_POINTER, ASM_CALL_CONSTRAINT is * required as well as this prevents certain creative GCC variants from * misplacing the ASM code. * * input: * - func: * Immediate, which tells the compiler that the function is referenced. * * - tos: * Register. The actual register is defined by the variable declaration. * * - function arguments: * The constraints are handed in via the 'argconstr' argument list. They * describe the register arguments which are used in @asm_call. * * clobbers: * Function calls can clobber anything except the callee-saved * registers. Tell the compiler. */ #define call_on_stack(stack, func, asm_call, argconstr...) … #define ASM_CALL_ARG0 … #define ASM_CALL_ARG1 … #define ASM_CALL_ARG2 … #define ASM_CALL_ARG3 … #define call_on_irqstack(func, asm_call, argconstr...) … /* Macros to assert type correctness for run_*_on_irqstack macros */ #define assert_function_type(func, proto) … #define assert_arg_type(arg, proto) … /* * Macro to invoke system vector and device interrupt C handlers. */ #define call_on_irqstack_cond(func, regs, asm_call, constr, c_args...) … /* * Function call sequence for __call_on_irqstack() for system vectors. * * Note that irq_enter_rcu() and irq_exit_rcu() do not use the input * mechanism because these functions are global and cannot be optimized out * when compiling a particular source file which uses one of these macros. * * The argument (regs) does not need to be pushed or stashed in a callee * saved register to be safe vs. the irq_enter_rcu() call because the * clobbers already prevent the compiler from storing it in a callee * clobbered register. As the compiler has to preserve @regs for the final * call to idtentry_exit() anyway, it's likely that it does not cause extra * effort for this asm magic. */ #define ASM_CALL_SYSVEC … #define SYSVEC_CONSTRAINTS … #define run_sysvec_on_irqstack_cond(func, regs) … /* * As in ASM_CALL_SYSVEC above the clobbers force the compiler to store * @regs and @vector in callee saved registers. */ #define ASM_CALL_IRQ … #define IRQ_CONSTRAINTS … #define run_irq_on_irqstack_cond(func, regs, vector) … #ifdef CONFIG_SOFTIRQ_ON_OWN_STACK /* * Macro to invoke __do_softirq on the irq stack. This is only called from * task context when bottom halves are about to be reenabled and soft * interrupts are pending to be processed. The interrupt stack cannot be in * use here. */ #define do_softirq_own_stack() … #endif #else /* CONFIG_X86_64 */ /* System vector handlers always run on the stack they interrupted. */ #define run_sysvec_on_irqstack_cond … /* Switches to the irq stack within func() */ #define run_irq_on_irqstack_cond … #endif /* !CONFIG_X86_64 */ #endif
Codebase Browser
linux