242 lines
7.5 KiB
C
242 lines
7.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_X86_IRQ_STACK_H
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#define _ASM_X86_IRQ_STACK_H
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#include <linux/ptrace.h>
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#include <linux/objtool.h>
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#include <asm/processor.h>
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#ifdef CONFIG_X86_64
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/*
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* Macro to inline switching to an interrupt stack and invoking function
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* calls from there. The following rules apply:
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*
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* - Ordering:
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*
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* 1. Write the stack pointer into the top most place of the irq
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* stack. This ensures that the various unwinders can link back to the
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* original stack.
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*
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* 2. Switch the stack pointer to the top of the irq stack.
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*
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* 3. Invoke whatever needs to be done (@asm_call argument)
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*
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* 4. Pop the original stack pointer from the top of the irq stack
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* which brings it back to the original stack where it left off.
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*
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* - Function invocation:
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*
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* To allow flexible usage of the macro, the actual function code including
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* the store of the arguments in the call ABI registers is handed in via
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* the @asm_call argument.
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*
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* - Local variables:
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*
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* @tos:
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* The @tos variable holds a pointer to the top of the irq stack and
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* _must_ be allocated in a non-callee saved register as this is a
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* restriction coming from objtool.
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*
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* Note, that (tos) is both in input and output constraints to ensure
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* that the compiler does not assume that R11 is left untouched in
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* case this macro is used in some place where the per cpu interrupt
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* stack pointer is used again afterwards
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*
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* - Function arguments:
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* The function argument(s), if any, have to be defined in register
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* variables at the place where this is invoked. Storing the
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* argument(s) in the proper register(s) is part of the @asm_call
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*
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* - Constraints:
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*
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* The constraints have to be done very carefully because the compiler
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* does not know about the assembly call.
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*
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* output:
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* As documented already above the @tos variable is required to be in
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* the output constraints to make the compiler aware that R11 cannot be
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* reused after the asm() statement.
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*
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* For builds with CONFIG_UNWINDER_FRAME_POINTER, ASM_CALL_CONSTRAINT is
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* required as well as this prevents certain creative GCC variants from
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* misplacing the ASM code.
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*
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* input:
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* - func:
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* Immediate, which tells the compiler that the function is referenced.
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*
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* - tos:
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* Register. The actual register is defined by the variable declaration.
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*
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* - function arguments:
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* The constraints are handed in via the 'argconstr' argument list. They
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* describe the register arguments which are used in @asm_call.
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*
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* clobbers:
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* Function calls can clobber anything except the callee-saved
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* registers. Tell the compiler.
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*/
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#define call_on_stack(stack, func, asm_call, argconstr...) \
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{ \
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register void *tos asm("r11"); \
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\
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tos = ((void *)(stack)); \
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\
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asm_inline volatile( \
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"movq %%rsp, (%[tos]) \n" \
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"movq %[tos], %%rsp \n" \
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\
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asm_call \
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\
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"popq %%rsp \n" \
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\
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: "+r" (tos), ASM_CALL_CONSTRAINT \
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: [__func] "i" (func), [tos] "r" (tos) argconstr \
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: "cc", "rax", "rcx", "rdx", "rsi", "rdi", "r8", "r9", "r10", \
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"memory" \
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); \
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}
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#define ASM_CALL_ARG0 \
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"call %P[__func] \n" \
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ASM_REACHABLE
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#define ASM_CALL_ARG1 \
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"movq %[arg1], %%rdi \n" \
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ASM_CALL_ARG0
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#define ASM_CALL_ARG2 \
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"movq %[arg2], %%rsi \n" \
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ASM_CALL_ARG1
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#define ASM_CALL_ARG3 \
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"movq %[arg3], %%rdx \n" \
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ASM_CALL_ARG2
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#define call_on_irqstack(func, asm_call, argconstr...) \
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call_on_stack(__this_cpu_read(pcpu_hot.hardirq_stack_ptr), \
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func, asm_call, argconstr)
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/* Macros to assert type correctness for run_*_on_irqstack macros */
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#define assert_function_type(func, proto) \
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static_assert(__builtin_types_compatible_p(typeof(&func), proto))
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#define assert_arg_type(arg, proto) \
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static_assert(__builtin_types_compatible_p(typeof(arg), proto))
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/*
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* Macro to invoke system vector and device interrupt C handlers.
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*/
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#define call_on_irqstack_cond(func, regs, asm_call, constr, c_args...) \
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{ \
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/* \
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* User mode entry and interrupt on the irq stack do not \
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* switch stacks. If from user mode the task stack is empty. \
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*/ \
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if (user_mode(regs) || __this_cpu_read(pcpu_hot.hardirq_stack_inuse)) { \
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irq_enter_rcu(); \
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func(c_args); \
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irq_exit_rcu(); \
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} else { \
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/* \
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* Mark the irq stack inuse _before_ and unmark _after_ \
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* switching stacks. Interrupts are disabled in both \
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* places. Invoke the stack switch macro with the call \
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* sequence which matches the above direct invocation. \
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*/ \
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__this_cpu_write(pcpu_hot.hardirq_stack_inuse, true); \
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call_on_irqstack(func, asm_call, constr); \
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__this_cpu_write(pcpu_hot.hardirq_stack_inuse, false); \
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} \
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}
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/*
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* Function call sequence for __call_on_irqstack() for system vectors.
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*
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* Note that irq_enter_rcu() and irq_exit_rcu() do not use the input
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* mechanism because these functions are global and cannot be optimized out
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* when compiling a particular source file which uses one of these macros.
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*
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* The argument (regs) does not need to be pushed or stashed in a callee
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* saved register to be safe vs. the irq_enter_rcu() call because the
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* clobbers already prevent the compiler from storing it in a callee
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* clobbered register. As the compiler has to preserve @regs for the final
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* call to idtentry_exit() anyway, it's likely that it does not cause extra
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* effort for this asm magic.
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*/
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#define ASM_CALL_SYSVEC \
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"call irq_enter_rcu \n" \
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ASM_CALL_ARG1 \
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"call irq_exit_rcu \n"
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#define SYSVEC_CONSTRAINTS , [arg1] "r" (regs)
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#define run_sysvec_on_irqstack_cond(func, regs) \
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{ \
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assert_function_type(func, void (*)(struct pt_regs *)); \
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assert_arg_type(regs, struct pt_regs *); \
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\
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call_on_irqstack_cond(func, regs, ASM_CALL_SYSVEC, \
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SYSVEC_CONSTRAINTS, regs); \
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}
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/*
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* As in ASM_CALL_SYSVEC above the clobbers force the compiler to store
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* @regs and @vector in callee saved registers.
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*/
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#define ASM_CALL_IRQ \
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"call irq_enter_rcu \n" \
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ASM_CALL_ARG2 \
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"call irq_exit_rcu \n"
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#define IRQ_CONSTRAINTS , [arg1] "r" (regs), [arg2] "r" ((unsigned long)vector)
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#define run_irq_on_irqstack_cond(func, regs, vector) \
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{ \
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assert_function_type(func, void (*)(struct pt_regs *, u32)); \
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assert_arg_type(regs, struct pt_regs *); \
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assert_arg_type(vector, u32); \
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\
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call_on_irqstack_cond(func, regs, ASM_CALL_IRQ, \
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IRQ_CONSTRAINTS, regs, vector); \
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}
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#ifdef CONFIG_SOFTIRQ_ON_OWN_STACK
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/*
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* Macro to invoke __do_softirq on the irq stack. This is only called from
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* task context when bottom halves are about to be reenabled and soft
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* interrupts are pending to be processed. The interrupt stack cannot be in
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* use here.
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*/
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#define do_softirq_own_stack() \
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{ \
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__this_cpu_write(pcpu_hot.hardirq_stack_inuse, true); \
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call_on_irqstack(__do_softirq, ASM_CALL_ARG0); \
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__this_cpu_write(pcpu_hot.hardirq_stack_inuse, false); \
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}
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#endif
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#else /* CONFIG_X86_64 */
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/* System vector handlers always run on the stack they interrupted. */
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#define run_sysvec_on_irqstack_cond(func, regs) \
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{ \
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irq_enter_rcu(); \
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func(regs); \
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irq_exit_rcu(); \
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}
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/* Switches to the irq stack within func() */
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#define run_irq_on_irqstack_cond(func, regs, vector) \
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{ \
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irq_enter_rcu(); \
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func(regs, vector); \
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irq_exit_rcu(); \
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}
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#endif /* !CONFIG_X86_64 */
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#endif
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