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Date: Tue, 25 Feb 2020 23:16:12 +0100 From: Thomas Gleixner <tglx@...utronix.de> To: LKML <linux-kernel@...r.kernel.org> Cc: x86@...nel.org, Steven Rostedt <rostedt@...dmis.org>, Brian Gerst <brgerst@...il.com>, Juergen Gross <jgross@...e.com>, Paolo Bonzini <pbonzini@...hat.com>, Arnd Bergmann <arnd@...db.de> Subject: [patch 06/24] x86/idtentry: Provide macros to define/declare IDT entry points Provide DECLARE/DEFINE_IDTENTRY() macros. DEFINE_IDTENTRY() provides a wrapper which acts as the function definition. The exception handler body is just appended to it with curly brackets. The entry point is marked notrace/noprobe so that irq tracing and the enter_from_user_mode() can be moved into the C-entry point. As all C-entries use the same macro (or a later variant) the necessary entry handling can be implemented at one central place. DECLARE_IDTENTRY() provides the function prototypes: - The C entry point cfunc - The ASM entry point asm_cfunc - The XEN/PV entry point xen_asm_cfunc They all follow the same naming convention. When included from ASM code DECLARE_IDTENTRY() is a macro which emits the low level entry point in assembly by instantiating idtentry. IDTENTRY is the simplest variant which just has a pt_regs argument. It's going to be used for all exceptions which have no error code. Signed-off-by: Thomas Gleixner <tglx@...utronix.de> --- arch/x86/entry/entry_32.S | 6 +++ arch/x86/entry/entry_64.S | 6 +++ arch/x86/include/asm/idtentry.h | 79 ++++++++++++++++++++++++++++++++++++++++ arch/x86/include/asm/traps.h | 2 - 4 files changed, 92 insertions(+), 1 deletion(-) --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -769,6 +769,12 @@ SYM_CODE_END(\asmsym) .endm /* + * Include the defines which emit the idt entries which are shared + * shared between 32 and 64 bit. + */ +#include <asm/idtentry.h> + +/* * %eax: prev task * %edx: next task */ --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -688,6 +688,12 @@ SYM_CODE_END(\asmsym) .endm /* + * Include the defines which emit the idt entries which are shared + * shared between 32 and 64 bit. + */ +#include <asm/idtentry.h> + +/* * Interrupt entry helper function. * * Entry runs with interrupts off. Stack layout at entry: --- /dev/null +++ b/arch/x86/include/asm/idtentry.h @@ -0,0 +1,79 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_X86_IDTENTRY_H +#define _ASM_X86_IDTENTRY_H + +/* Interrupts/Exceptions */ +#include <asm/trapnr.h> + +#ifndef __ASSEMBLY__ + +/** + * idtentry_enter - Handle state tracking on idtentry + * @regs: Pointer to pt_regs of interrupted context + * + * Place holder for now. + */ +static __always_inline void idtentry_enter(struct pt_regs *regs) +{ +} + +/** + * idtentry_exit - Prepare returning to low level ASM code + * + * Place holder for now. + */ +static __always_inline void idtentry_exit(struct pt_regs *regs) +{ +} + +/** + * DECLARE_IDTENTRY - Declare functions for simple IDT entry points + * No error code pushed by hardware + * @vector: Vector number (ignored for C) + * @func: Function name of the entry point + * + * Declares three functions: + * - The ASM entry point: asm_##func + * - The XEN PV trap entry point: xen_##func (maybe unused) + * - The C handler called from the ASM entry point + */ +#define DECLARE_IDTENTRY(vector, func) \ + asmlinkage void asm_##func(void); \ + asmlinkage void xen_asm_##func(void); \ + __visible void func(struct pt_regs *regs) + +/** + * DEFINE_IDTENTRY - Emit code for simple IDT entry points + * @func: Function name of the entry point + * + * @func is called from ASM entry code with interrupts disabled. + * + * The macro is written so it acts as function definition. Append the + * body with a pair of curly brackets. + * + * idtentry_enter() contains common code which has to be invoked before + * arbitrary code in the body. idtentry_exit() contains common code + * which has to run before returning to the low level assembly code. + */ +#define DEFINE_IDTENTRY(func) \ +static __always_inline void __##func(struct pt_regs *regs); \ + \ +__visible notrace void func(struct pt_regs *regs) \ +{ \ + idtentry_enter(regs); \ + __##func (regs); \ + idtentry_exit(regs); \ +} \ +NOKPROBE_SYMBOL(func); \ + \ +static __always_inline void __##func(struct pt_regs *regs) + +#else /* !__ASSEMBLY__ */ + +/* Defines for ASM code to construct the IDT entries */ +#define DECLARE_IDTENTRY(vector, func) \ + idtentry vector asm_##func func has_error_code=0 + +#endif /* __ASSEMBLY__ */ + +#endif --- a/arch/x86/include/asm/traps.h +++ b/arch/x86/include/asm/traps.h @@ -6,8 +6,8 @@ #include <linux/kprobes.h> #include <asm/debugreg.h> +#include <asm/idtentry.h> #include <asm/siginfo.h> /* TRAP_TRACE, ... */ -#include <asm/trapnr.h> #define dotraplinkage __visible
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