x86/entry/32: Provide macro to emit IDT entry stubs (60400677) · Commits · 戴 / test

arch/x86/entry/entry_32.S

+68 −0

Original line number	Diff line number	Diff line
		@@ -44,6 +44,7 @@
		#include <asm/asm.h>
		#include <asm/smap.h>
		#include <asm/frame.h>
		#include <asm/trapnr.h>
		#include <asm/nospec-branch.h>

		#include "calling.h"
		@@ -726,6 +727,31 @@

		.Lend_\@:
		.endm

		/**
		* idtentry - Macro to generate entry stubs for simple IDT entries
		* @vector: Vector number
		* @asmsym: ASM symbol for the entry point
		* @cfunc: C function to be called
		* @has_error_code: Hardware pushed error code on stack
		* @sane: Compatibility flag with 64bit
		*/
		.macro idtentry vector asmsym cfunc has_error_code:req sane=0
		SYM_CODE_START(\asmsym)
		ASM_CLAC
		cld

		.if \has_error_code == 0
		pushl $0 /* Clear the error code */
		.endif

		/* Push the C-function address into the GS slot */
		pushl $\cfunc
		/* Invoke the common exception entry */
		jmp handle_exception
		SYM_CODE_END(\asmsym)
		.endm

		/*
		* %eax: prev task
		* %edx: next task
		@@ -1517,6 +1543,48 @@ SYM_CODE_START_LOCAL_NOALIGN(common_exception)
		jmp ret_from_exception
		SYM_CODE_END(common_exception)

		SYM_CODE_START_LOCAL_NOALIGN(handle_exception)
		/* the function address is in %gs's slot on the stack */
		SAVE_ALL switch_stacks=1 skip_gs=1 unwind_espfix=1
		ENCODE_FRAME_POINTER

		/* fixup %gs */
		GS_TO_REG %ecx
		movl PT_GS(%esp), %edi # get the function address
		REG_TO_PTGS %ecx
		SET_KERNEL_GS %ecx

		/* fixup orig %eax */
		movl PT_ORIG_EAX(%esp), %edx # get the error code
		movl $-1, PT_ORIG_EAX(%esp) # no syscall to restart

		movl %esp, %eax # pt_regs pointer
		CALL_NOSPEC edi

		#ifdef CONFIG_VM86
		movl PT_EFLAGS(%esp), %eax # mix EFLAGS and CS
		movb PT_CS(%esp), %al
		andl $(X86_EFLAGS_VM \| SEGMENT_RPL_MASK), %eax
		#else
		/*
		* We can be coming here from child spawned by kernel_thread().
		*/
		movl PT_CS(%esp), %eax
		andl $SEGMENT_RPL_MASK, %eax
		#endif
		cmpl $USER_RPL, %eax # returning to v8086 or userspace ?
		jnb ret_to_user

		PARANOID_EXIT_TO_KERNEL_MODE
		BUG_IF_WRONG_CR3
		RESTORE_REGS 4
		jmp .Lirq_return

		ret_to_user:
		movl %esp, %eax
		jmp restore_all_switch_stack
		SYM_CODE_END(handle_exception)

		SYM_CODE_START(debug)
		/*
		* Entry from sysenter is now handled in common_exception

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