From 60400677e1280dae7d903e5997fb1cfabb22d4bd Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 25 Feb 2020 23:16:11 +0100 Subject: x86/entry/32: Provide macro to emit IDT entry stubs 32 and 64 bit have unnecessary different ways to populate the exception entry code. Provide a idtentry macro which allows to consolidate all of that. Signed-off-by: Thomas Gleixner Reviewed-by: Alexandre Chartre Acked-by: Andy Lutomirski Acked-by: Peter Zijlstra Link: https://lkml.kernel.org/r/20200505134904.166735365@linutronix.de --- arch/x86/entry/entry_32.S | 68 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 68 insertions(+) (limited to 'arch/x86') diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S index d9da0b7f38ff..eb64e78052e1 100644 --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -44,6 +44,7 @@ #include #include #include +#include #include #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 -- cgit v1.2.3