Commit d7729050 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

x86/entry/32: Convert IRET exception to IDTENTRY_SW 



Convert the IRET exception handler to IDTENTRY_SW. This is slightly
different than the conversions of hardware exceptions as the IRET exception
is invoked via an exception table when IRET faults. So it just uses the
IDTENTRY_SW mechanism for consistency. It does not emit ASM code as it does
not fit the other idtentry exceptions.

  - Implement the C entry point with DEFINE_IDTENTRY_SW() which maps to
    DEFINE_IDTENTRY()
  - Fixup the XEN/PV code
  - Remove the old prototypes
  - Remove the RCU warning as the new entry macro ensures correctness

No functional change.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarAlexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
Acked-by: default avatarAndy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200505134906.128769226@linutronix.de
parent 48227e21

arch/x86/entry/entry_32.S

+7 −7
Original line number Diff line number Diff line
@@ -1147,9 +1147,9 @@ restore_all_kernel: 
	jmp	.Lirq_return



.section .fixup, "ax"

SYM_CODE_START(iret_exc)

SYM_CODE_START(asm_iret_error)

	pushl	$0				# no error code

	pushl	$do_iret_error

	pushl	$iret_error



#ifdef CONFIG_DEBUG_ENTRY

	/*
@@ -1163,10 +1163,10 @@ SYM_CODE_START(iret_exc) 
	popl	%eax

#endif



	jmp	common_exception

SYM_CODE_END(iret_exc)

	jmp	handle_exception

SYM_CODE_END(asm_iret_error)

.previous

	_ASM_EXTABLE(.Lirq_return, iret_exc)

	_ASM_EXTABLE(.Lirq_return, asm_iret_error)

SYM_FUNC_END(entry_INT80_32)



.macro FIXUP_ESPFIX_STACK
@@ -1293,7 +1293,7 @@ SYM_FUNC_END(name) 
#ifdef CONFIG_PARAVIRT

SYM_CODE_START(native_iret)

	iret

	_ASM_EXTABLE(native_iret, iret_exc)

	_ASM_EXTABLE(native_iret, asm_iret_error)

SYM_CODE_END(native_iret)

#endif
@@ -1358,7 +1358,7 @@ SYM_FUNC_START(xen_failsafe_callback) 
	popl	%eax

	lea	16(%esp), %esp

	jz	5f

	jmp	iret_exc

	jmp	asm_iret_error

5:	pushl	$-1				/* orig_ax = -1 => not a system call */

	SAVE_ALL

	ENCODE_FRAME_POINTER

arch/x86/include/asm/idtentry.h

+10 −0
Original line number Diff line number Diff line
@@ -57,6 +57,10 @@ __visible noinstr void func(struct pt_regs *regs) \ 
									\

static __always_inline void __##func(struct pt_regs *regs)



/* Special case for 32bit IRET 'trap' */

#define DECLARE_IDTENTRY_SW	DECLARE_IDTENTRY

#define DEFINE_IDTENTRY_SW	DEFINE_IDTENTRY



/**

 * DECLARE_IDTENTRY_ERRORCODE - Declare functions for simple IDT entry points

 *				Error code pushed by hardware
@@ -111,6 +115,9 @@ static __always_inline void __##func(struct pt_regs *regs, \ 
#define DECLARE_IDTENTRY_ERRORCODE(vector, func)			\

	idtentry vector asm_##func func has_error_code=1 sane=1



/* Special case for 32bit IRET 'trap'. Do not emit ASM code */

#define DECLARE_IDTENTRY_SW(vector, func)



#endif /* __ASSEMBLY__ */



/*
@@ -133,6 +140,9 @@ DECLARE_IDTENTRY(X86_TRAP_SPURIOUS, exc_spurious_interrupt_bug); 
DECLARE_IDTENTRY(X86_TRAP_MF,		exc_coprocessor_error);

DECLARE_IDTENTRY(X86_TRAP_XF,		exc_simd_coprocessor_error);



/* 32bit software IRET trap. Do not emit ASM code */

DECLARE_IDTENTRY_SW(X86_TRAP_IRET,	iret_error);



/* Simple exception entries with error code pushed by hardware */

DECLARE_IDTENTRY_ERRORCODE(X86_TRAP_TS,	exc_invalid_tss);

DECLARE_IDTENTRY_ERRORCODE(X86_TRAP_NP,	exc_segment_not_present);

arch/x86/include/asm/traps.h

+0 −3
Original line number Diff line number Diff line
@@ -39,9 +39,6 @@ dotraplinkage void do_nmi(struct pt_regs *regs, long error_code); 
dotraplinkage void do_int3(struct pt_regs *regs, long error_code);

dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code, unsigned long cr2);

dotraplinkage void do_page_fault(struct pt_regs *regs, unsigned long error_code, unsigned long address);

#ifdef CONFIG_X86_32

dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code);

#endif

dotraplinkage void do_mce(struct pt_regs *regs, long error_code);



#ifdef CONFIG_X86_64

arch/x86/kernel/traps.c

+3 −5
Original line number Diff line number Diff line
@@ -925,14 +925,12 @@ DEFINE_IDTENTRY(exc_device_not_available) 
}



#ifdef CONFIG_X86_32

dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)

DEFINE_IDTENTRY_SW(iret_error)

{

	RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");

	local_irq_enable();



	if (notify_die(DIE_TRAP, "iret exception", regs, error_code,

	if (notify_die(DIE_TRAP, "iret exception", regs, 0,

			X86_TRAP_IRET, SIGILL) != NOTIFY_STOP) {

		do_trap(X86_TRAP_IRET, SIGILL, "iret exception", regs, error_code,

		do_trap(X86_TRAP_IRET, SIGILL, "iret exception", regs, 0,

			ILL_BADSTK, (void __user *)NULL);

	}

	local_irq_disable();

arch/x86/xen/xen-asm_32.S

+1 −1
Original line number Diff line number Diff line
@@ -117,7 +117,7 @@ iret_restore_end: 


1:	iret

xen_iret_end_crit:

	_ASM_EXTABLE(1b, iret_exc)

	_ASM_EXTABLE(1b, asm_iret_error)



hyper_iret:

	/* put this out of line since its very rarely used */

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