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x86/entry/32: Convert IRET exception to IDTENTRY_SW

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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: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200505134906.128769226@linutronix.de
This commit is contained in:
Thomas Gleixner 2020-02-25 23:16:30 +01:00
parent 48227e21f7
commit d77290507a
5 changed files with 21 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
arch/x86/entry/entry_32.S
View File

@ -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

10
arch/x86/include/asm/idtentry.h
View File

@ -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);

3
arch/x86/include/asm/traps.h
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@ -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

8
arch/x86/kernel/traps.c
View File

@ -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();

2
arch/x86/xen/xen-asm_32.S
View File

@ -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 */