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: 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

diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index c93fb73af03982671a8c6120d853b37edf4701b6..f7a5f1cda058aa031e2abcbd5a89f028cddfe949 100644 (file)
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -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

diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h
index 99d4759bd9147f39f8a67b1476a77e7037b3d5f5..ee6ebfef7e57ddc682b372224139d55b1546c4dd 100644 (file)
--- a/arch/x86/include/asm/idtentry.h
+++ b/arch/x86/include/asm/idtentry.h
@@ -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);

diff --git a/arch/x86/include/asm/traps.h b/arch/x86/include/asm/traps.h
index e7eb7532233d3e2569db2447933be66b3e7c99b2..5774d0b6cf77d3b7fb8c7140121f5c65623972a6 100644 (file)
--- a/arch/x86/include/asm/traps.h
+++ b/arch/x86/include/asm/traps.h
@@ -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

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 1702922ebd9c1b61e0190fcb8abef59c0ed55766..b28a64d7691fbc6ebfbaf6b033d96a2c90d0d25b 100644 (file)
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -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();

diff --git a/arch/x86/xen/xen-asm_32.S b/arch/x86/xen/xen-asm_32.S
index 2712e915530632b2a15a7f64d76a19dbded26d3a..812ff01e4e3414bf0b55646af025b8102c6478b4 100644 (file)
--- a/arch/x86/xen/xen-asm_32.S
+++ b/arch/x86/xen/xen-asm_32.S
@@ -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 */