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x86/irq: Convey vector as argument and not in ptregs

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Device interrupts which go through do_IRQ() or the spurious interrupt
handler have their separate entry code on 64 bit for no good reason.

Both 32 and 64 bit transport the vector number through ORIG_[RE]AX in
pt_regs. Further the vector number is forced to fit into an u8 and is
complemented and offset by 0x80 so it's in the signed character
range. Otherwise GAS would expand the pushq to a 5 byte instruction for any
vector > 0x7F.

Treat the vector number like an error code and hand it to the C function as
argument. This allows to get rid of the extra entry code in a later step.

Simplify the error code push magic by implementing the pushq imm8 via a
'.byte 0x6a, vector' sequence so GAS is not able to screw it up. As the
pushq imm8 is sign extending the resulting error code needs to be truncated
to 8 bits in C code.

Originally-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Andy Lutomirski <luto@kernel.org>
Link: https://lore.kernel.org/r/20200521202118.796915981@linutronix.de
This commit is contained in:
Thomas Gleixner
2020-05-21 22:05:34 +02:00
parent 79b9c18302
commit 633260fa14
11 changed files with 103 additions and 78 deletions
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33
arch/x86/entry/entry_32.S
View File

@@ -1215,40 +1215,15 @@ SYM_FUNC_END(entry_INT80_32)
#endif
.endm
/*
* Build the entry stubs with some assembler magic.
* We pack 1 stub into every 8-byte block.
*/
.align 8
SYM_CODE_START(irq_entries_start)
vector=FIRST_EXTERNAL_VECTOR
.rept (FIRST_SYSTEM_VECTOR - FIRST_EXTERNAL_VECTOR)
pushl $(~vector+0x80) /* Note: always in signed byte range */
vector=vector+1
jmp common_interrupt
.align 8
.endr
SYM_CODE_END(irq_entries_start)
#ifdef CONFIG_X86_LOCAL_APIC
.align 8
SYM_CODE_START(spurious_entries_start)
vector=FIRST_SYSTEM_VECTOR
.rept (NR_VECTORS - FIRST_SYSTEM_VECTOR)
pushl $(~vector+0x80) /* Note: always in signed byte range */
vector=vector+1
jmp common_spurious
.align 8
.endr
SYM_CODE_END(spurious_entries_start)
SYM_CODE_START_LOCAL(common_spurious)
ASM_CLAC
addl $-0x80, (%esp) /* Adjust vector into the [-256, -1] range */
SAVE_ALL switch_stacks=1
ENCODE_FRAME_POINTER
TRACE_IRQS_OFF
movl %esp, %eax
movl PT_ORIG_EAX(%esp), %edx /* get the vector from stack */
movl $-1, PT_ORIG_EAX(%esp) /* no syscall to restart */
call smp_spurious_interrupt
jmp ret_from_intr
SYM_CODE_END(common_spurious)
@@ -1261,12 +1236,12 @@ SYM_CODE_END(common_spurious)
.p2align CONFIG_X86_L1_CACHE_SHIFT
SYM_CODE_START_LOCAL(common_interrupt)
ASM_CLAC
addl $-0x80, (%esp) /* Adjust vector into the [-256, -1] range */
SAVE_ALL switch_stacks=1
ENCODE_FRAME_POINTER
TRACE_IRQS_OFF
movl %esp, %eax
movl PT_ORIG_EAX(%esp), %edx /* get the vector from stack */
movl $-1, PT_ORIG_EAX(%esp) /* no syscall to restart */
call do_IRQ
jmp ret_from_intr
SYM_CODE_END(common_interrupt)