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x86/xen: Get rid of paravirt op adjust_exception_frame 

When running as Xen pv-guest the exception frame on the stack contains
%r11 and %rcx additional to the other data pushed by the processor.

Instead of having a paravirt op being called for each exception type
prepend the Xen specific code to each exception entry. When running as
Xen pv-guest just use the exception entry with prepended instructions,
otherwise use the entry without the Xen specific code.

[ tglx: Merged through tip to avoid ugly merge conflict ]

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: xen-devel@lists.xenproject.org
Cc: boris.ostrovsky@oracle.com
Cc: luto@amacapital.net
Link: http://lkml.kernel.org/r/20170831174249.26853-1-jg@pfupf.net
This commit is contained in:
Juergen Gross 2017-08-31 19:42:49 +02:00 committed by Thomas Gleixner
parent ef1d4deab9
commit 5878d5d6fd
12 changed files with 133 additions and 77 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
arch/x86/entry/entry_64.S
View File

@ -821,7 +821,6 @@ ENTRY(\sym)
.endif
ASM_CLAC
PARAVIRT_ADJUST_EXCEPTION_FRAME
.ifeq \has_error_code
pushq $-1 /* ORIG_RAX: no syscall to restart */
@ -967,7 +966,7 @@ ENTRY(do_softirq_own_stack)
ENDPROC(do_softirq_own_stack)
#ifdef CONFIG_XEN
idtentry xen_hypervisor_callback xen_do_hypervisor_callback has_error_code=0
idtentry hypervisor_callback xen_do_hypervisor_callback has_error_code=0
/*
* A note on the "critical region" in our callback handler.
@ -1034,8 +1033,6 @@ ENTRY(xen_failsafe_callback)
movq 8(%rsp), %r11
addq $0x30, %rsp
pushq $0 /* RIP */
pushq %r11
pushq %rcx
UNWIND_HINT_IRET_REGS offset=8
jmp general_protection
1: /* Segment mismatch => Category 1 (Bad segment). Retry the IRET. */
@ -1066,9 +1063,8 @@ idtentry int3 do_int3 has_error_code=0 paranoid=1 shift_ist=DEBUG_STACK
idtentry stack_segment do_stack_segment has_error_code=1
#ifdef CONFIG_XEN
idtentry xen_debug do_debug has_error_code=0
idtentry xen_int3 do_int3 has_error_code=0
idtentry xen_stack_segment do_stack_segment has_error_code=1
idtentry xendebug do_debug has_error_code=0
idtentry xenint3 do_int3 has_error_code=0
#endif
idtentry general_protection do_general_protection has_error_code=1
@ -1232,20 +1228,9 @@ ENTRY(error_exit)
END(error_exit)
/* Runs on exception stack */
/* XXX: broken on Xen PV */
ENTRY(nmi)
UNWIND_HINT_IRET_REGS
/*
* Fix up the exception frame if we're on Xen.
* PARAVIRT_ADJUST_EXCEPTION_FRAME is guaranteed to push at most
* one value to the stack on native, so it may clobber the rdx
* scratch slot, but it won't clobber any of the important
* slots past it.
*
* Xen is a different story, because the Xen frame itself overlaps
* the "NMI executing" variable.
*/
PARAVIRT_ADJUST_EXCEPTION_FRAME
/*
* We allow breakpoints in NMIs. If a breakpoint occurs, then
* the iretq it performs will take us out of NMI context.

1
arch/x86/entry/entry_64_compat.S
View File

@ -293,7 +293,6 @@ ENTRY(entry_INT80_compat)
/*
* Interrupts are off on entry.
*/
PARAVIRT_ADJUST_EXCEPTION_FRAME
ASM_CLAC /* Do this early to minimize exposure */
SWAPGS

5
arch/x86/include/asm/paravirt.h
View File

@ -960,11 +960,6 @@ extern void default_banner(void);
#define GET_CR2_INTO_RAX \
call PARA_INDIRECT(pv_mmu_ops+PV_MMU_read_cr2)
#define PARAVIRT_ADJUST_EXCEPTION_FRAME \
PARA_SITE(PARA_PATCH(pv_irq_ops, PV_IRQ_adjust_exception_frame), \
CLBR_NONE, \
call PARA_INDIRECT(pv_irq_ops+PV_IRQ_adjust_exception_frame))
#define USERGS_SYSRET64 \
PARA_SITE(PARA_PATCH(pv_cpu_ops, PV_CPU_usergs_sysret64), \
CLBR_NONE, \

3
arch/x86/include/asm/paravirt_types.h
View File

@ -196,9 +196,6 @@ struct pv_irq_ops {
void (*safe_halt)(void);
void (*halt)(void);
#ifdef CONFIG_X86_64
void (*adjust_exception_frame)(void);
#endif
} __no_randomize_layout;
struct pv_mmu_ops {

3
arch/x86/include/asm/proto.h
View File

@ -24,6 +24,9 @@ void entry_SYSENTER_compat(void);
void __end_entry_SYSENTER_compat(void);
void entry_SYSCALL_compat(void);
void entry_INT80_compat(void);
#if defined(CONFIG_X86_64) && defined(CONFIG_XEN_PV)
void xen_entry_INT80_compat(void);
#endif
#endif
void x86_configure_nx(void);

28
arch/x86/include/asm/traps.h
View File

@ -13,9 +13,6 @@ asmlinkage void divide_error(void);
asmlinkage void debug(void);
asmlinkage void nmi(void);
asmlinkage void int3(void);
asmlinkage void xen_debug(void);
asmlinkage void xen_int3(void);
asmlinkage void xen_stack_segment(void);
asmlinkage void overflow(void);
asmlinkage void bounds(void);
asmlinkage void invalid_op(void);
@ -38,6 +35,31 @@ asmlinkage void machine_check(void);
#endif /* CONFIG_X86_MCE */
asmlinkage void simd_coprocessor_error(void);
#if defined(CONFIG_X86_64) && defined(CONFIG_XEN_PV)
asmlinkage void xen_divide_error(void);
asmlinkage void xen_xendebug(void);
asmlinkage void xen_xenint3(void);
asmlinkage void xen_nmi(void);
asmlinkage void xen_overflow(void);
asmlinkage void xen_bounds(void);
asmlinkage void xen_invalid_op(void);
asmlinkage void xen_device_not_available(void);
asmlinkage void xen_double_fault(void);
asmlinkage void xen_coprocessor_segment_overrun(void);
asmlinkage void xen_invalid_TSS(void);
asmlinkage void xen_segment_not_present(void);
asmlinkage void xen_stack_segment(void);
asmlinkage void xen_general_protection(void);
asmlinkage void xen_page_fault(void);
asmlinkage void xen_spurious_interrupt_bug(void);
asmlinkage void xen_coprocessor_error(void);
asmlinkage void xen_alignment_check(void);
#ifdef CONFIG_X86_MCE
asmlinkage void xen_machine_check(void);
#endif /* CONFIG_X86_MCE */
asmlinkage void xen_simd_coprocessor_error(void);
#endif
dotraplinkage void do_divide_error(struct pt_regs *, long);
dotraplinkage void do_debug(struct pt_regs *, long);
dotraplinkage void do_nmi(struct pt_regs *, long);

1
arch/x86/kernel/asm-offsets_64.c
View File

@ -20,7 +20,6 @@ static char syscalls_ia32[] = {
int main(void)
{
#ifdef CONFIG_PARAVIRT
OFFSET(PV_IRQ_adjust_exception_frame, pv_irq_ops, adjust_exception_frame);
OFFSET(PV_CPU_usergs_sysret64, pv_cpu_ops, usergs_sysret64);
OFFSET(PV_CPU_swapgs, pv_cpu_ops, swapgs);
BLANK();

3
arch/x86/kernel/paravirt.c
View File

@ -319,9 +319,6 @@ __visible struct pv_irq_ops pv_irq_ops = {
.irq_enable = __PV_IS_CALLEE_SAVE(native_irq_enable),
.safe_halt = native_safe_halt,
.halt = native_halt,
#ifdef CONFIG_X86_64
.adjust_exception_frame = paravirt_nop,
#endif
};
__visible struct pv_cpu_ops pv_cpu_ops = {

98
arch/x86/xen/enlighten_pv.c
View File

@ -579,6 +579,70 @@ static void xen_write_ldt_entry(struct desc_struct *dt, int entrynum,
preempt_enable();
}
#ifdef CONFIG_X86_64
struct trap_array_entry {
void (*orig)(void);
void (*xen)(void);
bool ist_okay;
};
static struct trap_array_entry trap_array[] = {
{ debug, xen_xendebug, true },
{ int3, xen_xenint3, true },
{ double_fault, xen_double_fault, true },
#ifdef CONFIG_X86_MCE
{ machine_check, xen_machine_check, true },
#endif
{ nmi, xen_nmi, true },
{ overflow, xen_overflow, false },
#ifdef CONFIG_IA32_EMULATION
{ entry_INT80_compat, xen_entry_INT80_compat, false },
#endif
{ page_fault, xen_page_fault, false },
{ divide_error, xen_divide_error, false },
{ bounds, xen_bounds, false },
{ invalid_op, xen_invalid_op, false },
{ device_not_available, xen_device_not_available, false },
{ coprocessor_segment_overrun, xen_coprocessor_segment_overrun, false },
{ invalid_TSS, xen_invalid_TSS, false },
{ segment_not_present, xen_segment_not_present, false },
{ stack_segment, xen_stack_segment, false },
{ general_protection, xen_general_protection, false },
{ spurious_interrupt_bug, xen_spurious_interrupt_bug, false },
{ coprocessor_error, xen_coprocessor_error, false },
{ alignment_check, xen_alignment_check, false },
{ simd_coprocessor_error, xen_simd_coprocessor_error, false },
};
static bool get_trap_addr(void **addr, unsigned int ist)
{
unsigned int nr;
bool ist_okay = false;
/*
* Replace trap handler addresses by Xen specific ones.
* Check for known traps using IST and whitelist them.
* The debugger ones are the only ones we care about.
* Xen will handle faults like double_fault, * so we should never see
* them. Warn if there's an unexpected IST-using fault handler.
*/
for (nr = 0; nr < ARRAY_SIZE(trap_array); nr++) {
struct trap_array_entry *entry = trap_array + nr;
if (*addr == entry->orig) {
*addr = entry->xen;
ist_okay = entry->ist_okay;
break;
}
}
if (WARN_ON(ist != 0 && !ist_okay))
return false;
return true;
}
#endif
static int cvt_gate_to_trap(int vector, const gate_desc *val,
struct trap_info *info)
{
@ -591,40 +655,8 @@ static int cvt_gate_to_trap(int vector, const gate_desc *val,
addr = gate_offset(val);
#ifdef CONFIG_X86_64
/*
* Look for known traps using IST, and substitute them
* appropriately. The debugger ones are the only ones we care
* about. Xen will handle faults like double_fault,
* so we should never see them. Warn if
* there's an unexpected IST-using fault handler.
*/
if (addr == (unsigned long)debug)
addr = (unsigned long)xen_debug;
else if (addr == (unsigned long)int3)
addr = (unsigned long)xen_int3;
else if (addr == (unsigned long)stack_segment)
addr = (unsigned long)xen_stack_segment;
else if (addr == (unsigned long)double_fault) {
/* Don't need to handle these */
if (!get_trap_addr((void **)&addr, val->bits.ist))
return 0;
#ifdef CONFIG_X86_MCE
} else if (addr == (unsigned long)machine_check) {
/*
* when xen hypervisor inject vMCE to guest,
* use native mce handler to handle it
*/
;
#endif
} else if (addr == (unsigned long)nmi)
/*
* Use the native version as well.
*/
;
else {
/* Some other trap using IST? */
if (WARN_ON(val->bits.ist != 0))
return 0;
}
#endif /* CONFIG_X86_64 */
info->address = addr;

3
arch/x86/xen/irq.c
View File

@ -123,9 +123,6 @@ static const struct pv_irq_ops xen_irq_ops __initconst = {
.safe_halt = xen_safe_halt,
.halt = xen_halt,
#ifdef CONFIG_X86_64
.adjust_exception_frame = xen_adjust_exception_frame,
#endif
};
void __init xen_init_irq_ops(void)

41
arch/x86/xen/xen-asm_64.S
View File

@ -16,11 +16,42 @@
#include <linux/linkage.h>
ENTRY(xen_adjust_exception_frame)
mov 8+0(%rsp), %rcx
mov 8+8(%rsp), %r11
ret $16
ENDPROC(xen_adjust_exception_frame)
.macro xen_pv_trap name
ENTRY(xen_\name)
pop %rcx
pop %r11
jmp \name
END(xen_\name)
.endm
xen_pv_trap divide_error
xen_pv_trap debug
xen_pv_trap xendebug
xen_pv_trap int3
xen_pv_trap xenint3
xen_pv_trap nmi
xen_pv_trap overflow
xen_pv_trap bounds
xen_pv_trap invalid_op
xen_pv_trap device_not_available
xen_pv_trap double_fault
xen_pv_trap coprocessor_segment_overrun
xen_pv_trap invalid_TSS
xen_pv_trap segment_not_present
xen_pv_trap stack_segment
xen_pv_trap general_protection
xen_pv_trap page_fault
xen_pv_trap spurious_interrupt_bug
xen_pv_trap coprocessor_error
xen_pv_trap alignment_check
#ifdef CONFIG_X86_MCE
xen_pv_trap machine_check
#endif /* CONFIG_X86_MCE */
xen_pv_trap simd_coprocessor_error
#ifdef CONFIG_IA32_EMULATION
xen_pv_trap entry_INT80_compat
#endif
xen_pv_trap hypervisor_callback
hypercall_iret = hypercall_page + __HYPERVISOR_iret * 32
/*

1
arch/x86/xen/xen-ops.h
View File

@ -138,7 +138,6 @@ __visible void xen_restore_fl_direct(unsigned long);
__visible void xen_iret(void);
__visible void xen_sysret32(void);
__visible void xen_sysret64(void);
__visible void xen_adjust_exception_frame(void);
extern int xen_panic_handler_init(void);