Re: [patch 03/26] Xen-paravirt_ops: use paravirt_nop to consistently mark no-op operations

Chris Wright
2007-03-16T21:59:38Z

* Jeremy Fitzhardinge (jeremy@goop.org) wrote:
> Chris Wright wrote:
> > how about __paravirt_nop_start < func < __paravirt_nop_end and preserve
> > the types?
> >
>
> Er? The reason for the (void *) cast is to stop gcc complaining about
> mismatched pointer types.

I mean like this (bunch of work, for a type check that we're really ignoring
anwyay, but this is the idea...)

diff -r 930fff55070e arch/i386/kernel/paravirt.c
--- a/arch/i386/kernel/paravirt.c Fri Mar 16 11:09:10 2007 -0700
+++ b/arch/i386/kernel/paravirt.c Fri Mar 16 14:48:04 2007 -0700
@@ -35,10 +35,60 @@
#include <asm/tlbflush.h>
#include <asm/timer.h>

-/* nop stub */
-void _paravirt_nop(void)
-{
-}
+/* nop stubs */
+void __paravirt_nop pv_nop_arch_setup(void)
+{
+}
+void __paravirt_nop pv_nop_set_lazy_mode(int mode)
+{
+}
+void __paravirt_nop pv_nop_alloc_pt(struct mm_struct *mm, u32 pfn)
+{
+}
+void __paravirt_nop pv_nop_alloc_pd(u32 pfn)
+{
+}
+void __paravirt_nop pv_nop_alloc_pd_clone(u32 pfn, u32 clonepfn, u32 start, u32 count)
+{
+}
+void __paravirt_nop pv_nop_release_pt(u32 pfn)
+{
+}
+void __paravirt_nop pv_nop_release_pd(u32 pfn)
+{
+}
+void __paravirt_nop pv_nop_pte_update(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
+{
+}
+void __paravirt_nop pv_nop_pte_update_defer(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
+{
+}
+void * __paravirt_nop pv_nop_kmap_atomic_pte(struct page *page, enum km_type type)
+{
+}
+void __paravirt_nop pv_nop_load_tr_desc(void)
+{
+}
+void __paravirt_nop pv_nop_activate_mm(struct mm_struct *prev, struct mm_struct *next)
+{
+}
+void __paravirt_nop pv_nop_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm)
+{
+}
+void __paravirt_nop pv_nop_exit_mmap(struct mm_struct *mm)
+{
+}
+void __paravirt_nop pv_nop_startup_ipi_hook(int phys_apicid, unsigned long start_eip, unsigned long start_esp)
+{
+}
+#ifdef CONFIG_X86_LOCAL_APIC
+void __paravirt_nop pv_nop_setup_boot_clock(void)
+{
+}
+void __paravirt_nop pv_nop_setup_secondary_clock(void)
+{
+}
+#endif

static void __init default_banner(void)
{
@@ -166,7 +216,7 @@ unsigned paravirt_patch_default(u8 type,
if (opfunc == NULL)
/* If there's no function, patch it with a ud2a (BUG) */
ret = paravirt_patch_insns(site, len, start_ud2a, end_ud2a);
- else if (opfunc == paravirt_nop)
+ else if (opfunc >= __paravirt_nop_start || opfunc < __paravirt_nop_end)
/* If the operation is a nop, then nop the callsite */
ret = paravirt_patch_nop();
else if (type == PARAVIRT_PATCH(iret) ||
@@ -521,7 +571,7 @@ struct paravirt_ops paravirt_ops = {

.patch = native_patch,
.banner = default_banner,
- .arch_setup = paravirt_nop,
+ .arch_setup = pv_nop_arch_setup,
.memory_setup = machine_specific_memory_setup,
.get_wallclock = native_get_wallclock,
.set_wallclock = native_set_wallclock,
@@ -577,7 +627,7 @@ struct paravirt_ops paravirt_ops = {
.setup_boot_clock = setup_boot_APIC_clock,
.setup_secondary_clock = setup_secondary_APIC_clock,
#endif
- .set_lazy_mode = paravirt_nop,
+ .set_lazy_mode = pv_nop_set_lazy_mode,

.pagetable_setup_start = native_pagetable_setup_start,
.pagetable_setup_done = native_pagetable_setup_done,
@@ -587,24 +637,24 @@ struct paravirt_ops paravirt_ops = {
.flush_tlb_single = native_flush_tlb_single,
.flush_tlb_others = native_flush_tlb_others,

- .alloc_pt = paravirt_nop,
- .alloc_pd = paravirt_nop,
- .alloc_pd_clone = paravirt_nop,
- .release_pt = paravirt_nop,
- .release_pd = paravirt_nop,
+ .alloc_pt = pv_nop_alloc_pt,
+ .alloc_pd = pv_nop_alloc_pd,
+ .alloc_pd_clone = pv_nop_alloc_pd_clone,
+ .release_pt = pv_nop_release_pt,
+ .release_pd = pv_nop_release_pd,

.set_pte = native_set_pte,
.set_pte_at = native_set_pte_at,
.set_pmd = native_set_pmd,
- .pte_update = paravirt_nop,
- .pte_update_defer = paravirt_nop,
+ .pte_update = pv_nop_pte_update,
+ .pte_update_defer = pv_nop_pte_update_defer,

.ptep_get_and_clear = native_ptep_get_and_clear,

#ifdef CONFIG_HIGHPTE
.kmap_atomic_pte = native_kmap_atomic_pte,
#else
- .kmap_atomic_pte = paravirt_nop,
+ .kmap_atomic_pte = pv_nop_kmap_atomic_pte,
#endif

#ifdef CONFIG_X86_PAE
@@ -627,11 +677,11 @@ struct paravirt_ops paravirt_ops = {
.irq_enable_sysexit = native_irq_enable_sysexit,
.iret = native_iret,

- .dup_mmap = paravirt_nop,
- .exit_mmap = paravirt_nop,
- .activate_mm = paravirt_nop,
-
- .startup_ipi_hook = paravirt_nop,
+ .dup_mmap = pv_nop_dup_mmap,
+ .exit_mmap = pv_nop_exit_mmap,
+ .activate_mm = pv_nop_activate_mm,
+
+ .startup_ipi_hook = pv_nop_startup_ipi_hook,
};

/*
diff -r 930fff55070e arch/i386/kernel/vmlinux.lds.S
--- a/arch/i386/kernel/vmlinux.lds.S Fri Mar 16 11:09:10 2007 -0700
+++ b/arch/i386/kernel/vmlinux.lds.S Fri Mar 16 14:16:42 2007 -0700
@@ -49,6 +49,9 @@ SECTIONS
SCHED_TEXT
LOCK_TEXT
KPROBES_TEXT
+ __paravirt_nop_start = .;
+ *(.paravirtnop)
+ __paravirt_nop_end = .;
*(.fixup)
*(.gnu.warning)
_etext = .; /* End of text section */
diff -r 930fff55070e arch/i386/xen/enlighten.c
--- a/arch/i386/xen/enlighten.c Fri Mar 16 11:09:10 2007 -0700
+++ b/arch/i386/xen/enlighten.c Fri Mar 16 14:53:37 2007 -0700
@@ -697,7 +697,7 @@ static const struct paravirt_ops xen_par
.iret = (void *)&hypercall_page[__HYPERVISOR_iret],
.irq_enable_sysexit = (void *)xen_sti_sysexit,

- .load_tr_desc = paravirt_nop,
+ .load_tr_desc = pv_nop_load_tr_desc,
.set_ldt = xen_set_ldt,
.load_gdt = xen_load_gdt,
.load_idt = xen_load_idt,
@@ -723,8 +723,8 @@ static const struct paravirt_ops xen_par
.apic_write = xen_apic_write,
.apic_write_atomic = xen_apic_write,
.apic_read = xen_apic_read,
- .setup_boot_clock = paravirt_nop,
- .setup_secondary_clock = paravirt_nop,
+ .setup_boot_clock = pv_nop_setup_boot_clock,
+ .setup_secondary_clock = pv_nop_setup_secondary_clock,
#endif

.flush_tlb_user = xen_flush_tlb,
@@ -732,8 +732,8 @@ static const struct paravirt_ops xen_par
.flush_tlb_single = xen_flush_tlb_single,
.flush_tlb_others = xen_flush_tlb_others,

- .pte_update = paravirt_nop,
- .pte_update_defer = paravirt_nop,
+ .pte_update = pv_nop_pte_update,
+ .pte_update_defer = pv_nop_pte_update_defer,

.pagetable_setup_start = xen_pagetable_setup_start,
.pagetable_setup_done = xen_pagetable_setup_done,
@@ -747,9 +747,9 @@ static const struct paravirt_ops xen_par

.alloc_pt = xen_alloc_pt_init,
.release_pt = xen_release_pt,
- .alloc_pd = paravirt_nop,
- .alloc_pd_clone = paravirt_nop,
- .release_pd = paravirt_nop,
+ .alloc_pd = pv_nop_alloc_pd,
+ .alloc_pd_clone = pv_nop_alloc_pd_clone,
+ .release_pd = pv_nop_release_pd,

.kmap_atomic_pte = xen_kmap_atomic_pte,

@@ -773,7 +773,7 @@ static const struct paravirt_ops xen_par
#endif /* PAE */

.set_lazy_mode = xen_set_lazy_mode,
- .startup_ipi_hook = paravirt_nop,
+ .startup_ipi_hook = pv_nop_startup_ipi_hook,
};

#ifdef CONFIG_SMP
diff -r 930fff55070e include/asm-i386/paravirt.h
--- a/include/asm-i386/paravirt.h Fri Mar 16 11:09:10 2007 -0700
+++ b/include/asm-i386/paravirt.h Fri Mar 16 14:50:18 2007 -0700
@@ -202,6 +202,30 @@ int native_write_msr(unsigned int msr, u
int native_write_msr(unsigned int msr, unsigned long long val);
unsigned long long native_read_tsc(void);
unsigned long long native_read_pmc(void);
+
+/* Paravirt nops */
+#define __paravirt_nop __attribute__ ((__section__ (".paravirtnop")))
+extern char __paravirt_nop_start[], __paravirt_nop_end[];
+
+void __paravirt_nop pv_nop_arch_setup(void);
+void __paravirt_nop pv_nop_set_lazy_mode(int mode);
+void __paravirt_nop pv_nop_alloc_pt(struct mm_struct *mm, u32 pfn);
+void __paravirt_nop pv_nop_alloc_pd(u32 pfn);
+void __paravirt_nop pv_nop_alloc_pd_clone(u32 pfn, u32 clonepfn, u32 start, u32 count);
+void __paravirt_nop pv_nop_release_pt(u32 pfn);
+void __paravirt_nop pv_nop_release_pd(u32 pfn);
+void __paravirt_nop pv_nop_pte_update(struct mm_struct *mm, unsigned long addr, pte_t *ptep);
+void __paravirt_nop pv_nop_pte_update_defer(struct mm_struct *mm, unsigned long addr, pte_t *ptep);
+void * __paravirt_nop pv_nop_kmap_atomic_pte(struct page *page, enum km_type type);
+void __paravirt_nop pv_nop_load_tr_desc(void);
+void __paravirt_nop pv_nop_activate_mm(struct mm_struct *prev, struct mm_struct *next);
+void __paravirt_nop pv_nop_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm);
+void __paravirt_nop pv_nop_exit_mmap(struct mm_struct *mm);
+void __paravirt_nop pv_nop_startup_ipi_hook(int phys_apicid, unsigned long start_eip, unsigned long start_esp);
+#ifdef CONFIG_X86_LOCAL_APIC
+void __paravirt_nop pv_nop_setup_boot_clock(void);
+void __paravirt_nop pv_nop_setup_secondary_clock(void);
+#endif

/* Mark a paravirt probe function. */
#define paravirt_probe(fn) \
@@ -876,9 +900,6 @@ static inline pte_t raw_ptep_get_and_cle
#define arch_enter_lazy_mmu_mode() PVOP_VCALL1(set_lazy_mode, PARAVIRT_LAZY_MMU)
#define arch_leave_lazy_mmu_mode() PVOP_VCALL1(set_lazy_mode, PARAVIRT_LAZY_NONE)

-void _paravirt_nop(void);
-#define paravirt_nop ((void *)_paravirt_nop)
-
/* These all sit in the .parainstructions section to tell us what to patch. */
struct paravirt_patch_site {
u8 *instr; /* original instructions */