Re: [patch] paravirt: isolate module ops

From: Rusty Russell
Date: Sat Jan 06 2007 - 01:26:19 EST

On Fri, 2007-01-05 at 16:31 -0800, Zachary Amsden wrote:
> Ingo Molnar wrote:
> > Subject: [patch] paravirt: isolate module ops
> > From: Ingo Molnar <mingo@xxxxxxx>
> >
> > only export those operations to modules that have been available to them
> > historically: irq disable/enable, io-delay, udelay, etc.
> >
> > this isolates that functionality from other paravirtualization
> > functionality that modules have no business messing with.
> >
> > boot and build tested with CONFIG_PARAVIRT=y.
> >
> > Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
> > ---
> > arch/i386/kernel/paravirt.c | 41 +++++++++++++++++++++++++++
> > include/asm-i386/delay.h | 4 +-
> > include/asm-i386/paravirt.h | 65 ++++++++++++++++++++++----------------------
> > 3 files changed, 75 insertions(+), 35 deletions(-)
> >
> > Index: linux/arch/i386/kernel/paravirt.c
> > ===================================================================
> > --- linux.orig/arch/i386/kernel/paravirt.c
> > +++ linux/arch/i386/kernel/paravirt.c
> > @@ -492,6 +492,7 @@ struct paravirt_ops paravirt_ops = {
> >
> > .patch = native_patch,
> > .banner = default_banner,
> > +
> > .arch_setup = native_nop,
> > .memory_setup = machine_specific_memory_setup,
> > .get_wallclock = native_get_wallclock,
> > @@ -566,4 +567,42 @@ struct paravirt_ops paravirt_ops = {
> > .irq_enable_sysexit = native_irq_enable_sysexit,
> > .iret = native_iret,
> > };
> > -EXPORT_SYMBOL(paravirt_ops);
> > +
> > +/*
> > + * These are exported to modules:
> > + */
> > +struct paravirt_ops paravirt_mod_ops = {
> > + .name = "bare hardware",
> > + .paravirt_enabled = 0,
> > + .kernel_rpl = 0,
> > +
> > + .patch = native_patch,
> >
>
> I don't think you want to leave that one... patching the kernel isn't
> something modules should be doing.

Yeah, this patch is terrible, but I know why Ingo did it; it's my fault
for not finishing my version yesterday (but allmodconfig takes a while
to build and every change to paravirt.h rebuilds the universe...).

So here's my variant, compile-tested with "make allmodconfig". Exports
individual functions, some of which can be reduced over time as the
modules involved are whacked into shape.

Note: it reduces the patching space by 1 byte (direct jumps vs indirect
jumps). If this a problem for any paravirt_ops backend in practice, we
can add noops...

Cheers,
Rusty.
PS. May break with other configurations...

Name: don't export paravirt_ops structure, do individual functions

Some of the more obscure ones are only used by one or two modules.
We can almost certainly reduce them with more work.

Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>

diff -r 48f31ae5d7b5 arch/i386/kernel/paravirt.c
--- a/arch/i386/kernel/paravirt.c Sat Jan 06 10:32:24 2007 +1100
+++ b/arch/i386/kernel/paravirt.c Sat Jan 06 17:23:12 2007 +1100
@@ -596,6 +596,154 @@ static int __init print_banner(void)
return 0;
}
core_initcall(print_banner);
+
+unsigned long paravirt_save_flags(void)
+{
+ return paravirt_ops.save_fl();
+}
+EXPORT_SYMBOL(paravirt_save_flags);
+
+void paravirt_restore_flags(unsigned long flags)
+{
+ paravirt_ops.restore_fl(flags);
+}
+EXPORT_SYMBOL(paravirt_restore_flags);
+
+void paravirt_irq_disable(void)
+{
+ paravirt_ops.irq_disable();
+}
+EXPORT_SYMBOL(paravirt_irq_disable);
+
+void paravirt_irq_enable(void)
+{
+ paravirt_ops.irq_enable();
+}
+EXPORT_SYMBOL(paravirt_irq_enable);
+
+void paravirt_io_delay(void)
+{
+ paravirt_ops.io_delay();
+}
+EXPORT_SYMBOL(paravirt_io_delay);
+
+void paravirt_const_udelay(unsigned long loops)
+{
+ paravirt_ops.const_udelay(loops);
+}
+EXPORT_SYMBOL(paravirt_const_udelay);
+
+u64 paravirt_read_msr(unsigned int msr, int *err)
+{
+ return paravirt_ops.read_msr(msr, err);
+}
+EXPORT_SYMBOL(paravirt_read_msr);
+
+int paravirt_write_msr(unsigned int msr, u64 val)
+{
+ return paravirt_ops.write_msr(msr, val);
+}
+EXPORT_SYMBOL(paravirt_write_msr);
+
+u64 paravirt_read_tsc(void)
+{
+ return paravirt_ops.read_tsc();
+}
+EXPORT_SYMBOL(paravirt_read_tsc);
+
+int paravirt_enabled(void)
+{
+ return paravirt_ops.paravirt_enabled;
+}
+EXPORT_SYMBOL(paravirt_enabled);
+
+void clts(void)
+{
+ paravirt_ops.clts();
+}
+EXPORT_SYMBOL(clts);
+
+unsigned long read_cr0(void)
+{
+ return paravirt_ops.read_cr0();
+}
+EXPORT_SYMBOL(read_cr0);
+
+void write_cr0(unsigned long cr0)
+{
+ paravirt_ops.write_cr0(cr0);
+}
+EXPORT_SYMBOL(write_cr0);
+
+void wbinvd(void)
+{
+ paravirt_ops.wbinvd();
+}
+EXPORT_SYMBOL(wbinvd);
+
+void raw_safe_halt(void)
+{
+ paravirt_ops.safe_halt();
+}
+EXPORT_SYMBOL(raw_safe_halt);
+
+void halt(void)
+{
+ paravirt_ops.safe_halt();
+}
+EXPORT_SYMBOL(halt);
+
+#ifdef CONFIG_X86_LOCAL_APIC
+void apic_write(unsigned long reg, unsigned long v)
+{
+ paravirt_ops.apic_write(reg,v);
+}
+EXPORT_SYMBOL_GPL(apic_write);
+
+unsigned long apic_read(unsigned long reg)
+{
+ return paravirt_ops.apic_read(reg);
+}
+EXPORT_SYMBOL_GPL(apic_read);
+#endif
+
+void __cpuid(unsigned int *eax, unsigned int *ebx,
+ unsigned int *ecx, unsigned int *edx)
+{
+ paravirt_ops.cpuid(eax, ebx, ecx, edx);
+}
+EXPORT_SYMBOL(__cpuid);
+
+#ifdef CONFIG_X86_PAE
+unsigned long long pgd_val(pgd_t x)
+{
+ return paravirt_ops.pgd_val(x);
+}
+unsigned long long pte_val(pte_t x)
+{
+ return paravirt_ops.pte_val(x);
+}
+pte_t __pte(unsigned long long x)
+{
+ return paravirt_ops.make_pte(x);
+}
+#else
+unsigned long pgd_val(pgd_t x)
+{
+ return paravirt_ops.pgd_val(x);
+}
+unsigned long pte_val(pte_t x)
+{
+ return paravirt_ops.pte_val(x);
+}
+pte_t __pte(unsigned long x)
+{
+ return paravirt_ops.make_pte(x);
+}
+#endif
+EXPORT_SYMBOL_GPL(pgd_val);
+EXPORT_SYMBOL_GPL(pte_val);
+EXPORT_SYMBOL_GPL(__pte);

/* We simply declare start_kernel to be the paravirt probe of last resort. */
paravirt_probe(start_kernel);
@@ -710,4 +858,3 @@ struct paravirt_ops paravirt_ops = {

.startup_ipi_hook = (void *)native_nop,
};
-EXPORT_SYMBOL(paravirt_ops);
diff -r 48f31ae5d7b5 include/asm-i386/delay.h
--- a/include/asm-i386/delay.h Sat Jan 06 10:32:24 2007 +1100
+++ b/include/asm-i386/delay.h Sat Jan 06 11:23:25 2007 +1100
@@ -17,9 +17,9 @@ extern void __delay(unsigned long loops)
extern void __delay(unsigned long loops);

#if defined(CONFIG_PARAVIRT) && !defined(USE_REAL_TIME_DELAY)
-#define udelay(n) paravirt_ops.const_udelay((n) * 0x10c7ul)
+#define udelay(n) paravirt_const_udelay((n) * 0x10c7ul)

-#define ndelay(n) paravirt_ops.const_udelay((n) * 5ul)
+#define ndelay(n) paravirt_const_udelay((n) * 5ul)

#else /* !PARAVIRT || USE_REAL_TIME_DELAY */

diff -r 48f31ae5d7b5 include/asm-i386/paravirt.h
--- a/include/asm-i386/paravirt.h Sat Jan 06 10:32:24 2007 +1100
+++ b/include/asm-i386/paravirt.h Sat Jan 06 16:46:14 2007 +1100
@@ -198,6 +198,18 @@ extern struct paravirt_ops paravirt_ops;

void native_pagetable_setup_start(pgd_t *pgd);

+/* These are the functions exported to modules. */
+unsigned long paravirt_save_flags(void);
+void paravirt_restore_flags(unsigned long flags);
+void paravirt_irq_disable(void);
+void paravirt_irq_enable(void);
+void paravirt_const_udelay(unsigned long loops);
+void paravirt_io_delay(void);
+u64 paravirt_read_msr(unsigned int msr, int *err);
+int paravirt_write_msr(unsigned int msr, u64 val);
+u64 paravirt_read_tsc(void);
+int paravirt_enabled(void);
+
#ifdef CONFIG_X86_PAE
fastcall unsigned long long native_pte_val(pte_t);
fastcall unsigned long long native_pmd_val(pmd_t);
@@ -216,8 +228,6 @@ fastcall pgd_t native_make_pgd(unsigned
fastcall pgd_t native_make_pgd(unsigned long pgd);
#endif

-#define paravirt_enabled() (paravirt_ops.paravirt_enabled)
-
static inline void load_esp0(struct tss_struct *tss,
struct thread_struct *thread)
{
@@ -241,11 +251,8 @@ static inline void do_time_init(void)
}

/* The paravirtualized CPUID instruction. */
-static inline void __cpuid(unsigned int *eax, unsigned int *ebx,
- unsigned int *ecx, unsigned int *edx)
-{
- paravirt_ops.cpuid(eax, ebx, ecx, edx);
-}
+void __cpuid(unsigned int *eax, unsigned int *ebx,
+ unsigned int *ecx, unsigned int *edx);

/*
* These special macros can be used to get or set a debugging register
@@ -253,10 +260,9 @@ static inline void __cpuid(unsigned int
#define get_debugreg(var, reg) var = paravirt_ops.get_debugreg(reg)
#define set_debugreg(val, reg) paravirt_ops.set_debugreg(reg, val)

-#define clts() paravirt_ops.clts()
-
-#define read_cr0() paravirt_ops.read_cr0()
-#define write_cr0(x) paravirt_ops.write_cr0(x)
+void clts(void);
+unsigned long read_cr0(void);
+void write_cr0(unsigned long);

#define read_cr2() paravirt_ops.read_cr2()
#define write_cr2(x) paravirt_ops.write_cr2(x)
@@ -270,62 +276,55 @@ static inline void __cpuid(unsigned int

#define raw_ptep_get_and_clear(xp) (paravirt_ops.ptep_get_and_clear(xp))

-static inline void raw_safe_halt(void)
-{
- paravirt_ops.safe_halt();
-}
-
-static inline void halt(void)
-{
- paravirt_ops.safe_halt();
-}
-#define wbinvd() paravirt_ops.wbinvd()
+void raw_safe_halt(void);
+void halt(void);
+void wbinvd(void);

#define get_kernel_rpl() (paravirt_ops.kernel_rpl)

#define rdmsr(msr,val1,val2) do { \
int _err; \
- u64 _l = paravirt_ops.read_msr(msr,&_err); \
+ u64 _l = paravirt_read_msr(msr,&_err); \
val1 = (u32)_l; \
val2 = _l >> 32; \
} while(0)

#define wrmsr(msr,val1,val2) do { \
u64 _l = ((u64)(val2) << 32) | (val1); \
- paravirt_ops.write_msr((msr), _l); \
+ paravirt_write_msr((msr), _l); \
} while(0)

#define rdmsrl(msr,val) do { \
int _err; \
- val = paravirt_ops.read_msr((msr),&_err); \
+ val = paravirt_read_msr((msr),&_err); \
} while(0)

-#define wrmsrl(msr,val) (paravirt_ops.write_msr((msr),(val)))
+#define wrmsrl(msr,val) (paravirt_write_msr((msr),(val)))
#define wrmsr_safe(msr,a,b) ({ \
u64 _l = ((u64)(b) << 32) | (a); \
- paravirt_ops.write_msr((msr),_l); \
+ paravirt_write_msr((msr),_l); \
})

/* rdmsr with exception handling */
#define rdmsr_safe(msr,a,b) ({ \
int _err; \
- u64 _l = paravirt_ops.read_msr(msr,&_err); \
+ u64 _l = paravirt_read_msr(msr,&_err); \
(*a) = (u32)_l; \
(*b) = _l >> 32; \
_err; })

#define rdtsc(low,high) do { \
- u64 _l = paravirt_ops.read_tsc(); \
+ u64 _l = paravirt_read_tsc(); \
low = (u32)_l; \
high = _l >> 32; \
} while(0)

#define rdtscl(low) do { \
- u64 _l = paravirt_ops.read_tsc(); \
+ u64 _l = paravirt_read_tsc(); \
low = (int)_l; \
} while(0)

-#define rdtscll(val) (val = paravirt_ops.read_tsc())
+#define rdtscll(val) (val = paravirt_read_tsc())

#define write_tsc(val1,val2) wrmsr(0x10, val1, val2)

@@ -351,11 +350,18 @@ static inline void halt(void)
(paravirt_ops.write_idt_entry((dt), (entry), (low), (high)))
#define set_iopl_mask(mask) (paravirt_ops.set_iopl_mask(mask))

-#define __pte(x) paravirt_ops.make_pte(x)
+/* FIXME: drivers/char/drm/drm_memory.h wants access to these. */
+#ifdef CONFIG_X86_PAE
+unsigned long long pgd_val(pgd_t x);
+unsigned long long pte_val(pte_t x);
+pte_t __pte(unsigned long long x);
+#else
+unsigned long pgd_val(pgd_t x);
+unsigned long pte_val(pte_t x);
+pte_t __pte(unsigned long x);
+#endif
+
#define __pgd(x) paravirt_ops.make_pgd(x)
-
-#define pte_val(x) paravirt_ops.pte_val(x)
-#define pgd_val(x) paravirt_ops.pgd_val(x)

#ifdef CONFIG_X86_PAE
#define __pmd(x) paravirt_ops.make_pmd(x)
@@ -363,12 +369,13 @@ static inline void halt(void)
#endif

/* The paravirtualized I/O functions */
+
static inline void slow_down_io(void) {
- paravirt_ops.io_delay();
+ paravirt_io_delay();
#ifdef REALLY_SLOW_IO
- paravirt_ops.io_delay();
- paravirt_ops.io_delay();
- paravirt_ops.io_delay();
+ paravirt_io_delay();
+ paravirt_io_delay();
+ paravirt_io_delay();
#endif
}

@@ -376,19 +383,12 @@ static inline void slow_down_io(void) {
/*
* Basic functions accessing APICs.
*/
-static inline void apic_write(unsigned long reg, unsigned long v)
-{
- paravirt_ops.apic_write(reg,v);
-}
+void apic_write(unsigned long reg, unsigned long v);
+unsigned long apic_read(unsigned long reg);

static inline void apic_write_atomic(unsigned long reg, unsigned long v)
{
paravirt_ops.apic_write_atomic(reg,v);
-}
-
-static inline unsigned long apic_read(unsigned long reg)
-{
- return paravirt_ops.apic_read(reg);
}
#endif

@@ -532,42 +532,38 @@ static inline unsigned long __raw_local_
unsigned long f;

__asm__ __volatile__(paravirt_alt( "pushl %%ecx; pushl %%edx;"
- "call *%1;"
+ "call paravirt_save_flags;"
"popl %%edx; popl %%ecx",
PARAVIRT_SAVE_FLAGS, CLBR_NONE)
- : "=a"(f): "m"(paravirt_ops.save_fl)
- : "memory", "cc");
+ : "=a"(f) : : "memory", "cc");
return f;
}

static inline void raw_local_irq_restore(unsigned long f)
{
__asm__ __volatile__(paravirt_alt( "pushl %%ecx; pushl %%edx;"
- "call *%1;"
+ "call paravirt_restore_flags;"
"popl %%edx; popl %%ecx",
PARAVIRT_RESTORE_FLAGS, CLBR_EAX)
- : "=a"(f) : "m" (paravirt_ops.restore_fl), "0"(f)
- : "memory", "cc");
+ : "=a"(f) : "0"(f) : "memory", "cc");
}

static inline void raw_local_irq_disable(void)
{
__asm__ __volatile__(paravirt_alt( "pushl %%ecx; pushl %%edx;"
- "call *%0;"
+ "call paravirt_irq_disable;"
"popl %%edx; popl %%ecx",
PARAVIRT_IRQ_DISABLE, CLBR_EAX)
- : : "m" (paravirt_ops.irq_disable)
- : "memory", "eax", "cc");
+ : : : "memory", "eax", "cc");
}

static inline void raw_local_irq_enable(void)
{
__asm__ __volatile__(paravirt_alt( "pushl %%ecx; pushl %%edx;"
- "call *%0;"
+ "call paravirt_irq_enable;"
"popl %%edx; popl %%ecx",
PARAVIRT_IRQ_ENABLE, CLBR_EAX)
- : : "m" (paravirt_ops.irq_enable)
- : "memory", "eax", "cc");
+ : : : "memory", "eax", "cc");
}

static inline unsigned long __raw_local_irq_save(void)
@@ -575,15 +571,13 @@ static inline unsigned long __raw_local_
unsigned long f;

__asm__ __volatile__(paravirt_alt( "pushl %%ecx; pushl %%edx;"
- "call *%1; pushl %%eax;"
- "call *%2; popl %%eax;"
- "popl %%edx; popl %%ecx",
+ "call paravirt_save_flags;"
+ "pushl %%eax;"
+ "call paravirt_irq_disable;"
+ "popl %%eax;popl %%edx; popl %%ecx",
PARAVIRT_SAVE_FLAGS_IRQ_DISABLE,
CLBR_NONE)
- : "=a"(f)
- : "m" (paravirt_ops.save_fl),
- "m" (paravirt_ops.irq_disable)
- : "memory", "cc");
+ : "=a"(f) : : "memory", "cc");
return f;
}

diff -r 48f31ae5d7b5 include/linux/irqflags.h
--- a/include/linux/irqflags.h Sat Jan 06 10:32:24 2007 +1100
+++ b/include/linux/irqflags.h Sat Jan 06 15:03:42 2007 +1100
@@ -74,11 +74,11 @@
#endif /* CONFIG_TRACE_IRQFLAGS_SUPPORT */

#ifdef CONFIG_TRACE_IRQFLAGS_SUPPORT
-#define safe_halt() \
- do { \
- trace_hardirqs_on(); \
- raw_safe_halt(); \
- } while (0)
+static inline void safe_halt(void)
+{
+ trace_hardirqs_on();
+ raw_safe_halt();
+}

#define local_save_flags(flags) raw_local_save_flags(flags)



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