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[PATCH] i386: PARAVIRT: Use patch site IDs computed from offset in pa…
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…ravirt_ops structure

Use patch type identifiers derived from the offset of the operation in
the paravirt_ops structure.  This avoids having to maintain a separate
enum for patch site types.

Also, since the identifier is derived from the offset into
paravirt_ops, the offset can be derived from the identifier.  This is
used to remove replicated information in the various callsite macros,
which has been a source of bugs in the past.

This patch also drops the fused save_fl+cli operation, which doesn't
really add much and makes things more complex - specifically because
it breaks the 1:1 relationship between identifiers and offsets.  If
this operation turns out to be particularly beneficial, then the right
answer is to define a new entrypoint for it.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Zachary Amsden <zach@vmware.com>
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Jeremy Fitzhardinge authored and Andi Kleen committed May 2, 2007
1 parent 98de032 commit d582203
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Showing 3 changed files with 104 additions and 126 deletions.
14 changes: 6 additions & 8 deletions arch/i386/kernel/paravirt.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -58,21 +58,19 @@ DEF_NATIVE(cli, "cli");
DEF_NATIVE(sti, "sti");
DEF_NATIVE(popf, "push %eax; popf");
DEF_NATIVE(pushf, "pushf; pop %eax");
DEF_NATIVE(pushf_cli, "pushf; pop %eax; cli");
DEF_NATIVE(iret, "iret");
DEF_NATIVE(sti_sysexit, "sti; sysexit");

static const struct native_insns
{
const char *start, *end;
} native_insns[] = {
[PARAVIRT_IRQ_DISABLE] = { start_cli, end_cli },
[PARAVIRT_IRQ_ENABLE] = { start_sti, end_sti },
[PARAVIRT_RESTORE_FLAGS] = { start_popf, end_popf },
[PARAVIRT_SAVE_FLAGS] = { start_pushf, end_pushf },
[PARAVIRT_SAVE_FLAGS_IRQ_DISABLE] = { start_pushf_cli, end_pushf_cli },
[PARAVIRT_INTERRUPT_RETURN] = { start_iret, end_iret },
[PARAVIRT_STI_SYSEXIT] = { start_sti_sysexit, end_sti_sysexit },
[PARAVIRT_PATCH(irq_disable)] = { start_cli, end_cli },
[PARAVIRT_PATCH(irq_enable)] = { start_sti, end_sti },
[PARAVIRT_PATCH(restore_fl)] = { start_popf, end_popf },
[PARAVIRT_PATCH(save_fl)] = { start_pushf, end_pushf },
[PARAVIRT_PATCH(iret)] = { start_iret, end_iret },
[PARAVIRT_PATCH(irq_enable_sysexit)] = { start_sti_sysexit, end_sti_sysexit },
};

static unsigned native_patch(u8 type, u16 clobbers, void *insns, unsigned len)
Expand Down
39 changes: 6 additions & 33 deletions arch/i386/kernel/vmi.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -83,11 +83,6 @@ extern struct paravirt_patch __start_parainstructions[],
#define MNEM_JMP 0xe9
#define MNEM_RET 0xc3

static char irq_save_disable_callout[] = {
MNEM_CALL, 0, 0, 0, 0,
MNEM_CALL, 0, 0, 0, 0,
MNEM_RET
};
#define IRQ_PATCH_INT_MASK 0
#define IRQ_PATCH_DISABLE 5

Expand Down Expand Up @@ -135,33 +130,17 @@ static unsigned patch_internal(int call, unsigned len, void *insns)
static unsigned vmi_patch(u8 type, u16 clobbers, void *insns, unsigned len)
{
switch (type) {
case PARAVIRT_IRQ_DISABLE:
case PARAVIRT_PATCH(irq_disable):
return patch_internal(VMI_CALL_DisableInterrupts, len, insns);
case PARAVIRT_IRQ_ENABLE:
case PARAVIRT_PATCH(irq_enable):
return patch_internal(VMI_CALL_EnableInterrupts, len, insns);
case PARAVIRT_RESTORE_FLAGS:
case PARAVIRT_PATCH(restore_fl):
return patch_internal(VMI_CALL_SetInterruptMask, len, insns);
case PARAVIRT_SAVE_FLAGS:
case PARAVIRT_PATCH(save_fl):
return patch_internal(VMI_CALL_GetInterruptMask, len, insns);
case PARAVIRT_SAVE_FLAGS_IRQ_DISABLE:
if (len >= 10) {
patch_internal(VMI_CALL_GetInterruptMask, len, insns);
patch_internal(VMI_CALL_DisableInterrupts, len-5, insns+5);
return 10;
} else {
/*
* You bastards didn't leave enough room to
* patch save_flags_irq_disable inline. Patch
* to a helper
*/
BUG_ON(len < 5);
*(char *)insns = MNEM_CALL;
patch_offset(insns, irq_save_disable_callout);
return 5;
}
case PARAVIRT_INTERRUPT_RETURN:
case PARAVIRT_PATCH(iret):
return patch_internal(VMI_CALL_IRET, len, insns);
case PARAVIRT_STI_SYSEXIT:
case PARAVIRT_PATCH(irq_enable_sysexit):
return patch_internal(VMI_CALL_SYSEXIT, len, insns);
default:
break;
Expand Down Expand Up @@ -796,12 +775,6 @@ static inline int __init activate_vmi(void)
para_fill(irq_disable, DisableInterrupts);
para_fill(irq_enable, EnableInterrupts);

/* irq_save_disable !!! sheer pain */
patch_offset(&irq_save_disable_callout[IRQ_PATCH_INT_MASK],
(char *)paravirt_ops.save_fl);
patch_offset(&irq_save_disable_callout[IRQ_PATCH_DISABLE],
(char *)paravirt_ops.irq_disable);

para_fill(wbinvd, WBINVD);
para_fill(read_tsc, RDTSC);

Expand Down
177 changes: 92 additions & 85 deletions include/asm-i386/paravirt.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -4,19 +4,8 @@
* para-virtualization: those hooks are defined here. */

#ifdef CONFIG_PARAVIRT
#include <linux/stringify.h>
#include <asm/page.h>

/* These are the most performance critical ops, so we want to be able to patch
* callers */
#define PARAVIRT_IRQ_DISABLE 0
#define PARAVIRT_IRQ_ENABLE 1
#define PARAVIRT_RESTORE_FLAGS 2
#define PARAVIRT_SAVE_FLAGS 3
#define PARAVIRT_SAVE_FLAGS_IRQ_DISABLE 4
#define PARAVIRT_INTERRUPT_RETURN 5
#define PARAVIRT_STI_SYSEXIT 6

/* Bitmask of what can be clobbered: usually at least eax. */
#define CLBR_NONE 0x0
#define CLBR_EAX 0x1
Expand Down Expand Up @@ -191,6 +180,28 @@ struct paravirt_ops

extern struct paravirt_ops paravirt_ops;

#define PARAVIRT_PATCH(x) \
(offsetof(struct paravirt_ops, x) / sizeof(void *))

#define paravirt_type(type) \
[paravirt_typenum] "i" (PARAVIRT_PATCH(type))
#define paravirt_clobber(clobber) \
[paravirt_clobber] "i" (clobber)

#define PARAVIRT_CALL "call *paravirt_ops+%c[paravirt_typenum]*4;"

#define _paravirt_alt(insn_string, type, clobber) \
"771:\n\t" insn_string "\n" "772:\n" \
".pushsection .parainstructions,\"a\"\n" \
" .long 771b\n" \
" .byte " type "\n" \
" .byte 772b-771b\n" \
" .short " clobber "\n" \
".popsection\n"

#define paravirt_alt(insn_string) \
_paravirt_alt(insn_string, "%c[paravirt_typenum]", "%c[paravirt_clobber]")

#define paravirt_enabled() (paravirt_ops.paravirt_enabled)

static inline void load_esp0(struct tss_struct *tss,
Expand Down Expand Up @@ -515,93 +526,89 @@ struct paravirt_patch_site {
extern struct paravirt_patch_site __parainstructions[],
__parainstructions_end[];

#define paravirt_alt(insn_string, typenum, clobber) \
"771:\n\t" insn_string "\n" "772:\n" \
".pushsection .parainstructions,\"a\"\n" \
" .long 771b\n" \
" .byte " __stringify(typenum) "\n" \
" .byte 772b-771b\n" \
" .short " __stringify(clobber) "\n" \
".popsection"

static inline unsigned long __raw_local_save_flags(void)
{
unsigned long f;

__asm__ __volatile__(paravirt_alt( "pushl %%ecx; pushl %%edx;"
"call *%1;"
"popl %%edx; popl %%ecx",
PARAVIRT_SAVE_FLAGS, CLBR_NONE)
: "=a"(f): "m"(paravirt_ops.save_fl)
: "memory", "cc");
asm volatile(paravirt_alt("pushl %%ecx; pushl %%edx;"
PARAVIRT_CALL
"popl %%edx; popl %%ecx")
: "=a"(f)
: paravirt_type(save_fl),
paravirt_clobber(CLBR_NONE)
: "memory", "cc");
return f;
}

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

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

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

static inline unsigned long __raw_local_irq_save(void)
{
unsigned long f;

__asm__ __volatile__(paravirt_alt( "pushl %%ecx; pushl %%edx;"
"call *%1; pushl %%eax;"
"call *%2; 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");
f = __raw_local_save_flags();
raw_local_irq_disable();
return f;
}

#define CLI_STRING paravirt_alt("pushl %%ecx; pushl %%edx;" \
"call *paravirt_ops+%c[irq_disable];" \
"popl %%edx; popl %%ecx", \
PARAVIRT_IRQ_DISABLE, CLBR_EAX)
#define CLI_STRING \
_paravirt_alt("pushl %%ecx; pushl %%edx;" \
"call *paravirt_ops+%c[paravirt_cli_type]*4;" \
"popl %%edx; popl %%ecx", \
"%c[paravirt_cli_type]", "%c[paravirt_clobber]")

#define STI_STRING \
_paravirt_alt("pushl %%ecx; pushl %%edx;" \
"call *paravirt_ops+%c[paravirt_sti_type]*4;" \
"popl %%edx; popl %%ecx", \
"%c[paravirt_sti_type]", "%c[paravirt_clobber]")

#define STI_STRING paravirt_alt("pushl %%ecx; pushl %%edx;" \
"call *paravirt_ops+%c[irq_enable];" \
"popl %%edx; popl %%ecx", \
PARAVIRT_IRQ_ENABLE, CLBR_EAX)
#define CLI_STI_CLOBBERS , "%eax"
#define CLI_STI_INPUT_ARGS \
#define CLI_STI_INPUT_ARGS \
, \
[irq_disable] "i" (offsetof(struct paravirt_ops, irq_disable)), \
[irq_enable] "i" (offsetof(struct paravirt_ops, irq_enable))
[paravirt_cli_type] "i" (PARAVIRT_PATCH(irq_disable)), \
[paravirt_sti_type] "i" (PARAVIRT_PATCH(irq_enable)), \
paravirt_clobber(CLBR_EAX)

#undef PARAVIRT_CALL

#else /* __ASSEMBLY__ */

#define PARA_PATCH(ptype, clobbers, ops) \
#define PARA_PATCH(off) ((off) / 4)

#define PARA_SITE(ptype, clobbers, ops) \
771:; \
ops; \
772:; \
Expand All @@ -612,25 +619,25 @@ static inline unsigned long __raw_local_irq_save(void)
.short clobbers; \
.popsection

#define INTERRUPT_RETURN \
PARA_PATCH(PARAVIRT_INTERRUPT_RETURN, CLBR_ANY, \
jmp *%cs:paravirt_ops+PARAVIRT_iret)

#define DISABLE_INTERRUPTS(clobbers) \
PARA_PATCH(PARAVIRT_IRQ_DISABLE, clobbers, \
pushl %ecx; pushl %edx; \
call *paravirt_ops+PARAVIRT_irq_disable; \
popl %edx; popl %ecx) \

#define ENABLE_INTERRUPTS(clobbers) \
PARA_PATCH(PARAVIRT_IRQ_ENABLE, clobbers, \
pushl %ecx; pushl %edx; \
call *%cs:paravirt_ops+PARAVIRT_irq_enable; \
popl %edx; popl %ecx)

#define ENABLE_INTERRUPTS_SYSEXIT \
PARA_PATCH(PARAVIRT_STI_SYSEXIT, CLBR_ANY, \
jmp *%cs:paravirt_ops+PARAVIRT_irq_enable_sysexit)
#define INTERRUPT_RETURN \
PARA_SITE(PARA_PATCH(PARAVIRT_iret), CLBR_ANY, \
jmp *%cs:paravirt_ops+PARAVIRT_iret)

#define DISABLE_INTERRUPTS(clobbers) \
PARA_SITE(PARA_PATCH(PARAVIRT_irq_disable), clobbers, \
pushl %ecx; pushl %edx; \
call *%cs:paravirt_ops+PARAVIRT_irq_disable; \
popl %edx; popl %ecx) \

#define ENABLE_INTERRUPTS(clobbers) \
PARA_SITE(PARA_PATCH(PARAVIRT_irq_enable), clobbers, \
pushl %ecx; pushl %edx; \
call *%cs:paravirt_ops+PARAVIRT_irq_enable; \
popl %edx; popl %ecx)

#define ENABLE_INTERRUPTS_SYSEXIT \
PARA_SITE(PARA_PATCH(PARAVIRT_irq_enable_sysexit), CLBR_ANY, \
jmp *%cs:paravirt_ops+PARAVIRT_irq_enable_sysexit)

#define GET_CR0_INTO_EAX \
call *paravirt_ops+PARAVIRT_read_cr0
Expand Down

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