From 41edafdb78feac1d1f8823846209975fde990633 Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Wed, 28 Jan 2009 14:35:02 -0800 Subject: x86/pvops: add a paravirt_ident functions to allow special patching Impact: Optimization Several paravirt ops implementations simply return their arguments, the most obvious being the make_pte/pte_val class of operations on native. On 32-bit, the identity function is literally a no-op, as the calling convention uses the same registers for the first argument and return. On 64-bit, it can be implemented with a single "mov". This patch adds special identity functions for 32 and 64 bit argument, and machinery to recognize them and replace them with either nops or a mov as appropriate. At the moment, the only users for the identity functions are the pagetable entry conversion functions. The result is a measureable improvement on pagetable-heavy benchmarks (2-3%, reducing the pvops overhead from 5 to 2%). Signed-off-by: Jeremy Fitzhardinge Signed-off-by: H. Peter Anvin --- arch/x86/include/asm/paravirt.h | 5 +++ arch/x86/kernel/paravirt.c | 75 ++++++++++++++++++++++++++++++++----- arch/x86/kernel/paravirt_patch_32.c | 12 ++++++ arch/x86/kernel/paravirt_patch_64.c | 15 ++++++++ 4 files changed, 98 insertions(+), 9 deletions(-) diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h index 17577888709..961d10c12f1 100644 --- a/arch/x86/include/asm/paravirt.h +++ b/arch/x86/include/asm/paravirt.h @@ -388,6 +388,8 @@ extern struct pv_lock_ops pv_lock_ops; asm("start_" #ops "_" #name ": " code "; end_" #ops "_" #name ":") unsigned paravirt_patch_nop(void); +unsigned paravirt_patch_ident_32(void *insnbuf, unsigned len); +unsigned paravirt_patch_ident_64(void *insnbuf, unsigned len); unsigned paravirt_patch_ignore(unsigned len); unsigned paravirt_patch_call(void *insnbuf, const void *target, u16 tgt_clobbers, @@ -1371,6 +1373,9 @@ static inline void __set_fixmap(unsigned /* enum fixed_addresses */ idx, } void _paravirt_nop(void); +u32 _paravirt_ident_32(u32); +u64 _paravirt_ident_64(u64); + #define paravirt_nop ((void *)_paravirt_nop) void paravirt_use_bytelocks(void); diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c index 202514be592..dd25e2b1593 100644 --- a/arch/x86/kernel/paravirt.c +++ b/arch/x86/kernel/paravirt.c @@ -44,6 +44,17 @@ void _paravirt_nop(void) { } +/* identity function, which can be inlined */ +u32 _paravirt_ident_32(u32 x) +{ + return x; +} + +u64 _paravirt_ident_64(u64 x) +{ + return x; +} + static void __init default_banner(void) { printk(KERN_INFO "Booting paravirtualized kernel on %s\n", @@ -138,9 +149,16 @@ unsigned paravirt_patch_default(u8 type, u16 clobbers, void *insnbuf, if (opfunc == NULL) /* If there's no function, patch it with a ud2a (BUG) */ ret = paravirt_patch_insns(insnbuf, len, ud2a, ud2a+sizeof(ud2a)); - else if (opfunc == paravirt_nop) + else if (opfunc == _paravirt_nop) /* If the operation is a nop, then nop the callsite */ ret = paravirt_patch_nop(); + + /* identity functions just return their single argument */ + else if (opfunc == _paravirt_ident_32) + ret = paravirt_patch_ident_32(insnbuf, len); + else if (opfunc == _paravirt_ident_64) + ret = paravirt_patch_ident_64(insnbuf, len); + else if (type == PARAVIRT_PATCH(pv_cpu_ops.iret) || type == PARAVIRT_PATCH(pv_cpu_ops.irq_enable_sysexit) || type == PARAVIRT_PATCH(pv_cpu_ops.usergs_sysret32) || @@ -373,6 +391,45 @@ struct pv_apic_ops pv_apic_ops = { #endif }; +typedef pte_t make_pte_t(pteval_t); +typedef pmd_t make_pmd_t(pmdval_t); +typedef pud_t make_pud_t(pudval_t); +typedef pgd_t make_pgd_t(pgdval_t); + +typedef pteval_t pte_val_t(pte_t); +typedef pmdval_t pmd_val_t(pmd_t); +typedef pudval_t pud_val_t(pud_t); +typedef pgdval_t pgd_val_t(pgd_t); + + +#if defined(CONFIG_X86_32) && !defined(CONFIG_X86_PAE) +/* 32-bit pagetable entries */ +#define paravirt_native_make_pte (make_pte_t *)_paravirt_ident_32 +#define paravirt_native_pte_val (pte_val_t *)_paravirt_ident_32 + +#define paravirt_native_make_pmd (make_pmd_t *)_paravirt_ident_32 +#define paravirt_native_pmd_val (pmd_val_t *)_paravirt_ident_32 + +#define paravirt_native_make_pud (make_pud_t *)_paravirt_ident_32 +#define paravirt_native_pud_val (pud_val_t *)_paravirt_ident_32 + +#define paravirt_native_make_pgd (make_pgd_t *)_paravirt_ident_32 +#define paravirt_native_pgd_val (pgd_val_t *)_paravirt_ident_32 +#else +/* 64-bit pagetable entries */ +#define paravirt_native_make_pte (make_pte_t *)_paravirt_ident_64 +#define paravirt_native_pte_val (pte_val_t *)_paravirt_ident_64 + +#define paravirt_native_make_pmd (make_pmd_t *)_paravirt_ident_64 +#define paravirt_native_pmd_val (pmd_val_t *)_paravirt_ident_64 + +#define paravirt_native_make_pud (make_pud_t *)_paravirt_ident_64 +#define paravirt_native_pud_val (pud_val_t *)_paravirt_ident_64 + +#define paravirt_native_make_pgd (make_pgd_t *)_paravirt_ident_64 +#define paravirt_native_pgd_val (pgd_val_t *)_paravirt_ident_64 +#endif + struct pv_mmu_ops pv_mmu_ops = { #ifndef CONFIG_X86_64 .pagetable_setup_start = native_pagetable_setup_start, @@ -424,21 +481,21 @@ struct pv_mmu_ops pv_mmu_ops = { .pmd_clear = native_pmd_clear, #endif .set_pud = native_set_pud, - .pmd_val = native_pmd_val, - .make_pmd = native_make_pmd, + .pmd_val = paravirt_native_pmd_val, + .make_pmd = paravirt_native_make_pmd, #if PAGETABLE_LEVELS == 4 - .pud_val = native_pud_val, - .make_pud = native_make_pud, + .pud_val = paravirt_native_pud_val, + .make_pud = paravirt_native_make_pud, .set_pgd = native_set_pgd, #endif #endif /* PAGETABLE_LEVELS >= 3 */ - .pte_val = native_pte_val, - .pgd_val = native_pgd_val, + .pte_val = paravirt_native_pte_val, + .pgd_val = paravirt_native_pgd_val, - .make_pte = native_make_pte, - .make_pgd = native_make_pgd, + .make_pte = paravirt_native_make_pte, + .make_pgd = paravirt_native_make_pgd, .dup_mmap = paravirt_nop, .exit_mmap = paravirt_nop, diff --git a/arch/x86/kernel/paravirt_patch_32.c b/arch/x86/kernel/paravirt_patch_32.c index 9fe644f4861..d9f32e6d6ab 100644 --- a/arch/x86/kernel/paravirt_patch_32.c +++ b/arch/x86/kernel/paravirt_patch_32.c @@ -12,6 +12,18 @@ DEF_NATIVE(pv_mmu_ops, read_cr3, "mov %cr3, %eax"); DEF_NATIVE(pv_cpu_ops, clts, "clts"); DEF_NATIVE(pv_cpu_ops, read_tsc, "rdtsc"); +unsigned paravirt_patch_ident_32(void *insnbuf, unsigned len) +{ + /* arg in %eax, return in %eax */ + return 0; +} + +unsigned paravirt_patch_ident_64(void *insnbuf, unsigned len) +{ + /* arg in %edx:%eax, return in %edx:%eax */ + return 0; +} + unsigned native_patch(u8 type, u16 clobbers, void *ibuf, unsigned long addr, unsigned len) { diff --git a/arch/x86/kernel/paravirt_patch_64.c b/arch/x86/kernel/paravirt_patch_64.c index 061d01df9ae..3f08f34f93e 100644 --- a/arch/x86/kernel/paravirt_patch_64.c +++ b/arch/x86/kernel/paravirt_patch_64.c @@ -19,6 +19,21 @@ DEF_NATIVE(pv_cpu_ops, usergs_sysret64, "swapgs; sysretq"); DEF_NATIVE(pv_cpu_ops, usergs_sysret32, "swapgs; sysretl"); DEF_NATIVE(pv_cpu_ops, swapgs, "swapgs"); +DEF_NATIVE(, mov32, "mov %edi, %eax"); +DEF_NATIVE(, mov64, "mov %rdi, %rax"); + +unsigned paravirt_patch_ident_32(void *insnbuf, unsigned len) +{ + return paravirt_patch_insns(insnbuf, len, + start__mov32, end__mov32); +} + +unsigned paravirt_patch_ident_64(void *insnbuf, unsigned len) +{ + return paravirt_patch_insns(insnbuf, len, + start__mov64, end__mov64); +} + unsigned native_patch(u8 type, u16 clobbers, void *ibuf, unsigned long addr, unsigned len) { -- cgit v1.2.3