mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson
synced 2025-10-31 14:30:50 +00:00
41edafdb78
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 <jeremy.fitzhardinge@citrix.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
62 lines
1.7 KiB
C
62 lines
1.7 KiB
C
#include <asm/paravirt.h>
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DEF_NATIVE(pv_irq_ops, irq_disable, "cli");
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DEF_NATIVE(pv_irq_ops, irq_enable, "sti");
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DEF_NATIVE(pv_irq_ops, restore_fl, "push %eax; popf");
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DEF_NATIVE(pv_irq_ops, save_fl, "pushf; pop %eax");
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DEF_NATIVE(pv_cpu_ops, iret, "iret");
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DEF_NATIVE(pv_cpu_ops, irq_enable_sysexit, "sti; sysexit");
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DEF_NATIVE(pv_mmu_ops, read_cr2, "mov %cr2, %eax");
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DEF_NATIVE(pv_mmu_ops, write_cr3, "mov %eax, %cr3");
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DEF_NATIVE(pv_mmu_ops, read_cr3, "mov %cr3, %eax");
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DEF_NATIVE(pv_cpu_ops, clts, "clts");
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DEF_NATIVE(pv_cpu_ops, read_tsc, "rdtsc");
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unsigned paravirt_patch_ident_32(void *insnbuf, unsigned len)
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{
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/* arg in %eax, return in %eax */
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return 0;
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}
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unsigned paravirt_patch_ident_64(void *insnbuf, unsigned len)
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{
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/* arg in %edx:%eax, return in %edx:%eax */
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return 0;
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}
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unsigned native_patch(u8 type, u16 clobbers, void *ibuf,
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unsigned long addr, unsigned len)
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{
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const unsigned char *start, *end;
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unsigned ret;
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#define PATCH_SITE(ops, x) \
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case PARAVIRT_PATCH(ops.x): \
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start = start_##ops##_##x; \
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end = end_##ops##_##x; \
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goto patch_site
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switch (type) {
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PATCH_SITE(pv_irq_ops, irq_disable);
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PATCH_SITE(pv_irq_ops, irq_enable);
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PATCH_SITE(pv_irq_ops, restore_fl);
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PATCH_SITE(pv_irq_ops, save_fl);
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PATCH_SITE(pv_cpu_ops, iret);
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PATCH_SITE(pv_cpu_ops, irq_enable_sysexit);
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PATCH_SITE(pv_mmu_ops, read_cr2);
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PATCH_SITE(pv_mmu_ops, read_cr3);
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PATCH_SITE(pv_mmu_ops, write_cr3);
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PATCH_SITE(pv_cpu_ops, clts);
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PATCH_SITE(pv_cpu_ops, read_tsc);
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patch_site:
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ret = paravirt_patch_insns(ibuf, len, start, end);
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break;
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default:
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ret = paravirt_patch_default(type, clobbers, ibuf, addr, len);
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break;
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}
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#undef PATCH_SITE
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return ret;
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}
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