From: Christophe Leroy Date: Mon, 15 Aug 2022 11:48:40 +0000 (+1000) Subject: powerpc/code-patching: Speed up page mapping/unmapping X-Git-Tag: v6.1-rc1~103^2~196 X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=8b4bb0ad00cb347f62e76a636ce08eb179c843fc;p=tomoyo%2Ftomoyo-test1.git powerpc/code-patching: Speed up page mapping/unmapping Since commit 591b4b268435 ("powerpc/code-patching: Pre-map patch area") the patch area is premapped so intermediate page tables are already allocated. Use __set_pte_at() directly instead of the heavy map_kernel_page(), at for unmapping just do a pte_clear() followed by a flush. __set_pte_at() can be used directly without the filters in set_pte_at() because we are mapping a normal page non executable. Make sure gcc knows text_poke_area is page aligned in order to optimise the flush. This change reduces by 66% the time needed to activate ftrace on an 8xx (588000 tb ticks instead of 1744000). Signed-off-by: Christophe Leroy [mpe: Add ptesync needed on radix to avoid spurious fault] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220815114840.1468656-1-mpe@ellerman.id.au --- diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c index 6edf0697a526..ad0cf3108dd0 100644 --- a/arch/powerpc/lib/code-patching.c +++ b/arch/powerpc/lib/code-patching.c @@ -94,17 +94,20 @@ void __init poking_init(void) static_branch_enable(&poking_init_done); } +static unsigned long get_patch_pfn(void *addr) +{ + if (IS_ENABLED(CONFIG_MODULES) && is_vmalloc_or_module_addr(addr)) + return vmalloc_to_pfn(addr); + else + return __pa_symbol(addr) >> PAGE_SHIFT; +} + /* * This can be called for kernel text or a module. */ static int map_patch_area(void *addr, unsigned long text_poke_addr) { - unsigned long pfn; - - if (IS_ENABLED(CONFIG_MODULES) && is_vmalloc_or_module_addr(addr)) - pfn = vmalloc_to_pfn(addr); - else - pfn = __pa_symbol(addr) >> PAGE_SHIFT; + unsigned long pfn = get_patch_pfn(addr); return map_kernel_page(text_poke_addr, (pfn << PAGE_SHIFT), PAGE_KERNEL); } @@ -149,17 +152,22 @@ static int __do_patch_instruction(u32 *addr, ppc_inst_t instr) int err; u32 *patch_addr; unsigned long text_poke_addr; + pte_t *pte; + unsigned long pfn = get_patch_pfn(addr); - text_poke_addr = (unsigned long)__this_cpu_read(text_poke_area)->addr; + text_poke_addr = (unsigned long)__this_cpu_read(text_poke_area)->addr & PAGE_MASK; patch_addr = (u32 *)(text_poke_addr + offset_in_page(addr)); - err = map_patch_area(addr, text_poke_addr); - if (err) - return err; + pte = virt_to_kpte(text_poke_addr); + __set_pte_at(&init_mm, text_poke_addr, pte, pfn_pte(pfn, PAGE_KERNEL), 0); + /* See ptesync comment in radix__set_pte_at() */ + if (radix_enabled()) + asm volatile("ptesync": : :"memory"); err = __patch_instruction(addr, instr, patch_addr); - unmap_patch_area(text_poke_addr); + pte_clear(&init_mm, text_poke_addr, pte); + flush_tlb_kernel_range(text_poke_addr, text_poke_addr + PAGE_SIZE); return err; }