Messages in this thread Patch in this message | | | From | Tong Tiangen <> | Subject | [PATCH -next 1/2] riscv/vdso: Move vdso data page up front | Date | Thu, 19 Aug 2021 03:06:49 +0000 |
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As commit 601255ae3c98 ("arm64: vdso: move data page before code pages"), the same issue exists on riscv, testcase is shown below, make sure that vdso.so is bigger than page size,
struct timespec tp; clock_gettime(5, &tp); printf("tv_sec: %ld, tv_nsec: %ld\n", tp.tv_sec, tp.tv_nsec);
without this patch, test result : tv_sec: 0, tv_nsec: 0 with this patch, test result : tv_sec: 1629271537, tv_nsec: 748000000
Move the vdso data page in front of the VDSO area to fix the issue.
In this patch, I moved the declaration of sys_riscv_flush_icache from asm/vdso.h to asm/syscall.h, the reason is asm/vdso.h is included in vdso.lds.S, If the declaration is placed here, This will introduce syntax error.
Fixes: ad5d1122b82fb ("riscv: use vDSO common flow to reduce the latency of the time-related functions") Signed-off-by: Tong Tiangen <tongtiangen@huawei.com> --- arch/riscv/include/asm/syscall.h | 2 ++ arch/riscv/include/asm/vdso.h | 4 +-- arch/riscv/kernel/vdso.c | 47 ++++++++++++++++++------------- arch/riscv/kernel/vdso/vdso.lds.S | 3 +- 4 files changed, 33 insertions(+), 23 deletions(-)
diff --git a/arch/riscv/include/asm/syscall.h b/arch/riscv/include/asm/syscall.h index b933b1583c9f..50704bd5ca3e 100644 --- a/arch/riscv/include/asm/syscall.h +++ b/arch/riscv/include/asm/syscall.h @@ -82,4 +82,6 @@ static inline int syscall_get_arch(struct task_struct *task) #endif } +asmlinkage long sys_riscv_flush_icache(uintptr_t, uintptr_t, uintptr_t); + #endif /* _ASM_RISCV_SYSCALL_H */ diff --git a/arch/riscv/include/asm/vdso.h b/arch/riscv/include/asm/vdso.h index 1453a2f563bc..564741266580 100644 --- a/arch/riscv/include/asm/vdso.h +++ b/arch/riscv/include/asm/vdso.h @@ -10,6 +10,8 @@ #include <linux/types.h> +#define __VVAR_PAGES 1 + #ifndef CONFIG_GENERIC_TIME_VSYSCALL struct vdso_data { }; @@ -29,6 +31,4 @@ struct vdso_data { (void __user *)((unsigned long)(base) + __vdso_##name); \ }) -asmlinkage long sys_riscv_flush_icache(uintptr_t, uintptr_t, uintptr_t); - #endif /* _ASM_RISCV_VDSO_H */ diff --git a/arch/riscv/kernel/vdso.c b/arch/riscv/kernel/vdso.c index 25a3b8849599..5fecd5529eff 100644 --- a/arch/riscv/kernel/vdso.c +++ b/arch/riscv/kernel/vdso.c @@ -14,12 +14,18 @@ #include <asm/page.h> #ifdef CONFIG_GENERIC_TIME_VSYSCALL #include <vdso/datapage.h> -#else -#include <asm/vdso.h> #endif +#include <asm/vdso.h> extern char vdso_start[], vdso_end[]; +enum vvar_pages { + VVAR_DATA_PAGE_OFFSET, + VVAR_NR_PAGES, +}; + +#define VVAR_SIZE (VVAR_NR_PAGES << PAGE_SHIFT) + static unsigned int vdso_pages __ro_after_init; static struct page **vdso_pagelist __ro_after_init; @@ -38,7 +44,7 @@ static int __init vdso_init(void) vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT; vdso_pagelist = - kcalloc(vdso_pages + 1, sizeof(struct page *), GFP_KERNEL); + kcalloc(vdso_pages + VVAR_NR_PAGES, sizeof(struct page *), GFP_KERNEL); if (unlikely(vdso_pagelist == NULL)) { pr_err("vdso: pagelist allocation failed\n"); return -ENOMEM; @@ -63,7 +69,9 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, unsigned long vdso_base, vdso_len; int ret; - vdso_len = (vdso_pages + 1) << PAGE_SHIFT; + BUILD_BUG_ON(VVAR_NR_PAGES != __VVAR_PAGES); + + vdso_len = (vdso_pages + VVAR_NR_PAGES) << PAGE_SHIFT; mmap_write_lock(mm); vdso_base = get_unmapped_area(NULL, 0, vdso_len, 0, 0); @@ -72,29 +80,28 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, goto end; } - /* - * Put vDSO base into mm struct. We need to do this before calling - * install_special_mapping or the perf counter mmap tracking code - * will fail to recognise it as a vDSO (since arch_vma_name fails). - */ - mm->context.vdso = (void *)vdso_base; + mm->context.vdso = NULL; + ret = install_special_mapping(mm, vdso_base, VVAR_SIZE, + (VM_READ | VM_MAYREAD), &vdso_pagelist[vdso_pages]); + if (unlikely(ret)) + goto end; ret = - install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT, + install_special_mapping(mm, vdso_base + VVAR_SIZE, + vdso_pages << PAGE_SHIFT, (VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC), vdso_pagelist); - if (unlikely(ret)) { - mm->context.vdso = NULL; + if (unlikely(ret)) goto end; - } - vdso_base += (vdso_pages << PAGE_SHIFT); - ret = install_special_mapping(mm, vdso_base, PAGE_SIZE, - (VM_READ | VM_MAYREAD), &vdso_pagelist[vdso_pages]); + /* + * Put vDSO base into mm struct. We need to do this before calling + * install_special_mapping or the perf counter mmap tracking code + * will fail to recognise it as a vDSO (since arch_vma_name fails). + */ + mm->context.vdso = (void *)vdso_base + VVAR_SIZE; - if (unlikely(ret)) - mm->context.vdso = NULL; end: mmap_write_unlock(mm); return ret; @@ -105,7 +112,7 @@ const char *arch_vma_name(struct vm_area_struct *vma) if (vma->vm_mm && (vma->vm_start == (long)vma->vm_mm->context.vdso)) return "[vdso]"; if (vma->vm_mm && (vma->vm_start == - (long)vma->vm_mm->context.vdso + PAGE_SIZE)) + (long)vma->vm_mm->context.vdso - VVAR_SIZE)) return "[vdso_data]"; return NULL; } diff --git a/arch/riscv/kernel/vdso/vdso.lds.S b/arch/riscv/kernel/vdso/vdso.lds.S index e6f558bca71b..e9111f700af0 100644 --- a/arch/riscv/kernel/vdso/vdso.lds.S +++ b/arch/riscv/kernel/vdso/vdso.lds.S @@ -3,12 +3,13 @@ * Copyright (C) 2012 Regents of the University of California */ #include <asm/page.h> +#include <asm/vdso.h> OUTPUT_ARCH(riscv) SECTIONS { - PROVIDE(_vdso_data = . + PAGE_SIZE); + PROVIDE(_vdso_data = . - __VVAR_PAGES * PAGE_SIZE); . = SIZEOF_HEADERS; .hash : { *(.hash) } :text -- 2.18.0.huawei.25
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