From bb4a23c994aebcd96c567a0be8e964d516bd4a61 Mon Sep 17 00:00:00 2001 From: Tong Tiangen Date: Wed, 1 Sep 2021 02:46:19 +0000 Subject: [PATCH 1/3] riscv/vdso: Refactor asm/vdso.h The asm/vdso.h will be included in vdso.lds.S in the next patch, the following cleanup is needed to avoid syntax error: 1.the declaration of sys_riscv_flush_icache() is moved into asm/syscall.h. 2.the definition of struct vdso_data is moved into kernel/vdso.c. 2.the definition of VDSO_SYMBOL is placed under "#ifndef __ASSEMBLY__". Also remove the redundant linux/types.h include. Signed-off-by: Tong Tiangen Reviewed-by: Kefeng Wang Signed-off-by: Palmer Dabbelt --- arch/riscv/include/asm/syscall.h | 1 + arch/riscv/include/asm/vdso.h | 16 ++++++++++------ arch/riscv/kernel/syscall_table.c | 1 - arch/riscv/kernel/vdso.c | 5 ++++- 4 files changed, 15 insertions(+), 8 deletions(-) diff --git a/arch/riscv/include/asm/syscall.h b/arch/riscv/include/asm/syscall.h index b933b1583c9f..34fbb3ea21d5 100644 --- a/arch/riscv/include/asm/syscall.h +++ b/arch/riscv/include/asm/syscall.h @@ -82,4 +82,5 @@ 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 893e47195e30..a4a979c89ea0 100644 --- a/arch/riscv/include/asm/vdso.h +++ b/arch/riscv/include/asm/vdso.h @@ -16,18 +16,22 @@ #ifdef CONFIG_MMU #include -#include +/* + * All systems with an MMU have a VDSO, but systems without an MMU don't + * support shared libraries and therefor don't have one. + */ +#ifdef CONFIG_MMU -#ifndef CONFIG_GENERIC_TIME_VSYSCALL -struct vdso_data { -}; -#endif +#ifndef __ASSEMBLY__ +#include #define VDSO_SYMBOL(base, name) \ (void __user *)((unsigned long)(base) + __vdso_##name##_offset) #endif /* CONFIG_MMU */ -asmlinkage long sys_riscv_flush_icache(uintptr_t, uintptr_t, uintptr_t); +#endif /* !__ASSEMBLY__ */ + +#endif /* CONFIG_MMU */ #endif /* _ASM_RISCV_VDSO_H */ diff --git a/arch/riscv/kernel/syscall_table.c b/arch/riscv/kernel/syscall_table.c index a63c667c27b3..44b1420a2270 100644 --- a/arch/riscv/kernel/syscall_table.c +++ b/arch/riscv/kernel/syscall_table.c @@ -7,7 +7,6 @@ #include #include #include -#include #include #undef __SYSCALL diff --git a/arch/riscv/kernel/vdso.c b/arch/riscv/kernel/vdso.c index 25a3b8849599..72e93d218335 100644 --- a/arch/riscv/kernel/vdso.c +++ b/arch/riscv/kernel/vdso.c @@ -12,10 +12,13 @@ #include #include #include +#include + #ifdef CONFIG_GENERIC_TIME_VSYSCALL #include #else -#include +struct vdso_data { +}; #endif extern char vdso_start[], vdso_end[]; From 78a743cd82a35ca0724179fc22834f06a2151fc2 Mon Sep 17 00:00:00 2001 From: Tong Tiangen Date: Wed, 1 Sep 2021 02:46:20 +0000 Subject: [PATCH 2/3] riscv/vdso: Move vdso data page up front 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. Fixes: ad5d1122b82fb ("riscv: use vDSO common flow to reduce the latency of the time-related functions") Signed-off-by: Tong Tiangen Reviewed-by: Kefeng Wang Signed-off-by: Palmer Dabbelt --- arch/riscv/include/asm/vdso.h | 2 ++ arch/riscv/kernel/vdso.c | 48 ++++++++++++++++++------------- arch/riscv/kernel/vdso/vdso.lds.S | 3 +- 3 files changed, 32 insertions(+), 21 deletions(-) diff --git a/arch/riscv/include/asm/vdso.h b/arch/riscv/include/asm/vdso.h index a4a979c89ea0..208e31bc5d1c 100644 --- a/arch/riscv/include/asm/vdso.h +++ b/arch/riscv/include/asm/vdso.h @@ -22,6 +22,8 @@ */ #ifdef CONFIG_MMU +#define __VVAR_PAGES 1 + #ifndef __ASSEMBLY__ #include diff --git a/arch/riscv/kernel/vdso.c b/arch/riscv/kernel/vdso.c index 72e93d218335..e7bd92d8749b 100644 --- a/arch/riscv/kernel/vdso.c +++ b/arch/riscv/kernel/vdso.c @@ -23,6 +23,13 @@ struct vdso_data { 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; @@ -41,7 +48,7 @@ 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; @@ -66,7 +73,9 @@ 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); @@ -75,29 +84,28 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, goto end; } + 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 + VVAR_SIZE, + vdso_pages << PAGE_SHIFT, + (VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC), + vdso_pagelist); + + if (unlikely(ret)) + 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 = (void *)vdso_base + VVAR_SIZE; - ret = - install_special_mapping(mm, vdso_base, vdso_pages << PAGE_SHIFT, - (VM_READ | VM_EXEC | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC), - vdso_pagelist); - - if (unlikely(ret)) { - mm->context.vdso = NULL; - 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]); - - if (unlikely(ret)) - mm->context.vdso = NULL; end: mmap_write_unlock(mm); return ret; @@ -108,7 +116,7 @@ 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 +#include OUTPUT_ARCH(riscv) SECTIONS { - PROVIDE(_vdso_data = . + PAGE_SIZE); + PROVIDE(_vdso_data = . - __VVAR_PAGES * PAGE_SIZE); . = SIZEOF_HEADERS; .hash : { *(.hash) } :text From 8bb0ab3ae7a4dbe6cf32deb830cf2bdbf5736867 Mon Sep 17 00:00:00 2001 From: Tong Tiangen Date: Wed, 1 Sep 2021 02:46:21 +0000 Subject: [PATCH 3/3] riscv/vdso: make arch_setup_additional_pages wait for mmap_sem for write killable riscv architectures relying on mmap_sem for write in their arch_setup_additional_pages. If the waiting task gets killed by the oom killer it would block oom_reaper from asynchronous address space reclaim and reduce the chances of timely OOM resolving. Wait for the lock in the killable mode and return with EINTR if the task got killed while waiting. Signed-off-by: Tong Tiangen Reviewed-by: Kefeng Wang Fixes: 76d2a0493a17 ("RISC-V: Init and Halt Code") Signed-off-by: Palmer Dabbelt --- arch/riscv/kernel/vdso.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/riscv/kernel/vdso.c b/arch/riscv/kernel/vdso.c index e7bd92d8749b..b70956d80408 100644 --- a/arch/riscv/kernel/vdso.c +++ b/arch/riscv/kernel/vdso.c @@ -77,7 +77,9 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, vdso_len = (vdso_pages + VVAR_NR_PAGES) << PAGE_SHIFT; - mmap_write_lock(mm); + if (mmap_write_lock_killable(mm)) + return -EINTR; + vdso_base = get_unmapped_area(NULL, 0, vdso_len, 0, 0); if (IS_ERR_VALUE(vdso_base)) { ret = vdso_base;