From 64d0e583ec61d4eea2d55644654a33fdb13144b7 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 3 Nov 2020 10:27:40 +0100 Subject: [PATCH 051/323] mips/crashdump: Simplify copy_oldmem_page() Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.215-rt107.tar.xz Replace kmap_atomic_pfn() with kmap_local_pfn() which is preemptible and can take page faults. Remove the indirection of the dump page and the related cruft which is not longer required. Signed-off-by: Thomas Gleixner Cc: Thomas Bogendoerfer Cc: linux-mips@vger.kernel.org Signed-off-by: Sebastian Andrzej Siewior --- arch/mips/kernel/crash_dump.c | 42 ++++++----------------------------- 1 file changed, 7 insertions(+), 35 deletions(-) diff --git a/arch/mips/kernel/crash_dump.c b/arch/mips/kernel/crash_dump.c index 01b2bd95ba1f7..9aba83e1eeb4e 100644 --- a/arch/mips/kernel/crash_dump.c +++ b/arch/mips/kernel/crash_dump.c @@ -5,8 +5,6 @@ #include #include -static void *kdump_buf_page; - /** * copy_oldmem_page - copy one page from "oldmem" * @pfn: page frame number to be copied @@ -17,51 +15,25 @@ static void *kdump_buf_page; * @userbuf: if set, @buf is in user address space, use copy_to_user(), * otherwise @buf is in kernel address space, use memcpy(). * - * Copy a page from "oldmem". For this page, there is no pte mapped + * Copy a page from "oldmem". For this page, there might be no pte mapped * in the current kernel. - * - * Calling copy_to_user() in atomic context is not desirable. Hence first - * copying the data to a pre-allocated kernel page and then copying to user - * space in non-atomic context. */ -ssize_t copy_oldmem_page(unsigned long pfn, char *buf, - size_t csize, unsigned long offset, int userbuf) +ssize_t copy_oldmem_page(unsigned long pfn, char *buf, size_t csize, + unsigned long offset, int userbuf) { void *vaddr; if (!csize) return 0; - vaddr = kmap_atomic_pfn(pfn); + vaddr = kmap_local_pfn(pfn); if (!userbuf) { - memcpy(buf, (vaddr + offset), csize); - kunmap_atomic(vaddr); + memcpy(buf, vaddr + offset, csize); } else { - if (!kdump_buf_page) { - pr_warn("Kdump: Kdump buffer page not allocated\n"); - - return -EFAULT; - } - copy_page(kdump_buf_page, vaddr); - kunmap_atomic(vaddr); - if (copy_to_user(buf, (kdump_buf_page + offset), csize)) - return -EFAULT; + if (copy_to_user(buf, vaddr + offset, csize)) + csize = -EFAULT; } return csize; } - -static int __init kdump_buf_page_init(void) -{ - int ret = 0; - - kdump_buf_page = kmalloc(PAGE_SIZE, GFP_KERNEL); - if (!kdump_buf_page) { - pr_warn("Kdump: Failed to allocate kdump buffer page\n"); - ret = -ENOMEM; - } - - return ret; -} -arch_initcall(kdump_buf_page_init); -- 2.44.0