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author | Thomas Gleixner <tglx@linutronix.de> | 2020-11-18 20:48:46 +0100 |
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committer | Thomas Gleixner <tglx@linutronix.de> | 2020-11-24 14:42:09 +0100 |
commit | 7e015a279853e747f5d4f957855ec5310848c501 (patch) | |
tree | 6fc9b359e5e80091aca57b4332bb8537d59b1399 /arch/x86/kernel/crash_dump_32.c | |
parent | e66f6e095486f0210fcf3c5eb3ecf13fa348be4c (diff) | |
download | linux-7e015a279853e747f5d4f957855ec5310848c501.tar.gz linux-7e015a279853e747f5d4f957855ec5310848c501.tar.bz2 linux-7e015a279853e747f5d4f957855ec5310848c501.zip |
x86/crashdump/32: Simplify copy_oldmem_page()
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 <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20201118204007.670851839@linutronix.de
Diffstat (limited to 'arch/x86/kernel/crash_dump_32.c')
-rw-r--r-- | arch/x86/kernel/crash_dump_32.c | 48 |
1 files changed, 10 insertions, 38 deletions
diff --git a/arch/x86/kernel/crash_dump_32.c b/arch/x86/kernel/crash_dump_32.c index 33ee47670b99..5fcac46aaf6b 100644 --- a/arch/x86/kernel/crash_dump_32.c +++ b/arch/x86/kernel/crash_dump_32.c @@ -13,8 +13,6 @@ #include <linux/uaccess.h> -static void *kdump_buf_page; - static inline bool is_crashed_pfn_valid(unsigned long pfn) { #ifndef CONFIG_X86_PAE @@ -41,15 +39,11 @@ static inline bool is_crashed_pfn_valid(unsigned long pfn) * @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 - * in the current kernel. We stitch up a pte, similar to kmap_atomic. - * - * 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. + * Copy a page from "oldmem". For this page, there might be no pte mapped + * in the current kernel. */ -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; @@ -59,38 +53,16 @@ ssize_t copy_oldmem_page(unsigned long pfn, char *buf, if (!is_crashed_pfn_valid(pfn)) return -EFAULT; - 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) { - printk(KERN_WARNING "Kdump: Kdump buffer page not" - " allocated\n"); - kunmap_atomic(vaddr); - 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; -} + kunmap_local(vaddr); -static int __init kdump_buf_page_init(void) -{ - int ret = 0; - - kdump_buf_page = kmalloc(PAGE_SIZE, GFP_KERNEL); - if (!kdump_buf_page) { - printk(KERN_WARNING "Kdump: Failed to allocate kdump buffer" - " page\n"); - ret = -ENOMEM; - } - - return ret; + return csize; } -arch_initcall(kdump_buf_page_init); |