From: Thomas Gleixner <tglx@linutronix•de>
To: LKML <linux-kernel@vger•kernel.org>
Cc: Juri Lelli <juri.lelli@redhat•com>,
linux-aio@kvack•org, Peter Zijlstra <peterz@infradead•org>,
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"David S. Miller" <davem@davemloft•net>,
linux-btrfs@vger•kernel.org, Greentime Hu <green.hu@gmail•com>
Subject: [patch V3 27/37] x86/crashdump/32: Simplify copy_oldmem_page()
Date: Tue, 03 Nov 2020 10:27:39 +0100 [thread overview]
Message-ID: <20201103095859.335366302@linutronix.de> (raw)
In-Reply-To: 20201103092712.714480842@linutronix.de
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>
---
V3: New patch
---
arch/x86/kernel/crash_dump_32.c | 48 ++++++++--------------------------------
1 file changed, 10 insertions(+), 38 deletions(-)
--- 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(
* @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 p
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);
next prev parent reply other threads:[~2020-11-03 12:27 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-03 9:27 [patch V3 00/37] mm/highmem: Preemptible variant of kmap_atomic & friends Thomas Gleixner
2020-11-03 9:27 ` [patch V3 01/37] mm/highmem: Un-EXPORT __kmap_atomic_idx() Thomas Gleixner
2020-11-03 9:27 ` [patch V3 02/37] highmem: Remove unused functions Thomas Gleixner
2020-11-03 9:27 ` [patch V3 03/37] fs: Remove asm/kmap_types.h includes Thomas Gleixner
2020-11-03 11:12 ` David Sterba
2020-11-03 9:27 ` [patch V3 04/37] sh/highmem: Remove all traces of unused cruft Thomas Gleixner
2020-11-03 9:27 ` [patch V3 05/37] asm-generic: Provide kmap_size.h Thomas Gleixner
2020-11-03 12:25 ` Arnd Bergmann
2020-11-03 9:27 ` [patch V3 06/37] highmem: Provide generic variant of kmap_atomic* Thomas Gleixner
2020-11-03 9:27 ` [patch V3 07/37] highmem: Make DEBUG_HIGHMEM functional Thomas Gleixner
2020-11-03 9:27 ` [patch V3 08/37] x86/mm/highmem: Use generic kmap atomic implementation Thomas Gleixner
2020-11-03 9:27 ` [patch V3 09/37] arc/mm/highmem: " Thomas Gleixner
2020-11-03 9:27 ` [patch V3 10/37] ARM: highmem: Switch to generic kmap atomic Thomas Gleixner
2020-11-12 8:10 ` Marek Szyprowski
2020-11-12 11:03 ` Thomas Gleixner
2020-11-12 11:07 ` Sebastian Andrzej Siewior
2020-11-03 9:27 ` [patch V3 11/37] csky/mm/highmem: " Thomas Gleixner
2020-11-03 9:27 ` [patch V3 12/37] microblaze/mm/highmem: " Thomas Gleixner
2020-11-03 9:27 ` [patch V3 13/37] mips/mm/highmem: " Thomas Gleixner
2020-11-03 9:27 ` [patch V3 14/37] nds32/mm/highmem: " Thomas Gleixner
2020-11-03 9:27 ` [patch V3 15/37] powerpc/mm/highmem: " Thomas Gleixner
2020-11-03 9:27 ` [patch V3 16/37] sparc/mm/highmem: " Thomas Gleixner
2020-11-03 9:27 ` [patch V3 17/37] xtensa/mm/highmem: " Thomas Gleixner
2020-11-03 9:27 ` [patch V3 18/37] highmem: Get rid of kmap_types.h Thomas Gleixner
2020-11-03 9:27 ` [patch V3 19/37] mm/highmem: Remove the old kmap_atomic cruft Thomas Gleixner
2020-11-03 9:27 ` [patch V3 20/37] io-mapping: Cleanup atomic iomap Thomas Gleixner
2020-11-03 9:27 ` [patch V3 21/37] Documentation/io-mapping: Remove outdated blurb Thomas Gleixner
2020-11-03 9:27 ` [patch V3 22/37] highmem: High implementation details and document API Thomas Gleixner
2020-11-03 17:48 ` Linus Torvalds
2020-11-03 19:00 ` Thomas Gleixner
2020-11-03 9:27 ` [patch V3 23/37] sched: Make migrate_disable/enable() independent of RT Thomas Gleixner
2020-11-03 9:27 ` [patch V3 24/37] sched: highmem: Store local kmaps in task struct Thomas Gleixner
2020-11-03 13:49 ` Thomas Gleixner
2020-11-03 13:51 ` [patch V4 " Thomas Gleixner
2020-11-03 9:27 ` [patch V3 25/37] mm/highmem: Provide kmap_local* Thomas Gleixner
2020-11-03 9:27 ` [patch V3 26/37] io-mapping: Provide iomap_local variant Thomas Gleixner
2020-11-03 9:27 ` Thomas Gleixner [this message]
2020-11-03 9:27 ` [patch V3 28/37] mips/crashdump: Simplify copy_oldmem_page() Thomas Gleixner
2020-11-03 9:27 ` [patch V3 29/37] ARM: mm: Replace kmap_atomic_pfn() Thomas Gleixner
2020-11-03 9:27 ` [patch V3 30/37] highmem: Remove kmap_atomic_pfn() Thomas Gleixner
2020-11-03 9:27 ` [patch V3 31/37] drm/ttm: Replace kmap_atomic() usage Thomas Gleixner
2020-11-03 9:27 ` [patch V3 32/37] drm/vmgfx: Replace kmap_atomic() Thomas Gleixner
2020-11-03 9:27 ` [patch V3 33/37] highmem: Remove kmap_atomic_prot() Thomas Gleixner
2020-11-03 9:27 ` [patch V3 34/37] drm/qxl: Replace io_mapping_map_atomic_wc() Thomas Gleixner
2020-11-03 9:27 ` [patch V3 35/37] drm/nouveau/device: " Thomas Gleixner
2020-11-03 9:27 ` [patch V3 36/37] drm/i915: " Thomas Gleixner
2020-11-03 9:27 ` [patch V3 37/37] io-mapping: Remove io_mapping_map_atomic_wc() Thomas Gleixner
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