diff options
Diffstat (limited to 'debian/patches-rt/0050-x86-crashdump-32-Simplify-copy_oldmem_page.patch')
| -rw-r--r-- | debian/patches-rt/0050-x86-crashdump-32-Simplify-copy_oldmem_page.patch | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/debian/patches-rt/0050-x86-crashdump-32-Simplify-copy_oldmem_page.patch b/debian/patches-rt/0050-x86-crashdump-32-Simplify-copy_oldmem_page.patch new file mode 100644 index 000000000..6f57ef059 --- /dev/null +++ b/debian/patches-rt/0050-x86-crashdump-32-Simplify-copy_oldmem_page.patch @@ -0,0 +1,99 @@ +From 9d9dd47b77d859a1261ac0dc98d94018bb5bb6a0 Mon Sep 17 00:00:00 2001 +From: Thomas Gleixner <tglx@linutronix.de> +Date: Tue, 3 Nov 2020 10:27:39 +0100 +Subject: [PATCH 050/323] x86/crashdump/32: Simplify copy_oldmem_page() +Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.204-rt100.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 <tglx@linutronix.de> +Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> +--- + arch/x86/kernel/crash_dump_32.c | 48 +++++++-------------------------- + 1 file 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); +-- +2.43.0 + |