Re: [PATCH v3 07/17] arm64, hibernate: move page handling function to new trans_pgd.c
flat view
From: James Morse <james.morse@arm.com>
Date: 2019-09-06 15:18:43
Also in:
kexec, linux-mm, lkml
Hi Pavel, On 21/08/2019 19:31, Pavel Tatashin wrote:
Now, that we abstracted the required functions move them to a new home. Later, we will generalize these function in order to be useful outside of hibernation.
quoted hunk ↗ jump to hunk
diff --git a/arch/arm64/mm/trans_pgd.c b/arch/arm64/mm/trans_pgd.c new file mode 100644 index 000000000000..00b62d8640c2 --- /dev/null +++ b/arch/arm64/mm/trans_pgd.c@@ -0,0 +1,211 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * Copyright (c) 2019, Microsoft Corporation. + * Pavel Tatashin <patatash@linux.microsoft.com>
Hmmm, while line-count isn't a useful metric: this file contains 41% of the code that was in hibernate.c, but has stripped the substantial copyright-pedigree that the hibernate code had built up over the years. (counting lines identified by 'cloc' as code, not comments or blank) If you are copying or moving a non trivial quantity of code, you need to preserve the copyright. Something like 'Derived from the arm64 hibernate support which has:'....
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+ */ + +/* + * Transitional tables are used during system transferring from one world to + * another: such as during hibernate restore, and kexec reboots. During these + * phases one cannot rely on page table not being overwritten.
I think you need to mention that hibernate and kexec are rewriting memory, and may overwrite the live page tables, therefore ...
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+ * + */ + +#include <asm/trans_pgd.h> +#include <asm/pgalloc.h> +#include <asm/pgtable.h> +#include <linux/suspend.h>
#include <linux/bug.h> #include <linux/mm.h> #include <linux/mmzone.h>
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+static void _copy_pte(pte_t *dst_ptep, pte_t *src_ptep, unsigned long addr) +{ + pte_t pte = READ_ONCE(*src_ptep); +
+ if (pte_valid(pte)) {quoted hunk ↗ jump to hunk
+ /* + * Resume will overwrite areas that may be marked + * read only (code, rodata). Clear the RDONLY bit from + * the temporary mappings we use during restore. + */ + set_pte(dst_ptep, pte_mkwrite(pte));
+ } else if (debug_pagealloc_enabled() && !pte_none(pte)) {quoted hunk ↗ jump to hunk
+ /* + * debug_pagealloc will removed the PTE_VALID bit if + * the page isn't in use by the resume kernel. It may have + * been in use by the original kernel, in which case we need + * to put it back in our copy to do the restore. + * + * Before marking this entry valid, check the pfn should + * be mapped. + */
+ BUG_ON(!pfn_valid(pte_pfn(pte)));
Thanks, James _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel