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SubjectRe: [PATCH 2/3] x86, hibernate: Extract the common code of 64/32 bit system
On Mon, 27 Aug 2018, Gu Zhimin wrote:
> diff --git a/arch/x86/power/hibernate.c b/arch/x86/power/hibernate.c
> new file mode 100644
> index 0000000..6f91f7b
> --- /dev/null
> +++ b/arch/x86/power/hibernate.c
> @@ -0,0 +1,255 @@
> +/*
> + * Hibernation support for x86
> + *
> + * Distribute under GPLv2

We have SPDX identifiers for that and not some randomly chosen license
hint.

> +
> +/*
> + * pfn_is_nosave - check if given pfn is in the 'nosave' section

This is a half baken kernel doc header.

> + */
> +

Random new line.

> +int pfn_is_nosave(unsigned long pfn)
> +{
> + unsigned long nosave_begin_pfn = __pa_symbol(&__nosave_begin) >> PAGE_SHIFT;
> + unsigned long nosave_end_pfn = PAGE_ALIGN(__pa_symbol(&__nosave_end)) >> PAGE_SHIFT;

Instead of blindly copying stuff please fix it so it matches kernel coding
rules.

> + return (pfn >= nosave_begin_pfn) && (pfn < nosave_end_pfn);

The brackets are pointless

> +}
> +
> +#ifdef CONFIG_X86_64
> +static int relocate_restore_code(void)
> +{
> + pgd_t *pgd;
> + p4d_t *p4d;
> + pud_t *pud;
> + pmd_t *pmd;
> + pte_t *pte;
> +
> + relocated_restore_code = get_safe_page(GFP_ATOMIC);
> + if (!relocated_restore_code)
> + return -ENOMEM;
> +
> + memcpy((void *)relocated_restore_code, core_restore_code, PAGE_SIZE);
> +
> + /* Make the page containing the relocated code executable */
> + pgd = (pgd_t *)__va(read_cr3_pa()) +
> + pgd_index(relocated_restore_code);
> + p4d = p4d_offset(pgd, relocated_restore_code);
> + if (p4d_large(*p4d)) {
> + set_p4d(p4d, __p4d(p4d_val(*p4d) & ~_PAGE_NX));
> + goto out;
> + }
> + pud = pud_offset(p4d, relocated_restore_code);
> + if (pud_large(*pud)) {
> + set_pud(pud, __pud(pud_val(*pud) & ~_PAGE_NX));
> + goto out;
> + }
> + pmd = pmd_offset(pud, relocated_restore_code);
> + if (pmd_large(*pmd)) {
> + set_pmd(pmd, __pmd(pmd_val(*pmd) & ~_PAGE_NX));
> + goto out;
> + }
> + pte = pte_offset_kernel(pmd, relocated_restore_code);
> + set_pte(pte, __pte(pte_val(*pte) & ~_PAGE_NX));
> +out:
> + __flush_tlb_all();
> + return 0;
> +}
> +
> +#define MD5_DIGEST_SIZE 16
> +
> +struct restore_data_record {
> + unsigned long jump_address;
> + unsigned long jump_address_phys;
> + unsigned long cr3;
> + unsigned long magic;
> + u8 e820_digest[MD5_DIGEST_SIZE];
> +};
> +
> +#if IS_BUILTIN(CONFIG_CRYPTO_MD5)
> +/**
> + * get_e820_md5 - calculate md5 according to given e820 table
> + *
> + * @table: the e820 table to be calculated
> + * @buf: the md5 result to be stored to
> + */
> +static int get_e820_md5(struct e820_table *table, void *buf)
> +{
> + struct crypto_shash *tfm;
> + struct shash_desc *desc;
> + int size;
> + int ret = 0;
> +
> + tfm = crypto_alloc_shash("md5", 0, 0);
> + if (IS_ERR(tfm))
> + return -ENOMEM;
> +
> + desc = kmalloc(sizeof(struct shash_desc) + crypto_shash_descsize(tfm),
> + GFP_KERNEL);
> + if (!desc) {
> + ret = -ENOMEM;
> + goto free_tfm;
> + }
> +
> + desc->tfm = tfm;
> + desc->flags = 0;
> +
> + size = offsetof(struct e820_table, entries) +
> + sizeof(struct e820_entry) * table->nr_entries;
> +
> + if (crypto_shash_digest(desc, (u8 *)table, size, buf))
> + ret = -EINVAL;
> +
> + kzfree(desc);
> +
> +free_tfm:
> + crypto_free_shash(tfm);
> + return ret;
> +}
> +
> +static void hibernation_e820_save(void *buf)
> +{
> + get_e820_md5(e820_table_firmware, buf);

So if get_e820_md5() fails, then it will hibernate nevertheless. Why is
that error code not propagated?

Thanks,

tglx

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