[PATCH v5 4/4] RISC-V: Add arch functions to support hibernation/suspend-to-disk
Alexandre Ghiti
alex at ghiti.fr
Fri Mar 10 01:58:32 PST 2023
Hi JeeHeng,
On 3/8/23 12:07, JeeHeng Sia wrote:
>
>> -----Original Message-----
>> From: Alexandre Ghiti <alex at ghiti.fr>
>> Sent: Wednesday, March 8, 2023 5:28 PM
>> To: JeeHeng Sia <jeeheng.sia at starfivetech.com>; paul.walmsley at sifive.com; palmer at dabbelt.com; aou at eecs.berkeley.edu
>> Cc: linux-riscv at lists.infradead.org; linux-kernel at vger.kernel.org; Leyfoon Tan <leyfoon.tan at starfivetech.com>; Mason Huo
>> <mason.huo at starfivetech.com>
>> Subject: Re: [PATCH v5 4/4] RISC-V: Add arch functions to support hibernation/suspend-to-disk
>>
>>
>> On 3/8/23 10:08, Alexandre Ghiti wrote:
>>> On 3/8/23 09:06, Sia Jee Heng wrote:
>>>> Low level Arch functions were created to support hibernation.
>>>> swsusp_arch_suspend() relies code from __cpu_suspend_enter() to write
>>>> cpu state onto the stack, then calling swsusp_save() to save the memory
>>>> image.
>>>>
>>>> Arch specific hibernation header is implemented and is utilized by the
>>>> arch_hibernation_header_restore() and arch_hibernation_header_save()
>>>> functions. The arch specific hibernation header consists of satp,
>>>> hartid,
>>>> and the cpu_resume address. The kernel built version is also need to be
>>>> saved into the hibernation image header to making sure only the same
>>>> kernel is restore when resume.
>>>>
>>>> swsusp_arch_resume() creates a temporary page table that covering only
>>>> the linear map. It copies the restore code to a 'safe' page, then start
>>>> to restore the memory image. Once completed, it restores the original
>>>> kernel's page table. It then calls into __hibernate_cpu_resume()
>>>> to restore the CPU context. Finally, it follows the normal hibernation
>>>> path back to the hibernation core.
>>>>
>>>> To enable hibernation/suspend to disk into RISCV, the below config
>>>> need to be enabled:
>>>> - CONFIG_ARCH_HIBERNATION_HEADER
>>>> - CONFIG_ARCH_HIBERNATION_POSSIBLE
>>>>
>>>> Signed-off-by: Sia Jee Heng <jeeheng.sia at starfivetech.com>
>>>> Reviewed-by: Ley Foon Tan <leyfoon.tan at starfivetech.com>
>>>> Reviewed-by: Mason Huo <mason.huo at starfivetech.com>
>>>> ---
>>>> arch/riscv/Kconfig | 6 +
>>>> arch/riscv/include/asm/assembler.h | 20 ++
>>>> arch/riscv/include/asm/suspend.h | 19 ++
>>>> arch/riscv/kernel/Makefile | 1 +
>>>> arch/riscv/kernel/asm-offsets.c | 5 +
>>>> arch/riscv/kernel/hibernate-asm.S | 77 ++++++
>>>> arch/riscv/kernel/hibernate.c | 424 +++++++++++++++++++++++++++++
>>>> 7 files changed, 552 insertions(+)
>>>> create mode 100644 arch/riscv/kernel/hibernate-asm.S
>>>> create mode 100644 arch/riscv/kernel/hibernate.c
>>>>
>>>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>>>> index c5e42cc37604..473c2a1a6884 100644
>>>> --- a/arch/riscv/Kconfig
>>>> +++ b/arch/riscv/Kconfig
>>>> @@ -707,6 +707,12 @@ menu "Power management options"
>>>> source "kernel/power/Kconfig"
>>>> +config ARCH_HIBERNATION_POSSIBLE
>>>> + def_bool y
>>>> +
>>>> +config ARCH_HIBERNATION_HEADER
>>>> + def_bool HIBERNATION
>>>> +
>>>> endmenu # "Power management options"
>>>> menu "CPU Power Management"
>>>> diff --git a/arch/riscv/include/asm/assembler.h
>>>> b/arch/riscv/include/asm/assembler.h
>>>> index ba59d38f8937..44b1457d3e95 100644
>>>> --- a/arch/riscv/include/asm/assembler.h
>>>> +++ b/arch/riscv/include/asm/assembler.h
>>>> @@ -59,4 +59,24 @@
>>>> REG_L s11, (SUSPEND_CONTEXT_REGS + PT_S11)(a0)
>>>> .endm
>>>> +/*
>>>> + * copy_page - copy 1 page (4KB) of data from source to destination
>>>> + * @a0 - destination
>>>> + * @a1 - source
>>>> + */
>>>> + .macro copy_page a0, a1
>>>> + lui a2, 0x1
>>>> + add a2, a2, a0
>>>> +1 :
>>>> + REG_L t0, 0(a1)
>>>> + REG_L t1, SZREG(a1)
>>>> +
>>>> + REG_S t0, 0(a0)
>>>> + REG_S t1, SZREG(a0)
>>>> +
>>>> + addi a0, a0, 2 * SZREG
>>>> + addi a1, a1, 2 * SZREG
>>>> + bne a2, a0, 1b
>>>> + .endm
>>>> +
>>>> #endif /* __ASM_ASSEMBLER_H */
>>>> diff --git a/arch/riscv/include/asm/suspend.h
>>>> b/arch/riscv/include/asm/suspend.h
>>>> index 67e047445662..02f87867389a 100644
>>>> --- a/arch/riscv/include/asm/suspend.h
>>>> +++ b/arch/riscv/include/asm/suspend.h
>>>> @@ -21,6 +21,11 @@ struct suspend_context {
>>>> #endif
>>>> };
>>>> +/*
>>>> + * Used by hibernation core and cleared during resume sequence
>>>> + */
>>>> +extern int in_suspend;
>>>> +
>>>> /* Low-level CPU suspend entry function */
>>>> int __cpu_suspend_enter(struct suspend_context *context);
>>>> @@ -36,4 +41,18 @@ int __cpu_resume_enter(unsigned long hartid,
>>>> unsigned long context);
>>>> /* Used to save and restore the CSRs */
>>>> void suspend_save_csrs(struct suspend_context *context);
>>>> void suspend_restore_csrs(struct suspend_context *context);
>>>> +
>>>> +/* Low-level API to support hibernation */
>>>> +int swsusp_arch_suspend(void);
>>>> +int swsusp_arch_resume(void);
>>>> +int arch_hibernation_header_save(void *addr, unsigned int max_size);
>>>> +int arch_hibernation_header_restore(void *addr);
>>>> +int __hibernate_cpu_resume(void);
>>>> +
>>>> +/* Used to resume on the CPU we hibernated on */
>>>> +int hibernate_resume_nonboot_cpu_disable(void);
>>>> +
>>>> +asmlinkage void hibernate_restore_image(unsigned long resume_satp,
>>>> unsigned long satp_temp,
>>>> + unsigned long cpu_resume);
>>>> +asmlinkage int hibernate_core_restore_code(void);
>>>> #endif
>>>> diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
>>>> index 4cf303a779ab..daab341d55e4 100644
>>>> --- a/arch/riscv/kernel/Makefile
>>>> +++ b/arch/riscv/kernel/Makefile
>>>> @@ -64,6 +64,7 @@ obj-$(CONFIG_MODULES) += module.o
>>>> obj-$(CONFIG_MODULE_SECTIONS) += module-sections.o
>>>> obj-$(CONFIG_CPU_PM) += suspend_entry.o suspend.o
>>>> +obj-$(CONFIG_HIBERNATION) += hibernate.o hibernate-asm.o
>>>> obj-$(CONFIG_FUNCTION_TRACER) += mcount.o ftrace.o
>>>> obj-$(CONFIG_DYNAMIC_FTRACE) += mcount-dyn.o
>>>> diff --git a/arch/riscv/kernel/asm-offsets.c
>>>> b/arch/riscv/kernel/asm-offsets.c
>>>> index df9444397908..d6a75aac1d27 100644
>>>> --- a/arch/riscv/kernel/asm-offsets.c
>>>> +++ b/arch/riscv/kernel/asm-offsets.c
>>>> @@ -9,6 +9,7 @@
>>>> #include <linux/kbuild.h>
>>>> #include <linux/mm.h>
>>>> #include <linux/sched.h>
>>>> +#include <linux/suspend.h>
>>>> #include <asm/kvm_host.h>
>>>> #include <asm/thread_info.h>
>>>> #include <asm/ptrace.h>
>>>> @@ -116,6 +117,10 @@ void asm_offsets(void)
>>>> OFFSET(SUSPEND_CONTEXT_REGS, suspend_context, regs);
>>>> + OFFSET(HIBERN_PBE_ADDR, pbe, address);
>>>> + OFFSET(HIBERN_PBE_ORIG, pbe, orig_address);
>>>> + OFFSET(HIBERN_PBE_NEXT, pbe, next);
>>>> +
>>>> OFFSET(KVM_ARCH_GUEST_ZERO, kvm_vcpu_arch, guest_context.zero);
>>>> OFFSET(KVM_ARCH_GUEST_RA, kvm_vcpu_arch, guest_context.ra);
>>>> OFFSET(KVM_ARCH_GUEST_SP, kvm_vcpu_arch, guest_context.sp);
>>>> diff --git a/arch/riscv/kernel/hibernate-asm.S
>>>> b/arch/riscv/kernel/hibernate-asm.S
>>>> new file mode 100644
>>>> index 000000000000..effaf5ca5da0
>>>> --- /dev/null
>>>> +++ b/arch/riscv/kernel/hibernate-asm.S
>>>> @@ -0,0 +1,77 @@
>>>> +/* SPDX-License-Identifier: GPL-2.0-only */
>>>> +/*
>>>> + * Hibernation low level support for RISCV.
>>>> + *
>>>> + * Copyright (C) 2023 StarFive Technology Co., Ltd.
>>>> + *
>>>> + * Author: Jee Heng Sia <jeeheng.sia at starfivetech.com>
>>>> + */
>>>> +
>>>> +#include <asm/asm.h>
>>>> +#include <asm/asm-offsets.h>
>>>> +#include <asm/assembler.h>
>>>> +#include <asm/csr.h>
>>>> +
>>>> +#include <linux/linkage.h>
>>>> +
>>>> +/*
>>>> + * int __hibernate_cpu_resume(void)
>>>> + * Switch back to the hibernated image's page table prior to
>>>> restoring the CPU
>>>> + * context.
>>>> + *
>>>> + * Always returns 0
>>>> + */
>>>> +ENTRY(__hibernate_cpu_resume)
>>>> + /* switch to hibernated image's page table. */
>>>> + csrw CSR_SATP, s0
>>>> + sfence.vma
>>>> +
>>>> + REG_L a0, hibernate_cpu_context
>>>> +
>>>> + suspend_restore_csrs
>>>> + suspend_restore_regs
>>>> +
>>>> + /* Return zero value. */
>>>> + mv a0, zero
>>>> +
>>>> + ret
>>>> +END(__hibernate_cpu_resume)
>>>> +
>>>> +/*
>>>> + * Prepare to restore the image.
>>>> + * a0: satp of saved page tables.
>>>> + * a1: satp of temporary page tables.
>>>> + * a2: cpu_resume.
>>>> + */
>>>> +ENTRY(hibernate_restore_image)
>>>> + mv s0, a0
>>>> + mv s1, a1
>>>> + mv s2, a2
>>>> + REG_L s4, restore_pblist
>>>> + REG_L a1, relocated_restore_code
>>>> +
>>>> + jalr a1
>>>> +END(hibernate_restore_image)
>>>> +
>>>> +/*
>>>> + * The below code will be executed from a 'safe' page.
>>>> + * It first switches to the temporary page table, then starts to
>>>> copy the pages
>>>> + * back to the original memory location. Finally, it jumps to
>>>> __hibernate_cpu_resume()
>>>> + * to restore the CPU context.
>>>> + */
>>>> +ENTRY(hibernate_core_restore_code)
>>>> + /* switch to temp page table. */
>>>> + csrw satp, s1
>>>> + sfence.vma
>>>> +.Lcopy:
>>>> + /* The below code will restore the hibernated image. */
>>>> + REG_L a1, HIBERN_PBE_ADDR(s4)
>>>> + REG_L a0, HIBERN_PBE_ORIG(s4)
>>>> +
>>>> + copy_page a0, a1
>>>> +
>>>> + REG_L s4, HIBERN_PBE_NEXT(s4)
>>>> + bnez s4, .Lcopy
>>>> +
>>>> + jalr s2
>>>> +END(hibernate_core_restore_code)
>>>> diff --git a/arch/riscv/kernel/hibernate.c
>>>> b/arch/riscv/kernel/hibernate.c
>>>> new file mode 100644
>>>> index 000000000000..8fab50122e54
>>>> --- /dev/null
>>>> +++ b/arch/riscv/kernel/hibernate.c
>>>> @@ -0,0 +1,424 @@
>>>> +// SPDX-License-Identifier: GPL-2.0-only
>>>> +/*
>>>> + * Hibernation support for RISCV
>>>> + *
>>>> + * Copyright (C) 2023 StarFive Technology Co., Ltd.
>>>> + *
>>>> + * Author: Jee Heng Sia <jeeheng.sia at starfivetech.com>
>>>> + */
>>>> +
>>>> +#include <asm/barrier.h>
>>>> +#include <asm/cacheflush.h>
>>>> +#include <asm/mmu_context.h>
>>>> +#include <asm/page.h>
>>>> +#include <asm/pgalloc.h>
>>>> +#include <asm/pgtable.h>
>>>> +#include <asm/sections.h>
>>>> +#include <asm/set_memory.h>
>>>> +#include <asm/smp.h>
>>>> +#include <asm/suspend.h>
>>>> +
>>>> +#include <linux/cpu.h>
>>>> +#include <linux/memblock.h>
>>>> +#include <linux/pm.h>
>>>> +#include <linux/sched.h>
>>>> +#include <linux/suspend.h>
>>>> +#include <linux/utsname.h>
>>>> +
>>>> +/* The logical cpu number we should resume on, initialised to a
>>>> non-cpu number. */
>>>> +static int sleep_cpu = -EINVAL;
>>>> +
>>>> +/* Pointer to the temporary resume page table. */
>>>> +static pgd_t *resume_pg_dir;
>>>> +
>>>> +/* CPU context to be saved. */
>>>> +struct suspend_context *hibernate_cpu_context;
>>>> +EXPORT_SYMBOL_GPL(hibernate_cpu_context);
>>>> +
>>>> +unsigned long relocated_restore_code;
>>>> +EXPORT_SYMBOL_GPL(relocated_restore_code);
>>>> +
>>>> +/**
>>>> + * struct arch_hibernate_hdr_invariants - container to store kernel
>>>> build version.
>>>> + * @uts_version: to save the build number and date so that the we do
>>>> not resume with
>>>> + * a different kernel.
>>>> + */
>>>> +struct arch_hibernate_hdr_invariants {
>>>> + char uts_version[__NEW_UTS_LEN + 1];
>>>> +};
>>>> +
>>>> +/**
>>>> + * struct arch_hibernate_hdr - helper parameters that help us to
>>>> restore the image.
>>>> + * @invariants: container to store kernel build version.
>>>> + * @hartid: to make sure same boot_cpu executes the
>>>> hibernate/restore code.
>>>> + * @saved_satp: original page table used by the hibernated image.
>>>> + * @restore_cpu_addr: the kernel's image address to restore the CPU
>>>> context.
>>>> + */
>>>> +static struct arch_hibernate_hdr {
>>>> + struct arch_hibernate_hdr_invariants invariants;
>>>> + unsigned long hartid;
>>>> + unsigned long saved_satp;
>>>> + unsigned long restore_cpu_addr;
>>>> +} resume_hdr;
>>>> +
>>>> +static void arch_hdr_invariants(struct arch_hibernate_hdr_invariants
>>>> *i)
>>>> +{
>>>> + memset(i, 0, sizeof(*i));
>>>> + memcpy(i->uts_version, init_utsname()->version,
>>>> sizeof(i->uts_version));
>>>> +}
>>>> +
>>>> +/*
>>>> + * Check if the given pfn is in the 'nosave' section.
>>>> + */
>>>> +int pfn_is_nosave(unsigned long pfn)
>>>> +{
>>>> + unsigned long nosave_begin_pfn = sym_to_pfn(&__nosave_begin);
>>>> + unsigned long nosave_end_pfn = sym_to_pfn(&__nosave_end - 1);
>>>> +
>>>> + return ((pfn >= nosave_begin_pfn) && (pfn <= nosave_end_pfn));
>>>> +}
>>>> +
>>>> +void notrace save_processor_state(void)
>>>> +{
>>>> + WARN_ON(num_online_cpus() != 1);
>>>> +}
>>>> +
>>>> +void notrace restore_processor_state(void)
>>>> +{
>>>> +}
>>>> +
>>>> +/*
>>>> + * Helper parameters need to be saved to the hibernation image header.
>>>> + */
>>>> +int arch_hibernation_header_save(void *addr, unsigned int max_size)
>>>> +{
>>>> + struct arch_hibernate_hdr *hdr = addr;
>>>> +
>>>> + if (max_size < sizeof(*hdr))
>>>> + return -EOVERFLOW;
>>>> +
>>>> + arch_hdr_invariants(&hdr->invariants);
>>>> +
>>>> + hdr->hartid = cpuid_to_hartid_map(sleep_cpu);
>>>> + hdr->saved_satp = csr_read(CSR_SATP);
>>>> + hdr->restore_cpu_addr = (unsigned long)__hibernate_cpu_resume;
>>>> +
>>>> + return 0;
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(arch_hibernation_header_save);
>>>> +
>>>> +/*
>>>> + * Retrieve the helper parameters from the hibernation image header.
>>>> + */
>>>> +int arch_hibernation_header_restore(void *addr)
>>>> +{
>>>> + struct arch_hibernate_hdr_invariants invariants;
>>>> + struct arch_hibernate_hdr *hdr = addr;
>>>> + int ret = 0;
>>>> +
>>>> + arch_hdr_invariants(&invariants);
>>>> +
>>>> + if (memcmp(&hdr->invariants, &invariants, sizeof(invariants))) {
>>>> + pr_crit("Hibernate image not generated by this kernel!\n");
>>>> + return -EINVAL;
>>>> + }
>>>> +
>>>> + sleep_cpu = riscv_hartid_to_cpuid(hdr->hartid);
>>>> + if (sleep_cpu < 0) {
>>>> + pr_crit("Hibernated on a CPU not known to this kernel!\n");
>>>> + sleep_cpu = -EINVAL;
>>>> + return -EINVAL;
>>>> + }
>>>> +
>>>> +#ifdef CONFIG_SMP
>>>> + ret = bringup_hibernate_cpu(sleep_cpu);
>>>> + if (ret) {
>>>> + sleep_cpu = -EINVAL;
>>>> + return ret;
>>>> + }
>>>> +#endif
>>>> + resume_hdr = *hdr;
>>>> +
>>>> + return ret;
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(arch_hibernation_header_restore);
>>>> +
>>>> +int swsusp_arch_suspend(void)
>>>> +{
>>>> + int ret = 0;
>>>> +
>>>> + if (__cpu_suspend_enter(hibernate_cpu_context)) {
>>>> + sleep_cpu = smp_processor_id();
>>>> + suspend_save_csrs(hibernate_cpu_context);
>>>> + ret = swsusp_save();
>>>> + } else {
>>>> + suspend_restore_csrs(hibernate_cpu_context);
>>>> + flush_tlb_all();
>>>> + flush_icache_all();
>>>> +
>>>> + /*
>>>> + * Tell the hibernation core that we've just restored the
>>>> memory.
>>>> + */
>>>> + in_suspend = 0;
>>>> + sleep_cpu = -EINVAL;
>>>> + }
>>>> +
>>>> + return ret;
>>>> +}
>>>> +
>>>> +static int temp_pgtable_map_pte(pmd_t *dst_pmdp, pmd_t *src_pmdp,
>>>> unsigned long start,
>>>> + unsigned long end, pgprot_t prot)
>>>> +{
>>>> + pte_t *src_ptep;
>>>> + pte_t *dst_ptep;
>>>> +
>>>> + if (pmd_none(READ_ONCE(*dst_pmdp))) {
>>>> + dst_ptep = (pte_t *)get_safe_page(GFP_ATOMIC);
>>>> + if (!dst_ptep)
>>>> + return -ENOMEM;
>>>> +
>>>> + pmd_populate_kernel(NULL, dst_pmdp, dst_ptep);
>>>> + }
>>>> +
>>>> + dst_ptep = pte_offset_kernel(dst_pmdp, start);
>>>> + src_ptep = pte_offset_kernel(src_pmdp, start);
>>>> +
>>>> + do {
>>>> + pte_t pte = READ_ONCE(*src_ptep);
>>>> +
>>>> + if (pte_present(pte))
>>>> + set_pte(dst_ptep, __pte(pte_val(pte) | pgprot_val(prot)));
>>>> + } while (dst_ptep++, src_ptep++, start += PAGE_SIZE, start < end);
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static int temp_pgtable_map_pmd(pud_t *dst_pudp, pud_t *src_pudp,
>>>> unsigned long start,
>>>> + unsigned long end, pgprot_t prot)
>>>> +{
>>>> + unsigned long next;
>>>> + unsigned long ret;
>>>> + pmd_t *src_pmdp;
>>>> + pmd_t *dst_pmdp;
>>>> +
>>>> + if (pud_none(READ_ONCE(*dst_pudp))) {
>>>> + dst_pmdp = (pmd_t *)get_safe_page(GFP_ATOMIC);
>>>> + if (!dst_pmdp)
>>>> + return -ENOMEM;
>>>> +
>>>> + pud_populate(NULL, dst_pudp, dst_pmdp);
>>>> + }
>>>> +
>>>> + dst_pmdp = pmd_offset(dst_pudp, start);
>>>> + src_pmdp = pmd_offset(src_pudp, start);
>>>> +
>>>> + do {
>>>> + pmd_t pmd = READ_ONCE(*src_pmdp);
>>>> +
>>>> + next = pmd_addr_end(start, end);
>>>> +
>>>> + if (pmd_none(pmd))
>>>> + continue;
>>>> +
>>>> + if (pmd_leaf(pmd)) {
>>>> + set_pmd(dst_pmdp, __pmd(pmd_val(pmd) | pgprot_val(prot)));
>>>> + } else {
>>>> + ret = temp_pgtable_map_pte(dst_pmdp, src_pmdp, start,
>>>> next, prot);
>>>> + if (ret)
>>>> + return -ENOMEM;
>>>> + }
>>>> + } while (dst_pmdp++, src_pmdp++, start = next, start != end);
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static int temp_pgtable_map_pud(p4d_t *dst_p4dp, p4d_t *src_p4dp,
>>>> unsigned long start,
>>>> + unsigned long end, pgprot_t prot)
>>>> +{
>>>> + unsigned long next;
>>>> + unsigned long ret;
>>>> + pud_t *dst_pudp;
>>>> + pud_t *src_pudp;
>>>> +
>>>> + if (p4d_none(READ_ONCE(*dst_p4dp))) {
>>>> + dst_pudp = (pud_t *)get_safe_page(GFP_ATOMIC);
>>>> + if (!dst_pudp)
>>>> + return -ENOMEM;
>>>> +
>>>> + p4d_populate(NULL, dst_p4dp, dst_pudp);
>>>> + }
>>>> +
>>>> + dst_pudp = pud_offset(dst_p4dp, start);
>>>> + src_pudp = pud_offset(src_p4dp, start);
>>>> +
>>>> + do {
>>>> + pud_t pud = READ_ONCE(*src_pudp);
>>>> +
>>>> + next = pud_addr_end(start, end);
>>>> +
>>>> + if (pud_none(pud))
>>>> + continue;
>>>> +
>>>> + if (pud_leaf(pud)) {
>>>> + set_pud(dst_pudp, __pud(pud_val(pud) | pgprot_val(prot)));
>>>> + } else {
>>>> + ret = temp_pgtable_map_pmd(dst_pudp, src_pudp, start,
>>>> next, prot);
>>>> + if (ret)
>>>> + return -ENOMEM;
>>>> + }
>>>> + } while (dst_pudp++, src_pudp++, start = next, start != end);
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static int temp_pgtable_map_p4d(pgd_t *dst_pgdp, pgd_t *src_pgdp,
>>>> unsigned long start,
>>>> + unsigned long end, pgprot_t prot)
>>>> +{
>>>> + unsigned long next;
>>>> + unsigned long ret;
>>>> + p4d_t *dst_p4dp;
>>>> + p4d_t *src_p4dp;
>>>> +
>>>> + if (pgd_none(READ_ONCE(*dst_pgdp))) {
>>>> + dst_p4dp = (p4d_t *)get_safe_page(GFP_ATOMIC);
>>>> + if (!dst_p4dp)
>>>> + return -ENOMEM;
>>>> +
>>>> + pgd_populate(NULL, dst_pgdp, dst_p4dp);
>>>> + }
>>>> +
>>>> + dst_p4dp = p4d_offset(dst_pgdp, start);
>>>> + src_p4dp = p4d_offset(src_pgdp, start);
>>>> +
>>>> + do {
>>>> + p4d_t p4d = READ_ONCE(*src_p4dp);
>>>> +
>>>> + next = p4d_addr_end(start, end);
>>>> +
>>>> + if (p4d_none(p4d))
>>>> + continue;
>>>> +
>>>> + if (p4d_leaf(p4d)) {
>>>> + set_p4d(dst_p4dp, __p4d(p4d_val(p4d) | pgprot_val(prot)));
>>>> + } else {
>>>> + ret = temp_pgtable_map_pud(dst_p4dp, src_p4dp, start,
>>>> next, prot);
>>>> + if (ret)
>>>> + return -ENOMEM;
>>>> + }
>>>> + } while (dst_p4dp++, src_p4dp++, start = next, start != end);
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static int temp_pgtable_mapping(pgd_t *pgdp, unsigned long start,
>>>> unsigned long end, pgprot_t prot)
>>>> +{
>>>> + pgd_t *dst_pgdp = pgd_offset_pgd(pgdp, start);
>>>> + pgd_t *src_pgdp = pgd_offset_k(start);
>>>> + unsigned long next;
>>>> + unsigned long ret;
>>>> +
>>>> + do {
>>>> + pgd_t pgd = READ_ONCE(*src_pgdp);
>>>> +
>>>> + next = pgd_addr_end(start, end);
>>>> +
>>>> + if (pgd_none(pgd))
>>>> + continue;
>>>> +
>>>> + if (pgd_leaf(pgd)) {
>>>> + set_pgd(dst_pgdp, __pgd(pgd_val(pgd) | pgprot_val(prot)));
>>>> + } else {
>>>> + ret = temp_pgtable_map_p4d(dst_pgdp, src_pgdp, start,
>>>> next, prot);
>>>> + if (ret)
>>>> + return -ENOMEM;
>>>> + }
>>>> + } while (dst_pgdp++, src_pgdp++, start = next, start != end);
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static unsigned long relocate_restore_code(void)
>>>> +{
>>>> + void *page = (void *)get_safe_page(GFP_ATOMIC);
>>>> +
>>>> + if (!page)
>>>> + return -ENOMEM;
>>>> +
>>>> + copy_page(page, hibernate_core_restore_code);
>>>> +
>>>> + /* Make the page containing the relocated code executable. */
>>>> + set_memory_x((unsigned long)page, 1);
>>>> +
>>>> + return (unsigned long)page;
>>>> +}
>>>> +
>>>> +int swsusp_arch_resume(void)
>>>> +{
>>>> + unsigned long end = (unsigned long)pfn_to_virt(max_low_pfn);
>>>> + unsigned long start = PAGE_OFFSET;
>>>> + int ret;
>>>> +
>>>> + /*
>>>> + * Memory allocated by get_safe_page() will be dealt with by the
>>>> hibernation core,
>>>> + * we don't need to free it here.
>>>> + */
>>>> + resume_pg_dir = (pgd_t *)get_safe_page(GFP_ATOMIC);
>>>> + if (!resume_pg_dir)
>>>> + return -ENOMEM;
>>>> +
>>>> + /*
>>>> + * Create a temporary page table and map the whole linear region
>>>> as executable and
>>>> + * writable.
>>>> + */
>>>> + ret = temp_pgtable_mapping(resume_pg_dir, start, end,
>>>> __pgprot(_PAGE_WRITE | _PAGE_EXEC));
>>>
>>> Hmm weird protections, PAGE_PRESENT and PAGE_READ are not even set.
>>> Shouldn't you use PAGE_KERNEL_EXEC instead?
>>
>> Forget this one, that's the protections you add, so that's good :)
> OK.
>>
>>>
>>>> + if (ret)
>>>> + return ret;
>>>> +
>>>> + /* Move the restore code to a new page so that it doesn't get
>>>> overwritten by itself. */
>>>> + relocated_restore_code = relocate_restore_code();
>>>> + if (relocated_restore_code == -ENOMEM)
>>>> + return -ENOMEM;
>>>> +
>>>> + /*
>>>> + * Map the __hibernate_cpu_resume() address to the temporary
>>>> page table so that the
>>>> + * restore code can jumps to it after finished restore the
>>>> image. The next execution
>>>> + * code doesn't find itself in a different address space after
>>>> switching over to the
>>>> + * original page table used by the hibernated image.
>>>> + *
>>>> + */
>>>> + start = (unsigned long)resume_hdr.restore_cpu_addr;
>>>> + end = start + PAGE_SIZE;
>>>> +
>>>> + ret = temp_pgtable_mapping(resume_pg_dir, start, end,
>>>> __pgprot(_PAGE_WRITE | _PAGE_EXEC));
>>>> + if (ret)
>>>> + return ret;
>>>
>>> You set the linear mapping as executable so no need for this.
> We need this mapping because the kernel addresses and the linear addresses in riscv-64bit are in different boundary. For example:
> Linear address start with 0xff60000000000000
> Kernel address start with 0xffffffff80000000
Ok I understand now that you need to map this into the temporary page
table: one nit though, since you copy the kernel mapping, no need to use
PAGE_WRITE | PAGE_EXEC, the protections are already correct.
Thanks,
Alex
>>>
>>>> +
>>>> + hibernate_restore_image(resume_hdr.saved_satp,
>>>> (PFN_DOWN(__pa(resume_pg_dir)) | satp_mode),
>>>> + resume_hdr.restore_cpu_addr);
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +#ifdef CONFIG_PM_SLEEP_SMP
>>>> +int hibernate_resume_nonboot_cpu_disable(void)
>>>> +{
>>>> + if (sleep_cpu < 0) {
>>>> + pr_err("Failing to resume from hibernate on an unknown CPU\n");
>>>> + return -ENODEV;
>>>> + }
>>>> +
>>>> + return freeze_secondary_cpus(sleep_cpu);
>>>> +}
>>>> +#endif
>>>> +
>>>> +static int __init riscv_hibernate_init(void)
>>>> +{
>>>> + hibernate_cpu_context = kzalloc(sizeof(*hibernate_cpu_context),
>>>> GFP_KERNEL);
>>>> +
>>>> + if (WARN_ON(!hibernate_cpu_context))
>>>> + return -ENOMEM;
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +early_initcall(riscv_hibernate_init);
>>> _______________________________________________
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>>> linux-riscv at lists.infradead.org
>>> http://lists.infradead.org/mailman/listinfo/linux-riscv
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