[PATCH v2 0/3] RISC-V Hibernation Support

[PATCH v2 0/3] RISC-V Hibernation Support

[Sia Jee Heng]

This series adds RISC-V Hibernation/suspend to disk support.
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_hibernation_header_restore() and arch_hibernation_header_save()
functions are implemented to prevent kernel crash when resume,
the kernel built version is 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, 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
- CONFIG_ARCH_RV64I
- CONFIG_64BIT

At high-level, this series includes the following changes:
1) Change suspend_save_csrs() and suspend_restore_csrs()
   to public function as these functions are common to
   suspend/hibernation. (patch 1)
2) Enhance kernel_page_present() function to support huge page. (patch 2)
3) Add arch/riscv low level functions to support
   hibernation/suspend to disk. (patch 3)

The above patches are based on kernel v6.2-rc3 and are tested on
StarFive VF2 SBC board. Hibernation for RV32 and ACPI platform mode are not
supported in this series at the moment.

Changes since v1:
- Rebased to kernel v6.2-rc3
- Fixed bot's compilation error

Sia Jee Heng (3):
  RISC-V: Change suspend_save_csrs and suspend_restore_csrs to public
    function
  RISC-V: mm: Enable huge page support to kernel_page_present() function
  RISC-V: Add arch functions to support hibernation/suspend-to-disk

 arch/riscv/Kconfig                |   8 +
 arch/riscv/include/asm/suspend.h  |  23 ++
 arch/riscv/kernel/Makefile        |   2 +-
 arch/riscv/kernel/asm-offsets.c   |   5 +
 arch/riscv/kernel/hibernate-asm.S | 123 +++++++++++
 arch/riscv/kernel/hibernate.c     | 353 ++++++++++++++++++++++++++++++
 arch/riscv/kernel/suspend.c       |   4 +-
 arch/riscv/mm/pageattr.c          |   6 +
 8 files changed, 521 insertions(+), 3 deletions(-)
 create mode 100644 arch/riscv/kernel/hibernate-asm.S
 create mode 100644 arch/riscv/kernel/hibernate.c


base-commit: 1fe4fd6f5cad346e598593af36caeadc4f5d4fa9
-- 
2.34.1


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[PATCH v2 1/3] RISC-V: Change suspend_save_csrs and suspend_restore_csrs to public function

[Sia Jee Heng]

Currently suspend_save_csrs() and suspend_restore_csrs() functions are
statically defined in the suspend.c. Change the function's attribute
to public so that the functions can be used by hibernation as well.

Signed-off-by: Sia Jee Heng <jeeheng.sia@starfivetech.com>
Reviewed-by: Ley Foon Tan <leyfoon.tan@starfivetech.com>
Reviewed-by: Mason Huo <mason.huo@starfivetech.com>
---
 arch/riscv/include/asm/suspend.h | 3 +++
 arch/riscv/kernel/suspend.c      | 4 ++--
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/include/asm/suspend.h b/arch/riscv/include/asm/suspend.h
index 8be391c2aecb..75419c5ca272 100644
--- a/arch/riscv/include/asm/suspend.h
+++ b/arch/riscv/include/asm/suspend.h
@@ -33,4 +33,7 @@ int cpu_suspend(unsigned long arg,
 /* Low-level CPU resume entry function */
 int __cpu_resume_enter(unsigned long hartid, unsigned long context);
 
+/* Used to save and restore the csr */
+void suspend_save_csrs(struct suspend_context *context);
+void suspend_restore_csrs(struct suspend_context *context);
 #endif
diff --git a/arch/riscv/kernel/suspend.c b/arch/riscv/kernel/suspend.c
index 9ba24fb8cc93..3c89b8ec69c4 100644
--- a/arch/riscv/kernel/suspend.c
+++ b/arch/riscv/kernel/suspend.c
@@ -8,7 +8,7 @@
 #include <asm/csr.h>
 #include <asm/suspend.h>
 
-static void suspend_save_csrs(struct suspend_context *context)
+void suspend_save_csrs(struct suspend_context *context)
 {
 	context->scratch = csr_read(CSR_SCRATCH);
 	context->tvec = csr_read(CSR_TVEC);
@@ -29,7 +29,7 @@ static void suspend_save_csrs(struct suspend_context *context)
 #endif
 }
 
-static void suspend_restore_csrs(struct suspend_context *context)
+void suspend_restore_csrs(struct suspend_context *context)
 {
 	csr_write(CSR_SCRATCH, context->scratch);
 	csr_write(CSR_TVEC, context->tvec);
-- 
2.34.1


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[PATCH v2 2/3] RISC-V: mm: Enable huge page support to kernel_page_present() function

[Sia Jee Heng]

Currently kernel_page_present() function doesn't support huge page
detection causes the function to mistakenly return false to the
hibernation core.

Add huge page detection to the function to solve the problem.

Signed-off-by: Sia Jee Heng <jeeheng.sia@starfivetech.com>
Reviewed-by: Ley Foon Tan <leyfoon.tan@starfivetech.com>
Reviewed-by: Mason Huo <mason.huo@starfivetech.com>
---
 arch/riscv/mm/pageattr.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/riscv/mm/pageattr.c b/arch/riscv/mm/pageattr.c
index 86c56616e5de..73fdec8c0a72 100644
--- a/arch/riscv/mm/pageattr.c
+++ b/arch/riscv/mm/pageattr.c
@@ -221,14 +221,20 @@ bool kernel_page_present(struct page *page)
 	p4d = p4d_offset(pgd, addr);
 	if (!p4d_present(*p4d))
 		return false;
+	if (p4d_leaf(*pud))
+		return true;
 
 	pud = pud_offset(p4d, addr);
 	if (!pud_present(*pud))
 		return false;
+	if (pud_leaf(*pud))
+		return true;
 
 	pmd = pmd_offset(pud, addr);
 	if (!pmd_present(*pmd))
 		return false;
+	if (pmd_leaf(*pmd))
+		return true;
 
 	pte = pte_offset_kernel(pmd, addr);
 	return pte_present(*pte);
-- 
2.34.1


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Re: [PATCH v2 2/3] RISC-V: mm: Enable huge page support to kernel_page_present() function

[Andrew Jones]

On Mon, Jan 09, 2023 at 02:24:06PM +0800, Sia Jee Heng wrote:
> Currently kernel_page_present() function doesn't support huge page
> detection causes the function to mistakenly return false to the
> hibernation core.
> 
> Add huge page detection to the function to solve the problem.
> 
> Signed-off-by: Sia Jee Heng <jeeheng.sia@starfivetech.com>
> Reviewed-by: Ley Foon Tan <leyfoon.tan@starfivetech.com>
> Reviewed-by: Mason Huo <mason.huo@starfivetech.com>
> ---
>  arch/riscv/mm/pageattr.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/arch/riscv/mm/pageattr.c b/arch/riscv/mm/pageattr.c
> index 86c56616e5de..73fdec8c0a72 100644
> --- a/arch/riscv/mm/pageattr.c
> +++ b/arch/riscv/mm/pageattr.c
> @@ -221,14 +221,20 @@ bool kernel_page_present(struct page *page)
>  	p4d = p4d_offset(pgd, addr);
>  	if (!p4d_present(*p4d))
>  		return false;
> +	if (p4d_leaf(*pud))
                      ^ p4d

I guess you got lucky with the stack garbage in your testing.

> +		return true;
>  
>  	pud = pud_offset(p4d, addr);
>  	if (!pud_present(*pud))
>  		return false;
> +	if (pud_leaf(*pud))
> +		return true;
>  
>  	pmd = pmd_offset(pud, addr);
>  	if (!pmd_present(*pmd))
>  		return false;
> +	if (pmd_leaf(*pmd))
> +		return true;
>  
>  	pte = pte_offset_kernel(pmd, addr);
>  	return pte_present(*pte);
> -- 
> 2.34.1
>

Thanks,
drew

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RE: [PATCH v2 2/3] RISC-V: mm: Enable huge page support to kernel_page_present() function

[JeeHeng Sia]

> -----Original Message-----
> From: Andrew Jones <ajones@ventanamicro.com>
> Sent: Monday, 9 January, 2023 10:45 PM
> To: JeeHeng Sia <jeeheng.sia@starfivetech.com>
> Cc: paul.walmsley@sifive.com; palmer@dabbelt.com;
> aou@eecs.berkeley.edu; linux-riscv@lists.infradead.org; linux-
> kernel@vger.kernel.org; Leyfoon Tan <leyfoon.tan@starfivetech.com>;
> Mason Huo <mason.huo@starfivetech.com>
> Subject: Re: [PATCH v2 2/3] RISC-V: mm: Enable huge page support to
> kernel_page_present() function
> 
> On Mon, Jan 09, 2023 at 02:24:06PM +0800, Sia Jee Heng wrote:
> > Currently kernel_page_present() function doesn't support huge page
> > detection causes the function to mistakenly return false to the
> > hibernation core.
> >
> > Add huge page detection to the function to solve the problem.
> >
> > Signed-off-by: Sia Jee Heng <jeeheng.sia@starfivetech.com>
> > Reviewed-by: Ley Foon Tan <leyfoon.tan@starfivetech.com>
> > Reviewed-by: Mason Huo <mason.huo@starfivetech.com>
> > ---
> >  arch/riscv/mm/pageattr.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git a/arch/riscv/mm/pageattr.c b/arch/riscv/mm/pageattr.c
> > index 86c56616e5de..73fdec8c0a72 100644
> > --- a/arch/riscv/mm/pageattr.c
> > +++ b/arch/riscv/mm/pageattr.c
> > @@ -221,14 +221,20 @@ bool kernel_page_present(struct page *page)
> >  	p4d = p4d_offset(pgd, addr);
> >  	if (!p4d_present(*p4d))
> >  		return false;
> > +	if (p4d_leaf(*pud))
>                       ^ p4d
> 
> I guess you got lucky with the stack garbage in your testing.
You are right. But the reason it is added here is because kernel page table walk is checking for the p4d_leaf as well. 
For example: walk_p4d_range() in the mm/pagewalk.c. So, I just trying to make it consistent to the Kernel page table walk mechanism.
Should I remove it?
> 
> > +		return true;
> >
> >  	pud = pud_offset(p4d, addr);
> >  	if (!pud_present(*pud))
> >  		return false;
> > +	if (pud_leaf(*pud))
> > +		return true;
> >
> >  	pmd = pmd_offset(pud, addr);
> >  	if (!pmd_present(*pmd))
> >  		return false;
> > +	if (pmd_leaf(*pmd))
> > +		return true;
> >
> >  	pte = pte_offset_kernel(pmd, addr);
> >  	return pte_present(*pte);
> > --
> > 2.34.1
> >
> 
> Thanks,
> drew

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Re: [PATCH v2 2/3] RISC-V: mm: Enable huge page support to kernel_page_present() function

[Andrew Jones]

On Tue, Jan 10, 2023 at 06:45:19AM +0000, JeeHeng Sia wrote:
> 
> 
> > -----Original Message-----
> > From: Andrew Jones <ajones@ventanamicro.com>
> > Sent: Monday, 9 January, 2023 10:45 PM
> > To: JeeHeng Sia <jeeheng.sia@starfivetech.com>
> > Cc: paul.walmsley@sifive.com; palmer@dabbelt.com;
> > aou@eecs.berkeley.edu; linux-riscv@lists.infradead.org; linux-
> > kernel@vger.kernel.org; Leyfoon Tan <leyfoon.tan@starfivetech.com>;
> > Mason Huo <mason.huo@starfivetech.com>
> > Subject: Re: [PATCH v2 2/3] RISC-V: mm: Enable huge page support to
> > kernel_page_present() function
> > 
> > On Mon, Jan 09, 2023 at 02:24:06PM +0800, Sia Jee Heng wrote:
> > > Currently kernel_page_present() function doesn't support huge page
> > > detection causes the function to mistakenly return false to the
> > > hibernation core.
> > >
> > > Add huge page detection to the function to solve the problem.
> > >
> > > Signed-off-by: Sia Jee Heng <jeeheng.sia@starfivetech.com>
> > > Reviewed-by: Ley Foon Tan <leyfoon.tan@starfivetech.com>
> > > Reviewed-by: Mason Huo <mason.huo@starfivetech.com>
> > > ---
> > >  arch/riscv/mm/pageattr.c | 6 ++++++
> > >  1 file changed, 6 insertions(+)
> > >
> > > diff --git a/arch/riscv/mm/pageattr.c b/arch/riscv/mm/pageattr.c
> > > index 86c56616e5de..73fdec8c0a72 100644
> > > --- a/arch/riscv/mm/pageattr.c
> > > +++ b/arch/riscv/mm/pageattr.c
> > > @@ -221,14 +221,20 @@ bool kernel_page_present(struct page *page)
> > >  	p4d = p4d_offset(pgd, addr);
> > >  	if (!p4d_present(*p4d))
> > >  		return false;
> > > +	if (p4d_leaf(*pud))
> >                       ^ p4d
> > 
> > I guess you got lucky with the stack garbage in your testing.
> You are right. But the reason it is added here is because kernel page table walk is checking for the p4d_leaf as well. 
> For example: walk_p4d_range() in the mm/pagewalk.c. So, I just trying to make it consistent to the Kernel page table walk mechanism.
> Should I remove it?

The only thing I see wrong with it is the use of the uninitialized
pointer. Just change 'pud' to 'p4d'.

Thanks,
drew

> > 
> > > +		return true;
> > >
> > >  	pud = pud_offset(p4d, addr);
> > >  	if (!pud_present(*pud))
> > >  		return false;
> > > +	if (pud_leaf(*pud))
> > > +		return true;
> > >
> > >  	pmd = pmd_offset(pud, addr);
> > >  	if (!pmd_present(*pmd))
> > >  		return false;
> > > +	if (pmd_leaf(*pmd))
> > > +		return true;
> > >
> > >  	pte = pte_offset_kernel(pmd, addr);
> > >  	return pte_present(*pte);
> > > --
> > > 2.34.1
> > >
> > 
> > Thanks,
> > drew

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[PATCH v2 3/3] RISC-V: Add arch functions to support hibernation/suspend-to-disk

[Sia Jee Heng]

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_hibernation_header_restore() and arch_hibernation_header_save()
functions are implemented to prevent kernel crash when resume,
the kernel built version is 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, 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
- CONFIG_ARCH_RV64I
- CONFIG_64BIT

Signed-off-by: Sia Jee Heng <jeeheng.sia@starfivetech.com>
Reviewed-by: Ley Foon Tan <leyfoon.tan@starfivetech.com>
Reviewed-by: Mason Huo <mason.huo@starfivetech.com>
---
 arch/riscv/Kconfig                |   8 +
 arch/riscv/include/asm/suspend.h  |  20 ++
 arch/riscv/kernel/Makefile        |   2 +-
 arch/riscv/kernel/asm-offsets.c   |   5 +
 arch/riscv/kernel/hibernate-asm.S | 123 +++++++++++
 arch/riscv/kernel/hibernate.c     | 353 ++++++++++++++++++++++++++++++
 6 files changed, 510 insertions(+), 1 deletion(-)
 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 e2b656043abf..3c2607b6bda7 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -690,6 +690,14 @@ menu "Power management options"
 
 source "kernel/power/Kconfig"
 
+config ARCH_HIBERNATION_POSSIBLE
+	def_bool y
+	depends on 64BIT
+
+config ARCH_HIBERNATION_HEADER
+	def_bool y
+	depends on HIBERNATION && 64BIT
+
 endmenu # "Power management options"
 
 menu "CPU Power Management"
diff --git a/arch/riscv/include/asm/suspend.h b/arch/riscv/include/asm/suspend.h
index 75419c5ca272..ebaf103aec40 100644
--- a/arch/riscv/include/asm/suspend.h
+++ b/arch/riscv/include/asm/suspend.h
@@ -21,6 +21,11 @@ struct suspend_context {
 #endif
 };
 
+/* This parameter will be assigned to 0 during resume and will be used by
+ * hibernation core for the subsequent resume sequence
+ */
+extern int in_suspend;
+
 /* Low-level CPU suspend entry function */
 int __cpu_suspend_enter(struct suspend_context *context);
 
@@ -36,4 +41,19 @@ int __cpu_resume_enter(unsigned long hartid, unsigned long context);
 /* Used to save and restore the csr */
 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);
+
+/* Used to restore the hibernated image */
+asmlinkage void restore_image(unsigned long resume_satp, unsigned long satp_temp,
+				unsigned long cpu_resume);
+asmlinkage int core_restore_code(void);
 #endif
diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
index 4cf303a779ab..df83b8cea631 100644
--- a/arch/riscv/kernel/Makefile
+++ b/arch/riscv/kernel/Makefile
@@ -64,7 +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..81d9dc98d0ad
--- /dev/null
+++ b/arch/riscv/kernel/hibernate-asm.S
@@ -0,0 +1,123 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Hibernation support specific for RISCV
+ *
+ * Copyright (C) 2023 StarFive Technology Co., Ltd.
+ *
+ * Author: Jee Heng Sia <jeeheng.sia@starfivetech.com>
+ */
+
+#include <asm/asm.h>
+#include <asm/asm-offsets.h>
+#include <asm/csr.h>
+#include <linux/linkage.h>
+
+/*
+ * These code are to be executed when resume from the hibernation.
+ *
+ * It begins with loads the temporary page table then restores the memory image.
+ * Finally branches to __hibernate_cpu_resume() to restore the state saved by
+ * swsusp_arch_suspend().
+ */
+
+/*
+ * int __hibernate_cpu_resume(void)
+ * Switch back to the hibernated image's page table prior to restore the CPU
+ * context.
+ *
+ * Always returns 0 to the C code.
+ */
+ENTRY(__hibernate_cpu_resume)
+        /* switch to hibernated image's page table */
+        csrw CSR_SATP, s0
+        sfence.vma
+
+	ld	a0, hibernate_cpu_context
+
+	/* Restore CSRs */
+	REG_L   t0, (SUSPEND_CONTEXT_REGS + PT_EPC)(a0)
+	csrw    CSR_EPC, t0
+	REG_L   t0, (SUSPEND_CONTEXT_REGS + PT_STATUS)(a0)
+	csrw    CSR_STATUS, t0
+	REG_L   t0, (SUSPEND_CONTEXT_REGS + PT_BADADDR)(a0)
+	csrw    CSR_TVAL, t0
+	REG_L   t0, (SUSPEND_CONTEXT_REGS + PT_CAUSE)(a0)
+	csrw    CSR_CAUSE, t0
+
+	/* Restore registers (except A0 and T0-T6) */
+	REG_L   ra, (SUSPEND_CONTEXT_REGS + PT_RA)(a0)
+	REG_L   sp, (SUSPEND_CONTEXT_REGS + PT_SP)(a0)
+	REG_L   gp, (SUSPEND_CONTEXT_REGS + PT_GP)(a0)
+	REG_L   tp, (SUSPEND_CONTEXT_REGS + PT_TP)(a0)
+
+	REG_L   s0, (SUSPEND_CONTEXT_REGS + PT_S0)(a0)
+	REG_L   s1, (SUSPEND_CONTEXT_REGS + PT_S1)(a0)
+	REG_L   a1, (SUSPEND_CONTEXT_REGS + PT_A1)(a0)
+	REG_L   a2, (SUSPEND_CONTEXT_REGS + PT_A2)(a0)
+	REG_L   a3, (SUSPEND_CONTEXT_REGS + PT_A3)(a0)
+	REG_L   a4, (SUSPEND_CONTEXT_REGS + PT_A4)(a0)
+	REG_L   a5, (SUSPEND_CONTEXT_REGS + PT_A5)(a0)
+	REG_L   a6, (SUSPEND_CONTEXT_REGS + PT_A6)(a0)
+	REG_L   a7, (SUSPEND_CONTEXT_REGS + PT_A7)(a0)
+	REG_L   s2, (SUSPEND_CONTEXT_REGS + PT_S2)(a0)
+	REG_L   s3, (SUSPEND_CONTEXT_REGS + PT_S3)(a0)
+	REG_L   s4, (SUSPEND_CONTEXT_REGS + PT_S4)(a0)
+	REG_L   s5, (SUSPEND_CONTEXT_REGS + PT_S5)(a0)
+	REG_L   s6, (SUSPEND_CONTEXT_REGS + PT_S6)(a0)
+	REG_L   s7, (SUSPEND_CONTEXT_REGS + PT_S7)(a0)
+	REG_L   s8, (SUSPEND_CONTEXT_REGS + PT_S8)(a0)
+	REG_L   s9, (SUSPEND_CONTEXT_REGS + PT_S9)(a0)
+	REG_L   s10, (SUSPEND_CONTEXT_REGS + PT_S10)(a0)
+	REG_L   s11, (SUSPEND_CONTEXT_REGS + PT_S11)(a0)
+
+	/* Return zero value */
+	add     a0, zero, 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(restore_image)
+	mv	s0, a0
+	mv	s1, a1
+	mv	s2, a2
+	ld      s4, restore_pblist
+	ld	a1, relocated_restore_code
+
+	jalr	a1
+END(restore_image)
+
+/*
+ * The below code will be executed from a 'safe' page.
+ * It first switches to the temporary page table, then start to copy the pages
+ * back to the original memory location. Finally, it jumps to the __hibernate_cpu_resume()
+ * to restore the CPU context.
+ */
+ENTRY(core_restore_code)
+	/* switch to temp page table */
+	csrw satp, s1
+	sfence.vma
+	beqz	s4, done
+loop:
+	/* The below code will restore the hibernated image. */
+	ld	a1, HIBERN_PBE_ADDR(s4)
+	ld	a0, HIBERN_PBE_ORIG(s4)
+
+	lui     a4, 0x1
+	add     a4, a4, a0
+copy:	ld      a5, 0(a1)
+	addi    a0, a0, 8
+	addi    a1, a1, 8
+	sd      a5, -8(a0)
+	bne     a4, a0, copy
+
+	ld	s4, HIBERN_PBE_NEXT(s4)
+	bnez	s4, loop
+done:
+	jalr	s2
+END(core_restore_code)
diff --git a/arch/riscv/kernel/hibernate.c b/arch/riscv/kernel/hibernate.c
new file mode 100644
index 000000000000..bd77c35958a8
--- /dev/null
+++ b/arch/riscv/kernel/hibernate.c
@@ -0,0 +1,353 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Hibernation support specific for RISCV
+ *
+ * Copyright (C) 2023 StarFive Technology Co., Ltd.
+ *
+ * Author: Jee Heng Sia <jeeheng.sia@starfivetech.com>
+ */
+
+#include <asm/barrier.h>
+#include <asm/cacheflush.h>
+#include <asm/mmu_context.h>
+#include <asm/page.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;
+
+/* CPU context to be saved */
+struct suspend_context *hibernate_cpu_context;
+
+unsigned long relocated_restore_code;
+
+/* Pointer to the temporary resume page tables */
+pgd_t *resume_pg_dir;
+
+/*
+ * Save the build number and date so that the we are not resume with a different kernel
+ */
+struct arch_hibernate_hdr_invariants {
+	char		uts_version[__NEW_UTS_LEN + 1];
+};
+
+/* Helper parameters that help us to restore the image.
+ * @hartid: To make sure same boot_cpu executing 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 inline 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(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(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();
+
+		/* Invalidated Icache */
+		flush_icache_all();
+
+		/*
+		 * Tell the hibernation core that we've just restored
+		 * the memory
+		 */
+		in_suspend = 0;
+		sleep_cpu = -EINVAL;
+	}
+
+	return ret;
+}
+
+#define temp_pgtable_map_pgd_next(pgdp, vaddr, prot)			\
+		(pgtable_l5_enabled ?					\
+		temp_pgtable_map_p4d(pgdp, vaddr, prot) :		\
+		(pgtable_l4_enabled ?					\
+		temp_pgtable_map_pud((pud_t *)pgdp, vaddr, prot) :	\
+		temp_pgtable_map_pmd((pmd_t *)pgdp, vaddr, prot)))
+
+static unsigned long temp_pgtable_map_pte(pte_t *ptep, unsigned long vaddr, pgprot_t prot)
+{
+	uintptr_t pte_idx = pte_index(vaddr);
+
+	ptep[pte_idx] = pfn_pte(PFN_DOWN(__pa(vaddr)), prot);
+
+	return 0;
+}
+
+static unsigned long temp_pgtable_map_pmd(pmd_t *pmdp, unsigned long vaddr, pgprot_t prot)
+{
+	uintptr_t pmd_idx = pmd_index(vaddr);
+	pte_t *ptep;
+
+	if (pmd_none(pmdp[pmd_idx])) {
+		ptep = (pte_t *) get_safe_page(GFP_ATOMIC);
+		if (!ptep)
+			return -ENOMEM;
+
+		memset(ptep, 0, PAGE_SIZE);
+		pmdp[pmd_idx] = pfn_pmd(PFN_DOWN(__pa(ptep)), PAGE_TABLE);
+	} else {
+		ptep = (pte_t *) __va(PFN_PHYS(_pmd_pfn(pmdp[pmd_idx])));
+	}
+
+	return temp_pgtable_map_pte(ptep, vaddr, prot);
+}
+
+static unsigned long temp_pgtable_map_pud(pud_t *pudp, unsigned long vaddr, pgprot_t prot)
+{
+
+	uintptr_t pud_index = pud_index(vaddr);
+	pmd_t *pmdp;
+
+	if (pud_val(pudp[pud_index]) == 0) {
+		pmdp = (pmd_t *) get_safe_page(GFP_ATOMIC);
+		if (!pmdp)
+			return -ENOMEM;
+
+		memset(pmdp, 0, PAGE_SIZE);
+		pudp[pud_index] = pfn_pud(PFN_DOWN(__pa(pmdp)), PAGE_TABLE);
+	} else {
+		pmdp = (pmd_t *) __va(PFN_PHYS(_pud_pfn(pudp[pud_index])));
+	}
+
+	return temp_pgtable_map_pmd(pmdp, vaddr, prot);
+}
+
+static unsigned long temp_pgtable_map_p4d(p4d_t *p4dp, unsigned long vaddr, pgprot_t prot)
+{
+	uintptr_t p4d_index = p4d_index(vaddr);
+	pud_t *pudp;
+
+	if (p4d_val(p4dp[p4d_index]) == 0) {
+		pudp = (pud_t *) get_safe_page(GFP_ATOMIC);
+		if (!pudp)
+			return -ENOMEM;
+
+		memset(pudp, 0, PAGE_SIZE);
+		p4dp[p4d_index] = pfn_p4d(PFN_DOWN(__pa(pudp)), PAGE_TABLE);
+	} else {
+		pudp = (pud_t *) __va(PFN_PHYS(_p4d_pfn(p4dp[p4d_index])));
+	}
+
+	return temp_pgtable_map_pud(pudp, vaddr, prot);
+}
+
+static unsigned long temp_pgtable_map_pgd(pgd_t *pgdp, unsigned long vaddr, pgprot_t prot)
+{
+	uintptr_t pgd_idx = pgd_index(vaddr);
+	void *nextp;
+
+	if (pgd_val(pgdp[pgd_idx]) == 0) {
+		nextp = (void *) get_safe_page(GFP_ATOMIC);
+		if (!nextp)
+			return -ENOMEM;
+
+		memset(nextp, 0, PAGE_SIZE);
+		pgdp[pgd_idx] = pfn_pgd(PFN_DOWN(__pa(nextp)), PAGE_TABLE);
+	} else {
+		nextp = (void *) __va(PFN_PHYS(_pgd_pfn(pgdp[pgd_idx])));
+	}
+
+	return temp_pgtable_map_pgd_next(nextp, vaddr, prot);
+}
+
+static unsigned long temp_pgtable_mapping(pgd_t *pgdp, unsigned long vaddr, pgprot_t prot)
+{
+	return temp_pgtable_map_pgd(pgdp, vaddr, prot);
+}
+
+static unsigned long relocate_restore_code(void)
+{
+	unsigned long ret;
+	void *page = (void *)get_safe_page(GFP_ATOMIC);
+
+	if (!page)
+		return -ENOMEM;
+
+	copy_page(page, core_restore_code);
+
+	/* Make the page containing the relocated code executable */
+	set_memory_x((unsigned long)page, 1);
+
+	ret = temp_pgtable_mapping(resume_pg_dir, (unsigned long)page, PAGE_KERNEL_READ_EXEC);
+	if (ret)
+		return ret;
+
+	return (unsigned long)page;
+}
+
+int swsusp_arch_resume(void)
+{
+	unsigned long addr = PAGE_OFFSET;
+	unsigned long 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;
+
+	/*
+	 * The pages need to be wrote-able when restoring the image.
+	 * Create a second copy of page table just for the linear map, and use this when
+	 * restoring.
+	 */
+	for (; addr <= (unsigned long)pfn_to_virt(max_low_pfn); addr += PAGE_SIZE) {
+		ret = temp_pgtable_mapping(resume_pg_dir, addr, PAGE_KERNEL);
+		if (ret)
+			return (int) 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 jump 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.
+	 */
+	ret = temp_pgtable_mapping(resume_pg_dir, (unsigned long)resume_hdr.restore_cpu_addr,
+				PAGE_KERNEL_READ_EXEC);
+	if (ret)
+		return ret;
+
+	restore_image(resume_hdr.saved_satp, (PFN_DOWN(__pa(resume_pg_dir)) | satp_mode),
+			resume_hdr.restore_cpu_addr);
+
+	return 0;
+}
+
+#ifdef CONFIG_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 = kcalloc(1, sizeof(struct suspend_context), GFP_KERNEL);
+
+	if (WARN_ON(!hibernate_cpu_context))
+		return -ENOMEM;
+
+	return 0;
+}
+
+early_initcall(riscv_hibernate__init);
-- 
2.34.1


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Re: [PATCH v2 3/3] RISC-V: Add arch functions to support hibernation/suspend-to-disk

[Andrew Jones]

On Mon, Jan 09, 2023 at 02:24:07PM +0800, 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_hibernation_header_restore() and arch_hibernation_header_save()
> functions are implemented to prevent kernel crash when resume,
> the kernel built version is saved into the hibernation image header
> to making sure only the same kernel is restore when resume.

Why does it crash with the generic version check?

> 
> swsusp_arch_resume() creates a temporary page table that covering only
> the linear map, 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
> - CONFIG_ARCH_RV64I
> - CONFIG_64BIT

What's blocking this for being for both 32-bit and 64-bit?

> 
> Signed-off-by: Sia Jee Heng <jeeheng.sia@starfivetech.com>
> Reviewed-by: Ley Foon Tan <leyfoon.tan@starfivetech.com>
> Reviewed-by: Mason Huo <mason.huo@starfivetech.com>
> ---
>  arch/riscv/Kconfig                |   8 +
>  arch/riscv/include/asm/suspend.h  |  20 ++
>  arch/riscv/kernel/Makefile        |   2 +-
>  arch/riscv/kernel/asm-offsets.c   |   5 +
>  arch/riscv/kernel/hibernate-asm.S | 123 +++++++++++
>  arch/riscv/kernel/hibernate.c     | 353 ++++++++++++++++++++++++++++++
>  6 files changed, 510 insertions(+), 1 deletion(-)
>  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 e2b656043abf..3c2607b6bda7 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -690,6 +690,14 @@ menu "Power management options"
>  
>  source "kernel/power/Kconfig"
>  
> +config ARCH_HIBERNATION_POSSIBLE
> +	def_bool y
> +	depends on 64BIT
> +
> +config ARCH_HIBERNATION_HEADER
> +	def_bool y
> +	depends on HIBERNATION && 64BIT
> +
>  endmenu # "Power management options"
>  
>  menu "CPU Power Management"
> diff --git a/arch/riscv/include/asm/suspend.h b/arch/riscv/include/asm/suspend.h
> index 75419c5ca272..ebaf103aec40 100644
> --- a/arch/riscv/include/asm/suspend.h
> +++ b/arch/riscv/include/asm/suspend.h
> @@ -21,6 +21,11 @@ struct suspend_context {
>  #endif
>  };
>  
> +/* This parameter will be assigned to 0 during resume and will be used by
> + * hibernation core for the subsequent resume sequence
> + */

Need /* on its own line

> +extern int in_suspend;

This declaration could be in arch/riscv/kernel/hibernate.c

> +
>  /* Low-level CPU suspend entry function */
>  int __cpu_suspend_enter(struct suspend_context *context);
>  
> @@ -36,4 +41,19 @@ int __cpu_resume_enter(unsigned long hartid, unsigned long context);
>  /* Used to save and restore the csr */
>  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);
> +
> +/* Used to restore the hibernated image */
> +asmlinkage void restore_image(unsigned long resume_satp, unsigned long satp_temp,
> +				unsigned long cpu_resume);
> +asmlinkage int core_restore_code(void);
>  #endif
> diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
> index 4cf303a779ab..df83b8cea631 100644
> --- a/arch/riscv/kernel/Makefile
> +++ b/arch/riscv/kernel/Makefile
> @@ -64,7 +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

Need blank line here

>  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..81d9dc98d0ad
> --- /dev/null
> +++ b/arch/riscv/kernel/hibernate-asm.S
> @@ -0,0 +1,123 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Hibernation support specific for RISCV
> + *
> + * Copyright (C) 2023 StarFive Technology Co., Ltd.
> + *
> + * Author: Jee Heng Sia <jeeheng.sia@starfivetech.com>
> + */
> +
> +#include <asm/asm.h>
> +#include <asm/asm-offsets.h>
> +#include <asm/csr.h>
> +#include <linux/linkage.h>
> +
> +/*
> + * These code are to be executed when resume from the hibernation.

This code is executed when resuming from hibernation.

> + *
> + * It begins with loads the temporary page table then restores the memory image.

loading

> + * Finally branches to __hibernate_cpu_resume() to restore the state saved by
> + * swsusp_arch_suspend().
> + */
> +
> +/*
> + * int __hibernate_cpu_resume(void)
> + * Switch back to the hibernated image's page table prior to restore the CPU
> + * context.
> + *
> + * Always returns 0 to the C code.
> + */
> +ENTRY(__hibernate_cpu_resume)
> +        /* switch to hibernated image's page table */
> +        csrw CSR_SATP, s0
> +        sfence.vma
> +
> +	ld	a0, hibernate_cpu_context
> +

From here down it's the same as what's in __cpu_resume_enter, so we could
factor it out of __cpu_resume_enter into a macro rather than duplicate it.

> +	/* Restore CSRs */
> +	REG_L   t0, (SUSPEND_CONTEXT_REGS + PT_EPC)(a0)
> +	csrw    CSR_EPC, t0
> +	REG_L   t0, (SUSPEND_CONTEXT_REGS + PT_STATUS)(a0)
> +	csrw    CSR_STATUS, t0
> +	REG_L   t0, (SUSPEND_CONTEXT_REGS + PT_BADADDR)(a0)
> +	csrw    CSR_TVAL, t0
> +	REG_L   t0, (SUSPEND_CONTEXT_REGS + PT_CAUSE)(a0)
> +	csrw    CSR_CAUSE, t0
> +
> +	/* Restore registers (except A0 and T0-T6) */
> +	REG_L   ra, (SUSPEND_CONTEXT_REGS + PT_RA)(a0)
> +	REG_L   sp, (SUSPEND_CONTEXT_REGS + PT_SP)(a0)
> +	REG_L   gp, (SUSPEND_CONTEXT_REGS + PT_GP)(a0)
> +	REG_L   tp, (SUSPEND_CONTEXT_REGS + PT_TP)(a0)
> +
> +	REG_L   s0, (SUSPEND_CONTEXT_REGS + PT_S0)(a0)
> +	REG_L   s1, (SUSPEND_CONTEXT_REGS + PT_S1)(a0)
> +	REG_L   a1, (SUSPEND_CONTEXT_REGS + PT_A1)(a0)
> +	REG_L   a2, (SUSPEND_CONTEXT_REGS + PT_A2)(a0)
> +	REG_L   a3, (SUSPEND_CONTEXT_REGS + PT_A3)(a0)
> +	REG_L   a4, (SUSPEND_CONTEXT_REGS + PT_A4)(a0)
> +	REG_L   a5, (SUSPEND_CONTEXT_REGS + PT_A5)(a0)
> +	REG_L   a6, (SUSPEND_CONTEXT_REGS + PT_A6)(a0)
> +	REG_L   a7, (SUSPEND_CONTEXT_REGS + PT_A7)(a0)
> +	REG_L   s2, (SUSPEND_CONTEXT_REGS + PT_S2)(a0)
> +	REG_L   s3, (SUSPEND_CONTEXT_REGS + PT_S3)(a0)
> +	REG_L   s4, (SUSPEND_CONTEXT_REGS + PT_S4)(a0)
> +	REG_L   s5, (SUSPEND_CONTEXT_REGS + PT_S5)(a0)
> +	REG_L   s6, (SUSPEND_CONTEXT_REGS + PT_S6)(a0)
> +	REG_L   s7, (SUSPEND_CONTEXT_REGS + PT_S7)(a0)
> +	REG_L   s8, (SUSPEND_CONTEXT_REGS + PT_S8)(a0)
> +	REG_L   s9, (SUSPEND_CONTEXT_REGS + PT_S9)(a0)
> +	REG_L   s10, (SUSPEND_CONTEXT_REGS + PT_S10)(a0)
> +	REG_L   s11, (SUSPEND_CONTEXT_REGS + PT_S11)(a0)
> +
> +	/* Return zero value */
> +	add     a0, zero, 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(restore_image)
> +	mv	s0, a0
> +	mv	s1, a1
> +	mv	s2, a2
> +	ld      s4, restore_pblist
> +	ld	a1, relocated_restore_code
> +
> +	jalr	a1
> +END(restore_image)
> +
> +/*
> + * The below code will be executed from a 'safe' page.
> + * It first switches to the temporary page table, then start to copy the pages
> + * back to the original memory location. Finally, it jumps to the __hibernate_cpu_resume()
> + * to restore the CPU context.
> + */
> +ENTRY(core_restore_code)
> +	/* switch to temp page table */
> +	csrw satp, s1
> +	sfence.vma
> +	beqz	s4, done
> +loop:
> +	/* The below code will restore the hibernated image. */
> +	ld	a1, HIBERN_PBE_ADDR(s4)
> +	ld	a0, HIBERN_PBE_ORIG(s4)
> +
> +	lui     a4, 0x1
> +	add     a4, a4, a0
> +copy:	ld      a5, 0(a1)

copy label should get its own line and how about changing it,
loop, and done to local symbol names, e.g. .Lcopy?

> +	addi    a0, a0, 8
> +	addi    a1, a1, 8
> +	sd      a5, -8(a0)
> +	bne     a4, a0, copy
> +
> +	ld	s4, HIBERN_PBE_NEXT(s4)
> +	bnez	s4, loop
> +done:
> +	jalr	s2
> +END(core_restore_code)
> diff --git a/arch/riscv/kernel/hibernate.c b/arch/riscv/kernel/hibernate.c
> new file mode 100644
> index 000000000000..bd77c35958a8
> --- /dev/null
> +++ b/arch/riscv/kernel/hibernate.c
> @@ -0,0 +1,353 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Hibernation support specific for RISCV
> + *
> + * Copyright (C) 2023 StarFive Technology Co., Ltd.
> + *
> + * Author: Jee Heng Sia <jeeheng.sia@starfivetech.com>
> + */
> +
> +#include <asm/barrier.h>
> +#include <asm/cacheflush.h>
> +#include <asm/mmu_context.h>
> +#include <asm/page.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;
> +
> +/* CPU context to be saved */
> +struct suspend_context *hibernate_cpu_context;
> +
> +unsigned long relocated_restore_code;
> +
> +/* Pointer to the temporary resume page tables */
> +pgd_t *resume_pg_dir;
> +
> +/*
> + * Save the build number and date so that the we are not resume with a different kernel
> + */
> +struct arch_hibernate_hdr_invariants {
> +	char		uts_version[__NEW_UTS_LEN + 1];
> +};
> +
> +/* Helper parameters that help us to restore the image.

Separate line for /*

> + * @hartid: To make sure same boot_cpu executing 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 inline 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(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

The #ifdef shouldn't be necessary.

> +	ret = bringup_hibernate_cpu(sleep_cpu);
> +	if (ret) {
> +		sleep_cpu = -EINVAL;
> +		return ret;
> +	}
> +#endif
> +	resume_hdr = *hdr;
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL(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();
> +
> +		/* Invalidated Icache */
> +		flush_icache_all();
> +
> +		/*
> +		 * Tell the hibernation core that we've just restored
> +		 * the memory
> +		 */
> +		in_suspend = 0;
> +		sleep_cpu = -EINVAL;
> +	}
> +
> +	return ret;
> +}
> +
> +#define temp_pgtable_map_pgd_next(pgdp, vaddr, prot)			\
> +		(pgtable_l5_enabled ?					\
> +		temp_pgtable_map_p4d(pgdp, vaddr, prot) :		\
> +		(pgtable_l4_enabled ?					\
> +		temp_pgtable_map_pud((pud_t *)pgdp, vaddr, prot) :	\
> +		temp_pgtable_map_pmd((pmd_t *)pgdp, vaddr, prot)))
> +
> +static unsigned long temp_pgtable_map_pte(pte_t *ptep, unsigned long vaddr, pgprot_t prot)
> +{
> +	uintptr_t pte_idx = pte_index(vaddr);
> +
> +	ptep[pte_idx] = pfn_pte(PFN_DOWN(__pa(vaddr)), prot);
> +
> +	return 0;
> +}
> +
> +static unsigned long temp_pgtable_map_pmd(pmd_t *pmdp, unsigned long vaddr, pgprot_t prot)
> +{
> +	uintptr_t pmd_idx = pmd_index(vaddr);
> +	pte_t *ptep;
> +
> +	if (pmd_none(pmdp[pmd_idx])) {
> +		ptep = (pte_t *) get_safe_page(GFP_ATOMIC);

No space between cast and function. Same comment for following functions.
I thought checkpatch complained about that.

> +		if (!ptep)
> +			return -ENOMEM;
> +
> +		memset(ptep, 0, PAGE_SIZE);
> +		pmdp[pmd_idx] = pfn_pmd(PFN_DOWN(__pa(ptep)), PAGE_TABLE);
> +	} else {
> +		ptep = (pte_t *) __va(PFN_PHYS(_pmd_pfn(pmdp[pmd_idx])));
> +	}
> +
> +	return temp_pgtable_map_pte(ptep, vaddr, prot);
> +}
> +
> +static unsigned long temp_pgtable_map_pud(pud_t *pudp, unsigned long vaddr, pgprot_t prot)
> +{
> +
> +	uintptr_t pud_index = pud_index(vaddr);
> +	pmd_t *pmdp;
> +
> +	if (pud_val(pudp[pud_index]) == 0) {
> +		pmdp = (pmd_t *) get_safe_page(GFP_ATOMIC);
> +		if (!pmdp)
> +			return -ENOMEM;
> +
> +		memset(pmdp, 0, PAGE_SIZE);
> +		pudp[pud_index] = pfn_pud(PFN_DOWN(__pa(pmdp)), PAGE_TABLE);
> +	} else {
> +		pmdp = (pmd_t *) __va(PFN_PHYS(_pud_pfn(pudp[pud_index])));
> +	}
> +
> +	return temp_pgtable_map_pmd(pmdp, vaddr, prot);
> +}
> +
> +static unsigned long temp_pgtable_map_p4d(p4d_t *p4dp, unsigned long vaddr, pgprot_t prot)
> +{
> +	uintptr_t p4d_index = p4d_index(vaddr);
> +	pud_t *pudp;
> +
> +	if (p4d_val(p4dp[p4d_index]) == 0) {
> +		pudp = (pud_t *) get_safe_page(GFP_ATOMIC);
> +		if (!pudp)
> +			return -ENOMEM;
> +
> +		memset(pudp, 0, PAGE_SIZE);
> +		p4dp[p4d_index] = pfn_p4d(PFN_DOWN(__pa(pudp)), PAGE_TABLE);
> +	} else {
> +		pudp = (pud_t *) __va(PFN_PHYS(_p4d_pfn(p4dp[p4d_index])));
> +	}
> +
> +	return temp_pgtable_map_pud(pudp, vaddr, prot);
> +}
> +
> +static unsigned long temp_pgtable_map_pgd(pgd_t *pgdp, unsigned long vaddr, pgprot_t prot)
> +{
> +	uintptr_t pgd_idx = pgd_index(vaddr);
> +	void *nextp;
> +
> +	if (pgd_val(pgdp[pgd_idx]) == 0) {
> +		nextp = (void *) get_safe_page(GFP_ATOMIC);
> +		if (!nextp)
> +			return -ENOMEM;
> +
> +		memset(nextp, 0, PAGE_SIZE);
> +		pgdp[pgd_idx] = pfn_pgd(PFN_DOWN(__pa(nextp)), PAGE_TABLE);
> +	} else {
> +		nextp = (void *) __va(PFN_PHYS(_pgd_pfn(pgdp[pgd_idx])));
> +	}
> +
> +	return temp_pgtable_map_pgd_next(nextp, vaddr, prot);
> +}
> +
> +static unsigned long temp_pgtable_mapping(pgd_t *pgdp, unsigned long vaddr, pgprot_t prot)
> +{
> +	return temp_pgtable_map_pgd(pgdp, vaddr, prot);
> +}
> +
> +static unsigned long relocate_restore_code(void)
> +{
> +	unsigned long ret;
> +	void *page = (void *)get_safe_page(GFP_ATOMIC);
> +
> +	if (!page)
> +		return -ENOMEM;
> +
> +	copy_page(page, core_restore_code);
> +
> +	/* Make the page containing the relocated code executable */
> +	set_memory_x((unsigned long)page, 1);
> +
> +	ret = temp_pgtable_mapping(resume_pg_dir, (unsigned long)page, PAGE_KERNEL_READ_EXEC);
> +	if (ret)
> +		return ret;
> +
> +	return (unsigned long)page;
> +}
> +
> +int swsusp_arch_resume(void)
> +{
> +	unsigned long addr = PAGE_OFFSET;
> +	unsigned long 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;
> +
> +	/*
> +	 * The pages need to be wrote-able when restoring the image.

writable

> +	 * Create a second copy of page table just for the linear map, and use this when
> +	 * restoring.
> +	 */
> +	for (; addr <= (unsigned long)pfn_to_virt(max_low_pfn); addr += PAGE_SIZE) {
> +		ret = temp_pgtable_mapping(resume_pg_dir, addr, PAGE_KERNEL);
> +		if (ret)
> +			return (int) 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 jump 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.
> +	 */
> +	ret = temp_pgtable_mapping(resume_pg_dir, (unsigned long)resume_hdr.restore_cpu_addr,
> +				PAGE_KERNEL_READ_EXEC);
> +	if (ret)
> +		return ret;
> +
> +	restore_image(resume_hdr.saved_satp, (PFN_DOWN(__pa(resume_pg_dir)) | satp_mode),
> +			resume_hdr.restore_cpu_addr);
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_SMP

Shouldn't this be 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)

It's more typical to only have a single underscore.

> +{
> +	hibernate_cpu_context = kcalloc(1, sizeof(struct suspend_context), GFP_KERNEL);
> +
> +	if (WARN_ON(!hibernate_cpu_context))
> +		return -ENOMEM;
> +
> +	return 0;
> +}
> +
> +early_initcall(riscv_hibernate__init);
> -- 
> 2.34.1
> 
>

Besides some nits and a couple questions, this looks to me. I'll try to
find some time to experiment with it as well.

Thanks,
drew

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Re: [PATCH v2 3/3] RISC-V: Add arch functions to support hibernation/suspend-to-disk

[Conor Dooley]

[-- Attachment #1.1: Type: text/plain, Size: 608 bytes --]

On Mon, Jan 09, 2023 at 08:36:24PM +0100, Andrew Jones wrote:
> On Mon, Jan 09, 2023 at 02:24:07PM +0800, Sia Jee Heng wrote:

> > To enable hibernation/suspend to disk into RISCV, the below config
> > need to be enabled:
> > - CONFIG_ARCH_HIBERNATION_HEADER
> > - CONFIG_ARCH_HIBERNATION_POSSIBLE
> > - CONFIG_ARCH_RV64I
> > - CONFIG_64BIT

> What's blocking this for being for both 32-bit and 64-bit?

Just from checking with b4 diff, it's because I told them they broke the
rv32 build with their v1 implementation.

I'd rather they fixed whatever the issue was with rv32 than ignored it.

Thanks,
Conor.


[-- Attachment #1.2: signature.asc --]
[-- Type: application/pgp-signature, Size: 228 bytes --]

[-- Attachment #2: Type: text/plain, Size: 161 bytes --]

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RE: [PATCH v2 3/3] RISC-V: Add arch functions to support hibernation/suspend-to-disk

[JeeHeng Sia]

> -----Original Message-----
> From: Conor Dooley <conor@kernel.org>
> Sent: Tuesday, 10 January, 2023 3:46 AM
> To: Andrew Jones <ajones@ventanamicro.com>
> Cc: JeeHeng Sia <jeeheng.sia@starfivetech.com>; paul.walmsley@sifive.com;
> palmer@dabbelt.com; aou@eecs.berkeley.edu; linux-
> riscv@lists.infradead.org; linux-kernel@vger.kernel.org; Leyfoon Tan
> <leyfoon.tan@starfivetech.com>; Mason Huo
> <mason.huo@starfivetech.com>
> Subject: Re: [PATCH v2 3/3] RISC-V: Add arch functions to support
> hibernation/suspend-to-disk
> 
> On Mon, Jan 09, 2023 at 08:36:24PM +0100, Andrew Jones wrote:
> > On Mon, Jan 09, 2023 at 02:24:07PM +0800, Sia Jee Heng wrote:
> 
> > > To enable hibernation/suspend to disk into RISCV, the below config
> > > need to be enabled:
> > > - CONFIG_ARCH_HIBERNATION_HEADER
> > > - CONFIG_ARCH_HIBERNATION_POSSIBLE
> > > - CONFIG_ARCH_RV64I
> > > - CONFIG_64BIT
> 
> > What's blocking this for being for both 32-bit and 64-bit?
> 
> Just from checking with b4 diff, it's because I told them they broke the
> rv32 build with their v1 implementation.
> 
> I'd rather they fixed whatever the issue was with rv32 than ignored it.
The main reason is because I don't have a rv32 system to verify the rv32 hibernation. I can submit another patch to support rv32 hibernation once I have the system or someone who has the rv32 system can submit the patch ontop. 
> 
> Thanks,
> Conor.


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Re: [PATCH v2 3/3] RISC-V: Add arch functions to support hibernation/suspend-to-disk

[Andrew Jones]

On Tue, Jan 10, 2023 at 07:00:38AM +0000, JeeHeng Sia wrote:
> 
> 
> > -----Original Message-----
> > From: Conor Dooley <conor@kernel.org>
> > Sent: Tuesday, 10 January, 2023 3:46 AM
> > To: Andrew Jones <ajones@ventanamicro.com>
> > Cc: JeeHeng Sia <jeeheng.sia@starfivetech.com>; paul.walmsley@sifive.com;
> > palmer@dabbelt.com; aou@eecs.berkeley.edu; linux-
> > riscv@lists.infradead.org; linux-kernel@vger.kernel.org; Leyfoon Tan
> > <leyfoon.tan@starfivetech.com>; Mason Huo
> > <mason.huo@starfivetech.com>
> > Subject: Re: [PATCH v2 3/3] RISC-V: Add arch functions to support
> > hibernation/suspend-to-disk
> > 
> > On Mon, Jan 09, 2023 at 08:36:24PM +0100, Andrew Jones wrote:
> > > On Mon, Jan 09, 2023 at 02:24:07PM +0800, Sia Jee Heng wrote:
> > 
> > > > To enable hibernation/suspend to disk into RISCV, the below config
> > > > need to be enabled:
> > > > - CONFIG_ARCH_HIBERNATION_HEADER
> > > > - CONFIG_ARCH_HIBERNATION_POSSIBLE
> > > > - CONFIG_ARCH_RV64I
> > > > - CONFIG_64BIT
> > 
> > > What's blocking this for being for both 32-bit and 64-bit?
> > 
> > Just from checking with b4 diff, it's because I told them they broke the
> > rv32 build with their v1 implementation.
> > 
> > I'd rather they fixed whatever the issue was with rv32 than ignored it.
> The main reason is because I don't have a rv32 system to verify the rv32 hibernation.

QEMU?

Thanks,
drew

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RE: [PATCH v2 3/3] RISC-V: Add arch functions to support hibernation/suspend-to-disk

[Leyfoon Tan]

[...]
> 
> > +{
> > +	hibernate_cpu_context = kcalloc(1, sizeof(struct suspend_context),
> GFP_KERNEL);
> > +
> > +	if (WARN_ON(!hibernate_cpu_context))
> > +		return -ENOMEM;
> > +
> > +	return 0;
> > +}
> > +
> > +early_initcall(riscv_hibernate__init);
> > --
> > 2.34.1
> >
> >
> 
> Besides some nits and a couple questions, this looks to me. I'll try to
> find some time to experiment with it as well.
FYI, you need use the latest OpenSBI tree. We also submitted these 2 patches below to fix the boot hartid. Resume from hibernation needs to be same hartid.


https://github.com/riscv-software-src/opensbi/commit/cb7e7c3325e68a9b4d5ea210b97cac693cf5814f
https://github.com/riscv-software-src/opensbi/commit/8020df8733b060f01e35b0b2bcb2b41e6b992e9b

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RE: [PATCH v2 3/3] RISC-V: Add arch functions to support hibernation/suspend-to-disk

[JeeHeng Sia]

> -----Original Message-----
> From: Andrew Jones <ajones@ventanamicro.com>
> Sent: Tuesday, 10 January, 2023 3:36 AM
> To: JeeHeng Sia <jeeheng.sia@starfivetech.com>
> Cc: paul.walmsley@sifive.com; palmer@dabbelt.com;
> aou@eecs.berkeley.edu; linux-riscv@lists.infradead.org; linux-
> kernel@vger.kernel.org; Leyfoon Tan <leyfoon.tan@starfivetech.com>;
> Mason Huo <mason.huo@starfivetech.com>
> Subject: Re: [PATCH v2 3/3] RISC-V: Add arch functions to support
> hibernation/suspend-to-disk
> 
> On Mon, Jan 09, 2023 at 02:24:07PM +0800, 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_hibernation_header_restore() and arch_hibernation_header_save()
> > functions are implemented to prevent kernel crash when resume,
> > the kernel built version is saved into the hibernation image header
> > to making sure only the same kernel is restore when resume.
> 
> Why does it crash with the generic version check?
The kernel could have different device driver enabled and the device drivers would find itself running in a different address space if restore with different kernel version.
> 
> >
> > swsusp_arch_resume() creates a temporary page table that covering only
> > the linear map, 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
> > - CONFIG_ARCH_RV64I
> > - CONFIG_64BIT
> 
> What's blocking this for being for both 32-bit and 64-bit?
> 
> >
> > Signed-off-by: Sia Jee Heng <jeeheng.sia@starfivetech.com>
> > Reviewed-by: Ley Foon Tan <leyfoon.tan@starfivetech.com>
> > Reviewed-by: Mason Huo <mason.huo@starfivetech.com>
> > ---
> >  arch/riscv/Kconfig                |   8 +
> >  arch/riscv/include/asm/suspend.h  |  20 ++
> >  arch/riscv/kernel/Makefile        |   2 +-
> >  arch/riscv/kernel/asm-offsets.c   |   5 +
> >  arch/riscv/kernel/hibernate-asm.S | 123 +++++++++++
> >  arch/riscv/kernel/hibernate.c     | 353 ++++++++++++++++++++++++++++++
> >  6 files changed, 510 insertions(+), 1 deletion(-)
> >  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 e2b656043abf..3c2607b6bda7 100644
> > --- a/arch/riscv/Kconfig
> > +++ b/arch/riscv/Kconfig
> > @@ -690,6 +690,14 @@ menu "Power management options"
> >
> >  source "kernel/power/Kconfig"
> >
> > +config ARCH_HIBERNATION_POSSIBLE
> > +	def_bool y
> > +	depends on 64BIT
> > +
> > +config ARCH_HIBERNATION_HEADER
> > +	def_bool y
> > +	depends on HIBERNATION && 64BIT
> > +
> >  endmenu # "Power management options"
> >
> >  menu "CPU Power Management"
> > diff --git a/arch/riscv/include/asm/suspend.h
> b/arch/riscv/include/asm/suspend.h
> > index 75419c5ca272..ebaf103aec40 100644
> > --- a/arch/riscv/include/asm/suspend.h
> > +++ b/arch/riscv/include/asm/suspend.h
> > @@ -21,6 +21,11 @@ struct suspend_context {
> >  #endif
> >  };
> >
> > +/* This parameter will be assigned to 0 during resume and will be used by
> > + * hibernation core for the subsequent resume sequence
> > + */
> 
> Need /* on its own line
Oops. Thanks. will fix it.
> 
> > +extern int in_suspend;
> 
> This declaration could be in arch/riscv/kernel/hibernate.c
Can't declare it to the .c file because checkpatch will report error if we do so.
> 
> > +
> >  /* Low-level CPU suspend entry function */
> >  int __cpu_suspend_enter(struct suspend_context *context);
> >
> > @@ -36,4 +41,19 @@ int __cpu_resume_enter(unsigned long hartid,
> unsigned long context);
> >  /* Used to save and restore the csr */
> >  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);
> > +
> > +/* Used to restore the hibernated image */
> > +asmlinkage void restore_image(unsigned long resume_satp, unsigned
> long satp_temp,
> > +				unsigned long cpu_resume);
> > +asmlinkage int core_restore_code(void);
> >  #endif
> > diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
> > index 4cf303a779ab..df83b8cea631 100644
> > --- a/arch/riscv/kernel/Makefile
> > +++ b/arch/riscv/kernel/Makefile
> > @@ -64,7 +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
> 
> Need blank line here
ok.
> 
> >  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..81d9dc98d0ad
> > --- /dev/null
> > +++ b/arch/riscv/kernel/hibernate-asm.S
> > @@ -0,0 +1,123 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only */
> > +/*
> > + * Hibernation support specific for RISCV
> > + *
> > + * Copyright (C) 2023 StarFive Technology Co., Ltd.
> > + *
> > + * Author: Jee Heng Sia <jeeheng.sia@starfivetech.com>
> > + */
> > +
> > +#include <asm/asm.h>
> > +#include <asm/asm-offsets.h>
> > +#include <asm/csr.h>
> > +#include <linux/linkage.h>
> > +
> > +/*
> > + * These code are to be executed when resume from the hibernation.
> 
> This code is executed when resuming from hibernation.
ok
> 
> > + *
> > + * It begins with loads the temporary page table then restores the memory
> image.
> 
> loading
ok
> 
> > + * Finally branches to __hibernate_cpu_resume() to restore the state
> saved by
> > + * swsusp_arch_suspend().
> > + */
> > +
> > +/*
> > + * int __hibernate_cpu_resume(void)
> > + * Switch back to the hibernated image's page table prior to restore the
> CPU
> > + * context.
> > + *
> > + * Always returns 0 to the C code.
> > + */
> > +ENTRY(__hibernate_cpu_resume)
> > +        /* switch to hibernated image's page table */
> > +        csrw CSR_SATP, s0
> > +        sfence.vma
> > +
> > +	ld	a0, hibernate_cpu_context
> > +
> 
> From here down it's the same as what's in __cpu_resume_enter, so we could
> factor it out of __cpu_resume_enter into a macro rather than duplicate it.
sure.
> 
> > +	/* Restore CSRs */
> > +	REG_L   t0, (SUSPEND_CONTEXT_REGS + PT_EPC)(a0)
> > +	csrw    CSR_EPC, t0
> > +	REG_L   t0, (SUSPEND_CONTEXT_REGS + PT_STATUS)(a0)
> > +	csrw    CSR_STATUS, t0
> > +	REG_L   t0, (SUSPEND_CONTEXT_REGS + PT_BADADDR)(a0)
> > +	csrw    CSR_TVAL, t0
> > +	REG_L   t0, (SUSPEND_CONTEXT_REGS + PT_CAUSE)(a0)
> > +	csrw    CSR_CAUSE, t0
> > +
> > +	/* Restore registers (except A0 and T0-T6) */
> > +	REG_L   ra, (SUSPEND_CONTEXT_REGS + PT_RA)(a0)
> > +	REG_L   sp, (SUSPEND_CONTEXT_REGS + PT_SP)(a0)
> > +	REG_L   gp, (SUSPEND_CONTEXT_REGS + PT_GP)(a0)
> > +	REG_L   tp, (SUSPEND_CONTEXT_REGS + PT_TP)(a0)
> > +
> > +	REG_L   s0, (SUSPEND_CONTEXT_REGS + PT_S0)(a0)
> > +	REG_L   s1, (SUSPEND_CONTEXT_REGS + PT_S1)(a0)
> > +	REG_L   a1, (SUSPEND_CONTEXT_REGS + PT_A1)(a0)
> > +	REG_L   a2, (SUSPEND_CONTEXT_REGS + PT_A2)(a0)
> > +	REG_L   a3, (SUSPEND_CONTEXT_REGS + PT_A3)(a0)
> > +	REG_L   a4, (SUSPEND_CONTEXT_REGS + PT_A4)(a0)
> > +	REG_L   a5, (SUSPEND_CONTEXT_REGS + PT_A5)(a0)
> > +	REG_L   a6, (SUSPEND_CONTEXT_REGS + PT_A6)(a0)
> > +	REG_L   a7, (SUSPEND_CONTEXT_REGS + PT_A7)(a0)
> > +	REG_L   s2, (SUSPEND_CONTEXT_REGS + PT_S2)(a0)
> > +	REG_L   s3, (SUSPEND_CONTEXT_REGS + PT_S3)(a0)
> > +	REG_L   s4, (SUSPEND_CONTEXT_REGS + PT_S4)(a0)
> > +	REG_L   s5, (SUSPEND_CONTEXT_REGS + PT_S5)(a0)
> > +	REG_L   s6, (SUSPEND_CONTEXT_REGS + PT_S6)(a0)
> > +	REG_L   s7, (SUSPEND_CONTEXT_REGS + PT_S7)(a0)
> > +	REG_L   s8, (SUSPEND_CONTEXT_REGS + PT_S8)(a0)
> > +	REG_L   s9, (SUSPEND_CONTEXT_REGS + PT_S9)(a0)
> > +	REG_L   s10, (SUSPEND_CONTEXT_REGS + PT_S10)(a0)
> > +	REG_L   s11, (SUSPEND_CONTEXT_REGS + PT_S11)(a0)
> > +
> > +	/* Return zero value */
> > +	add     a0, zero, 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(restore_image)
> > +	mv	s0, a0
> > +	mv	s1, a1
> > +	mv	s2, a2
> > +	ld      s4, restore_pblist
> > +	ld	a1, relocated_restore_code
> > +
> > +	jalr	a1
> > +END(restore_image)
> > +
> > +/*
> > + * The below code will be executed from a 'safe' page.
> > + * It first switches to the temporary page table, then start to copy the
> pages
> > + * back to the original memory location. Finally, it jumps to the
> __hibernate_cpu_resume()
> > + * to restore the CPU context.
> > + */
> > +ENTRY(core_restore_code)
> > +	/* switch to temp page table */
> > +	csrw satp, s1
> > +	sfence.vma
> > +	beqz	s4, done
> > +loop:
> > +	/* The below code will restore the hibernated image. */
> > +	ld	a1, HIBERN_PBE_ADDR(s4)
> > +	ld	a0, HIBERN_PBE_ORIG(s4)
> > +
> > +	lui     a4, 0x1
> > +	add     a4, a4, a0
> > +copy:	ld      a5, 0(a1)
> 
> copy label should get its own line and how about changing it,
ok
> loop, and done to local symbol names, e.g. .Lcopy?
I think better to use two local symbol names, i.e .Lcopy and .Ldone
> 
> > +	addi    a0, a0, 8
> > +	addi    a1, a1, 8
> > +	sd      a5, -8(a0)
> > +	bne     a4, a0, copy
> > +
> > +	ld	s4, HIBERN_PBE_NEXT(s4)
> > +	bnez	s4, loop
> > +done:
> > +	jalr	s2
> > +END(core_restore_code)
> > diff --git a/arch/riscv/kernel/hibernate.c b/arch/riscv/kernel/hibernate.c
> > new file mode 100644
> > index 000000000000..bd77c35958a8
> > --- /dev/null
> > +++ b/arch/riscv/kernel/hibernate.c
> > @@ -0,0 +1,353 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * Hibernation support specific for RISCV
> > + *
> > + * Copyright (C) 2023 StarFive Technology Co., Ltd.
> > + *
> > + * Author: Jee Heng Sia <jeeheng.sia@starfivetech.com>
> > + */
> > +
> > +#include <asm/barrier.h>
> > +#include <asm/cacheflush.h>
> > +#include <asm/mmu_context.h>
> > +#include <asm/page.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;
> > +
> > +/* CPU context to be saved */
> > +struct suspend_context *hibernate_cpu_context;
> > +
> > +unsigned long relocated_restore_code;
> > +
> > +/* Pointer to the temporary resume page tables */
> > +pgd_t *resume_pg_dir;
> > +
> > +/*
> > + * Save the build number and date so that the we are not resume with a
> different kernel
> > + */
> > +struct arch_hibernate_hdr_invariants {
> > +	char		uts_version[__NEW_UTS_LEN + 1];
> > +};
> > +
> > +/* Helper parameters that help us to restore the image.
> 
> Separate line for /*
ok
> 
> > + * @hartid: To make sure same boot_cpu executing 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 inline 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(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
> 
> The #ifdef shouldn't be necessary.
We need the #ifdef CONFIG_SMP is because the bringup_hibernate_cpu() is defined under the guardian of ifdef CONFIG_SMP.
One will face compile error if the CONFIG_SMP was disabled for a single cpu testing.
> 
> > +	ret = bringup_hibernate_cpu(sleep_cpu);
> > +	if (ret) {
> > +		sleep_cpu = -EINVAL;
> > +		return ret;
> > +	}
> > +#endif
> > +	resume_hdr = *hdr;
> > +
> > +	return ret;
> > +}
> > +EXPORT_SYMBOL(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();
> > +
> > +		/* Invalidated Icache */
> > +		flush_icache_all();
> > +
> > +		/*
> > +		 * Tell the hibernation core that we've just restored
> > +		 * the memory
> > +		 */
> > +		in_suspend = 0;
> > +		sleep_cpu = -EINVAL;
> > +	}
> > +
> > +	return ret;
> > +}
> > +
> > +#define temp_pgtable_map_pgd_next(pgdp, vaddr, prot)
> 	\
> > +		(pgtable_l5_enabled ?					\
> > +		temp_pgtable_map_p4d(pgdp, vaddr, prot) :		\
> > +		(pgtable_l4_enabled ?					\
> > +		temp_pgtable_map_pud((pud_t *)pgdp, vaddr, prot) :	\
> > +		temp_pgtable_map_pmd((pmd_t *)pgdp, vaddr, prot)))
> > +
> > +static unsigned long temp_pgtable_map_pte(pte_t *ptep, unsigned long
> vaddr, pgprot_t prot)
> > +{
> > +	uintptr_t pte_idx = pte_index(vaddr);
> > +
> > +	ptep[pte_idx] = pfn_pte(PFN_DOWN(__pa(vaddr)), prot);
> > +
> > +	return 0;
> > +}
> > +
> > +static unsigned long temp_pgtable_map_pmd(pmd_t *pmdp, unsigned
> long vaddr, pgprot_t prot)
> > +{
> > +	uintptr_t pmd_idx = pmd_index(vaddr);
> > +	pte_t *ptep;
> > +
> > +	if (pmd_none(pmdp[pmd_idx])) {
> > +		ptep = (pte_t *) get_safe_page(GFP_ATOMIC);
> 
> No space between cast and function. Same comment for following functions.
> I thought checkpatch complained about that.
Ok. But it is weird that checkpatch doesn't report the issue.
> 
> > +		if (!ptep)
> > +			return -ENOMEM;
> > +
> > +		memset(ptep, 0, PAGE_SIZE);
> > +		pmdp[pmd_idx] = pfn_pmd(PFN_DOWN(__pa(ptep)),
> PAGE_TABLE);
> > +	} else {
> > +		ptep = (pte_t *)
> __va(PFN_PHYS(_pmd_pfn(pmdp[pmd_idx])));
> > +	}
> > +
> > +	return temp_pgtable_map_pte(ptep, vaddr, prot);
> > +}
> > +
> > +static unsigned long temp_pgtable_map_pud(pud_t *pudp, unsigned long
> vaddr, pgprot_t prot)
> > +{
> > +
> > +	uintptr_t pud_index = pud_index(vaddr);
> > +	pmd_t *pmdp;
> > +
> > +	if (pud_val(pudp[pud_index]) == 0) {
> > +		pmdp = (pmd_t *) get_safe_page(GFP_ATOMIC);
> > +		if (!pmdp)
> > +			return -ENOMEM;
> > +
> > +		memset(pmdp, 0, PAGE_SIZE);
> > +		pudp[pud_index] = pfn_pud(PFN_DOWN(__pa(pmdp)),
> PAGE_TABLE);
> > +	} else {
> > +		pmdp = (pmd_t *)
> __va(PFN_PHYS(_pud_pfn(pudp[pud_index])));
> > +	}
> > +
> > +	return temp_pgtable_map_pmd(pmdp, vaddr, prot);
> > +}
> > +
> > +static unsigned long temp_pgtable_map_p4d(p4d_t *p4dp, unsigned long
> vaddr, pgprot_t prot)
> > +{
> > +	uintptr_t p4d_index = p4d_index(vaddr);
> > +	pud_t *pudp;
> > +
> > +	if (p4d_val(p4dp[p4d_index]) == 0) {
> > +		pudp = (pud_t *) get_safe_page(GFP_ATOMIC);
> > +		if (!pudp)
> > +			return -ENOMEM;
> > +
> > +		memset(pudp, 0, PAGE_SIZE);
> > +		p4dp[p4d_index] = pfn_p4d(PFN_DOWN(__pa(pudp)),
> PAGE_TABLE);
> > +	} else {
> > +		pudp = (pud_t *)
> __va(PFN_PHYS(_p4d_pfn(p4dp[p4d_index])));
> > +	}
> > +
> > +	return temp_pgtable_map_pud(pudp, vaddr, prot);
> > +}
> > +
> > +static unsigned long temp_pgtable_map_pgd(pgd_t *pgdp, unsigned long
> vaddr, pgprot_t prot)
> > +{
> > +	uintptr_t pgd_idx = pgd_index(vaddr);
> > +	void *nextp;
> > +
> > +	if (pgd_val(pgdp[pgd_idx]) == 0) {
> > +		nextp = (void *) get_safe_page(GFP_ATOMIC);
> > +		if (!nextp)
> > +			return -ENOMEM;
> > +
> > +		memset(nextp, 0, PAGE_SIZE);
> > +		pgdp[pgd_idx] = pfn_pgd(PFN_DOWN(__pa(nextp)),
> PAGE_TABLE);
> > +	} else {
> > +		nextp = (void *) __va(PFN_PHYS(_pgd_pfn(pgdp[pgd_idx])));
> > +	}
> > +
> > +	return temp_pgtable_map_pgd_next(nextp, vaddr, prot);
> > +}
> > +
> > +static unsigned long temp_pgtable_mapping(pgd_t *pgdp, unsigned long
> vaddr, pgprot_t prot)
> > +{
> > +	return temp_pgtable_map_pgd(pgdp, vaddr, prot);
> > +}
> > +
> > +static unsigned long relocate_restore_code(void)
> > +{
> > +	unsigned long ret;
> > +	void *page = (void *)get_safe_page(GFP_ATOMIC);
> > +
> > +	if (!page)
> > +		return -ENOMEM;
> > +
> > +	copy_page(page, core_restore_code);
> > +
> > +	/* Make the page containing the relocated code executable */
> > +	set_memory_x((unsigned long)page, 1);
> > +
> > +	ret = temp_pgtable_mapping(resume_pg_dir, (unsigned long)page,
> PAGE_KERNEL_READ_EXEC);
> > +	if (ret)
> > +		return ret;
> > +
> > +	return (unsigned long)page;
> > +}
> > +
> > +int swsusp_arch_resume(void)
> > +{
> > +	unsigned long addr = PAGE_OFFSET;
> > +	unsigned long 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;
> > +
> > +	/*
> > +	 * The pages need to be wrote-able when restoring the image.
> 
> writable
ok
> 
> > +	 * Create a second copy of page table just for the linear map, and use
> this when
> > +	 * restoring.
> > +	 */
> > +	for (; addr <= (unsigned long)pfn_to_virt(max_low_pfn); addr +=
> PAGE_SIZE) {
> > +		ret = temp_pgtable_mapping(resume_pg_dir, addr,
> PAGE_KERNEL);
> > +		if (ret)
> > +			return (int) 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 jump 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.
> > +	 */
> > +	ret = temp_pgtable_mapping(resume_pg_dir, (unsigned
> long)resume_hdr.restore_cpu_addr,
> > +				PAGE_KERNEL_READ_EXEC);
> > +	if (ret)
> > +		return ret;
> > +
> > +	restore_image(resume_hdr.saved_satp,
> (PFN_DOWN(__pa(resume_pg_dir)) | satp_mode),
> > +			resume_hdr.restore_cpu_addr);
> > +
> > +	return 0;
> > +}
> > +
> > +#ifdef CONFIG_SMP
> 
> Shouldn't this be CONFIG_PM_SLEEP_SMP ?
Yes, you are right. Will change it.

> 
> > +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)
> 
> It's more typical to only have a single underscore.
Oops. Will fix it. Thanks.
> 
> > +{
> > +	hibernate_cpu_context = kcalloc(1, sizeof(struct suspend_context),
> GFP_KERNEL);
> > +
> > +	if (WARN_ON(!hibernate_cpu_context))
> > +		return -ENOMEM;
> > +
> > +	return 0;
> > +}
> > +
> > +early_initcall(riscv_hibernate__init);
> > --
> > 2.34.1
> >
> >
> 
> Besides some nits and a couple questions, this looks to me. I'll try to
> find some time to experiment with it as well.
> 
> Thanks,
> drew

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Re: [PATCH v2 3/3] RISC-V: Add arch functions to support hibernation/suspend-to-disk

[Andrew Jones]

On Tue, Jan 10, 2023 at 08:37:01AM +0000, JeeHeng Sia wrote:
> 
> 
> > -----Original Message-----
> > From: Andrew Jones <ajones@ventanamicro.com>
> > Sent: Tuesday, 10 January, 2023 3:36 AM
> > To: JeeHeng Sia <jeeheng.sia@starfivetech.com>
> > Cc: paul.walmsley@sifive.com; palmer@dabbelt.com;
> > aou@eecs.berkeley.edu; linux-riscv@lists.infradead.org; linux-
> > kernel@vger.kernel.org; Leyfoon Tan <leyfoon.tan@starfivetech.com>;
> > Mason Huo <mason.huo@starfivetech.com>
> > Subject: Re: [PATCH v2 3/3] RISC-V: Add arch functions to support
> > hibernation/suspend-to-disk
> > 
> > On Mon, Jan 09, 2023 at 02:24:07PM +0800, 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_hibernation_header_restore() and arch_hibernation_header_save()
> > > functions are implemented to prevent kernel crash when resume,
> > > the kernel built version is saved into the hibernation image header
> > > to making sure only the same kernel is restore when resume.
> > 
> > Why does it crash with the generic version check?
> The kernel could have different device driver enabled and the device drivers would find itself running in a different address space if restore with different kernel version.

That part I understood, but I was wondering why the generic check which
compares kernel version and more wasn't sufficient. I answered my own
question though. Extra data needs to be stored to the header (hartid,
satp, etc.), so we need an arch-specific hibernation header. However we
*still* need the version for the version check, so some of the generic
check is reproduced in the arch-specific header. Please update the commit
message with this more detailed explanation.

...
> > > +extern int in_suspend;
> > 
> > This declaration could be in arch/riscv/kernel/hibernate.c
> Can't declare it to the .c file because checkpatch will report error if we do so.

Error or warning? It makes more sense to me to be where it needs to be,
but it doesn't matter too much either way.

...
> > > +	/* The below code will restore the hibernated image. */
> > > +	ld	a1, HIBERN_PBE_ADDR(s4)
> > > +	ld	a0, HIBERN_PBE_ORIG(s4)
> > > +
> > > +	lui     a4, 0x1
> > > +	add     a4, a4, a0
> > > +copy:	ld      a5, 0(a1)
> > 
> > copy label should get its own line and how about changing it,
> ok
> > loop, and done to local symbol names, e.g. .Lcopy?
> I think better to use two local symbol names, i.e .Lcopy and .Ldone

Two? You currently have three labels which all serve purposes.

BTW, maybe unrolling the copy loop a bit as arm64 does with its copy_page
macro would be a good idea.

...
> > > +		sleep_cpu = -EINVAL;
> > > +		return -EINVAL;
> > > +	}
> > > +
> > > +#ifdef CONFIG_SMP
> > 
> > The #ifdef shouldn't be necessary.
> We need the #ifdef CONFIG_SMP is because the bringup_hibernate_cpu() is defined under the guardian of ifdef CONFIG_SMP.
> One will face compile error if the CONFIG_SMP was disabled for a single cpu testing.

Ah, you're right. It's interesting that arm64 doesn't appear to guard that
call.

Thanks,
drew

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Re: [PATCH v2 3/3] RISC-V: Add arch functions to support hibernation/suspend-to-disk

[Conor Dooley]

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Hey JeeHeng,

On Tue, Jan 10, 2023 at 08:37:01AM +0000, JeeHeng Sia wrote:
> > From: Andrew Jones <ajones@ventanamicro.com>
> > On Mon, Jan 09, 2023 at 02:24:07PM +0800, Sia Jee Heng wrote:

> > > +/* Helper parameters that help us to restore the image.
> > 
> > Separate line for /*
> ok

I'm not sure why this one struct has an actual description that
resembles kerneldoc, when nothing else does - but why not make it
actually kerneldoc, as you're almost there as things stand:
https://docs.kernel.org/doc-guide/kernel-doc.html#structure-union-and-enumeration-documentation

> > > + * @hartid: To make sure same boot_cpu executing 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.

^^ also your mail client is doing some really odd things wrapping wise.

> > > +static unsigned long temp_pgtable_map_pmd(pmd_t *pmdp, unsigned
> > long vaddr, pgprot_t prot)
> > > +{
> > > +	uintptr_t pmd_idx = pmd_index(vaddr);
> > > +	pte_t *ptep;
> > > +
> > > +	if (pmd_none(pmdp[pmd_idx])) {
> > > +		ptep = (pte_t *) get_safe_page(GFP_ATOMIC);
> > 
> > No space between cast and function. Same comment for following functions.
> > I thought checkpatch complained about that.
> Ok. But it is weird that checkpatch doesn't report the issue.

It does:
20:08:17 conor /stuff/linux$ ./scripts/checkpatch.pl --strict --terse -g HEAD~3..HEAD
7481f133eb0310496742c27d15a20fdd2c499d29:97: CHECK: Alignment should match open parenthesis
[...]
7481f133eb0310496742c27d15a20fdd2c499d29:370: CHECK: No space is necessary after a cast
[...]
7481f133eb0310496742c27d15a20fdd2c499d29:460: CHECK: No space is necessary after a cast
7481f133eb0310496742c27d15a20fdd2c499d29:467: CHECK: No space is necessary after a cast
7481f133eb0310496742c27d15a20fdd2c499d29:475: CHECK: Blank lines aren't necessary after an open brace '{'
7481f133eb0310496742c27d15a20fdd2c499d29:480: CHECK: No space is necessary after a cast
7481f133eb0310496742c27d15a20fdd2c499d29:487: CHECK: No space is necessary after a cast
7481f133eb0310496742c27d15a20fdd2c499d29:499: CHECK: No space is necessary after a cast
7481f133eb0310496742c27d15a20fdd2c499d29:506: CHECK: No space is necessary after a cast
7481f133eb0310496742c27d15a20fdd2c499d29:518: CHECK: No space is necessary after a cast
7481f133eb0310496742c27d15a20fdd2c499d29:525: CHECK: No space is necessary after a cast
7481f133eb0310496742c27d15a20fdd2c499d29:577: CHECK: No space is necessary after a cast
7481f133eb0310496742c27d15a20fdd2c499d29:591: CHECK: Alignment should match open parenthesis
7481f133eb0310496742c27d15a20fdd2c499d29:596: CHECK: Alignment should match open parenthesis
total: 0 errors, 1 warnings, 21 checks, 545 lines checked

The patchwork automation seems to have ignored this patchset for some
reason. It was stuck on a patchset for some reason and this one may
have got skipped when I tried to sort that out.
Ordinarily, you'd see it complaining about these sorts of things.

Thanks,
Conor.


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RE: [PATCH v2 3/3] RISC-V: Add arch functions to support hibernation/suspend-to-disk

[JeeHeng Sia]

> -----Original Message-----
> From: Conor Dooley <conor@kernel.org>
> Sent: Wednesday, 11 January, 2023 4:22 AM
> To: JeeHeng Sia <jeeheng.sia@starfivetech.com>
> Cc: Andrew Jones <ajones@ventanamicro.com>; paul.walmsley@sifive.com; palmer@dabbelt.com; aou@eecs.berkeley.edu; linux-
> riscv@lists.infradead.org; linux-kernel@vger.kernel.org; Leyfoon Tan <leyfoon.tan@starfivetech.com>; Mason Huo
> <mason.huo@starfivetech.com>
> Subject: Re: [PATCH v2 3/3] RISC-V: Add arch functions to support hibernation/suspend-to-disk
> 
> Hey JeeHeng,
> 
> On Tue, Jan 10, 2023 at 08:37:01AM +0000, JeeHeng Sia wrote:
> > > From: Andrew Jones <ajones@ventanamicro.com>
> > > On Mon, Jan 09, 2023 at 02:24:07PM +0800, Sia Jee Heng wrote:
> 
> > > > +/* Helper parameters that help us to restore the image.
> > >
> > > Separate line for /*
> > ok
> 
> I'm not sure why this one struct has an actual description that
> resembles kerneldoc, when nothing else does - but why not make it
> actually kerneldoc, as you're almost there as things stand:
> https://docs.kernel.org/doc-guide/kernel-doc.html#structure-union-and-enumeration-documentation
Thanks. This is a good info, will work on it.
> 
> > > > + * @hartid: To make sure same boot_cpu executing 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.
> 
> ^^ also your mail client is doing some really odd things wrapping wise.
Oops. Hope I have fixed it in this round..
> 
> > > > +static unsigned long temp_pgtable_map_pmd(pmd_t *pmdp, unsigned
> > > long vaddr, pgprot_t prot)
> > > > +{
> > > > +	uintptr_t pmd_idx = pmd_index(vaddr);
> > > > +	pte_t *ptep;
> > > > +
> > > > +	if (pmd_none(pmdp[pmd_idx])) {
> > > > +		ptep = (pte_t *) get_safe_page(GFP_ATOMIC);
> > >
> > > No space between cast and function. Same comment for following functions.
> > > I thought checkpatch complained about that.
> > Ok. But it is weird that checkpatch doesn't report the issue.
> 
> It does:
ok, will double check again.
> 20:08:17 conor /stuff/linux$ ./scripts/checkpatch.pl --strict --terse -g HEAD~3..HEAD
> 7481f133eb0310496742c27d15a20fdd2c499d29:97: CHECK: Alignment should match open parenthesis
> [...]
> 7481f133eb0310496742c27d15a20fdd2c499d29:370: CHECK: No space is necessary after a cast
> [...]
> 7481f133eb0310496742c27d15a20fdd2c499d29:460: CHECK: No space is necessary after a cast
> 7481f133eb0310496742c27d15a20fdd2c499d29:467: CHECK: No space is necessary after a cast
> 7481f133eb0310496742c27d15a20fdd2c499d29:475: CHECK: Blank lines aren't necessary after an open brace '{'
> 7481f133eb0310496742c27d15a20fdd2c499d29:480: CHECK: No space is necessary after a cast
> 7481f133eb0310496742c27d15a20fdd2c499d29:487: CHECK: No space is necessary after a cast
> 7481f133eb0310496742c27d15a20fdd2c499d29:499: CHECK: No space is necessary after a cast
> 7481f133eb0310496742c27d15a20fdd2c499d29:506: CHECK: No space is necessary after a cast
> 7481f133eb0310496742c27d15a20fdd2c499d29:518: CHECK: No space is necessary after a cast
> 7481f133eb0310496742c27d15a20fdd2c499d29:525: CHECK: No space is necessary after a cast
> 7481f133eb0310496742c27d15a20fdd2c499d29:577: CHECK: No space is necessary after a cast
> 7481f133eb0310496742c27d15a20fdd2c499d29:591: CHECK: Alignment should match open parenthesis
> 7481f133eb0310496742c27d15a20fdd2c499d29:596: CHECK: Alignment should match open parenthesis
> total: 0 errors, 1 warnings, 21 checks, 545 lines checked
> 
> The patchwork automation seems to have ignored this patchset for some
> reason. It was stuck on a patchset for some reason and this one may
> have got skipped when I tried to sort that out.
> Ordinarily, you'd see it complaining about these sorts of things.
> 
> Thanks,
> Conor.


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