RE: [PATCH v4 2/4] RISC-V: Factor out common code of __cpu_resume_enter()

[JeeHeng Sia]

> -----Original Message-----
> From: Andrew Jones <ajones@xxxxxxxxxxxxxxxx>
> Sent: Thursday, 23 February, 2023 2:52 PM
> To: JeeHeng Sia <jeeheng.sia@xxxxxxxxxxxxxxxx>
> Cc: paul.walmsley@xxxxxxxxxx; palmer@xxxxxxxxxxx; aou@xxxxxxxxxxxxxxxxx; linux-riscv@xxxxxxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; Leyfoon Tan <leyfoon.tan@xxxxxxxxxxxxxxxx>; Mason Huo <mason.huo@xxxxxxxxxxxxxxxx>
> Subject: Re: [PATCH v4 2/4] RISC-V: Factor out common code of __cpu_resume_enter()
> 
> On Tue, Feb 21, 2023 at 10:35:21AM +0800, Sia Jee Heng wrote:
> > The cpu_resume() function is very similar for the suspend to disk and
> > suspend to ram cases. Factor out the common code into restore_csr macro
> > and restore_reg macro.
> >
> > Signed-off-by: Sia Jee Heng <jeeheng.sia@xxxxxxxxxxxxxxxx>
> > ---
> >  arch/riscv/include/asm/assembler.h | 62 ++++++++++++++++++++++++++++++
> >  arch/riscv/kernel/suspend_entry.S  | 34 ++--------------
> >  2 files changed, 65 insertions(+), 31 deletions(-)
> >  create mode 100644 arch/riscv/include/asm/assembler.h
> >
> > diff --git a/arch/riscv/include/asm/assembler.h b/arch/riscv/include/asm/assembler.h
> > new file mode 100644
> > index 000000000000..727a97735493
> > --- /dev/null
> > +++ b/arch/riscv/include/asm/assembler.h
> > @@ -0,0 +1,62 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only */
> > +/*
> > + * Copyright (C) 2023 StarFive Technology Co., Ltd.
> > + *
> > + * Author: Jee Heng Sia <jeeheng.sia@xxxxxxxxxxxxxxxx>
> > + */
> > +
> > +#ifndef __ASSEMBLY__
> > +#error "Only include this from assembly code"
> > +#endif
> > +
> > +#ifndef __ASM_ASSEMBLER_H
> > +#define __ASM_ASSEMBLER_H
> > +
> > +#include <asm/asm.h>
> > +#include <asm/asm-offsets.h>
> > +#include <asm/csr.h>
> > +
> > +/*
> > + * restore_csr - restore hart's CSR value
> > + */
> > +	.macro restore_csr
> 
> Since there are more than one, 'restore_csrs' would be more appropriate
> and s/CSR value/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
> > +	.endm
> > +
> > +/*
> > + * restore_reg - Restore registers (except A0 and T0-T6)
> > + */
> > +	.macro restore_reg
> 
> restore_regs
> 
> > +		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)
> > +	.endm
> > +
> > +#endif	/* __ASM_ASSEMBLER_H */
> > diff --git a/arch/riscv/kernel/suspend_entry.S b/arch/riscv/kernel/suspend_entry.S
> > index aafcca58c19d..74a8fab8e0f6 100644
> > --- a/arch/riscv/kernel/suspend_entry.S
> > +++ b/arch/riscv/kernel/suspend_entry.S
> > @@ -7,6 +7,7 @@
> >  #include <linux/linkage.h>
> >  #include <asm/asm.h>
> >  #include <asm/asm-offsets.h>
> > +#include <asm/assembler.h>
> >  #include <asm/csr.h>
> >  #include <asm/xip_fixup.h>
> >
> > @@ -83,39 +84,10 @@ ENTRY(__cpu_resume_enter)
> >  	add	a0, a1, zero
> >
> >  	/* 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_csr
> >
> >  	/* 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)
> > +	restore_reg
> >
> >  	/* Return zero value */
> >  	add	a0, zero, zero
> > --
> > 2.34.1
> >
> 
> Otherwise,
> 
> Reviewed-by: Andrew Jones <ajones@xxxxxxxxxxxxxxxx>
noted with thanks
> 
> Thanks,
> drew