Re: [PATCH 7/9] riscv: remove duplicate macros from ptrace.h

Re: [PATCH 7/9] riscv: remove duplicate macros from ptrace.h

[Paul Walmsley]

On Thu, 11 Apr 2019, Christoph Hellwig wrote:

> No need to have two names for the same thing.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

This is probably worth cleaning up across the entire tree.  

asm-{generic,x86,arm64,powerpc}/ptrace.h all define similar GET_IP/SET_IP
macros - although it seems that arch/riscv is the only architecture that 
uses them.


- Paul


> ---
>  arch/riscv/include/asm/ptrace.h | 21 ++++++---------------
>  arch/riscv/kernel/stacktrace.c  |  8 ++++----
>  arch/riscv/kernel/traps.c       |  2 +-
>  3 files changed, 11 insertions(+), 20 deletions(-)
> 
> diff --git a/arch/riscv/include/asm/ptrace.h b/arch/riscv/include/asm/ptrace.h
> index d35ec2f41381..9c867a4bac83 100644
> --- a/arch/riscv/include/asm/ptrace.h
> +++ b/arch/riscv/include/asm/ptrace.h
> @@ -70,47 +70,38 @@ struct pt_regs {
>  
>  
>  /* Helpers for working with the instruction pointer */
> -#define GET_IP(regs) ((regs)->sepc)
> -#define SET_IP(regs, val) (GET_IP(regs) = (val))
> -
>  static inline unsigned long instruction_pointer(struct pt_regs *regs)
>  {
> -	return GET_IP(regs);
> +	return regs->sepc;
>  }
>  static inline void instruction_pointer_set(struct pt_regs *regs,
>  					   unsigned long val)
>  {
> -	SET_IP(regs, val);
> +	regs->sepc = val;
>  }
>  
>  #define profile_pc(regs) instruction_pointer(regs)
>  
>  /* Helpers for working with the user stack pointer */
> -#define GET_USP(regs) ((regs)->sp)
> -#define SET_USP(regs, val) (GET_USP(regs) = (val))
> -
>  static inline unsigned long user_stack_pointer(struct pt_regs *regs)
>  {
> -	return GET_USP(regs);
> +	return regs->sp;
>  }
>  static inline void user_stack_pointer_set(struct pt_regs *regs,
>  					  unsigned long val)
>  {
> -	SET_USP(regs, val);
> +	regs->sp =  val;
>  }
>  
>  /* Helpers for working with the frame pointer */
> -#define GET_FP(regs) ((regs)->s0)
> -#define SET_FP(regs, val) (GET_FP(regs) = (val))
> -
>  static inline unsigned long frame_pointer(struct pt_regs *regs)
>  {
> -	return GET_FP(regs);
> +	return regs->s0;
>  }
>  static inline void frame_pointer_set(struct pt_regs *regs,
>  				     unsigned long val)
>  {
> -	SET_FP(regs, val);
> +	regs->s0 = val;
>  }
>  
>  static inline unsigned long regs_return_value(struct pt_regs *regs)
> diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c
> index a4b1d94371a0..25fe0ff81f9e 100644
> --- a/arch/riscv/kernel/stacktrace.c
> +++ b/arch/riscv/kernel/stacktrace.c
> @@ -33,9 +33,9 @@ static void notrace walk_stackframe(struct task_struct *task,
>  	unsigned long fp, sp, pc;
>  
>  	if (regs) {
> -		fp = GET_FP(regs);
> -		sp = GET_USP(regs);
> -		pc = GET_IP(regs);
> +		fp = frame_pointer(regs);
> +		sp = user_stack_pointer(regs);
> +		pc = instruction_pointer(regs);
>  	} else if (task == NULL || task == current) {
>  		const register unsigned long current_sp __asm__ ("sp");
>  		fp = (unsigned long)__builtin_frame_address(0);
> @@ -83,7 +83,7 @@ static void notrace walk_stackframe(struct task_struct *task,
>  
>  	if (regs) {
>  		sp = GET_USP(regs);
> -		pc = GET_IP(regs);
> +		pc = instruction_pointer(regs);
>  	} else if (task == NULL || task == current) {
>  		const register unsigned long current_sp __asm__ ("sp");
>  		sp = current_sp;
> diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
> index 24a9333dda2c..86731a2fa218 100644
> --- a/arch/riscv/kernel/traps.c
> +++ b/arch/riscv/kernel/traps.c
> @@ -70,7 +70,7 @@ void do_trap(struct pt_regs *regs, int signo, int code,
>  	    && printk_ratelimit()) {
>  		pr_info("%s[%d]: unhandled signal %d code 0x%x at 0x" REG_FMT,
>  			tsk->comm, task_pid_nr(tsk), signo, code, addr);
> -		print_vma_addr(KERN_CONT " in ", GET_IP(regs));
> +		print_vma_addr(KERN_CONT " in ", instruction_pointer(regs));
>  		pr_cont("\n");
>  		show_regs(regs);
>  	}
> -- 
> 2.20.1
> 
> 
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv
> 

Re: [PATCH 7/9] riscv: remove duplicate macros from ptrace.h

[Christoph Hellwig]

On Thu, Apr 25, 2019 at 12:13:18PM -0700, Paul Walmsley wrote:
> 
> 
> On Thu, 11 Apr 2019, Christoph Hellwig wrote:
> 
> > No need to have two names for the same thing.
> > 
> > Signed-off-by: Christoph Hellwig <hch@lst.de>
> 
> This is probably worth cleaning up across the entire tree.  
> 
> asm-{generic,x86,arm64,powerpc}/ptrace.h all define similar GET_IP/SET_IP
> macros - although it seems that arch/riscv is the only architecture that 
> uses them.

Yes, we had that discussion before.  I've started on a series for that,
but it is unlikely to touch riscv.

Re: [PATCH 9/9] riscv: call pm_power_off from machine_halt / machine_power_off

[Paul Walmsley]

On Thu, 11 Apr 2019, Christoph Hellwig wrote:

> This way any override of pm_power_off also affects the halt path and
> we don't need additional infrastructure for it.
> 
> Also remove the pm_power_off export - at least for now we don't have
> any modular drivers overriding it.

I'd propose that we keep the pm_power_off export - both to align with 
other architectures:

$ fgrep -r pm_power_off arch/ | grep EXPORT
arch/s390/kernel/setup.c:EXPORT_SYMBOL_GPL(pm_power_off);
arch/m68k/kernel/process.c:EXPORT_SYMBOL(pm_power_off);
arch/hexagon/kernel/reset.c:EXPORT_SYMBOL(pm_power_off);
arch/ia64/kernel/process.c:EXPORT_SYMBOL(pm_power_off);
arch/sparc/kernel/process_32.c:EXPORT_SYMBOL(pm_power_off);
arch/sparc/kernel/reboot.c:EXPORT_SYMBOL(pm_power_off);
arch/sh/kernel/reboot.c:EXPORT_SYMBOL(pm_power_off);
arch/um/kernel/reboot.c:EXPORT_SYMBOL(pm_power_off);
arch/openrisc/kernel/process.c:EXPORT_SYMBOL(pm_power_off);
arch/nios2/kernel/process.c:EXPORT_SYMBOL(pm_power_off);
arch/arc/kernel/reset.c:EXPORT_SYMBOL(pm_power_off);
arch/arm/kernel/reboot.c:EXPORT_SYMBOL(pm_power_off);
arch/nds32/kernel/process.c:EXPORT_SYMBOL(pm_power_off);
arch/csky/kernel/power.c:EXPORT_SYMBOL(pm_power_off);
arch/alpha/kernel/process.c:EXPORT_SYMBOL(pm_power_off);
arch/arm64/kernel/process.c:EXPORT_SYMBOL_GPL(pm_power_off);
arch/unicore32/kernel/process.c:EXPORT_SYMBOL(pm_power_off);
arch/c6x/kernel/process.c:EXPORT_SYMBOL(pm_power_off);
arch/xtensa/kernel/process.c:EXPORT_SYMBOL(pm_power_off);
arch/h8300/kernel/process.c:EXPORT_SYMBOL(pm_power_off);
arch/powerpc/kernel/setup-common.c:EXPORT_SYMBOL_GPL(pm_power_off);
arch/mips/kernel/reset.c:EXPORT_SYMBOL(pm_power_off);
arch/riscv/kernel/reset.c:EXPORT_SYMBOL(pm_power_off);
arch/microblaze/kernel/process.c:EXPORT_SYMBOL(pm_power_off);
arch/x86/kernel/reboot.c:EXPORT_SYMBOL(pm_power_off);
arch/parisc/kernel/process.c:EXPORT_SYMBOL(pm_power_off);
$

and to make sure there's no hassle with the drivers that expect to assign 
something to it:

$ fgrep -r pm_power_off drivers/ | fgrep =  | cut -f1 -d:  | sort -u | wc -l
39
$

For what it's worth, I agree with the implied criticism that reassigning 
pm_power_off is not a good interface.  There is the obvious problem that 
more than one chunk of independent code could all try to assign to 
pm_power_off.  However, to avoid creating a RISC-V-specific mess when 
someone uses a TI PMIC driver on a RISC-V board, or tries to use ACPI with 
RISC-V, fixing that seems best done as a separate tree-wide series.

...

Replacing machine_power_off() with a call to your default_power_off() 
looks fine to me.  However I think it makes sense to change our existing 
machine_halt() (which was not added by your patch).  Looking at other 
major architectures - x86, ARM64, and ARM - they don't actually try to 
power down the system in machine_halt(), instead just entering an 
infinite loop, WFI, or calling into firmware or a hypervisor.  I'd propose 
that we align with that approach.


- Paul

> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  arch/riscv/kernel/reset.c | 15 +++++++++------
>  1 file changed, 9 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/riscv/kernel/reset.c b/arch/riscv/kernel/reset.c
> index 2a53d26ffdd6..ed637aee514b 100644
> --- a/arch/riscv/kernel/reset.c
> +++ b/arch/riscv/kernel/reset.c
> @@ -12,11 +12,15 @@
>   */
>  
>  #include <linux/reboot.h>
> -#include <linux/export.h>
>  #include <asm/sbi.h>
>  
> -void (*pm_power_off)(void) = machine_power_off;
> -EXPORT_SYMBOL(pm_power_off);
> +static void default_power_off(void)
> +{
> +	sbi_shutdown();
> +	while (1);
> +}
> +
> +void (*pm_power_off)(void) = default_power_off;
>  
>  void machine_restart(char *cmd)
>  {
> @@ -26,11 +30,10 @@ void machine_restart(char *cmd)
>  
>  void machine_halt(void)
>  {
> -	machine_power_off();
> +	pm_power_off();
>  }
>  
>  void machine_power_off(void)
>  {
> -	sbi_shutdown();
> -	while (1);
> +	pm_power_off();
>  }
> -- 
> 2.20.1
> 
> 
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv
> 

Re: [PATCH 7/9] riscv: remove duplicate macros from ptrace.h

[Paul Walmsley]

On Thu, 25 Apr 2019, Christoph Hellwig wrote:

> On Thu, Apr 25, 2019 at 12:13:18PM -0700, Paul Walmsley wrote:
> > 
> > 
> > On Thu, 11 Apr 2019, Christoph Hellwig wrote:
> > 
> > > No need to have two names for the same thing.
> > > 
> > > Signed-off-by: Christoph Hellwig <hch@lst.de>
> > 
> > This is probably worth cleaning up across the entire tree.  
> > 
> > asm-{generic,x86,arm64,powerpc}/ptrace.h all define similar GET_IP/SET_IP
> > macros - although it seems that arch/riscv is the only architecture that 
> > uses them.
> 
> Yes, we had that discussion before.  I've started on a series for that,
> but it is unlikely to touch riscv.

OK, if you're planning to post a separate series for that across the tree, 
then:

Reviewed-by: Paul Walmsley <paul.walmsley@sifive.com>

for this RISC-V patch.


- Paul