linux-kernel - Re: [PATCH 2/2] x86/acpi: Call acpi_enter_sleep_state via an asmlinkage C function from assembler.

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Date:	Wed, 18 Apr 2012 21:48:14 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc:	ming.m.lin@...el.com, linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org, lenb@...nel.org,
	linux-acpi@...r.kernel.org, hpa@...or.com, x86@...nel.org
Subject: Re: [PATCH 2/2] x86/acpi: Call acpi_enter_sleep_state via an asmlinkage C function from assembler.

On Wednesday, April 18, 2012, Konrad Rzeszutek Wilk wrote:
> With commit a2ef5c4fd44ce3922435139393b89f2cce47f576
> "ACPI: Move module parameter gts and bfs to sleep.c" the
> wake_sleep_flags is required when calling acpi_enter_sleep_state.
> 
> The assembler code in wakeup_*.S did not do that. One solution
> is to call it from assembler and stick the wake_sleep_flags on
> the stack (for 32-bit) or in %esi (for 64-bit). hpa and rafael
> both suggested however to create a wrapper function to call
> acpi_enter_sleep_state and call said wrapper function
> ("acpi_enter_s3") from assembler.
> 
> For 32-bit, the acpi_enter_s3 ends up looking as so:
> 
>   push   %ebp
>   mov    %esp,%ebp
>   sub    $0x8,%esp
>   movzbl 0xc1809314,%eax [wake_sleep_flags]
>   movl   $0x3,(%esp)
>   mov    %eax,0x4(%esp)
>   call   0xc12d1fa0 <acpi_enter_sleep_state>
>   leave
>   ret
> 
> And 64-bit:
> 
>   movzbl 0x9afde1(%rip),%esi        [wake_sleep_flags]
>   push   %rbp
>   mov    $0x3,%edi
>   mov    %rsp,%rbp
>   callq  0xffffffff812e9800 <acpi_enter_sleep_state>
>   leaveq
>   retq
> 
> Suggested-by: H. Peter Anvin <hpa@...or.com>
> [v2: Remove extra assembler operations, per hpa review]
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>

Acked-by: Rafael J. Wysocki <rjw@...k.pl>

> ---
>  arch/x86/kernel/acpi/sleep.c     |    4 ++++
>  arch/x86/kernel/acpi/sleep.h     |    2 ++
>  arch/x86/kernel/acpi/wakeup_32.S |    4 +---
>  arch/x86/kernel/acpi/wakeup_64.S |    4 +---
>  4 files changed, 8 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
> index 103b6ab..146a49c 100644
> --- a/arch/x86/kernel/acpi/sleep.c
> +++ b/arch/x86/kernel/acpi/sleep.c
> @@ -24,6 +24,10 @@ unsigned long acpi_realmode_flags;
>  static char temp_stack[4096];
>  #endif
>  
> +asmlinkage void acpi_enter_s3(void)
> +{
> +	acpi_enter_sleep_state(3, wake_sleep_flags);
> +}
>  /**
>   * acpi_suspend_lowlevel - save kernel state
>   *
> diff --git a/arch/x86/kernel/acpi/sleep.h b/arch/x86/kernel/acpi/sleep.h
> index fe5fdda..d68677a 100644
> --- a/arch/x86/kernel/acpi/sleep.h
> +++ b/arch/x86/kernel/acpi/sleep.h
> @@ -3,6 +3,7 @@
>   */
>  
>  #include <asm/trampoline.h>
> +#include <linux/linkage.h>
>  
>  extern unsigned long saved_video_mode;
>  extern long saved_magic;
> @@ -10,6 +11,7 @@ extern long saved_magic;
>  extern int wakeup_pmode_return;
>  
>  extern u8 wake_sleep_flags;
> +extern asmlinkage void acpi_enter_s3(void);
>  
>  extern unsigned long acpi_copy_wakeup_routine(unsigned long);
>  extern void wakeup_long64(void);
> diff --git a/arch/x86/kernel/acpi/wakeup_32.S b/arch/x86/kernel/acpi/wakeup_32.S
> index 13ab720..7261083 100644
> --- a/arch/x86/kernel/acpi/wakeup_32.S
> +++ b/arch/x86/kernel/acpi/wakeup_32.S
> @@ -74,9 +74,7 @@ restore_registers:
>  ENTRY(do_suspend_lowlevel)
>  	call	save_processor_state
>  	call	save_registers
> -	pushl	$3
> -	call	acpi_enter_sleep_state
> -	addl	$4, %esp
> +	call	acpi_enter_s3
>  
>  #	In case of S3 failure, we'll emerge here.  Jump
>  # 	to ret_point to recover
> diff --git a/arch/x86/kernel/acpi/wakeup_64.S b/arch/x86/kernel/acpi/wakeup_64.S
> index 8ea5164..014d1d2 100644
> --- a/arch/x86/kernel/acpi/wakeup_64.S
> +++ b/arch/x86/kernel/acpi/wakeup_64.S
> @@ -71,9 +71,7 @@ ENTRY(do_suspend_lowlevel)
>  	movq	%rsi, saved_rsi
>  
>  	addq	$8, %rsp
> -	movl	$3, %edi
> -	xorl	%eax, %eax
> -	call	acpi_enter_sleep_state
> +	call	acpi_enter_s3
>  	/* in case something went wrong, restore the machine status and go on */
>  	jmp	resume_point
>  
> 

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