Re: [PATCH AUTOSEL 4.14 02/15] s390/hibernate: fix error handling when suspend cpu != resume cpu

Pavel Machek
2018-10-26T09:05:43Z

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On Mon 2018-10-22 06:20:13, Sasha Levin wrote:
> From: Gerald Schaefer <gerald.schaefer@de.ibm.com>
>
> [ Upstream commit 55a5542a546238354d1f209f794414168cf8c71d ]
>
> The resume code checks if the resume cpu is the same as the suspend cpu.
> If not, and if it is also not possible to switch to the suspend cpu, an
> error message should be printed and the resume process should be stopped
> by loading a disabled wait psw.
>
> The current logic is broken in multiple ways, the message is never printed,
> and the disabled wait psw never loaded because the kernel panics before that:
> - sam31 and SIGP_SET_ARCHITECTURE to ESA mode is wrong, this will break
> on the first 64bit instruction in sclp_early_printk().
> - The init stack should be used, but the stack pointer is not set up correctly
> (missing aghi %r15,-STACK_FRAME_OVERHEAD).
> - __sclp_early_printk() checks the sclp_init_state. If it is not
> sclp_init_state_uninitialized, it simply returns w/o printing anything.
> In the resumed kernel however, sclp_init_state will never be uninitialized.

Stable patches should fix one bug, and one bug only.

pavel
> ---
> arch/s390/include/asm/sclp.h | 3 ++-
> arch/s390/kernel/early_printk.c | 2 +-
> arch/s390/kernel/swsusp.S | 8 +++-----
> drivers/s390/char/sclp_early_core.c | 11 ++++++++---
> 4 files changed, 14 insertions(+), 10 deletions(-)
>
> diff --git a/arch/s390/include/asm/sclp.h b/arch/s390/include/asm/sclp.h
> index d3c1a8a2e3ad..d90a84770ce5 100644
> --- a/arch/s390/include/asm/sclp.h
> +++ b/arch/s390/include/asm/sclp.h
> @@ -107,7 +107,8 @@ int sclp_early_get_core_info(struct sclp_core_info *info);
> void sclp_early_get_ipl_info(struct sclp_ipl_info *info);
> void sclp_early_detect(void);
> void sclp_early_printk(const char *s);
> -void __sclp_early_printk(const char *s, unsigned int len);
> +void sclp_early_printk_force(const char *s);
> +void __sclp_early_printk(const char *s, unsigned int len, unsigned int force);
>
> int _sclp_get_core_info(struct sclp_core_info *info);
> int sclp_core_configure(u8 core);
> diff --git a/arch/s390/kernel/early_printk.c b/arch/s390/kernel/early_printk.c
> index 9431784d7796..40c1dfec944e 100644
> --- a/arch/s390/kernel/early_printk.c
> +++ b/arch/s390/kernel/early_printk.c
> @@ -10,7 +10,7 @@
>
> static void sclp_early_write(struct console *con, const char *s, unsigned int len)
> {
> - __sclp_early_printk(s, len);
> + __sclp_early_printk(s, len, 0);
> }
>
> static struct console sclp_early_console = {
> diff --git a/arch/s390/kernel/swsusp.S b/arch/s390/kernel/swsusp.S
> index a049a7b9d6e8..c1a080b11ae9 100644
> --- a/arch/s390/kernel/swsusp.S
> +++ b/arch/s390/kernel/swsusp.S
> @@ -198,12 +198,10 @@ pgm_check_entry:
>
> /* Suspend CPU not available -> panic */
> larl %r15,init_thread_union
> - ahi %r15,1<<(PAGE_SHIFT+THREAD_SIZE_ORDER)
> + aghi %r15,1<<(PAGE_SHIFT+THREAD_SIZE_ORDER)
> + aghi %r15,-STACK_FRAME_OVERHEAD
> larl %r2,.Lpanic_string
> - lghi %r1,0
> - sam31
> - sigp %r1,%r0,SIGP_SET_ARCHITECTURE
> - brasl %r14,sclp_early_printk
> + brasl %r14,sclp_early_printk_force
> larl %r3,.Ldisabled_wait_31
> lpsw 0(%r3)
> 4:
> diff --git a/drivers/s390/char/sclp_early_core.c b/drivers/s390/char/sclp_early_core.c
> index edeb2597b0b8..4daf797a6423 100644
> --- a/drivers/s390/char/sclp_early_core.c
> +++ b/drivers/s390/char/sclp_early_core.c
> @@ -188,11 +188,11 @@ static int sclp_early_setup(int disable, int *have_linemode, int *have_vt220)
> * Output one or more lines of text on the SCLP console (VT220 and /
> * or line-mode).
> */
> -void __sclp_early_printk(const char *str, unsigned int len)
> +void __sclp_early_printk(const char *str, unsigned int len, unsigned int force)
> {
> int have_linemode, have_vt220;
>
> - if (sclp_init_state != sclp_init_state_uninitialized)
> + if (!force && sclp_init_state != sclp_init_state_uninitialized)
> return;
> if (sclp_early_setup(0, &have_linemode, &have_vt220) != 0)
> return;
> @@ -205,5 +205,10 @@ void __sclp_early_printk(const char *str, unsigned int len)
>
> void sclp_early_printk(const char *str)
> {
> - __sclp_early_printk(str, strlen(str));
> + __sclp_early_printk(str, strlen(str), 0);
> +}
> +
> +void sclp_early_printk_force(const char *str)
> +{
> + __sclp_early_printk(str, strlen(str), 1);
> }

--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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