Message-ID: <20190321093920.beng2d3tbfvydbud@rric.localdomain>
Date:   Thu, 21 Mar 2019 09:39:28 +0000
From:   Robert Richter <rrichter@...vell.com>
To:     Ard Biesheuvel <ard.biesheuvel@...aro.org>
CC:     Tony Luck <tony.luck@...el.com>, Fenghua Yu <fenghua.yu@...el.com>,
        "Thomas Gleixner" <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "Borislav Petkov" <bp@...en8.de>, "H. Peter Anvin" <hpa@...or.com>,
        "x86@...nel.org" <x86@...nel.org>,
        Jean Delvare <jdelvare@...e.com>,
        Marcin Benka <mbenka@...vell.com>,
        "linux-ia64@...r.kernel.org" <linux-ia64@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>
Subject: Re: [PATCH v2] efi: Unify dmi setup code over architectures
 arm/arm64, io64 and x86

On 20.03.19 23:02:09, Ard Biesheuvel wrote:
> On Wed, 20 Mar 2019 at 16:23, Robert Richter <rrichter@...vell.com> wrote:
> >
> > On 20.03.19 14:16:07, Robert Richter wrote:
> > > On 20.03.19 13:05:37, Robert Richter wrote:
> > > > @@ -167,6 +167,7 @@ static int __init arm_dmi_init(void)
> > > >      * itself, depends on dmi_scan_machine() having been called already.
> > > >      */
> > > >     dmi_scan_machine();
> > > > +   dmi_memdev_walk();
> > > >     if (dmi_available)
> > > >             dmi_set_dump_stack_arch_desc();
> > > >     return 0;
> > >
> > > After
> > >
> > >  [PATCH] efi/arm: Show SMBIOS bank/device location in cper and
> > >   ghes error logs
> > >
> > > wents in for arm/arm64, we can unify the code. See patch below.
> >
> > V2 with the fix in arm_dmi_init() below.
> >
> > -Robert
> >
> >
> > -- >8 --
> > From: Robert Richter <rrichter@...vell.com>
> > Subject: [PATCH v2] efi: Unify dmi setup code over architectures arm/arm64,
> >  io64 and x86
> >
> > All architectures (arm/arm64, io64 and x86) do the same here, so unify
> > the code.
> >
> > Note: We do not need to call dump_stack_set_arch_desc() in case of
> > !dmi_available. Both strings, dmi_ids_string and dump_stack_arch_
> > desc_str are initialized zero and thus nothing would change.
> >
> 
> I don't understand the last sentence - we do not need to call
> dump_stack_set_arch_desc() when !dmi_available, but we do so anyway,
> right? Doesn't that wipe the arch description we set based on the DT
> machine name?

No, in dmi_setup() we exit early when !dmi_available. So for arm/arm64
nothing changed. But for x86 and ia64 we no longer call dump_stack_
set_arch_desc() in this case. This is ok since both strings,
dmi_ids_string and dump_stack_arch_desc_str, are initialized zero and
copying one to the other does not change anything.

-Robert

> 
> > Signed-off-by: Robert Richter <rrichter@...vell.com>
> > ---
> >  arch/ia64/kernel/setup.c           |  4 +---
> >  arch/x86/kernel/setup.c            |  6 ++----
> >  drivers/firmware/dmi_scan.c        | 28 +++++++++++++++-------------
> >  drivers/firmware/efi/arm-runtime.c |  7 ++-----
> >  include/linux/dmi.h                |  8 ++------
> >  5 files changed, 22 insertions(+), 31 deletions(-)
> >
> > diff --git a/arch/ia64/kernel/setup.c b/arch/ia64/kernel/setup.c
> > index 583a3746d70b..c9cfa760cd57 100644
> > --- a/arch/ia64/kernel/setup.c
> > +++ b/arch/ia64/kernel/setup.c
> > @@ -1058,9 +1058,7 @@ check_bugs (void)
> >
> >  static int __init run_dmi_scan(void)
> >  {
> > -       dmi_scan_machine();
> > -       dmi_memdev_walk();
> > -       dmi_set_dump_stack_arch_desc();
> > +       dmi_setup();
> >         return 0;
> >  }
> >  core_initcall(run_dmi_scan);
> > diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> > index 3d872a527cd9..3773905cd2c1 100644
> > --- a/arch/x86/kernel/setup.c
> > +++ b/arch/x86/kernel/setup.c
> > @@ -1005,13 +1005,11 @@ void __init setup_arch(char **cmdline_p)
> >         if (efi_enabled(EFI_BOOT))
> >                 efi_init();
> >
> > -       dmi_scan_machine();
> > -       dmi_memdev_walk();
> > -       dmi_set_dump_stack_arch_desc();
> > +       dmi_setup();
> >
> >         /*
> >          * VMware detection requires dmi to be available, so this
> > -        * needs to be done after dmi_scan_machine(), for the boot CPU.
> > +        * needs to be done after dmi_setup(), for the boot CPU.
> >          */
> >         init_hypervisor_platform();
> >
> > diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c
> > index 099d83e4e910..fae2d5c43314 100644
> > --- a/drivers/firmware/dmi_scan.c
> > +++ b/drivers/firmware/dmi_scan.c
> > @@ -416,11 +416,8 @@ static void __init save_mem_devices(const struct dmi_header *dm, void *v)
> >         nr++;
> >  }
> >
> > -void __init dmi_memdev_walk(void)
> > +static void __init dmi_memdev_walk(void)
> >  {
> > -       if (!dmi_available)
> > -               return;
> > -
> >         if (dmi_walk_early(count_mem_devices) == 0 && dmi_memdev_nr) {
> >                 dmi_memdev = dmi_alloc(sizeof(*dmi_memdev) * dmi_memdev_nr);
> >                 if (dmi_memdev)
> > @@ -614,7 +611,7 @@ static int __init dmi_smbios3_present(const u8 *buf)
> >         return 1;
> >  }
> >
> > -void __init dmi_scan_machine(void)
> > +static void __init dmi_scan_machine(void)
> >  {
> >         char __iomem *p, *q;
> >         char buf[32];
> > @@ -769,15 +766,20 @@ static int __init dmi_init(void)
> >  subsys_initcall(dmi_init);
> >
> >  /**
> > - * dmi_set_dump_stack_arch_desc - set arch description for dump_stack()
> > + *     dmi_setup - scan and setup DMI system information
> >   *
> > - * Invoke dump_stack_set_arch_desc() with DMI system information so that
> > - * DMI identifiers are printed out on task dumps.  Arch boot code should
> > - * call this function after dmi_scan_machine() if it wants to print out DMI
> > - * identifiers on task dumps.
> > + *     Scan the DMI system information. This setups DMI identifiers
> > + *     (dmi_system_id) for printing it out on task dumps and prepares
> > + *     DIMM entry information (dmi_memdev_info) from the SMBIOS table
> > + *     for using this when reporting memory errors.
> >   */
> > -void __init dmi_set_dump_stack_arch_desc(void)
> > +void __init dmi_setup(void)
> >  {
> > +       dmi_scan_machine();
> > +       if (!dmi_available)
> > +               return;
> > +
> > +       dmi_memdev_walk();
> >         dump_stack_set_arch_desc("%s", dmi_ids_string);
> >  }
> >
> > @@ -841,7 +843,7 @@ static bool dmi_is_end_of_table(const struct dmi_system_id *dmi)
> >   *     returns non zero or we hit the end. Callback function is called for
> >   *     each successful match. Returns the number of matches.
> >   *
> > - *     dmi_scan_machine must be called before this function is called.
> > + *     dmi_setup must be called before this function is called.
> >   */
> >  int dmi_check_system(const struct dmi_system_id *list)
> >  {
> > @@ -871,7 +873,7 @@ EXPORT_SYMBOL(dmi_check_system);
> >   *     Walk the blacklist table until the first match is found.  Return the
> >   *     pointer to the matching entry or NULL if there's no match.
> >   *
> > - *     dmi_scan_machine must be called before this function is called.
> > + *     dmi_setup must be called before this function is called.
> >   */
> >  const struct dmi_system_id *dmi_first_match(const struct dmi_system_id *list)
> >  {
> > diff --git a/drivers/firmware/efi/arm-runtime.c b/drivers/firmware/efi/arm-runtime.c
> > index 4a0dfe4ab829..e2ac5fa5531b 100644
> > --- a/drivers/firmware/efi/arm-runtime.c
> > +++ b/drivers/firmware/efi/arm-runtime.c
> > @@ -162,14 +162,11 @@ void efi_virtmap_unload(void)
> >  static int __init arm_dmi_init(void)
> >  {
> >         /*
> > -        * On arm64/ARM, DMI depends on UEFI, and dmi_scan_machine() needs to
> > +        * On arm64/ARM, DMI depends on UEFI, and dmi_setup() needs to
> >          * be called early because dmi_id_init(), which is an arch_initcall
> >          * itself, depends on dmi_scan_machine() having been called already.
> >          */
> > -       dmi_scan_machine();
> > -       dmi_memdev_walk();
> > -       if (dmi_available)
> > -               dmi_set_dump_stack_arch_desc();
> > +       dmi_setup();
> >         return 0;
> >  }
> >  core_initcall(arm_dmi_init);
> > diff --git a/include/linux/dmi.h b/include/linux/dmi.h
> > index c46fdb36700b..8de8c4f15163 100644
> > --- a/include/linux/dmi.h
> > +++ b/include/linux/dmi.h
> > @@ -102,9 +102,7 @@ const struct dmi_system_id *dmi_first_match(const struct dmi_system_id *list);
> >  extern const char * dmi_get_system_info(int field);
> >  extern const struct dmi_device * dmi_find_device(int type, const char *name,
> >         const struct dmi_device *from);
> > -extern void dmi_scan_machine(void);
> > -extern void dmi_memdev_walk(void);
> > -extern void dmi_set_dump_stack_arch_desc(void);
> > +extern void dmi_setup(void);
> >  extern bool dmi_get_date(int field, int *yearp, int *monthp, int *dayp);
> >  extern int dmi_get_bios_year(void);
> >  extern int dmi_name_in_vendors(const char *str);
> > @@ -122,9 +120,7 @@ static inline int dmi_check_system(const struct dmi_system_id *list) { return 0;
> >  static inline const char * dmi_get_system_info(int field) { return NULL; }
> >  static inline const struct dmi_device * dmi_find_device(int type, const char *name,
> >         const struct dmi_device *from) { return NULL; }
> > -static inline void dmi_scan_machine(void) { return; }
> > -static inline void dmi_memdev_walk(void) { }
> > -static inline void dmi_set_dump_stack_arch_desc(void) { }
> > +static inline void dmi_setup(void) { }
> >  static inline bool dmi_get_date(int field, int *yearp, int *monthp, int *dayp)
> >  {
> >         if (yearp)
> > --
> > 2.20.1
> >

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