[PATCH v2 1/2] smbios: add parsing API

[Bin Meng]

On Mon, Nov 2, 2020 at 5:21 PM Christian Gmeiner
<christian.gmeiner at gmail.com> wrote:
>
> ping and a short question: would it make more sense to put the parsing
> code into smbios.c and unconditionally compile it?

I think it's fine to leave this as a separte module.

Reviewed-by: Bin Meng <bmeng.cn at gmail.com>

But nits below:

>
> Am Mi., 7. Okt. 2020 um 14:33 Uhr schrieb Christian Gmeiner
> <christian.gmeiner at gmail.com>:
> >
> > Add an very simple API to be able to access SMBIOS strings

an -> a

> > like vendor, model and bios version.
> >
> > Signed-off-by: Christian Gmeiner <christian.gmeiner at gmail.com>
> > ---
> >  include/smbios.h    | 27 +++++++++++++
> >  lib/Kconfig         |  6 +++
> >  lib/Makefile        |  1 +
> >  lib/smbios-parser.c | 96 +++++++++++++++++++++++++++++++++++++++++++++
> >  4 files changed, 130 insertions(+)
> >  create mode 100644 lib/smbios-parser.c
> >
> > diff --git a/include/smbios.h b/include/smbios.h
> > index 97b9ddce23..ed60c00fae 100644
> > --- a/include/smbios.h
> > +++ b/include/smbios.h
> > @@ -237,4 +237,31 @@ typedef int (*smbios_write_type)(ulong *addr, int handle);
> >   */
> >  ulong write_smbios_table(ulong addr);
> >
> > +/**
> > + * smbios_entry() - Get a vaild struct smbios_entry pointer

typo: valid

> > + *
> > + * @address:   address where smbios tables is located
> > + * @size:      size of smbios table
> > + * @return:    NULL or a valid pointer to a struct smbios_entry
> > + */
> > +const struct smbios_entry *smbios_entry(u64 address, u32 size);
> > +
> > +/**
> > + * smbios_header() - Search for SMBIOS header type
> > + *
> > + * @entry:     pointer to a struct smbios_entry
> > + * @type:      SMBIOS type
> > + * @return:    NULL or a valid pointer to a struct smbios_header
> > + */
> > +const struct smbios_header *smbios_header(const struct smbios_entry *entry, int type);
> > +
> > +/**
> > + * smbios_string() - Return string from SMBIOS
> > + *
> > + * @header:    pointer to struct smbios_header
> > + * @index:     string index
> > + * @return:    NULL or a valid const char pointer
> > + */
> > +const char *smbios_string(const struct smbios_header *header, int index);
> > +
> >  #endif /* _SMBIOS_H_ */
> > diff --git a/lib/Kconfig b/lib/Kconfig
> > index 8efb154f73..c92131b7bc 100644
> > --- a/lib/Kconfig
> > +++ b/lib/Kconfig
> > @@ -667,6 +667,12 @@ config OID_REGISTRY
> >         help
> >           Enable fast lookup object identifier registry.
> >
> > +config SMBIOS_PARSER
> > +       bool "SMBIOS parser"
> > +       default n

nits: remove default n, because it is Kconfig default

> > +       help
> > +         A simple parser for SMBIOS data.
> > +
> >  source lib/efi/Kconfig
> >  source lib/efi_loader/Kconfig
> >  source lib/optee/Kconfig
> > diff --git a/lib/Makefile b/lib/Makefile
> > index 0cd7bea282..0383fddf2c 100644
> > --- a/lib/Makefile
> > +++ b/lib/Makefile
> > @@ -37,6 +37,7 @@ obj-$(CONFIG_FIT) += fdtdec_common.o
> >  obj-$(CONFIG_TEST_FDTDEC) += fdtdec_test.o
> >  obj-$(CONFIG_GZIP_COMPRESSED) += gzip.o
> >  obj-$(CONFIG_GENERATE_SMBIOS_TABLE) += smbios.o
> > +obj-$(CONFIG_SMBIOS_PARSER) += smbios-parser.o
> >  obj-$(CONFIG_IMAGE_SPARSE) += image-sparse.o
> >  obj-y += ldiv.o
> >  obj-$(CONFIG_XXHASH) += xxhash.o
> > diff --git a/lib/smbios-parser.c b/lib/smbios-parser.c
> > new file mode 100644
> > index 0000000000..b89f988ef9
> > --- /dev/null
> > +++ b/lib/smbios-parser.c
> > @@ -0,0 +1,96 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * Copyright (C) 2020, Bachmann electronic GmbH
> > + */
> > +
> > +#include <common.h>
> > +#include <smbios.h>
> > +
> > +static inline int verify_checksum(const struct smbios_entry *e)
> > +{
> > +       /*
> > +        * Checksums for SMBIOS tables are calculated to have a value, so that
> > +        * the sum over all bytes yields zero (using unsigned 8 bit arithmetic).
> > +        */
> > +       u8 *byte = (u8 *)e;
> > +       u8 sum = 0;
> > +
> > +       for (int i = 0; i < e->length; i++)
> > +               sum += byte[i];
> > +
> > +       return sum;
> > +}
> > +
> > +const struct smbios_entry *smbios_entry(u64 address, u32 size)
> > +{
> > +       const struct smbios_entry *entry = (struct smbios_entry *)(uintptr_t)address;
> > +
> > +       if (!address | !size)
> > +               return NULL;
> > +
> > +       if (memcmp(entry->anchor, "_SM_", 4))
> > +               return NULL;
> > +
> > +       if (verify_checksum(entry))
> > +               return NULL;
> > +
> > +       return entry;
> > +}
> > +
> > +static const struct smbios_header *next_header(const struct smbios_header *curr)
> > +{
> > +       u8 *pos = ((u8 *)curr) + curr->length;
> > +
> > +       /* search for _double_ NULL bytes */
> > +       while (!((*pos == 0) && (*(pos + 1) == 0)))
> > +               pos++;
> > +
> > +       /* step behind the double NULL bytes */
> > +       pos += 2;
> > +
> > +       return (struct smbios_header *)pos;
> > +}
> > +
> > +const struct smbios_header *smbios_header(const struct smbios_entry *entry, int type)
> > +{
> > +       const unsigned int num_header = entry->struct_count;
> > +       const struct smbios_header *header = (struct smbios_header *)entry->struct_table_address;
> > +
> > +       for (unsigned int i = 0; i < num_header; i++) {
> > +               if (header->type == type)
> > +                       return header;
> > +
> > +               header = next_header(header);
> > +       }
> > +
> > +       return NULL;
> > +}
> > +
> > +static const char *string_from_smbios_table(const struct smbios_header *header,
> > +                                           int idx)
> > +{
> > +       unsigned int i = 1;
> > +       u8 *pos;
> > +
> > +       if (!header)
> > +               return NULL;
> > +
> > +       pos = ((u8 *)header) + header->length;
> > +
> > +       while (i < idx) {
> > +               if (*pos == 0x0)
> > +                       i++;
> > +
> > +               pos++;
> > +       }
> > +
> > +       return (const char *)pos;
> > +}
> > +
> > +const char *smbios_string(const struct smbios_header *header, int index)
> > +{
> > +       if (!header)
> > +               return NULL;
> > +
> > +       return string_from_smbios_table(header, index);
> > +}
> > --
> > 2.28.0

Regards,
Bin