Le 08/08/2022 à 17:43, gjoyce@xxxxxxxxxxxxxxxxxx a écrit :
> From: Greg Joyce <gjoyce@xxxxxxxxxxxxxxxxxx>
>
> Generic kernel subsystems may rely on platform specific persistent
> KeyStore to store objects containing sensitive key material. In such case,
> they need to access architecture specific functions to perform read/write
> operations on these variables.
>
> Define the generic variable read/write prototypes to be implemented by
> architecture specific versions. The default(weak) implementations of
> these prototypes return -EOPNOTSUPP unless overridden by architecture
> versions.
>
> Signed-off-by: Greg Joyce <gjoyce@xxxxxxxxxxxxxxxxxx>
> ---
> include/linux/arch_vars.h | 23 +++++++++++++++++++++++
> lib/Makefile | 2 +-
> lib/arch_vars.c | 25 +++++++++++++++++++++++++
> 3 files changed, 49 insertions(+), 1 deletion(-)
> create mode 100644 include/linux/arch_vars.h
> create mode 100644 lib/arch_vars.c
>
> diff --git a/include/linux/arch_vars.h b/include/linux/arch_vars.h
> new file mode 100644
> index 000000000000..9c280ff9432e
> --- /dev/null
> +++ b/include/linux/arch_vars.h
> @@ -0,0 +1,23 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Platform variable opearations.
Is it platform specific or architecture specific ?
> + *
> + * Copyright (C) 2022 IBM Corporation
> + *
> + * These are the accessor functions (read/write) for architecture specific
> + * variables. Specific architectures can provide overrides.
"variables" is a very generic word which I think doesn't match what you
want to do.
For me "variables" are local variables and global variables in a C file.
Here it seems to be something completely different hence the name is
really meaningfull and misleading.
> + *
> + */
> +
> +#include <linux/kernel.h>
> +
> +enum arch_variable_type {
arch_variable_type ? What's that ? variable types are char, short, long,
long long, etc ...
> + ARCH_VAR_OPAL_KEY = 0, /* SED Opal Authentication Key */
> + ARCH_VAR_OTHER = 1, /* Other type of variable */
> + ARCH_VAR_MAX = 1, /* Maximum type value */
> +};
Why the hell do you need an enum for two values only ?
> +
> +int arch_read_variable(enum arch_variable_type type, char *varname,
> + void *varbuf, u_int *varlen);
> +int arch_write_variable(enum arch_variable_type type, char *varname,
> + void *varbuf, u_int varlen);
> diff --git a/lib/Makefile b/lib/Makefile
> index f99bf61f8bbc..b90c4cb0dbbb 100644
> --- a/lib/Makefile
> +++ b/lib/Makefile
> @@ -48,7 +48,7 @@ obj-y += bcd.o sort.o parser.o debug_locks.o random32.o \
> bsearch.o find_bit.o llist.o memweight.o kfifo.o \
> percpu-refcount.o rhashtable.o \
> once.o refcount.o usercopy.o errseq.o bucket_locks.o \
> - generic-radix-tree.o
> + generic-radix-tree.o arch_vars.o
> obj-$(CONFIG_STRING_SELFTEST) += test_string.o
> obj-y += string_helpers.o
> obj-$(CONFIG_TEST_STRING_HELPERS) += test-string_helpers.o
> diff --git a/lib/arch_vars.c b/lib/arch_vars.c
> new file mode 100644
> index 000000000000..e6f16d7d09c1
> --- /dev/null
> +++ b/lib/arch_vars.c
The name is meaningless, too generic.
> @@ -0,0 +1,25 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Platform variable operations.
platform versus architecture ?
> + *
> + * Copyright (C) 2022 IBM Corporation
> + *
> + * These are the accessor functions (read/write) for architecture specific
> + * variables. Specific architectures can provide overrides.
> + *
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/arch_vars.h>
> +
> +int __weak arch_read_variable(enum arch_variable_type type, char *varname,
> + void *varbuf, u_int *varlen)
Sorry, to read a variable, I use READ_ONCE or I read it directly.
> +{
> + return -EOPNOTSUPP;
> +}
> +
> +int __weak arch_write_variable(enum arch_variable_type type, char *varname,
> + void *varbuf, u_int varlen)
> +{
> + return -EOPNOTSUPP;
> +}
