lib/firmware_table: Provide buffer length argument to cdat_table_parse()

There exist card implementations with a CDAT table using a fixed size
buffer, but with entries filled in that do not fill the whole table
length size. Then, the last entry in the CDAT table may not mark the
end of the CDAT table buffer specified by the length field in the CDAT
header. It can be shorter with trailing unused (zero'ed) data. The
actual table length is determined while reading all CDAT entries of
the table with DOE.

If the table is greater than expected (containing zero'ed trailing
data), the CDAT parser fails with:

[ 48.691717] Malformed DSMAS table length: (24:0)
[ 48.702084] [CDAT:0x00] Invalid zero length
[ 48.711460] cxl_port endpoint1: Failed to parse CDAT: -22

In addition, a check of the table buffer length is missing to prevent
an out-of-bound access then parsing the CDAT table.

Hardening code against device returning borked table. Fix that by
providing an optional buffer length argument to
acpi_parse_entries_array() that can be used by cdat_table_parse() to
propagate the buffer size down to its users to check the buffer
length. This also prevents a possible out-of-bound access mentioned.

Add a check to warn about a malformed CDAT table length.

Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: Len Brown <lenb@kernel.org>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Robert Richter <rrichter@amd.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/ZdEnopFO0Tl3t2O1@rric.localdomain
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

lib/firmware_table: tables: Add CDAT table parsing support

The CDAT table is very similar to ACPI tables when it comes to sub-table
and entry structures. The helper functions can be also used to parse the
CDAT table. Add support to the helper functions to deal with an external
CDAT table, and also handle the endieness since CDAT can be processed by a
BE host. Export a function cdat_table_parse() for CXL driver to parse
a CDAT table.

In order to minimize ACPICA code changes, __force is being utilized to deal
with the case of a big endian (BE) host parsing a CDAT. All CDAT data
structure variables are being force casted to __leX as appropriate.

Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: Len Brown <lenb@kernel.org>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/170319615131.2212653.10932785667981494238.stgit@djiang5-mobl3
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

ACPI: tables: Correct and clean up the logic of acpi_parse_entries_array()

The original intention of acpi_parse_entries_array() is to return the
number of all matching entries on success. This number may be greater than
the value of the max_entries parameter. When this happens, the function
will output a warning message, indicating that `count - max_entries`
matching entries remain unprocessed and have been ignored.

However, commit 4ceacd02f5a1 ("ACPI / table: Always count matched and
successfully parsed entries") changed this logic to return the number of
entries successfully processed by the handler. In this case, when the
max_entries parameter is not zero, the number of entries successfully
processed can never be greater than the value of max_entries. In other
words, the expression `count > max_entries` will always evaluate to false.
This means that the logic in the final if statement will never be executed.

Commit 99b0efd7c886 ("ACPI / tables: do not report the number of entries
ignored by acpi_parse_entries()") mentioned this issue, but it tried to fix
it by removing part of the warning message. This is meaningless because the
pr_warn statement will never be executed in the first place.

Commit 8726d4f44150 ("ACPI / tables: fix acpi_parse_entries_array() so it
traverses all subtables") introduced an errs variable, which is intended to
make acpi_parse_entries_array() always traverse all of the subtables,
calling as many of the callbacks as possible. However, it seems that the
commit does not achieve this goal. For example, when a handler returns an
error, none of the handlers will be called again in the subsequent
iterations. This result appears to be no different from before the change.

This patch corrects and cleans up the logic of acpi_parse_entries_array(),
making it return the number of all matching entries, rather than the number
of entries successfully processed by handlers. Additionally, if an error
occurs when executing a handler, the function will return -EINVAL immediately.

This patch should not affect existing users of acpi_parse_entries_array().

Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

ACPI: Fix ARM32 platforms compile issue introduced by fw_table changes

Linus reported that:
After commit a103f46633fd the kernel stopped compiling for
several ARM32 platforms that I am building with a bare metal
compiler. Bare metal compilers (arm-none-eabi-) don't
define __linux__.

This is because the header <acpi/platform/acenv.h> is now
in the include path for <linux/irq.h>:

CC arch/arm/kernel/irq.o
CC kernel/sysctl.o
CC crypto/api.o
In file included from ../include/acpi/acpi.h:22,
from ../include/linux/fw_table.h:29,
from ../include/linux/acpi.h:18,
from ../include/linux/irqchip.h:14,
from ../arch/arm/kernel/irq.c:25:
../include/acpi/platform/acenv.h:218:2: error: #error Unknown target environment
218 | #error Unknown target environment
| ^~~~~

The issue is caused by the introducing of splitting out the ACPI code to
support the new generic fw_table code.

Rafael suggested [1] moving the fw_table.h include in linux/acpi.h to below
the linux/mutex.h. Remove the two includes in fw_table.h. Replace
linux/fw_table.h include in fw_table.c with linux/acpi.h.

Link: https://lore.kernel.org/linux-acpi/CAJZ5v0idWdJq3JSqQWLG5q+b+b=zkEdWR55rGYEoxh7R6N8kFQ@mail.gmail.com/
Fixes: a103f46633fd ("acpi: Move common tables helper functions to common lib")
Closes: https://lore.kernel.org/linux-acpi/20231114-arm-build-bug-v1-1-458745fe32a4@linaro.org/
Reported-by: Linus Walleij <linus.walleij@linaro.org>
Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

lib/fw_table: Remove acpi_parse_entries_array() export

Stephen reports that the ACPI helper library rework,
CONFIG_FIRMWARE_TABLE, introduces a new compiler warning:

WARNING: modpost: vmlinux: acpi_parse_entries_array: EXPORT_SYMBOL used
for init symbol. Remove __init or EXPORT_SYMBOL.

Delete this export as it turns out it is unneeded, and future work wraps
this in another exported helper. Note that in general
EXPORT_SYMBOL_ACPI_LIB() is needed for exporting symbols that are marked
__init_or_acpilib, but in this case no export is required.

Fixes: a103f46633fd ("acpi: Move common tables helper functions to common lib")
Cc: Dave Jiang <dave.jiang@intel.com>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Closes: http://lore.kernel.org/r/20231030160523.670a7569@canb.auug.org.au
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/169896282222.70775.940454758280866379.stgit@dwillia2-xfh.jf.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

acpi: Move common tables helper functions to common lib

Some of the routines in ACPI driver/acpi/tables.c can be shared with
parsing CDAT. CDAT is a device-provided data structure that is formatted
similar to a platform provided ACPI table. CDAT is used by CXL and can
exist on platforms that do not use ACPI. Split out the common routine
from ACPI to accommodate platforms that do not support ACPI and move that
to /lib. The common routines can be built outside of ACPI if
FIRMWARE_TABLES is selected.

Link: https://lore.kernel.org/linux-cxl/CAJZ5v0jipbtTNnsA0-o5ozOk8ZgWnOg34m34a9pPenTyRLj=6A@mail.gmail.com/
Suggested-by: "Rafael J. Wysocki" <rafael@kernel.org>
Reviewed-by: Hanjun Guo <guohanjun@huawei.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Acked-by: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/169713683430.2205276.17899451119920103445.stgit@djiang5-mobl3
Signed-off-by: Dan Williams <dan.j.williams@intel.com>