This is not great: I'd much rather introduce a typedef that is a "ACPI
name byte buffer", and use that to mark these special 4-byte ACPI names
that do not use NUL termination.
But as noted in the previous commit ("gcc-15: make 'unterminated string
initialization' just a warning") gcc doesn't actually seem to support
that notion, so instead you have to just mark every single array
declaration individually.
So this is not pretty, but this gets rid of the bulk of the annoying
warnings during an allmodconfig build for me.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Considering this case:
1. A program opens a sysfs table file 65535 times, it can increase
validation_count and first increment cause the table to be mapped:
validation_count = 65535
2. AML execution causes "Load" to be executed on the same
table, this time it cannot increase validation_count, so
validation_count remains:
validation_count = 65535
3. The program closes sysfs table file 65535 times, it can decrease
validation_count and the last decrement cause the table to be
unmapped:
validation_count = 0
4. AML code still accessing the loaded table, kernel crash can be
observed.
To prevent that from happening, add a validation_count threashold.
When it is reached, the validation_count can no longer be
incremented/decremented to invalidate the table descriptor (means
preventing table unmappings)
Note that code added in acpi_tb_put_table() is actually a no-op but
changes the warning message into a "warn once" one. Lv Zheng.
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
[ rjw: Changelog, comments ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
ACPICA commit cac6790954d4d752a083e6122220b8a22febcd07
This patch back ports Linux acpi_get_table_with_size() and
early_acpi_os_unmap_memory() into ACPICA upstream to reduce divergences.
The 2 APIs are used by Linux as table management APIs for long time, it
contains a hidden logic that during the early stage, the mapped tables
should be unmapped before the early stage ends.
During the early stage, tables are handled by the following sequence:
acpi_get_table_with_size();
parse the table
early_acpi_os_unmap_memory();
During the late stage, tables are handled by the following sequence:
acpi_get_table();
parse the table
Linux uses acpi_gbl_permanent_mmap to distinguish the early stage and the
late stage.
The reasoning of introducing acpi_get_table_with_size() is: ACPICA will
remember the early mapped pointer in acpi_get_table() and Linux isn't able to
prevent ACPICA from using the wrong early mapped pointer during the late
stage as there is no API provided from ACPICA to be an inverse of
acpi_get_table() to forget the early mapped pointer.
But how ACPICA can work with the early/late stage requirement? Inside of
ACPICA, tables are ensured to be remained in "INSTALLED" state during the
early stage, and they are carefully not transitioned to "VALIDATED" state
until the late stage. So the same logic is in fact implemented inside of
ACPICA in a different way. The gap is only that the feature is not provided
to the OSPMs in an accessible external API style.
It then is possible to fix the gap by providing an inverse of
acpi_get_table() from ACPICA, so that the two Linux sequences can be
combined:
acpi_get_table();
parse the table
acpi_put_table();
In order to work easier with the current Linux code, acpi_get_table() and
acpi_put_table() is implemented in a usage counting based style:
1. When the usage count of the table is increased from 0 to 1, table is
mapped and .Pointer is set with the mapping address (VALIDATED);
2. When the usage count of the table is decreased from 1 to 0, .Pointer
is unset and the mapping address is unmapped (INVALIDATED).
So that we can deploy the new APIs to Linux with minimal effort by just
invoking acpi_get_table() in acpi_get_table_with_size() and invoking
acpi_put_table() in early_acpi_os_unmap_memory(). Lv Zheng.
Link: https://github.com/acpica/acpica/commit/cac67909
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
ACPICA commit 34ccd43af3fd1870fddfac0617dd0ba706963558
Remove all vestiges of the version 2 FADT which never was included
in the ACPI specification.
This enabled significant cleanup of both the data table compiler
and the disassembler.
Added many clarification comments to associate each FADT version
with the version of the ACPI spec where it was originally
defined.
Link: https://github.com/acpica/acpica/commit/34ccd43a
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
