| Message ID | 1434051911-14665-3-git-send-email-al.stone@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Jun 11, 2015 at 08:45:10PM +0100, al.stone@linaro.org wrote: > From: Al Stone <al.stone@linaro.org> > > The BAD_MADT_ENTRY() macro is designed to work for all of the subtables > of the MADT. In the ACPI 5.1 version of the spec, the struct for the > GICC subtable (struct acpi_madt_generic_interrupt) is 76 bytes long; in > ACPI 6.0, the struct is 80 bytes long. But, there is only one definition > in ACPICA for this struct -- and that is the 6.0 version. Hence, when > BAD_MADT_ENTRY() compares the struct size to the length in the GICC > subtable, it fails if 5.1 structs are in use, and there are systems in > the wild that have them. > > This patch adds the BAD_MADT_GICC_ENTRY() that checks the GICC subtable > only, accounting for the difference in specification versions that are > possible. The BAD_MADT_ENTRY() will continue to work as is for all other > MADT subtables. Unfortunately that's nothing new, it seems. ia64 put in place a quite nifty solution to that (I *guess* owing to ACPI 3.0 updates to Local sapic specs), have a look at: arch/ia64/kernel/acpi.c acpi_parse_lsacpi() /*Skip BAD_MADT_ENTRY check, as lsapic size could vary */ We remove the check, job done ;-) > Signed-off-by: Al Stone <al.stone@linaro.org> > Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org> > Reviewed-by: Graeme Gregory <graeme.gregory@linaro.org> > > CC: Rafael J. Wysocki <rjw@rjwysocki.net> > CC: Len Brown <lenb@kernel.org> > > --- > include/linux/acpi.h | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/include/linux/acpi.h b/include/linux/acpi.h > index 33ed313..8a83f91 100644 > --- a/include/linux/acpi.h > +++ b/include/linux/acpi.h > @@ -127,6 +127,13 @@ static inline void acpi_initrd_override(void *data, size_t size) > (!entry) || (unsigned long)entry + sizeof(*entry) > end || \ > ((struct acpi_subtable_header *)entry)->length < sizeof(*entry)) > > +#define BAD_MADT_GICC_ENTRY(entry, end) ( \ > + (!entry) || (unsigned long)entry + sizeof(*entry) > end || \ > + ((ACPI_FADT_SPEC_VERSION == ACPI_SPEC_VERSION(5,1)) && \ > + (entry->header.length != 76)) || \ > + ((ACPI_FADT_SPEC_VERSION == ACPI_SPEC_VERSION(6,0)) && \ > + (entry->header.length != 80))) I would make those length magic numbers ACPICA defines at least. It is not a GICC only issue, that's true for all MADT subtables that change size with versions so, maybe we can replace the sizeof(*entry) in BAD_MADT_ENTRY with a macro compound statement returning the subtable length (where you can add a switch case on entry->type and return sizeof(*entry) in the default case) ? Overkill ? Certainly ugly, but at least you do not need to patch anything else. I am inclined to relegate these checks to ACPICA tools (statically) altogether. It is better to check Len and Rafael opinion on this first before coding it. Lorenzo
On 06/12/2015 08:52 AM, Lorenzo Pieralisi wrote: > On Thu, Jun 11, 2015 at 08:45:10PM +0100, al.stone@linaro.org wrote: >> From: Al Stone <al.stone@linaro.org> >> >> The BAD_MADT_ENTRY() macro is designed to work for all of the subtables >> of the MADT. In the ACPI 5.1 version of the spec, the struct for the >> GICC subtable (struct acpi_madt_generic_interrupt) is 76 bytes long; in >> ACPI 6.0, the struct is 80 bytes long. But, there is only one definition >> in ACPICA for this struct -- and that is the 6.0 version. Hence, when >> BAD_MADT_ENTRY() compares the struct size to the length in the GICC >> subtable, it fails if 5.1 structs are in use, and there are systems in >> the wild that have them. >> >> This patch adds the BAD_MADT_GICC_ENTRY() that checks the GICC subtable >> only, accounting for the difference in specification versions that are >> possible. The BAD_MADT_ENTRY() will continue to work as is for all other >> MADT subtables. > > Unfortunately that's nothing new, it seems. ia64 put in place a quite > nifty solution to that (I *guess* owing to ACPI 3.0 updates to Local > sapic specs), have a look at: > > arch/ia64/kernel/acpi.c acpi_parse_lsacpi() > > /*Skip BAD_MADT_ENTRY check, as lsapic size could vary */ > > We remove the check, job done ;-) Heh. Yes, that's one way to do it :). >> Signed-off-by: Al Stone <al.stone@linaro.org> >> Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org> >> Reviewed-by: Graeme Gregory <graeme.gregory@linaro.org> >> >> CC: Rafael J. Wysocki <rjw@rjwysocki.net> >> CC: Len Brown <lenb@kernel.org> >> >> --- >> include/linux/acpi.h | 7 +++++++ >> 1 file changed, 7 insertions(+) >> >> diff --git a/include/linux/acpi.h b/include/linux/acpi.h >> index 33ed313..8a83f91 100644 >> --- a/include/linux/acpi.h >> +++ b/include/linux/acpi.h >> @@ -127,6 +127,13 @@ static inline void acpi_initrd_override(void *data, size_t size) >> (!entry) || (unsigned long)entry + sizeof(*entry) > end || \ >> ((struct acpi_subtable_header *)entry)->length < sizeof(*entry)) >> >> +#define BAD_MADT_GICC_ENTRY(entry, end) ( \ >> + (!entry) || (unsigned long)entry + sizeof(*entry) > end || \ >> + ((ACPI_FADT_SPEC_VERSION == ACPI_SPEC_VERSION(5,1)) && \ >> + (entry->header.length != 76)) || \ >> + ((ACPI_FADT_SPEC_VERSION == ACPI_SPEC_VERSION(6,0)) && \ >> + (entry->header.length != 80))) > > I would make those length magic numbers ACPICA defines at least. Yup, you're right. I'll fix that. > It is not a GICC only issue, that's true for all MADT subtables that change > size with versions so, maybe we can replace the sizeof(*entry) in > BAD_MADT_ENTRY with a macro compound statement returning the subtable > length (where you can add a switch case on entry->type and return > sizeof(*entry) in the default case) ? > > Overkill ? Certainly ugly, but at least you do not need to patch anything > else. There is precedent for this; there's a function to print MADT subtable entries with exactly this structure. And yeah, it's a bit ugly, but it does the job. > I am inclined to relegate these checks to ACPICA tools (statically) > altogether. Interestingly enough, the acpi_table_print_madt_entry() function I was referring to is in the drivers/acpi code, not ACPICA. I wonder what the history is on that and why it ended up there... > It is better to check Len and Rafael opinion on this first before coding it. > > Lorenzo > Yup. Agreed.
diff --git a/include/linux/acpi.h b/include/linux/acpi.h index 33ed313..8a83f91 100644 --- a/include/linux/acpi.h +++ b/include/linux/acpi.h @@ -127,6 +127,13 @@ static inline void acpi_initrd_override(void *data, size_t size) (!entry) || (unsigned long)entry + sizeof(*entry) > end || \ ((struct acpi_subtable_header *)entry)->length < sizeof(*entry)) +#define BAD_MADT_GICC_ENTRY(entry, end) ( \ + (!entry) || (unsigned long)entry + sizeof(*entry) > end || \ + ((ACPI_FADT_SPEC_VERSION == ACPI_SPEC_VERSION(5,1)) && \ + (entry->header.length != 76)) || \ + ((ACPI_FADT_SPEC_VERSION == ACPI_SPEC_VERSION(6,0)) && \ + (entry->header.length != 80))) + char * __acpi_map_table (unsigned long phys_addr, unsigned long size); void __acpi_unmap_table(char *map, unsigned long size); int early_acpi_boot_init(void);