v2:
https://lore.kernel.org/all/[email protected]/
- Split initial patch in 3.
- Add links to static-analysis reports.
Some cases were not correctly evaluated when updating
init_cache_level()'s prototype, in particular if CONFIG_ACPI_PPTT is
not defined. Fix them.
The initial diagnostic was done thanks to:
- the kernel test robot <[email protected]>
Link: https://lore.kernel.org/all/[email protected]/
- Dan Carpenter <[email protected]>
Link: https://lore.kernel.org/all/Y86iruJPuwNN7rZw@kili/
Pierre Gondois (3):
cacheinfo: Initialize variables in fetch_cache_info()
cacheinfo: Make default acpi_get_cache_info() return an error
cacheinfo: Remove unused check in init_cache_level()
arch/arm64/kernel/cacheinfo.c | 5 +----
drivers/base/cacheinfo.c | 2 +-
include/linux/cacheinfo.h | 2 +-
3 files changed, 3 insertions(+), 6 deletions(-)
--
2.25.1
Set potentially uninitialized variables to 0. This is particularly
relevant when CONFIG_ACPI_PPTT is not set.
Reported-by: kernel test robot <[email protected]>
Link: https://lore.kernel.org/all/[email protected]/
Reported-by: Dan Carpenter <[email protected]>
Link: https://lore.kernel.org/all/Y86iruJPuwNN7rZw@kili/
Fixes: 5944ce092b97 ("arch_topology: Build cacheinfo from primary CPU")
Signed-off-by: Pierre Gondois <[email protected]>
---
drivers/base/cacheinfo.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
index 418a18acc8f9..f6573c335f4c 100644
--- a/drivers/base/cacheinfo.c
+++ b/drivers/base/cacheinfo.c
@@ -424,7 +424,7 @@ int allocate_cache_info(int cpu)
int fetch_cache_info(unsigned int cpu)
{
struct cpu_cacheinfo *this_cpu_ci;
- unsigned int levels, split_levels;
+ unsigned int levels = 0, split_levels = 0;
int ret;
if (acpi_disabled) {
--
2.25.1
commit bd500361a937 ("ACPI: PPTT: Update acpi_find_last_cache_level()
to acpi_get_cache_info()")
updates the prototype of acpi_get_cache_info(). The cache 'levels'
is update through a pointer and not the return value of the function.
If CONFIG_ACPI_PPTT is not defined, acpi_get_cache_info() doesn't
update its *levels and *split_levels parameters and returns 0.
This can lead to a faulty behaviour.
Make acpi_get_cache_info() return an error code if CONFIG_ACPI_PPTT
is not defined.
Also,
In init_cache_level(), if no PPTT is present or CONFIG_ACPI_PPTT is
not defined, instead of aborting if acpi_get_cache_info() returns an
error code, just continue. This allows to try fetching the cache
information from clidr_el1.
Signed-off-by: Pierre Gondois <[email protected]>
---
arch/arm64/kernel/cacheinfo.c | 2 +-
include/linux/cacheinfo.h | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/kernel/cacheinfo.c b/arch/arm64/kernel/cacheinfo.c
index d3fe9542c370..bf348b8d321f 100644
--- a/arch/arm64/kernel/cacheinfo.c
+++ b/arch/arm64/kernel/cacheinfo.c
@@ -59,7 +59,7 @@ int init_cache_level(unsigned int cpu)
} else {
ret = acpi_get_cache_info(cpu, &fw_level, NULL);
if (ret < 0)
- return ret;
+ fw_level = 0;
}
if (fw_level < 0)
diff --git a/include/linux/cacheinfo.h b/include/linux/cacheinfo.h
index dfef57077cd0..908e19d17f49 100644
--- a/include/linux/cacheinfo.h
+++ b/include/linux/cacheinfo.h
@@ -100,7 +100,7 @@ static inline
int acpi_get_cache_info(unsigned int cpu,
unsigned int *levels, unsigned int *split_levels)
{
- return 0;
+ return -ENOENT;
}
#else
int acpi_get_cache_info(unsigned int cpu,
--
2.25.1
commit e75d18cecbb3 ("arm64: cacheinfo: Fix incorrect assignment
of signed error value to unsigned fw_level")
checks the fw_level value in init_cache_level() in case the value is
negative.
Remove this check as the error code is not returned through
fw_level anymore, and reset fw_level if acpi_get_cache_info()
failed. This allows to try fetching the cache information from
clidr_el1.
Signed-off-by: Pierre Gondois <[email protected]>
---
arch/arm64/kernel/cacheinfo.c | 3 ---
1 file changed, 3 deletions(-)
diff --git a/arch/arm64/kernel/cacheinfo.c b/arch/arm64/kernel/cacheinfo.c
index bf348b8d321f..c307f69e9b55 100644
--- a/arch/arm64/kernel/cacheinfo.c
+++ b/arch/arm64/kernel/cacheinfo.c
@@ -62,9 +62,6 @@ int init_cache_level(unsigned int cpu)
fw_level = 0;
}
- if (fw_level < 0)
- return fw_level;
-
if (level < fw_level) {
/*
* some external caches not specified in CLIDR_EL1
--
2.25.1
On Tue, Jan 24, 2023 at 04:40:48PM +0100, Pierre Gondois wrote:
> commit e75d18cecbb3 ("arm64: cacheinfo: Fix incorrect assignment
> of signed error value to unsigned fw_level")
> checks the fw_level value in init_cache_level() in case the value is
> negative.
> Remove this check as the error code is not returned through
> fw_level anymore, and reset fw_level if acpi_get_cache_info()
> failed. This allows to try fetching the cache information from
> clidr_el1.
I dunno anything about clidr_el1, but the mechanics of the change seem
fair. There is a non-acpi path too, which shouldn't return negative
numbers either so LGTM.
> Signed-off-by: Pierre Gondois <[email protected]>
> ---
> arch/arm64/kernel/cacheinfo.c | 3 ---
> 1 file changed, 3 deletions(-)
>
> diff --git a/arch/arm64/kernel/cacheinfo.c b/arch/arm64/kernel/cacheinfo.c
> index bf348b8d321f..c307f69e9b55 100644
> --- a/arch/arm64/kernel/cacheinfo.c
> +++ b/arch/arm64/kernel/cacheinfo.c
> @@ -62,9 +62,6 @@ int init_cache_level(unsigned int cpu)
> fw_level = 0;
> }
>
> - if (fw_level < 0)
> - return fw_level;
> -
> if (level < fw_level) {
> /*
> * some external caches not specified in CLIDR_EL1
> --
> 2.25.1
>
On Tue, Jan 24, 2023 at 04:40:47PM +0100, Pierre Gondois wrote:
> commit bd500361a937 ("ACPI: PPTT: Update acpi_find_last_cache_level()
> to acpi_get_cache_info()")
> updates the prototype of acpi_get_cache_info(). The cache 'levels'
> is update through a pointer and not the return value of the function.
>
> If CONFIG_ACPI_PPTT is not defined, acpi_get_cache_info() doesn't
> update its *levels and *split_levels parameters and returns 0.
> This can lead to a faulty behaviour.
>
> Make acpi_get_cache_info() return an error code if CONFIG_ACPI_PPTT
> is not defined.
> Also,
>
> In init_cache_level(), if no PPTT is present or CONFIG_ACPI_PPTT is
> not defined, instead of aborting if acpi_get_cache_info() returns an
> error code, just continue. This allows to try fetching the cache
> information from clidr_el1.
Again, dunno jack about clidr_el1. But the change here seems sane once
more? I was going to suggest throwing away ret entirely and just
initialising fw_level to zero, since the function inside
acpi_get_cache_level() that actually modifies it comes after the last
error return anyway - but that probably would just leave you exposed to
a change in the core code that doesn't also update the callsites.
Plus this looks more deliberate IMO. On that basis, LGTM.
> Signed-off-by: Pierre Gondois <[email protected]>
> ---
> arch/arm64/kernel/cacheinfo.c | 2 +-
> include/linux/cacheinfo.h | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/kernel/cacheinfo.c b/arch/arm64/kernel/cacheinfo.c
> index d3fe9542c370..bf348b8d321f 100644
> --- a/arch/arm64/kernel/cacheinfo.c
> +++ b/arch/arm64/kernel/cacheinfo.c
> @@ -59,7 +59,7 @@ int init_cache_level(unsigned int cpu)
> } else {
> ret = acpi_get_cache_info(cpu, &fw_level, NULL);
> if (ret < 0)
> - return ret;
> + fw_level = 0;
> }
>
> if (fw_level < 0)
> diff --git a/include/linux/cacheinfo.h b/include/linux/cacheinfo.h
> index dfef57077cd0..908e19d17f49 100644
> --- a/include/linux/cacheinfo.h
> +++ b/include/linux/cacheinfo.h
> @@ -100,7 +100,7 @@ static inline
> int acpi_get_cache_info(unsigned int cpu,
> unsigned int *levels, unsigned int *split_levels)
> {
> - return 0;
> + return -ENOENT;
> }
> #else
> int acpi_get_cache_info(unsigned int cpu,
> --
> 2.25.1
>
On Tue, Jan 24, 2023 at 04:40:46PM +0100, Pierre Gondois wrote:
> Set potentially uninitialized variables to 0. This is particularly
> relevant when CONFIG_ACPI_PPTT is not set.
>
> Reported-by: kernel test robot <[email protected]>
> Link: https://lore.kernel.org/all/[email protected]/
> Reported-by: Dan Carpenter <[email protected]>
> Link: https://lore.kernel.org/all/Y86iruJPuwNN7rZw@kili/
> Fixes: 5944ce092b97 ("arch_topology: Build cacheinfo from primary CPU")
> Signed-off-by: Pierre Gondois <[email protected]>
Reviewed-by: Conor Dooley <[email protected]>
Thanks for the quick respin Pierre :)
> ---
> drivers/base/cacheinfo.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
> index 418a18acc8f9..f6573c335f4c 100644
> --- a/drivers/base/cacheinfo.c
> +++ b/drivers/base/cacheinfo.c
> @@ -424,7 +424,7 @@ int allocate_cache_info(int cpu)
> int fetch_cache_info(unsigned int cpu)
> {
> struct cpu_cacheinfo *this_cpu_ci;
> - unsigned int levels, split_levels;
> + unsigned int levels = 0, split_levels = 0;
> int ret;
>
> if (acpi_disabled) {
> --
> 2.25.1
>