Re: [PATCH v5 09/19] arch_topology: Use the last level cache information from the cacheinfo
From: <Conor.Dooley@microchip.com>
Date: 2022-06-30 22:08:03
Also in:
linux-riscv, lkml
Subsystem:
driver core, kobjects, debugfs and sysfs, the rest · Maintainers:
Greg Kroah-Hartman, "Rafael J. Wysocki", Danilo Krummrich, Linus Torvalds
On 30/06/2022 21:21, Sudeep Holla wrote:
On Thu, Jun 30, 2022 at 08:13:55PM +0000, Conor.Dooley@microchip.com wrote:quoted
I didn't have the time to go digging into things, but the following macro looked odd: #define per_cpu_cacheinfo_idx(cpu, idx) \ (per_cpu_cacheinfo(cpu) + (idx)) Maybe it is just badly named, but is this getting the per_cpu_cacheinfo and then incrementing intentionally, or is it meant to get the per_cpu_cacheinfo of cpu + idx?OK, basically per_cpu_cacheinfo(cpu) get the information for a cpu while per_cpu_cacheinfo_idx(cpu, idx) will fetch the information for a given cpu and given index within the cpu. So we are incrementing the pointer by the index. These work just fine on arm64 platform.
Right, that's what I figured but wanted to be sure.
Not sure if compiler is optimising something as I still can't understand how we can end up with valid llc but fw_token as NULL.
See idk about that. The following fails to boot. index 167abfa6f37d..9d45c37fb004 100644
--- a/drivers/base/cacheinfo.c
+++ b/drivers/base/cacheinfo.c@@ -36,6 +36,8 @@ struct cpu_cacheinfo *get_cpu_cacheinfo(unsigned int cpu) static inline bool cache_leaves_are_shared(struct cacheinfo *this_leaf, struct cacheinfo *sib_leaf) { + if (!this_leaf || !sib_leaf) + return false; /* * For non DT/ACPI systems, assume unique level 1 caches, * system-wide shared caches for all other levels. This will be used
@@ -74,8 +76,12 @@ bool last_level_cache_is_shared(unsigned int cpu_x, unsigned int cpu_y) llc_x = per_cpu_cacheinfo_idx(cpu_x, cache_leaves(cpu_x) - 1); llc_y = per_cpu_cacheinfo_idx(cpu_y, cache_leaves(cpu_y) - 1); + if (!llc_x || !llc_y){ + printk("llc was null\n"); + return false; + } - return cache_leaves_are_shared(llc_x, llc_y); + return false; //cache_leaves_are_shared(llc_x, llc_y); } #ifdef CONFIG_OF
and this boots:
diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c
index 167abfa6f37d..01900908fe31 100644
--- a/drivers/base/cacheinfo.c
+++ b/drivers/base/cacheinfo.c@@ -36,6 +36,8 @@ struct cpu_cacheinfo *get_cpu_cacheinfo(unsigned int cpu) static inline bool cache_leaves_are_shared(struct cacheinfo *this_leaf, struct cacheinfo *sib_leaf) { + if (!this_leaf || !sib_leaf) + return false; /* * For non DT/ACPI systems, assume unique level 1 caches, * system-wide shared caches for all other levels. This will be used
@@ -75,7 +77,7 @@ bool last_level_cache_is_shared(unsigned int cpu_x, unsigned int cpu_y) llc_x = per_cpu_cacheinfo_idx(cpu_x, cache_leaves(cpu_x) - 1); llc_y = per_cpu_cacheinfo_idx(cpu_y, cache_leaves(cpu_y) - 1); - return cache_leaves_are_shared(llc_x, llc_y); + return false; //cache_leaves_are_shared(llc_x, llc_y); } #ifdef CONFIG_OF
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