+ /* ensure param1/param2 existed */
+ if (!(param_extension || acpi5))
+ goto inject;
+
+ /* ensure injection is memory related */
+ if (type & ACPI5_VENDOR_BIT) {
+ if (vendor_flags != SETWA_FLAGS_MEM)
+ goto inject;
+ } else if (!(type & MEM_ERROR_MASK))
+ goto inject;
Maybe a comment before all these three goto blocks saying why we are jumping
around. Perhaps:
/* We need extra sanity checks for memory errors. Other types leap directly to injection */
+
+ /*
+ * When error injection type is memory related, param2 is the address
+ * mask of param1. This mask is used to ensure that the final address
+ * (param1 & param2) is meaningful. If param2 has a *weird* style
+ * like 0xf0f0f0f0f0f0f0f0, it means the injection address can be
+ * anywhere around param1, and that must be forbidden. In that reason,
+ * PAGE_MASK is employed to avoid injection address discontinuous.
+ * If one finds a special case not to satisfy this requirement, please
+ * fix it.
+ */
+ pfn = PFN_DOWN(param1 & param2);
+ if (!page_is_ram(pfn) || ((param2 & PAGE_MASK) != PAGE_MASK))
+ return -EINVAL;
This has too much comment (rare!) and is still too complicated. Split the tests apart?
/*
* Disallow crazy address masks that give BIOS leeway to pick injection address
* almost anywhere. Insist on page or better granularity
*/
if ((param2 & PAGE_MASK) != PAGE_MASK)
return -EINVAL;
/* make sure target address is normal memory */
pfn = PFN_DOWN(param1 & param2);
if (!page_is_ram(pfn))
return -EINVAL;
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