[PATCH v4 04/10] kern/ieee1275/init: ppc64: Add support for alignment requirements

[Stefan Berger <stefanb@linux.ibm.com>]

Add support for memory alignment requirements and adjust a candidate
address to it before checking whether the block is large enough. This
must be done in this order since the alignment adjustment can make a
block smaller than what was requested.

None of the current callers has memory alignment requirements but the
ieee1275 loader for kernel and initrd will use it to convey them.

Signed-off-by: stefan Berger <stefanb@linux.ibm.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: Pavithra Prakash <pavrampu@in.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Carolyn Scherrer <cpscherr@us.ibm.com>
Cc: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Cc: Sourabh Jain <sourabhjain@linux.ibm.com>
---
 grub-core/kern/ieee1275/init.c        | 14 ++++++++++++++
 include/grub/powerpc/ieee1275/alloc.h |  1 +
 2 files changed, 15 insertions(+)

diff --git a/grub-core/kern/ieee1275/init.c b/grub-core/kern/ieee1275/init.c
index 6d5fb573a..d71d4b682 100644
--- a/grub-core/kern/ieee1275/init.c
+++ b/grub-core/kern/ieee1275/init.c
@@ -502,6 +502,20 @@ regions_claim (grub_uint64_t addr, grub_uint64_t len, grub_memory_type_t type,
             }
         }
     }
+
+  /* Honor alignment restrictions on candidate addr */
+  if (rcr->align)
+    {
+      grub_uint64_t align_addr = ALIGN_UP (addr, rcr->align);
+      grub_uint64_t d = align_addr - addr;
+
+      if (d > len)
+        return 0;
+
+      len -= d;
+      addr = align_addr;
+    }
+
   if (rcr->flags & GRUB_MM_ADD_REGION_CONSECUTIVE && len < rcr->total)
     return 0;
 
diff --git a/include/grub/powerpc/ieee1275/alloc.h b/include/grub/powerpc/ieee1275/alloc.h
index 9aaea4d46..9258eded1 100644
--- a/include/grub/powerpc/ieee1275/alloc.h
+++ b/include/grub/powerpc/ieee1275/alloc.h
@@ -29,6 +29,7 @@ struct regions_claim_request {
   grub_uint32_t total;    /* number of requested bytes */
   bool init_region;       /* whether to add memory to the heap using grub_mm_init_region() */
   grub_uint64_t addr;     /* result address */
+  grub_size_t align;      /* alignment restrictions */
 };
 
 #endif /* GRUB_POWERPC_IEEE1275_ALLOC_HEADER */
-- 
2.25.1


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