[Xen-devel] [PATCH 19/20] xen/arm: Pair call to set_fixmap with call to clear_fixmap in copy_from_paddr

[Julien Grall <julien.grall@xxxxxxx>]

At the moment, set_fixmap may replace a valid entry without following
the break-before-make sequence. This may result to TLB conflict abort.

Rather than dealing with Break-Before-Make in set_fixmap, every call to
set_fixmap is paired with a call to clear_fixmap.

Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
---
 xen/arch/arm/kernel.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/xen/arch/arm/kernel.c b/xen/arch/arm/kernel.c
index e3ffdb2fa1..389bef2afa 100644
--- a/xen/arch/arm/kernel.c
+++ b/xen/arch/arm/kernel.c
@@ -58,13 +58,12 @@ void __init copy_from_paddr(void *dst, paddr_t paddr, 
unsigned long len)
         set_fixmap(FIXMAP_MISC, maddr_to_mfn(paddr), PAGE_HYPERVISOR_WC);
         memcpy(dst, src + s, l);
         clean_dcache_va_range(dst, l);
+        clear_fixmap(FIXMAP_MISC);
 
         paddr += l;
         dst += l;
         len -= l;
     }
-
-    clear_fixmap(FIXMAP_MISC);
 }
 
 static void __init place_modules(struct kernel_info *info,
-- 
2.11.0


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