From: Julien Grall Date: Mon, 22 Feb 2021 12:01:18 +0000 (+0000) Subject: xen/page_alloc: Remove dead code in alloc_domheap_pages() X-Git-Tag: archive/raspbian/4.16.0+51-g0941d6cb-1+rpi1~2^2~42^2~482 X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=5268b2dcf7e5342c8a51ceb4bed3e7740c69f5c1;p=xen.git xen/page_alloc: Remove dead code in alloc_domheap_pages() Since commit 1aac966e24e9 "xen: support RAM at addresses 0 and 4096", bits_to_zone() will never return 0 and it is expected that we have minimum 2 zones. Therefore the check in alloc_domheap_pages() is unnecessary and can be removed. However, for sanity, it is replaced with an ASSERT(). Also take the opportunity to switch from min_t() to min() as bits_to_zone() cannot return a negative value. The macro is tweaked to make it clearer. This bug was discovered and resolved using Coverity Static Analysis Security Testing (SAST) by Synopsys, Inc. Signed-off-by: Julien Grall Reviewed-by: Jan Beulich --- diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c index ace6333c18..958ba0cd92 100644 --- a/xen/common/page_alloc.c +++ b/xen/common/page_alloc.c @@ -441,7 +441,7 @@ mfn_t __init alloc_boot_pages(unsigned long nr_pfns, unsigned long pfn_align) #define MEMZONE_XEN 0 #define NR_ZONES (PADDR_BITS - PAGE_SHIFT + 1) -#define bits_to_zone(b) (((b) < (PAGE_SHIFT + 1)) ? 1 : ((b) - PAGE_SHIFT)) +#define bits_to_zone(b) (((b) < (PAGE_SHIFT + 1)) ? 1U : ((b) - PAGE_SHIFT)) #define page_to_zone(pg) (is_xen_heap_page(pg) ? MEMZONE_XEN : \ (flsl(mfn_x(page_to_mfn(pg))) ? : 1)) @@ -2336,8 +2336,9 @@ struct page_info *alloc_domheap_pages( bits = domain_clamp_alloc_bitsize(memflags & MEMF_no_owner ? NULL : d, bits ? : (BITS_PER_LONG+PAGE_SHIFT)); - if ( (zone_hi = min_t(unsigned int, bits_to_zone(bits), zone_hi)) == 0 ) - return NULL; + + zone_hi = min(bits_to_zone(bits), zone_hi); + ASSERT(zone_hi != 0); if ( memflags & MEMF_no_owner ) memflags |= MEMF_no_refcount;