On 6/30/23 20:46, Warner Losh wrote:
On Fri, Jun 30, 2023 at 7:22 AM Richard Henderson <richard.hender...@linaro.org <mailto:richard.hender...@linaro.org>> wrote:The previous check returned -1 when any page within [start, start+len) is unmapped, not when all are unmapped. Cc: Warner Losh <i...@bsdimp.com <mailto:i...@bsdimp.com>> Cc: Kyle Evans <kev...@freebsd.org <mailto:kev...@freebsd.org>> Signed-off-by: Richard Henderson <richard.hender...@linaro.org <mailto:richard.hender...@linaro.org>> --- bsd-user/mmap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/bsd-user/mmap.c b/bsd-user/mmap.c index 565b9f97ed..07b5b8055e 100644 --- a/bsd-user/mmap.c +++ b/bsd-user/mmap.c @@ -609,7 +609,7 @@ abi_long target_mmap(abi_ulong start, abi_ulong len, int prot, } /* Reject the mapping if any page within the range is mapped */ - if ((flags & MAP_EXCL) && page_check_range(start, len, 0) < 0) { + if ((flags & MAP_EXCL) && !page_check_range_empty(start, end - 1)) {Won't computing end overflow if start is 1<<32 - len? Then subtracting one here would be too late.
-fwrapv, so fully twos-compliment. So start per above, end == 0, end - 1 == UINT32_MAX. See also the rest of the linux-user code, wherein I work with "last == end - 1". Which has the advantage of preserving comparison order: start < last. r~
