From f6105f89d5a809cb2fbcac318da9fa8981576a51 Mon Sep 17 00:00:00 2001 From: Corinna Vinschen Date: Thu, 13 Jul 2006 08:33:34 +0000 Subject: [PATCH] * exceptions.cc (_cygtls::handle_exceptions): Call new mmap_is_attached_or_noreserve_page function in case of access violation and allow application to retry access on noreserve pages. * mmap.cc (mmap_is_attached_or_noreserve_page): Changed from mmap_is_attached_page. Handle also noreserve pages now. Change comment accordingly. * winsup.h (mmap_is_attached_or_noreserve_page): Declare instead of mmap_is_attached_page. --- winsup/cygwin/ChangeLog | 11 +++++++++++ winsup/cygwin/exceptions.cc | 14 ++++++++----- winsup/cygwin/mmap.cc | 39 +++++++++++++++++++++++++------------ winsup/cygwin/winsup.h | 2 +- 4 files changed, 48 insertions(+), 18 deletions(-) diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog index 0ff39df4d..0a3b7c2d9 100644 --- a/winsup/cygwin/ChangeLog +++ b/winsup/cygwin/ChangeLog @@ -1,3 +1,14 @@ +2006-07-13 Corinna Vinschen + + * exceptions.cc (_cygtls::handle_exceptions): Call new + mmap_is_attached_or_noreserve_page function in case of access violation + and allow application to retry access on noreserve pages. + * mmap.cc (mmap_is_attached_or_noreserve_page): Changed from + mmap_is_attached_page. Handle also noreserve pages now. Change + comment accordingly. + * winsup.h (mmap_is_attached_or_noreserve_page): Declare instead of + mmap_is_attached_page. + 2006-07-12 Corinna Vinschen * mmap.cc (mmap_record::alloc_page_map): Don't call VirtualProtect diff --git a/winsup/cygwin/exceptions.cc b/winsup/cygwin/exceptions.cc index 4d078dd10..12c6e0687 100644 --- a/winsup/cygwin/exceptions.cc +++ b/winsup/cygwin/exceptions.cc @@ -526,17 +526,21 @@ _cygtls::handle_exceptions (EXCEPTION_RECORD *e, exception_list *frame, CONTEXT break; case STATUS_ACCESS_VIOLATION: - if (mmap_is_attached_page (e->ExceptionInformation[1])) - { + switch (mmap_is_attached_or_noreserve_page (e->ExceptionInformation[1])) + { + case 2: /* MAP_NORESERVE page, now commited. */ + return 0; + case 1: /* MAP_NORESERVE page, commit failed, or + access to mmap page beyond EOF. */ si.si_signo = SIGBUS; si.si_code = BUS_OBJERR; - } - else - { + break; + default: MEMORY_BASIC_INFORMATION m; VirtualQuery ((PVOID) e->ExceptionInformation[1], &m, sizeof m); si.si_signo = SIGSEGV; si.si_code = m.State == MEM_FREE ? SEGV_MAPERR : SEGV_ACCERR; + break; } break; diff --git a/winsup/cygwin/mmap.cc b/winsup/cygwin/mmap.cc index 7ca176c88..193ed7c0f 100644 --- a/winsup/cygwin/mmap.cc +++ b/winsup/cygwin/mmap.cc @@ -900,13 +900,25 @@ map::del_list (unsigned i) } /* This function is called from exception_handler when a segmentation - violation has happened. The function should return true, if the - faulting address (the parameter) is within attached pages. In this - case the exception_handler raises SIGBUS, as demanded by the memory - protection extension described in SUSv3 (see the mmap man page). - If false is returned, a normal SIGSEGV is raised. */ -bool -mmap_is_attached_page (ULONG_PTR addr) + violation has happened. We have two cases to check here. + + First, is it an address within "attached" mmap pages (indicated by + the __PROT_ATTACH protection, see there)? In this case the function + returns 1 and the exception_handler raises SIGBUS, as demanded by the + memory protection extension described in SUSv3 (see the mmap man + page). + + Second, check if the address is within "noreserve" mmap pages + (indicated by MAP_NORESERVE flag). If so, the function calls + VirtualAlloc to commit the page and returns 2. The exception handler + then just returns with 0 and the affected application retries the + failing memory access. If VirtualAlloc fails, the function returns + 1, so that the exception handler raises a SIGBUS, as described in the + MAP_NORESERVE man pages for Linux and Solaris. + + In any other case 0 is returned and a normal SIGSEGV is raised. */ +int +mmap_is_attached_or_noreserve_page (ULONG_PTR addr) { list *map_list; long record_idx; @@ -916,13 +928,16 @@ mmap_is_attached_page (ULONG_PTR addr) addr = rounddown (addr, pagesize); if (!(map_list = mmapped_areas.get_list_by_fd (-1))) - return false; + return 0; if ((record_idx = map_list->search_record ((caddr_t)addr, pagesize, u_addr, u_len, -1)) < 0) - return false; - if (!map_list->get_record (record_idx)->attached ()) - return false; - return true; + return 0; + if (map_list->get_record (record_idx)->attached ()) + return 1; + if (!map_list->get_record (record_idx)->noreserve ()) + return 0; + DWORD new_prot = map_list->get_record (record_idx)->gen_protect (); + return VirtualAlloc ((void *)addr, pagesize, MEM_COMMIT, new_prot) ? 2 : 1; } static caddr_t diff --git a/winsup/cygwin/winsup.h b/winsup/cygwin/winsup.h index 9a1039dc1..727151406 100644 --- a/winsup/cygwin/winsup.h +++ b/winsup/cygwin/winsup.h @@ -299,7 +299,7 @@ size_t getsystempagesize (); /* mmap functions. */ void mmap_init (); -bool mmap_is_attached_page (ULONG_PTR); +int mmap_is_attached_or_noreserve_page (ULONG_PTR addr); int winprio_to_nice (DWORD) __attribute__ ((regparm (1))); DWORD nice_to_winprio (int &) __attribute__ ((regparm (1)));