From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:55464) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Ui2j7-0004Gs-AN for qemu-devel@nongnu.org; Thu, 30 May 2013 09:17:14 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Ui2j2-0005Vd-IW for qemu-devel@nongnu.org; Thu, 30 May 2013 09:17:09 -0400 Date: Thu, 30 May 2013 09:16:45 -0400 From: Luiz Capitulino Message-ID: <20130530091645.08e47dbb@redhat.com> In-Reply-To: <51A75122.9020305@redhat.com> References: <20130528141922.135a6dd0@redhat.com> <20130530085932.5db02527@redhat.com> <51A75122.9020305@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] walk_pml4e(): fix abort on bad PML4E/PDPTE/PDE/PTE addresses List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Laszlo Ersek Cc: qiaonuohan@cn.fujitsu.com, afaerber@suse.de, qemu-stable@nongnu.org, qemu-devel On Thu, 30 May 2013 15:16:18 +0200 Laszlo Ersek wrote: > On 05/30/13 14:59, Luiz Capitulino wrote: > > On Tue, 28 May 2013 14:19:22 -0400 > > Luiz Capitulino wrote: > > > >> The code used to walk IA-32e page-tables, and possibly PAE page-tables, > >> uses the bit mask ~0xfff to get the next PML4E/PDPTE/PDE/PTE address. > >> > >> However, as we use a uint64_t to store the resulting address, that mask > >> gets expanded to 0xfffffffffffff000 which not only ends up selecting > >> reserved bits but also selects the XD bit (execute-disable) which > >> happens to be enabled by Windows 8, causing qemu_get_ram_ptr() to abort. > >> > >> This commit fixes that problem by replacing ~0xfff by a correct mask > >> that only selects the address bit range (ie. bits 51:12). > >> > >> Signed-off-by: Luiz Capitulino > > > > Ping? Wen? > > > > Would be nice get a Reviewed-by before merging... > > I didn't miss your submission and did find it OK, I just felt unsure > about stating so, because "simple" patches like this are prime territory > to burn someone's R-b's worth (ie. to expose a reviewer's lack of > information / experience). But hey, what can I lose? The patch does look > good to me, so Thank you Laszlo! It's also new territory for me, that's why I'm asking for reviews (otherwise I'd just sneak it in some pull request :-) > > Reviewed-by: Laszlo Ersek > > > > >> --- > >> > >> PS: I (obviously) don't any more core dumps with this patch applied, but > >> I couldn't check if the Windows dump is correct (does anyone know > >> how to do this?). I did quickly check on Linux though. > >> > >> target-i386/arch_memory_mapping.c | 10 ++++++---- > >> 1 file changed, 6 insertions(+), 4 deletions(-) > >> > >> diff --git a/target-i386/arch_memory_mapping.c b/target-i386/arch_memory_mapping.c > >> index 844893f..24884bd 100644 > >> --- a/target-i386/arch_memory_mapping.c > >> +++ b/target-i386/arch_memory_mapping.c > >> @@ -75,6 +75,8 @@ static void walk_pte2(MemoryMappingList *list, > >> } > >> > >> /* PAE Paging or IA-32e Paging */ > >> +#define PLM4_ADDR_MASK 0xffffffffff000 /* selects bits 51:12 */ > >> + > >> static void walk_pde(MemoryMappingList *list, hwaddr pde_start_addr, > >> int32_t a20_mask, target_ulong start_line_addr) > >> { > >> @@ -105,7 +107,7 @@ static void walk_pde(MemoryMappingList *list, hwaddr pde_start_addr, > >> continue; > >> } > >> > >> - pte_start_addr = (pde & ~0xfff) & a20_mask; > >> + pte_start_addr = (pde & PLM4_ADDR_MASK) & a20_mask; > >> walk_pte(list, pte_start_addr, a20_mask, line_addr); > >> } > >> } > >> @@ -208,7 +210,7 @@ static void walk_pdpe(MemoryMappingList *list, > >> continue; > >> } > >> > >> - pde_start_addr = (pdpe & ~0xfff) & a20_mask; > >> + pde_start_addr = (pdpe & PLM4_ADDR_MASK) & a20_mask; > >> walk_pde(list, pde_start_addr, a20_mask, line_addr); > >> } > >> } > >> @@ -231,7 +233,7 @@ static void walk_pml4e(MemoryMappingList *list, > >> } > >> > >> line_addr = ((i & 0x1ffULL) << 39) | (0xffffULL << 48); > >> - pdpe_start_addr = (pml4e & ~0xfff) & a20_mask; > >> + pdpe_start_addr = (pml4e & PLM4_ADDR_MASK) & a20_mask; > >> walk_pdpe(list, pdpe_start_addr, a20_mask, line_addr); > >> } > >> } > >> @@ -249,7 +251,7 @@ int cpu_get_memory_mapping(MemoryMappingList *list, CPUArchState *env) > >> if (env->hflags & HF_LMA_MASK) { > >> hwaddr pml4e_addr; > >> > >> - pml4e_addr = (env->cr[3] & ~0xfff) & env->a20_mask; > >> + pml4e_addr = (env->cr[3] & PLM4_ADDR_MASK) & env->a20_mask; > >> walk_pml4e(list, pml4e_addr, env->a20_mask); > >> } else > >> #endif > > > > >