From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Mosberger Date: Wed, 08 Jun 2005 05:18:39 +0000 Subject: RE: gate page oops Message-Id: <17062.32687.12421.554474@napali.hpl.hp.com> List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org >>>>> On Mon, 6 Jun 2005 17:06:23 -0700, David Mosberger said: David> I (finally) looked into this again and my current thinking is David> that it may be better to go back to mapping the two pages David> consecutively. The gate-related code has an implicit David> assumption that the gate-area is occupying a single region of David> memory (that _could_ be changed, though). Re-enabling the David> HAVE_BUGG_SEGREL code unconditionally should do that, at the David> expense of increasing the size of the kernel's ELF image by David> 16KB. I need to double-check, but I think there won't be any David> other negative side-effects. Well, it's easier to just map the holes with zero-pages. The cost is trivial (a few more non-zero kernel page-table entries) and it passes all my testing (including coredumping and gdb single-stepping over an EPC syscall). Unless there are any objections, please apply (for 2.6.12, hopefully). --david [IA64] Fill holes in FIXADDR_USER space with zero pages. This fixes an oops reported by Jason Baron. arch/ia64/mm/init.c | 19 +++++++++++++++++-- 1 files changed, 17 insertions(+), 2 deletions(-) diff --git a/arch/ia64/mm/init.c b/arch/ia64/mm/init.c --- a/arch/ia64/mm/init.c +++ b/arch/ia64/mm/init.c @@ -305,8 +305,9 @@ setup_gate (void) struct page *page; /* - * Map the gate page twice: once read-only to export the ELF headers etc. and once - * execute-only page to enable privilege-promotion via "epc": + * Map the gate page twice: once read-only to export the ELF + * headers etc. and once execute-only page to enable + * privilege-promotion via "epc": */ page = virt_to_page(ia64_imva(__start_gate_section)); put_kernel_page(page, GATE_ADDR, PAGE_READONLY); @@ -315,6 +316,20 @@ setup_gate (void) put_kernel_page(page, GATE_ADDR + PAGE_SIZE, PAGE_GATE); #else put_kernel_page(page, GATE_ADDR + PERCPU_PAGE_SIZE, PAGE_GATE); + /* Fill in the holes (if any) with read-only zero pages: */ + { + unsigned long addr; + + for (addr = GATE_ADDR + PAGE_SIZE; + addr < GATE_ADDR + PERCPU_PAGE_SIZE; + addr += PAGE_SIZE) + { + put_kernel_page(ZERO_PAGE(0), addr, + PAGE_READONLY); + put_kernel_page(ZERO_PAGE(0), addr + PERCPU_PAGE_SIZE, + PAGE_READONLY); + } + } #endif ia64_patch_gate(); }