From: dave.long@linaro.org (David Long)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC PATCH] uprobes: copy to user-space xol page with proper cache flushing
Date: Tue, 15 Apr 2014 13:19:27 -0400 [thread overview]
Message-ID: <534D6A1F.70102@linaro.org> (raw)
In-Reply-To: <20140415154637.GA3560@redhat.com>
On 04/15/14 11:46, Oleg Nesterov wrote:
>
> But. Please do not add copy_to_user_page() into copy_to_page() (as your patch
> did). This is certainly not what uprobe_write_opcode() wants, we do not want
> or need "flush" in this case. The same for __create_xol_area().
>
It looked me like a call to a new __copy_to_user_page(current->mm, ...) in xol_get_insn_slot()
would be in line with David Miller's suggestion and would cure the problem on ARM (and hopefuly
be more philosophically correct for all architectures):
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 04709b6..b418626 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1287,6 +1287,7 @@ static unsigned long xol_get_insn_slot(struct uprobe *uprobe)
{
struct xol_area *area;
unsigned long xol_vaddr;
+ void *kaddr;
area = get_xol_area();
if (!area)
@@ -1297,13 +1298,11 @@ static unsigned long xol_get_insn_slot(struct uprobe *uprobe)
return 0;
/* Initialize the slot */
- copy_to_page(area->page, xol_vaddr,
- &uprobe->arch.ixol, sizeof(uprobe->arch.ixol));
- /*
- * We probably need flush_icache_user_range() but it needs vma.
- * This should work on supported architectures too.
- */
- flush_dcache_page(area->page);
+ kaddr = kmap_atomic(area->page);
+ __copy_to_user_page(current->mm, area->page, xol_vaddr,
+ kaddr + (xol_vaddr & ~PAGE_MASK),
+ &uprobe->arch.ixol, sizeof(uprobe->arch.ixol), true);
+ kunmap_atomic(kaddr);
return xol_vaddr;
}
Opinions? It's possible this approach isn't good enough. Cache operations and VM
are not my strong suit.
-dl
next prev parent reply other threads:[~2014-04-15 17:19 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-09 5:58 [PATCH v2] ARM: uprobes need icache flush after xol write Victor Kamensky
2014-04-09 5:58 ` Victor Kamensky
2014-04-09 18:23 ` David Long
2014-04-09 18:45 ` Oleg Nesterov
2014-04-09 19:13 ` Victor Kamensky
2014-04-09 19:19 ` Russell King - ARM Linux
2014-04-11 3:42 ` [RFC PATCH] uprobes: copy to user-space xol page with proper cache flushing David Long
2014-04-11 3:45 ` David Long
2014-04-11 4:36 ` David Miller
2014-04-11 14:26 ` Victor Kamensky
2014-04-11 14:35 ` Oleg Nesterov
2014-04-11 14:55 ` Victor Kamensky
2014-04-11 14:56 ` Oleg Nesterov
2014-04-11 15:22 ` Oleg Nesterov
2014-04-11 15:30 ` Russell King - ARM Linux
2014-04-11 17:24 ` Oleg Nesterov
2014-04-11 17:38 ` Oleg Nesterov
2014-04-11 18:00 ` David Miller
2014-04-11 18:25 ` Oleg Nesterov
2014-04-11 17:50 ` Linus Torvalds
2014-04-11 18:02 ` David Miller
2014-04-11 18:11 ` Linus Torvalds
2014-04-11 18:19 ` David Miller
2014-04-11 18:24 ` Linus Torvalds
2014-04-11 18:58 ` David Miller
2014-04-11 19:24 ` Linus Torvalds
2014-04-11 18:13 ` Victor Kamensky
2014-04-11 18:36 ` Oleg Nesterov
2014-04-14 18:59 ` Oleg Nesterov
2014-04-14 20:05 ` Victor Kamensky
2014-04-14 21:40 ` Victor Kamensky
2014-04-15 16:26 ` Oleg Nesterov
2014-04-15 15:46 ` Oleg Nesterov
2014-04-15 16:46 ` Victor Kamensky
2014-04-15 17:19 ` David Long [this message]
2014-04-15 17:38 ` David Miller
2014-04-15 17:49 ` Oleg Nesterov
2014-04-15 17:50 ` David Miller
2014-04-15 18:07 ` Oleg Nesterov
2014-04-15 18:27 ` David Miller
2014-04-15 18:46 ` Oleg Nesterov
2014-04-15 17:43 ` Oleg Nesterov
2014-04-15 17:46 ` David Miller
2014-04-15 18:03 ` Oleg Nesterov
2014-04-15 18:30 ` David Miller
2014-04-15 18:47 ` Russell King - ARM Linux
2014-04-15 18:53 ` David Miller
2014-04-15 18:50 ` David Miller
2014-04-15 19:29 ` Russell King - ARM Linux
2014-04-15 19:51 ` David Miller
2014-04-15 19:39 ` David Long
2014-04-15 19:53 ` David Miller
2014-04-16 1:42 ` Victor Kamensky
2014-04-16 2:22 ` David Miller
2014-04-16 2:24 ` David Miller
2014-04-16 3:06 ` Victor Kamensky
2014-04-16 3:17 ` David Miller
2014-04-11 17:43 ` David Miller
2014-04-11 15:32 ` Peter Zijlstra
2014-04-11 16:00 ` Russell King - ARM Linux
2014-04-11 18:39 ` Peter Zijlstra
2014-04-11 15:37 ` Victor Kamensky
2014-04-11 16:22 ` Oleg Nesterov
2014-04-11 15:42 ` Linus Torvalds
2014-04-11 13:08 ` Oleg Nesterov
2014-04-23 10:45 ` Catalin Marinas
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