From: will.deacon@arm•com (Will Deacon)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v7 8/9] ARM: vdso initialization, mapping, and synchronization
Date: Wed, 2 Jul 2014 15:40:50 +0100 [thread overview]
Message-ID: <20140702144050.GD24879@arm.com> (raw)
In-Reply-To: <CALCETrWeTeeuz4vW6wrhtDrdg54O-hhFbspfKEEunRZ0zf7ZBg@mail.gmail.com>
Hi Andy,
On Tue, Jul 01, 2014 at 03:17:23PM +0100, Andy Lutomirski wrote:
> On Tue, Jul 1, 2014 at 7:15 AM, Will Deacon <will.deacon@arm•com> wrote:
> > On Tue, Jul 01, 2014 at 03:11:04PM +0100, Nathan Lynch wrote:
> >> I believe Andy is suggesting separate VMAs (with different VM flags) for
> >> the VDSO's data and code. So, breakpoints in code would work, but
> >> attempts to modify the data page via ptrace() would fail outright
> >> instead of silently COWing.
> >
> > Ah, yes. That makes a lot of sense for the data page -- we should do
> > something similar on arm64 too, since the CoW will break everything for the
> > task being debugged. We could also drop the EXEC flags too.
>
> If you do this, I have a slight preference for the new vma being
> called "[vvar]" to match x86. It'll make the CRIU people happy if and
> when they port it to ARM.
I quickly hacked something (see below) and now I see the following in
/proc/$$/maps:
7fa1574000-7fa1575000 r-xp 00000000 00:00 0 [vdso]
7fa1575000-7fa1576000 r--p 00000000 00:00 0 [vvar]
Is that what you're after?
Will
--->8
diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index 50384fec56c4..84cafbc3eb54 100644
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c
@@ -138,11 +138,12 @@ int arch_setup_additional_pages(struct linux_binprm *bprm,
int uses_interp)
{
struct mm_struct *mm = current->mm;
- unsigned long vdso_base, vdso_mapping_len;
+ unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
int ret;
+ vdso_text_len = vdso_pages << PAGE_SHIFT;
/* Be sure to map the data page */
- vdso_mapping_len = (vdso_pages + 1) << PAGE_SHIFT;
+ vdso_mapping_len = vdso_text_len + PAGE_SIZE;
down_write(&mm->mmap_sem);
vdso_base = get_unmapped_area(NULL, 0, vdso_mapping_len, 0, 0);
@@ -152,35 +153,52 @@ int arch_setup_additional_pages(struct linux_binprm *bprm,
}
mm->context.vdso = (void *)vdso_base;
- ret = install_special_mapping(mm, vdso_base, vdso_mapping_len,
+ ret = install_special_mapping(mm, vdso_base, vdso_text_len,
VM_READ|VM_EXEC|
VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
vdso_pagelist);
- if (ret) {
- mm->context.vdso = NULL;
+ if (ret)
+ goto up_fail;
+
+ vdso_base += vdso_text_len;
+ ret = install_special_mapping(mm, vdso_base, PAGE_SIZE,
+ VM_READ|VM_MAYREAD,
+ vdso_pagelist + vdso_pages);
+ if (ret)
goto up_fail;
- }
-up_fail:
up_write(&mm->mmap_sem);
+ return 0;
+up_fail:
+ mm->context.vdso = NULL;
+ up_write(&mm->mmap_sem);
return ret;
}
const char *arch_vma_name(struct vm_area_struct *vma)
{
+ unsigned long vdso_text;
+
+ if (!vma->vm_mm)
+ return NULL;
+
+ vdso_text = (unsigned long)vma->vm_mm->context.vdso;
+
/*
* We can re-use the vdso pointer in mm_context_t for identifying
* the vectors page for compat applications. The vDSO will always
* sit above TASK_UNMAPPED_BASE and so we don't need to worry about
* it conflicting with the vectors base.
*/
- if (vma->vm_mm && vma->vm_start == (long)vma->vm_mm->context.vdso) {
+ if (vma->vm_start == vdso_text) {
#ifdef CONFIG_COMPAT
if (vma->vm_start == AARCH32_VECTORS_BASE)
return "[vectors]";
#endif
return "[vdso]";
+ } else if (vma->vm_start == (vdso_text + (vdso_pages << PAGE_SHIFT))) {
+ return "[vvar]";
}
return NULL;
next prev parent reply other threads:[~2014-07-02 14:40 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-23 3:11 [PATCH v7 0/9] ARM: VDSO Nathan Lynch
2014-06-23 3:11 ` [PATCH v7 1/9] clocksource: arm_arch_timer: change clocksource name if CP15 unavailable Nathan Lynch
2014-06-23 3:11 ` [PATCH v7 2/9] clocksource: arm_arch_timer: enable counter access for 32-bit ARM Nathan Lynch
2014-06-23 3:11 ` [PATCH v7 3/9] ARM: arch_timer: remove unused functions Nathan Lynch
2014-06-23 3:11 ` [PATCH v7 4/9] arm64: " Nathan Lynch
2014-06-23 3:11 ` [PATCH v7 5/9] ARM: place sigpage at a random offset above stack Nathan Lynch
2014-06-23 3:11 ` [PATCH v7 6/9] ARM: miscellaneous vdso infrastructure, preparation Nathan Lynch
2014-06-30 10:11 ` Arnd Bergmann
2014-06-30 12:27 ` Nathan Lynch
2014-06-30 13:06 ` Arnd Bergmann
2014-06-23 3:11 ` [PATCH v7 7/9] ARM: add vdso user-space code Nathan Lynch
2014-06-28 9:53 ` Russell King - ARM Linux
2014-06-28 10:03 ` Russell King - ARM Linux
2014-06-30 15:56 ` Andy Lutomirski
2014-06-28 15:19 ` Nathan Lynch
2014-06-28 15:26 ` Russell King - ARM Linux
2014-06-28 16:13 ` Nathan Lynch
2014-06-28 18:12 ` Russell King - ARM Linux
2014-06-28 19:45 ` Nathan Lynch
2014-06-28 20:11 ` Russell King - ARM Linux
2014-06-28 21:35 ` Nathan Lynch
2014-06-29 8:34 ` Russell King - ARM Linux
2014-06-29 15:48 ` Nathan Lynch
2014-06-29 16:07 ` Russell King - ARM Linux
2014-06-29 23:04 ` Nathan Lynch
2014-06-30 21:33 ` Andy Lutomirski
2014-06-30 15:59 ` Andy Lutomirski
2014-06-30 16:50 ` Nathan Lynch
2014-06-30 21:29 ` Andy Lutomirski
2014-07-01 9:00 ` Will Deacon
2014-07-01 13:34 ` Nathan Lynch
2014-07-01 14:11 ` Andy Lutomirski
2014-07-01 13:28 ` Nathan Lynch
2014-07-01 14:56 ` Andy Lutomirski
2014-06-23 3:11 ` [PATCH v7 8/9] ARM: vdso initialization, mapping, and synchronization Nathan Lynch
2014-06-30 21:37 ` Andy Lutomirski
2014-07-01 9:03 ` Will Deacon
2014-07-01 14:11 ` Nathan Lynch
2014-07-01 14:15 ` Will Deacon
2014-07-01 14:17 ` Andy Lutomirski
2014-07-01 17:27 ` Christopher Covington
2014-07-02 14:40 ` Will Deacon [this message]
2014-07-02 15:54 ` Andy Lutomirski
2014-07-02 16:18 ` Nathan Lynch
2014-07-02 16:27 ` Will Deacon
2014-07-02 16:47 ` Andy Lutomirski
2014-07-02 17:24 ` Will Deacon
2014-07-02 18:34 ` Andy Lutomirski
2014-07-02 18:54 ` Will Deacon
2014-07-22 0:14 ` Andy Lutomirski
2014-07-22 8:13 ` Will Deacon
2014-07-01 14:01 ` Nathan Lynch
2014-07-01 14:09 ` Andy Lutomirski
2014-07-01 14:14 ` Russell King - ARM Linux
2014-06-23 3:11 ` [PATCH v7 9/9] ARM: add CONFIG_VDSO Kconfig and Makefile bits Nathan Lynch
2014-06-27 8:51 ` [PATCH v7 0/9] ARM: VDSO Jan Glauber
2014-06-27 8:57 ` Russell King - ARM Linux
2014-06-27 9:41 ` Ard Biesheuvel
2014-06-27 9:46 ` Russell King - ARM Linux
2014-06-27 17:01 ` Nathan Lynch
2014-06-28 9:42 ` Russell King - ARM Linux
2014-06-28 9:55 ` Russell King - ARM Linux
2014-06-28 14:49 ` Russell King - ARM Linux
2014-06-30 7:27 ` Arnd Bergmann
2014-06-30 7:43 ` Arnd Bergmann
2014-06-30 18:27 ` Nathan Lynch
2014-06-27 16:00 ` Nathan Lynch
2014-06-30 16:03 ` Andy Lutomirski
2014-06-30 8:12 ` Ard Biesheuvel
2014-07-01 16:34 ` Nathan Lynch
2014-07-01 20:08 ` Ard Biesheuvel
2014-07-01 22:44 ` Russell King - ARM Linux
2014-06-30 14:40 ` Will Deacon
2014-06-30 15:42 ` Nathan Lynch
2014-06-30 21:56 ` Andy Lutomirski
2014-07-01 9:04 ` Will Deacon
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20140702144050.GD24879@arm.com \
--to=will.deacon@arm$(echo .)com \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox