path: root/results/classifier/zero-shot/118/all/1895080

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pgb_reserved_va: Assertion `addr == test' failed

This problem occurs on CentOS-7.5 (64-bit) with qemu-5.1.0, qemu head (commit 9435a8b3dd35f1f926f1b9127e8a906217a5518a) for riscv32-linux-user.

Firstly, compile fails:
Compiling C object libqemu-riscv32-linux-user.fa.p/linux-user_strace.c.o
../qemu.git/linux-user/strace.c:1210:18: error: ‘FALLOC_FL_KEEP_SIZE’ undeclared here (not in a function)
     FLAG_GENERIC(FALLOC_FL_KEEP_SIZE),

I have to add below include to linux-user/strace.c
diff --git a/linux-user/strace.c b/linux-user/strace.c
index 11fea14fba..22e51d4a8a 100644
--- a/linux-user/strace.c
+++ b/linux-user/strace.c
@@ -7,6 +7,7 @@
 #include <sys/mount.h>
 #include <arpa/inet.h>
 #include <netinet/tcp.h>
+#include <linux/falloc.h>
 #include <linux/if_packet.h>
 #include <linux/netlink.h>
 #include <sched.h>

Then trying qemu-riscv32 with a simple ELF, I get:
linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr == test' failed.

strace shows that:
mmap(0x1000, 4294963200, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x10000
write(2, "qemu-riscv32: ../qemu.git/linux-"..., 103qemu-riscv32: ../qemu.git/linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr == test' failed.
) = 103

The source code is in the function pgb_reserved_va (linux-user/elfload.c). I think mmap cannot guarantee that the returned pointer (test) equals to the parameter of addr. So is this a bug to assert (addr == test)?

Attached configure script and test ELF file.

Thanks.



Le 10/09/2020 à 07:21, Launchpad Bug Tracker a écrit :
> This problem occurs on CentOS-7.5 (64-bit) with qemu-5.1.0, qemu head
> (commit 9435a8b3dd35f1f926f1b9127e8a906217a5518a) for riscv32-linux-
> user.

I tried to build qemu-5.1 on CentOS-7.5.1 but as python 3.5 is not
available, I gave up.

> Firstly, compile fails:
> Compiling C object libqemu-riscv32-linux-user.fa.p/linux-user_strace.c.o
> ../qemu.git/linux-user/strace.c:1210:18: error: ‘FALLOC_FL_KEEP_SIZE’ undeclared here (not in a function)
>      FLAG_GENERIC(FALLOC_FL_KEEP_SIZE),
> 
> I have to add below include to linux-user/strace.c
> diff --git a/linux-user/strace.c b/linux-user/strace.c
> index 11fea14fba..22e51d4a8a 100644
> --- a/linux-user/strace.c
> +++ b/linux-user/strace.c
> @@ -7,6 +7,7 @@
>  #include <sys/mount.h>
>  #include <arpa/inet.h>
>  #include <netinet/tcp.h>
> +#include <linux/falloc.h>
>  #include <linux/if_packet.h>
>  #include <linux/netlink.h>
>  #include <sched.h>

In fact, fallocate(2) says fcntl.h must be included.
And qemu/osdep.h includes it.
So you should not have this problem.

> 
> Then trying qemu-riscv32 with a simple ELF, I get:
> linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr == test' failed.
> 
> strace shows that:
> mmap(0x1000, 4294963200, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x10000
> write(2, "qemu-riscv32: ../qemu.git/linux-"..., 103qemu-riscv32: ../qemu.git/linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr == test' failed.
> ) = 103
> 
> The source code is in the function pgb_reserved_va (linux-
> user/elfload.c). I think mmap cannot guarantee that the returned pointer
> (test) equals to the parameter of addr. So is this a bug to assert (addr
> == test)?

I think Alex Bennée knows better this code than I do, so cc'ing him.

Thnaks
Laurent


> This problem occurs on CentOS-7.5 (64-bit) with qemu-5.1.0, qemu head
> > (commit 9435a8b3dd35f1f926f1b9127e8a906217a5518a) for riscv32-linux-
> > user.
>
> I tried to build qemu-5.1 on CentOS-7.5.1 but as python 3.5 is not
> available, I gave up.
>

Thank you for your effort. I installed python3 with yum:
python3.x86_64                           3.6.8-10.el7              @centos
Then maybe you can specify python3 in configure with
"--python=/bin/python3" in case configure cannot find it.


>
> > Firstly, compile fails:
> > Compiling C object libqemu-riscv32-linux-user.fa.p/linux-user_strace.c.o
> > ../qemu.git/linux-user/strace.c:1210:18: error: ‘FALLOC_FL_KEEP_SIZE’
> undeclared here (not in a function)
> >      FLAG_GENERIC(FALLOC_FL_KEEP_SIZE),
> >
> > I have to add below include to linux-user/strace.c
> > diff --git a/linux-user/strace.c b/linux-user/strace.c
> > index 11fea14fba..22e51d4a8a 100644
> > --- a/linux-user/strace.c
> > +++ b/linux-user/strace.c
> > @@ -7,6 +7,7 @@
> >  #include <sys/mount.h>
> >  #include <arpa/inet.h>
> >  #include <netinet/tcp.h>
> > +#include <linux/falloc.h>
> >  #include <linux/if_packet.h>
> >  #include <linux/netlink.h>
> >  #include <sched.h>
>
> In fact, fallocate(2) says fcntl.h must be included.
> And qemu/osdep.h includes it.
> So you should not have this problem.
>

I tried to save the file after pre-processing, namely strace.i. Though
_GNU_SOURCE is defined and fcntl.h is included, falloc.h is not included,
in which FALLOC_FL_KEEP_SIZE is defined. I'm not sure if it's some
environmental problem.

Thanks.

>
> > Then trying qemu-riscv32 with a simple ELF, I get:
> > linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr == test'
> failed.
> >
> > strace shows that:
> > mmap(0x1000, 4294963200, PROT_NONE,
> MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x10000
> > write(2, "qemu-riscv32: ../qemu.git/linux-"..., 103qemu-riscv32:
> ../qemu.git/linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr ==
> test' failed.
> > ) = 103
> >
> > The source code is in the function pgb_reserved_va (linux-
> > user/elfload.c). I think mmap cannot guarantee that the returned pointer
> > (test) equals to the parameter of addr. So is this a bug to assert (addr
> > == test)?
>
> I think Alex Bennée knows better this code than I do, so cc'ing him.
>
> Thnaks
> Laurent
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1895080
>
> Title:
>   pgb_reserved_va: Assertion `addr == test' failed
>
> Status in QEMU:
>   New
>
> Bug description:
>   This problem occurs on CentOS-7.5 (64-bit) with qemu-5.1.0, qemu head
>   (commit 9435a8b3dd35f1f926f1b9127e8a906217a5518a) for riscv32-linux-
>   user.
>
>   Firstly, compile fails:
>   Compiling C object libqemu-riscv32-linux-user.fa.p/linux-user_strace.c.o
>   ../qemu.git/linux-user/strace.c:1210:18: error: ‘FALLOC_FL_KEEP_SIZE’
> undeclared here (not in a function)
>        FLAG_GENERIC(FALLOC_FL_KEEP_SIZE),
>
>   I have to add below include to linux-user/strace.c
>   diff --git a/linux-user/strace.c b/linux-user/strace.c
>   index 11fea14fba..22e51d4a8a 100644
>   --- a/linux-user/strace.c
>   +++ b/linux-user/strace.c
>   @@ -7,6 +7,7 @@
>    #include <sys/mount.h>
>    #include <arpa/inet.h>
>    #include <netinet/tcp.h>
>   +#include <linux/falloc.h>
>    #include <linux/if_packet.h>
>    #include <linux/netlink.h>
>    #include <sched.h>
>
>   Then trying qemu-riscv32 with a simple ELF, I get:
>   linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr == test'
> failed.
>
>   strace shows that:
>   mmap(0x1000, 4294963200, PROT_NONE,
> MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x10000
>   write(2, "qemu-riscv32: ../qemu.git/linux-"..., 103qemu-riscv32:
> ../qemu.git/linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr ==
> test' failed.
>   ) = 103
>
>   The source code is in the function pgb_reserved_va (linux-
>   user/elfload.c). I think mmap cannot guarantee that the returned
>   pointer (test) equals to the parameter of addr. So is this a bug to
>   assert (addr == test)?
>
>   Attached configure script and test ELF file.
>
>   Thanks.
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/qemu/+bug/1895080/+subscriptions
>


Have you got a static version of the test binary (or a mini rootfs with the libraries it needs)?

Have you got a static version of the test binary (or a mini rootfs with
> the libraries it needs)?
>

If the problem occurs, it does not reach the stage of the dependent
libraries  of the test ELF. Anyway, I've attached the static test binary as
hello.static.elf.
Thanks


> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1895080
>
> Title:
>   pgb_reserved_va: Assertion `addr == test' failed
>
> Status in QEMU:
>   New
>
> Bug description:
>   This problem occurs on CentOS-7.5 (64-bit) with qemu-5.1.0, qemu head
>   (commit 9435a8b3dd35f1f926f1b9127e8a906217a5518a) for riscv32-linux-
>   user.
>
>   Firstly, compile fails:
>   Compiling C object libqemu-riscv32-linux-user.fa.p/linux-user_strace.c.o
>   ../qemu.git/linux-user/strace.c:1210:18: error: ‘FALLOC_FL_KEEP_SIZE’
> undeclared here (not in a function)
>        FLAG_GENERIC(FALLOC_FL_KEEP_SIZE),
>
>   I have to add below include to linux-user/strace.c
>   diff --git a/linux-user/strace.c b/linux-user/strace.c
>   index 11fea14fba..22e51d4a8a 100644
>   --- a/linux-user/strace.c
>   +++ b/linux-user/strace.c
>   @@ -7,6 +7,7 @@
>    #include <sys/mount.h>
>    #include <arpa/inet.h>
>    #include <netinet/tcp.h>
>   +#include <linux/falloc.h>
>    #include <linux/if_packet.h>
>    #include <linux/netlink.h>
>    #include <sched.h>
>
>   Then trying qemu-riscv32 with a simple ELF, I get:
>   linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr == test'
> failed.
>
>   strace shows that:
>   mmap(0x1000, 4294963200, PROT_NONE,
> MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x10000
>   write(2, "qemu-riscv32: ../qemu.git/linux-"..., 103qemu-riscv32:
> ../qemu.git/linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr ==
> test' failed.
>   ) = 103
>
>   The source code is in the function pgb_reserved_va (linux-
>   user/elfload.c). I think mmap cannot guarantee that the returned
>   pointer (test) equals to the parameter of addr. So is this a bug to
>   assert (addr == test)?
>
>   Attached configure script and test ELF file.
>
>   Thanks.
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/qemu/+bug/1895080/+subscriptions
>



Laurent Vivier <email address hidden> writes:

> Le 10/09/2020 à 07:21, Launchpad Bug Tracker a écrit :
>> This problem occurs on CentOS-7.5 (64-bit) with qemu-5.1.0, qemu head
>> (commit 9435a8b3dd35f1f926f1b9127e8a906217a5518a) for riscv32-linux-
>> user.
>
> I tried to build qemu-5.1 on CentOS-7.5.1 but as python 3.5 is not
> available, I gave up.
>
>> Firstly, compile fails:
>> Compiling C object libqemu-riscv32-linux-user.fa.p/linux-user_strace.c.o
>> ../qemu.git/linux-user/strace.c:1210:18: error: ‘FALLOC_FL_KEEP_SIZE’ undeclared here (not in a function)
>>      FLAG_GENERIC(FALLOC_FL_KEEP_SIZE),
>> 
>> I have to add below include to linux-user/strace.c
>> diff --git a/linux-user/strace.c b/linux-user/strace.c
>> index 11fea14fba..22e51d4a8a 100644
>> --- a/linux-user/strace.c
>> +++ b/linux-user/strace.c
>> @@ -7,6 +7,7 @@
>>  #include <sys/mount.h>
>>  #include <arpa/inet.h>
>>  #include <netinet/tcp.h>
>> +#include <linux/falloc.h>
>>  #include <linux/if_packet.h>
>>  #include <linux/netlink.h>
>>  #include <sched.h>
>
> In fact, fallocate(2) says fcntl.h must be included.
> And qemu/osdep.h includes it.
> So you should not have this problem.
>
>> 
>> Then trying qemu-riscv32 with a simple ELF, I get:
>> linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr == test' failed.
>> 
>> strace shows that:
>> mmap(0x1000, 4294963200, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x10000
>> write(2, "qemu-riscv32: ../qemu.git/linux-"..., 103qemu-riscv32: ../qemu.git/linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr == test' failed.
>> ) = 103
>> 
>> The source code is in the function pgb_reserved_va (linux-
>> user/elfload.c). I think mmap cannot guarantee that the returned pointer
>> (test) equals to the parameter of addr. So is this a bug to assert (addr
>> == test)?
>
> I think Alex Bennée knows better this code than I do, so cc'ing him.

It should be able to do so because the earlier code (pgb_static) checks
for a hole the size of reserved_va in the host memory map. This should
be fairly easy for 32 bit guests given the amount of spare address space
you have on a 64 bit system.

I'm assuming CentOS 7.5 actually has a definition for
MAP_FIXED_NOREPLACE which should ensure we get what we asked for -
otherwise we are in the position of hoping the kernel honours what we
asked for.

>
> Thnaks
> Laurent


-- 
Alex Bennée



Alex Bennée <email address hidden> writes:

> Laurent Vivier <email address hidden> writes:
>
<snip>
>>> Then trying qemu-riscv32 with a simple ELF, I get:
>>> linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr == test' failed.
>>> 
>>> strace shows that:
>>> mmap(0x1000, 4294963200, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x10000
>>> write(2, "qemu-riscv32: ../qemu.git/linux-"..., 103qemu-riscv32: ../qemu.git/linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr == test' failed.
>>> ) = 103
>>> 
>>> The source code is in the function pgb_reserved_va (linux-
>>> user/elfload.c). I think mmap cannot guarantee that the returned pointer
>>> (test) equals to the parameter of addr. So is this a bug to assert (addr
>>> == test)?
>>
> I'm assuming CentOS 7.5 actually has a definition for
> MAP_FIXED_NOREPLACE which should ensure we get what we asked for -
> otherwise we are in the position of hoping the kernel honours what we
> asked for.

Doh re-reading I see it's not set in the strace output. Maybe we should
promote the assert case to the failure leg so we have:

    if (addr == MAP_FAILED || addr != test) {
        error_report(...)
    }

so we at least fail with a user friendly error rather than an abort?

-- 
Alex Bennée


No, it's not set by CentOS-7.5.
Does it mean that we just cannot run the ELF in such a case? I've tried
many times, the assert always fails. Maybe, we can blame CentOS-7.5.
BTW: with the option "-p 65536", the case runs successfully.

On Fri, Sep 11, 2020 at 5:50 PM Alex Bennée <email address hidden>
wrote:

> Alex Bennée <email address hidden> writes:
>
> > Laurent Vivier <email address hidden> writes:
> >
> <snip>
> >>> Then trying qemu-riscv32 with a simple ELF, I get:
> >>> linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr == test'
> failed.
> >>>
> >>> strace shows that:
> >>> mmap(0x1000, 4294963200, PROT_NONE,
> MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x10000
> >>> write(2, "qemu-riscv32: ../qemu.git/linux-"..., 103qemu-riscv32:
> ../qemu.git/linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr ==
> test' failed.
> >>> ) = 103
> >>>
> >>> The source code is in the function pgb_reserved_va (linux-
> >>> user/elfload.c). I think mmap cannot guarantee that the returned
> pointer
> >>> (test) equals to the parameter of addr. So is this a bug to assert
> (addr
> >>> == test)?
> >>
> > I'm assuming CentOS 7.5 actually has a definition for
> > MAP_FIXED_NOREPLACE which should ensure we get what we asked for -
> > otherwise we are in the position of hoping the kernel honours what we
> > asked for.
>
> Doh re-reading I see it's not set in the strace output. Maybe we should
> promote the assert case to the failure leg so we have:
>
>     if (addr == MAP_FAILED || addr != test) {
>         error_report(...)
>     }
>
> so we at least fail with a user friendly error rather than an abort?
>
> --
> Alex Bennée
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1895080
>
> Title:
>   pgb_reserved_va: Assertion `addr == test' failed
>
> Status in QEMU:
>   New
>
> Bug description:
>   This problem occurs on CentOS-7.5 (64-bit) with qemu-5.1.0, qemu head
>   (commit 9435a8b3dd35f1f926f1b9127e8a906217a5518a) for riscv32-linux-
>   user.
>
>   Firstly, compile fails:
>   Compiling C object libqemu-riscv32-linux-user.fa.p/linux-user_strace.c.o
>   ../qemu.git/linux-user/strace.c:1210:18: error: ‘FALLOC_FL_KEEP_SIZE’
> undeclared here (not in a function)
>        FLAG_GENERIC(FALLOC_FL_KEEP_SIZE),
>
>   I have to add below include to linux-user/strace.c
>   diff --git a/linux-user/strace.c b/linux-user/strace.c
>   index 11fea14fba..22e51d4a8a 100644
>   --- a/linux-user/strace.c
>   +++ b/linux-user/strace.c
>   @@ -7,6 +7,7 @@
>    #include <sys/mount.h>
>    #include <arpa/inet.h>
>    #include <netinet/tcp.h>
>   +#include <linux/falloc.h>
>    #include <linux/if_packet.h>
>    #include <linux/netlink.h>
>    #include <sched.h>
>
>   Then trying qemu-riscv32 with a simple ELF, I get:
>   linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr == test'
> failed.
>
>   strace shows that:
>   mmap(0x1000, 4294963200, PROT_NONE,
> MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x10000
>   write(2, "qemu-riscv32: ../qemu.git/linux-"..., 103qemu-riscv32:
> ../qemu.git/linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr ==
> test' failed.
>   ) = 103
>
>   The source code is in the function pgb_reserved_va (linux-
>   user/elfload.c). I think mmap cannot guarantee that the returned
>   pointer (test) equals to the parameter of addr. So is this a bug to
>   assert (addr == test)?
>
>   Attached configure script and test ELF file.
>
>   Thanks.
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/qemu/+bug/1895080/+subscriptions
>



Hansni Bu <email address hidden> writes:

> No, it's not set by CentOS-7.5.
> Does it mean that we just cannot run the ELF in such a case? I've tried
> many times, the assert always fails. Maybe, we can blame CentOS-7.5.

The trouble is without MAP_FIXED_NOREPLACE we are at the mercy of the
host kernel to allow the address request to be honoured. A plain
MAP_FIXED won't do as it can clober existing mappings. In theory a
suitable hole has been identified but sometimes the kernel makes a
decision to offset the suggested mapping for it's own reasons. 

> BTW: with the option "-p 65536", the case runs successfully.

Hmm interesting. I wonder if we are seeing a fail due to mmap_min_addr?
What does:

  /proc/sys/vm/mmap_min_addr

give you on the system?

You can manually set the reserved_va and the base address using -R and
-B although that is more of a developer work around. I think moving the
assert to the condition above would be an improvement just because it
tells us what the requested base address was and what the kernel decided
to give us.

>
> On Fri, Sep 11, 2020 at 5:50 PM Alex Bennée <email address hidden>
> wrote:
>
>> Alex Bennée <email address hidden> writes:
>>
>> > Laurent Vivier <email address hidden> writes:
>> >
>> <snip>
>> >>> Then trying qemu-riscv32 with a simple ELF, I get:
>> >>> linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr == test'
>> failed.
>> >>>
>> >>> strace shows that:
>> >>> mmap(0x1000, 4294963200, PROT_NONE,
>> MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x10000
>> >>> write(2, "qemu-riscv32: ../qemu.git/linux-"..., 103qemu-riscv32:
>> ../qemu.git/linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr ==
>> test' failed.
>> >>> ) = 103
>> >>>
>> >>> The source code is in the function pgb_reserved_va (linux-
>> >>> user/elfload.c). I think mmap cannot guarantee that the returned
>> pointer
>> >>> (test) equals to the parameter of addr. So is this a bug to assert
>> (addr
>> >>> == test)?
>> >>
>> > I'm assuming CentOS 7.5 actually has a definition for
>> > MAP_FIXED_NOREPLACE which should ensure we get what we asked for -
>> > otherwise we are in the position of hoping the kernel honours what we
>> > asked for.
>>
>> Doh re-reading I see it's not set in the strace output. Maybe we should
>> promote the assert case to the failure leg so we have:
>>
>>     if (addr == MAP_FAILED || addr != test) {
>>         error_report(...)
>>     }
>>
>> so we at least fail with a user friendly error rather than an abort?
>>
>> --
>> Alex Bennée
>>
>> --
>> You received this bug notification because you are subscribed to the bug
>> report.
>> https://bugs.launchpad.net/bugs/1895080
>>
>> Title:
>>   pgb_reserved_va: Assertion `addr == test' failed
>>
>> Status in QEMU:
>>   New
>>
>> Bug description:
>>   This problem occurs on CentOS-7.5 (64-bit) with qemu-5.1.0, qemu head
>>   (commit 9435a8b3dd35f1f926f1b9127e8a906217a5518a) for riscv32-linux-
>>   user.
>>
>>   Firstly, compile fails:
>>   Compiling C object libqemu-riscv32-linux-user.fa.p/linux-user_strace.c.o
>>   ../qemu.git/linux-user/strace.c:1210:18: error: ‘FALLOC_FL_KEEP_SIZE’
>> undeclared here (not in a function)
>>        FLAG_GENERIC(FALLOC_FL_KEEP_SIZE),
>>
>>   I have to add below include to linux-user/strace.c
>>   diff --git a/linux-user/strace.c b/linux-user/strace.c
>>   index 11fea14fba..22e51d4a8a 100644
>>   --- a/linux-user/strace.c
>>   +++ b/linux-user/strace.c
>>   @@ -7,6 +7,7 @@
>>    #include <sys/mount.h>
>>    #include <arpa/inet.h>
>>    #include <netinet/tcp.h>
>>   +#include <linux/falloc.h>
>>    #include <linux/if_packet.h>
>>    #include <linux/netlink.h>
>>    #include <sched.h>
>>
>>   Then trying qemu-riscv32 with a simple ELF, I get:
>>   linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr == test'
>> failed.
>>
>>   strace shows that:
>>   mmap(0x1000, 4294963200, PROT_NONE,
>> MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x10000
>>   write(2, "qemu-riscv32: ../qemu.git/linux-"..., 103qemu-riscv32:
>> ../qemu.git/linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr ==
>> test' failed.
>>   ) = 103
>>
>>   The source code is in the function pgb_reserved_va (linux-
>>   user/elfload.c). I think mmap cannot guarantee that the returned
>>   pointer (test) equals to the parameter of addr. So is this a bug to
>>   assert (addr == test)?
>>
>>   Attached configure script and test ELF file.
>>
>>   Thanks.
>>
>> To manage notifications about this bug go to:
>> https://bugs.launchpad.net/qemu/+bug/1895080/+subscriptions
>>


-- 
Alex Bennée


> > No, it's not set by CentOS-7.5.
> > Does it mean that we just cannot run the ELF in such a case? I've tried
> > many times, the assert always fails. Maybe, we can blame CentOS-7.5.
>
> The trouble is without MAP_FIXED_NOREPLACE we are at the mercy of the
> host kernel to allow the address request to be honoured. A plain
> MAP_FIXED won't do as it can clober existing mappings. In theory a
> suitable hole has been identified but sometimes the kernel makes a
> decision to offset the suggested mapping for it's own reasons.
>

MAP_FIXED_NOREPLACE is quite a new feature.


> > BTW: with the option "-p 65536", the case runs successfully.
>
> Hmm interesting. I wonder if we are seeing a fail due to mmap_min_addr?
> What does:
>
>   /proc/sys/vm/mmap_min_addr
>
> give you on the system?
>

It gives me 4096. And guest_base has this value. Maybe that's the strange
point. mmap_min_addr give us 0x1000. While we are requesting this address,
the kernel gives us 0x10000.


>
> You can manually set the reserved_va and the base address using -R and
> -B although that is more of a developer work around. I think moving the
> assert to the condition above would be an improvement just because it
> tells us what the requested base address was and what the kernel decided
> to give us.
>

Setting guest_base with -B to 0x10000 works. Tried some -R values, no luck.
Agree to print a more hintful message.


>
> >
> > On Fri, Sep 11, 2020 at 5:50 PM Alex Bennée <email address hidden>
> > wrote:
> >
> >> Alex Bennée <email address hidden> writes:
> >>
> >> > Laurent Vivier <email address hidden> writes:
> >> >
> >> <snip>
> >> >>> Then trying qemu-riscv32 with a simple ELF, I get:
> >> >>> linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr == test'
> >> failed.
> >> >>>
> >> >>> strace shows that:
> >> >>> mmap(0x1000, 4294963200, PROT_NONE,
> >> MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x10000
> >> >>> write(2, "qemu-riscv32: ../qemu.git/linux-"..., 103qemu-riscv32:
> >> ../qemu.git/linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr
> ==
> >> test' failed.
> >> >>> ) = 103
> >> >>>
> >> >>> The source code is in the function pgb_reserved_va (linux-
> >> >>> user/elfload.c). I think mmap cannot guarantee that the returned
> >> pointer
> >> >>> (test) equals to the parameter of addr. So is this a bug to assert
> >> (addr
> >> >>> == test)?
> >> >>
> >> > I'm assuming CentOS 7.5 actually has a definition for
> >> > MAP_FIXED_NOREPLACE which should ensure we get what we asked for -
> >> > otherwise we are in the position of hoping the kernel honours what we
> >> > asked for.
> >>
> >> Doh re-reading I see it's not set in the strace output. Maybe we should
> >> promote the assert case to the failure leg so we have:
> >>
> >>     if (addr == MAP_FAILED || addr != test) {
> >>         error_report(...)
> >>     }
> >>
> >> so we at least fail with a user friendly error rather than an abort?
> >>
> >> --
> >> Alex Bennée
> >>
> >> --
> >> You received this bug notification because you are subscribed to the bug
> >> report.
> >> https://bugs.launchpad.net/bugs/1895080
> >>
> >> Title:
> >>   pgb_reserved_va: Assertion `addr == test' failed
> >>
> >> Status in QEMU:
> >>   New
> >>
> >> Bug description:
> >>   This problem occurs on CentOS-7.5 (64-bit) with qemu-5.1.0, qemu head
> >>   (commit 9435a8b3dd35f1f926f1b9127e8a906217a5518a) for riscv32-linux-
> >>   user.
> >>
> >>   Firstly, compile fails:
> >>   Compiling C object
> libqemu-riscv32-linux-user.fa.p/linux-user_strace.c.o
> >>   ../qemu.git/linux-user/strace.c:1210:18: error: ‘FALLOC_FL_KEEP_SIZE’
> >> undeclared here (not in a function)
> >>        FLAG_GENERIC(FALLOC_FL_KEEP_SIZE),
> >>
> >>   I have to add below include to linux-user/strace.c
> >>   diff --git a/linux-user/strace.c b/linux-user/strace.c
> >>   index 11fea14fba..22e51d4a8a 100644
> >>   --- a/linux-user/strace.c
> >>   +++ b/linux-user/strace.c
> >>   @@ -7,6 +7,7 @@
> >>    #include <sys/mount.h>
> >>    #include <arpa/inet.h>
> >>    #include <netinet/tcp.h>
> >>   +#include <linux/falloc.h>
> >>    #include <linux/if_packet.h>
> >>    #include <linux/netlink.h>
> >>    #include <sched.h>
> >>
> >>   Then trying qemu-riscv32 with a simple ELF, I get:
> >>   linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr == test'
> >> failed.
> >>
> >>   strace shows that:
> >>   mmap(0x1000, 4294963200, PROT_NONE,
> >> MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x10000
> >>   write(2, "qemu-riscv32: ../qemu.git/linux-"..., 103qemu-riscv32:
> >> ../qemu.git/linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr
> ==
> >> test' failed.
> >>   ) = 103
> >>
> >>   The source code is in the function pgb_reserved_va (linux-
> >>   user/elfload.c). I think mmap cannot guarantee that the returned
> >>   pointer (test) equals to the parameter of addr. So is this a bug to
> >>   assert (addr == test)?
> >>
> >>   Attached configure script and test ELF file.
> >>
> >>   Thanks.
> >>
> >> To manage notifications about this bug go to:
> >> https://bugs.launchpad.net/qemu/+bug/1895080/+subscriptions
> >>
>
>
> --
> Alex Bennée
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1895080
>
> Title:
>   pgb_reserved_va: Assertion `addr == test' failed
>
> Status in QEMU:
>   New
>
> Bug description:
>   This problem occurs on CentOS-7.5 (64-bit) with qemu-5.1.0, qemu head
>   (commit 9435a8b3dd35f1f926f1b9127e8a906217a5518a) for riscv32-linux-
>   user.
>
>   Firstly, compile fails:
>   Compiling C object libqemu-riscv32-linux-user.fa.p/linux-user_strace.c.o
>   ../qemu.git/linux-user/strace.c:1210:18: error: ‘FALLOC_FL_KEEP_SIZE’
> undeclared here (not in a function)
>        FLAG_GENERIC(FALLOC_FL_KEEP_SIZE),
>
>   I have to add below include to linux-user/strace.c
>   diff --git a/linux-user/strace.c b/linux-user/strace.c
>   index 11fea14fba..22e51d4a8a 100644
>   --- a/linux-user/strace.c
>   +++ b/linux-user/strace.c
>   @@ -7,6 +7,7 @@
>    #include <sys/mount.h>
>    #include <arpa/inet.h>
>    #include <netinet/tcp.h>
>   +#include <linux/falloc.h>
>    #include <linux/if_packet.h>
>    #include <linux/netlink.h>
>    #include <sched.h>
>
>   Then trying qemu-riscv32 with a simple ELF, I get:
>   linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr == test'
> failed.
>
>   strace shows that:
>   mmap(0x1000, 4294963200, PROT_NONE,
> MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x10000
>   write(2, "qemu-riscv32: ../qemu.git/linux-"..., 103qemu-riscv32:
> ../qemu.git/linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr ==
> test' failed.
>   ) = 103
>
>   The source code is in the function pgb_reserved_va (linux-
>   user/elfload.c). I think mmap cannot guarantee that the returned
>   pointer (test) equals to the parameter of addr. So is this a bug to
>   assert (addr == test)?
>
>   Attached configure script and test ELF file.
>
>   Thanks.
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/qemu/+bug/1895080/+subscriptions
>



Hansni Bu <email address hidden> writes:

>> > No, it's not set by CentOS-7.5.
>> > Does it mean that we just cannot run the ELF in such a case? I've tried
>> > many times, the assert always fails. Maybe, we can blame CentOS-7.5.
>>
>> The trouble is without MAP_FIXED_NOREPLACE we are at the mercy of the
>> host kernel to allow the address request to be honoured. A plain
>> MAP_FIXED won't do as it can clober existing mappings. In theory a
>> suitable hole has been identified but sometimes the kernel makes a
>> decision to offset the suggested mapping for it's own reasons.
>>
>
> MAP_FIXED_NOREPLACE is quite a new feature.
>
>
>> > BTW: with the option "-p 65536", the case runs successfully.
>>
>> Hmm interesting. I wonder if we are seeing a fail due to mmap_min_addr?
>> What does:
>>
>>   /proc/sys/vm/mmap_min_addr
>>
>> give you on the system?
>>
>
> It gives me 4096. And guest_base has this value. Maybe that's the strange
> point. mmap_min_addr give us 0x1000. While we are requesting this address,
> the kernel gives us 0x10000.

Yeah the meaning of mmap_min_addr should be exactly that which is odd
why the kernel doesn't honour the request. That said it seems to be a
user tweakable knob so you could just up it.

>>
>> You can manually set the reserved_va and the base address using -R and
>> -B although that is more of a developer work around. I think moving the
>> assert to the condition above would be an improvement just because it
>> tells us what the requested base address was and what the kernel decided
>> to give us.
>>
>
> Setting guest_base with -B to 0x10000 works. Tried some -R values, no luck.
> Agree to print a more hintful message.

OK - one other test you try is running inside a chroot which *does not*
have visibility of /proc. That will cause it to fall back to the old
probing technique of trying multiple mmap operations to find the hole. I
suspect that works because the attempt to map 0x1000 would fail the
check. The reason we default to probing /proc/self/map now is that brute
force technique falls over when trying to probe for a hole on 64 bit
systems, especially when built with stack protection/clang debug
instrumentation.

In the meantime I'll spin up a patch to improve the failure mode.

>
>
>>
>> >
>> > On Fri, Sep 11, 2020 at 5:50 PM Alex Bennée <email address hidden>
>> > wrote:
>> >
>> >> Alex Bennée <email address hidden> writes:
>> >>
>> >> > Laurent Vivier <email address hidden> writes:
>> >> >
>> >> <snip>
>> >> >>> Then trying qemu-riscv32 with a simple ELF, I get:
>> >> >>> linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr == test'
>> >> failed.
>> >> >>>
>> >> >>> strace shows that:
>> >> >>> mmap(0x1000, 4294963200, PROT_NONE,
>> >> MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x10000
>> >> >>> write(2, "qemu-riscv32: ../qemu.git/linux-"..., 103qemu-riscv32:
>> >> ../qemu.git/linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr
>> ==
>> >> test' failed.
>> >> >>> ) = 103
>> >> >>>
>> >> >>> The source code is in the function pgb_reserved_va (linux-
>> >> >>> user/elfload.c). I think mmap cannot guarantee that the returned
>> >> pointer
>> >> >>> (test) equals to the parameter of addr. So is this a bug to assert
>> >> (addr
>> >> >>> == test)?
>> >> >>
>> >> > I'm assuming CentOS 7.5 actually has a definition for
>> >> > MAP_FIXED_NOREPLACE which should ensure we get what we asked for -
>> >> > otherwise we are in the position of hoping the kernel honours what we
>> >> > asked for.
>> >>
>> >> Doh re-reading I see it's not set in the strace output. Maybe we should
>> >> promote the assert case to the failure leg so we have:
>> >>
>> >>     if (addr == MAP_FAILED || addr != test) {
>> >>         error_report(...)
>> >>     }
>> >>
>> >> so we at least fail with a user friendly error rather than an abort?
>> >>
>> >> --
>> >> Alex Bennée
>> >>
>> >> --
>> >> You received this bug notification because you are subscribed to the bug
>> >> report.
>> >> https://bugs.launchpad.net/bugs/1895080
>> >>
>> >> Title:
>> >>   pgb_reserved_va: Assertion `addr == test' failed
>> >>
>> >> Status in QEMU:
>> >>   New
>> >>
>> >> Bug description:
>> >>   This problem occurs on CentOS-7.5 (64-bit) with qemu-5.1.0, qemu head
>> >>   (commit 9435a8b3dd35f1f926f1b9127e8a906217a5518a) for riscv32-linux-
>> >>   user.
>> >>
>> >>   Firstly, compile fails:
>> >>   Compiling C object
>> libqemu-riscv32-linux-user.fa.p/linux-user_strace.c.o
>> >>   ../qemu.git/linux-user/strace.c:1210:18: error: ‘FALLOC_FL_KEEP_SIZE’
>> >> undeclared here (not in a function)
>> >>        FLAG_GENERIC(FALLOC_FL_KEEP_SIZE),
>> >>
>> >>   I have to add below include to linux-user/strace.c
>> >>   diff --git a/linux-user/strace.c b/linux-user/strace.c
>> >>   index 11fea14fba..22e51d4a8a 100644
>> >>   --- a/linux-user/strace.c
>> >>   +++ b/linux-user/strace.c
>> >>   @@ -7,6 +7,7 @@
>> >>    #include <sys/mount.h>
>> >>    #include <arpa/inet.h>
>> >>    #include <netinet/tcp.h>
>> >>   +#include <linux/falloc.h>
>> >>    #include <linux/if_packet.h>
>> >>    #include <linux/netlink.h>
>> >>    #include <sched.h>
>> >>
>> >>   Then trying qemu-riscv32 with a simple ELF, I get:
>> >>   linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr == test'
>> >> failed.
>> >>
>> >>   strace shows that:
>> >>   mmap(0x1000, 4294963200, PROT_NONE,
>> >> MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x10000
>> >>   write(2, "qemu-riscv32: ../qemu.git/linux-"..., 103qemu-riscv32:
>> >> ../qemu.git/linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr
>> ==
>> >> test' failed.
>> >>   ) = 103
>> >>
>> >>   The source code is in the function pgb_reserved_va (linux-
>> >>   user/elfload.c). I think mmap cannot guarantee that the returned
>> >>   pointer (test) equals to the parameter of addr. So is this a bug to
>> >>   assert (addr == test)?
>> >>
>> >>   Attached configure script and test ELF file.
>> >>
>> >>   Thanks.
>> >>
>> >> To manage notifications about this bug go to:
>> >> https://bugs.launchpad.net/qemu/+bug/1895080/+subscriptions
>> >>
>>
>>
>> --
>> Alex Bennée
>>
>> --
>> You received this bug notification because you are subscribed to the bug
>> report.
>> https://bugs.launchpad.net/bugs/1895080
>>
>> Title:
>>   pgb_reserved_va: Assertion `addr == test' failed
>>
>> Status in QEMU:
>>   New
>>
>> Bug description:
>>   This problem occurs on CentOS-7.5 (64-bit) with qemu-5.1.0, qemu head
>>   (commit 9435a8b3dd35f1f926f1b9127e8a906217a5518a) for riscv32-linux-
>>   user.
>>
>>   Firstly, compile fails:
>>   Compiling C object libqemu-riscv32-linux-user.fa.p/linux-user_strace.c.o
>>   ../qemu.git/linux-user/strace.c:1210:18: error: ‘FALLOC_FL_KEEP_SIZE’
>> undeclared here (not in a function)
>>        FLAG_GENERIC(FALLOC_FL_KEEP_SIZE),
>>
>>   I have to add below include to linux-user/strace.c
>>   diff --git a/linux-user/strace.c b/linux-user/strace.c
>>   index 11fea14fba..22e51d4a8a 100644
>>   --- a/linux-user/strace.c
>>   +++ b/linux-user/strace.c
>>   @@ -7,6 +7,7 @@
>>    #include <sys/mount.h>
>>    #include <arpa/inet.h>
>>    #include <netinet/tcp.h>
>>   +#include <linux/falloc.h>
>>    #include <linux/if_packet.h>
>>    #include <linux/netlink.h>
>>    #include <sched.h>
>>
>>   Then trying qemu-riscv32 with a simple ELF, I get:
>>   linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr == test'
>> failed.
>>
>>   strace shows that:
>>   mmap(0x1000, 4294963200, PROT_NONE,
>> MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x10000
>>   write(2, "qemu-riscv32: ../qemu.git/linux-"..., 103qemu-riscv32:
>> ../qemu.git/linux-user/elfload.c:2341: pgb_reserved_va: Assertion `addr ==
>> test' failed.
>>   ) = 103
>>
>>   The source code is in the function pgb_reserved_va (linux-
>>   user/elfload.c). I think mmap cannot guarantee that the returned
>>   pointer (test) equals to the parameter of addr. So is this a bug to
>>   assert (addr == test)?
>>
>>   Attached configure script and test ELF file.
>>
>>   Thanks.
>>
>> To manage notifications about this bug go to:
>> https://bugs.launchpad.net/qemu/+bug/1895080/+subscriptions
>>


-- 
Alex Bennée


On older kernels which don't implement MAP_FIXED_NOREPLACE the kernel
may still fail to give us the address we asked for despite having
already probed the map for a valid hole. Asserting isn't particularly
useful to the user so let us move the check up and expand the
error_report a little to give them a fighting chance of working around
the problem.

Ameliorates: ee94743034
Cc: Bug 1895080 <email address hidden>
Signed-off-by: Alex Bennée <email address hidden>
---
 linux-user/elfload.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index 4961e6119e2..f6022fd7049 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -2331,14 +2331,13 @@ static void pgb_reserved_va(const char *image_name, abi_ulong guest_loaddr,
     assert(guest_base != 0);
     test = g2h(0);
     addr = mmap(test, reserved_va, PROT_NONE, flags, -1, 0);
-    if (addr == MAP_FAILED) {
+    if (addr == MAP_FAILED || addr != test) {
         error_report("Unable to reserve 0x%lx bytes of virtual address "
-                     "space (%s) for use as guest address space (check your "
-                     "virtual memory ulimit setting or reserve less "
-                     "using -R option)", reserved_va, strerror(errno));
+                     "space at %p (%s) for use as guest address space (check your"
+                     "virtual memory ulimit setting, min_mmap_addr or reserve less "
+                     "using -R option)", reserved_va, test, strerror(errno));
         exit(EXIT_FAILURE);
     }
-    assert(addr == test);
 }
 
 void probe_guest_base(const char *image_name, abi_ulong guest_loaddr,
-- 
2.20.1



On older kernels which don't implement MAP_FIXED_NOREPLACE the kernel
may still fail to give us the address we asked for despite having
already probed the map for a valid hole. Asserting isn't particularly
useful to the user so let us move the check up and expand the
error_report a little to give them a fighting chance of working around
the problem.

Ameliorates: ee94743034
Cc: Bug 1895080 <email address hidden>
Signed-off-by: Alex Bennée <email address hidden>
---
 linux-user/elfload.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index 4961e6119e24..f6022fd70493 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -2331,14 +2331,13 @@ static void pgb_reserved_va(const char *image_name, abi_ulong guest_loaddr,
     assert(guest_base != 0);
     test = g2h(0);
     addr = mmap(test, reserved_va, PROT_NONE, flags, -1, 0);
-    if (addr == MAP_FAILED) {
+    if (addr == MAP_FAILED || addr != test) {
         error_report("Unable to reserve 0x%lx bytes of virtual address "
-                     "space (%s) for use as guest address space (check your "
-                     "virtual memory ulimit setting or reserve less "
-                     "using -R option)", reserved_va, strerror(errno));
+                     "space at %p (%s) for use as guest address space (check your"
+                     "virtual memory ulimit setting, min_mmap_addr or reserve less "
+                     "using -R option)", reserved_va, test, strerror(errno));
         exit(EXIT_FAILURE);
     }
-    assert(addr == test);
 }
 
 void probe_guest_base(const char *image_name, abi_ulong guest_loaddr,
-- 
2.20.1



chroot works as you expected.
And the patch makes sense.
Thanks.

On older kernels which don't implement MAP_FIXED_NOREPLACE the kernel
may still fail to give us the address we asked for despite having
already probed the map for a valid hole. Asserting isn't particularly
useful to the user so let us move the check up and expand the
error_report a little to give them a fighting chance of working around
the problem.

Ameliorates: ee94743034
Cc: Bug 1895080 <email address hidden>
Signed-off-by: Alex Bennée <email address hidden>
---
 linux-user/elfload.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index 4961e6119e24..f6022fd70493 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -2331,14 +2331,13 @@ static void pgb_reserved_va(const char *image_name, abi_ulong guest_loaddr,
     assert(guest_base != 0);
     test = g2h(0);
     addr = mmap(test, reserved_va, PROT_NONE, flags, -1, 0);
-    if (addr == MAP_FAILED) {
+    if (addr == MAP_FAILED || addr != test) {
         error_report("Unable to reserve 0x%lx bytes of virtual address "
-                     "space (%s) for use as guest address space (check your "
-                     "virtual memory ulimit setting or reserve less "
-                     "using -R option)", reserved_va, strerror(errno));
+                     "space at %p (%s) for use as guest address space (check your"
+                     "virtual memory ulimit setting, min_mmap_addr or reserve less "
+                     "using -R option)", reserved_va, test, strerror(errno));
         exit(EXIT_FAILURE);
     }
-    assert(addr == test);
 }
 
 void probe_guest_base(const char *image_name, abi_ulong guest_loaddr,
-- 
2.20.1



Le 15/09/2020 à 15:43, Alex Bennée a écrit :
> On older kernels which don't implement MAP_FIXED_NOREPLACE the kernel
> may still fail to give us the address we asked for despite having
> already probed the map for a valid hole. Asserting isn't particularly
> useful to the user so let us move the check up and expand the
> error_report a little to give them a fighting chance of working around
> the problem.
> 
> Ameliorates: ee94743034
> Cc: Bug 1895080 <email address hidden>
> Signed-off-by: Alex Bennée <email address hidden>
> ---
>  linux-user/elfload.c | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/linux-user/elfload.c b/linux-user/elfload.c
> index 4961e6119e24..f6022fd70493 100644
> --- a/linux-user/elfload.c
> +++ b/linux-user/elfload.c
> @@ -2331,14 +2331,13 @@ static void pgb_reserved_va(const char *image_name, abi_ulong guest_loaddr,
>      assert(guest_base != 0);
>      test = g2h(0);
>      addr = mmap(test, reserved_va, PROT_NONE, flags, -1, 0);
> -    if (addr == MAP_FAILED) {
> +    if (addr == MAP_FAILED || addr != test) {
>          error_report("Unable to reserve 0x%lx bytes of virtual address "
> -                     "space (%s) for use as guest address space (check your "
> -                     "virtual memory ulimit setting or reserve less "
> -                     "using -R option)", reserved_va, strerror(errno));
> +                     "space at %p (%s) for use as guest address space (check your"
> +                     "virtual memory ulimit setting, min_mmap_addr or reserve less "
> +                     "using -R option)", reserved_va, test, strerror(errno));
>          exit(EXIT_FAILURE);
>      }
> -    assert(addr == test);
>  }
>  
>  void probe_guest_base(const char *image_name, abi_ulong guest_loaddr,
> 

Reviewed-by: Laurent Vivier <email address hidden>


On older kernels which don't implement MAP_FIXED_NOREPLACE the kernel
may still fail to give us the address we asked for despite having
already probed the map for a valid hole. Asserting isn't particularly
useful to the user so let us move the check up and expand the
error_report a little to give them a fighting chance of working around
the problem.

Signed-off-by: Alex Bennée <email address hidden>
Reviewed-by: Laurent Vivier <email address hidden>
Reviewed-by: Richard Henderson <email address hidden>
Cc: Bug 1895080 <email address hidden>
Ameliorates: ee94743034
Message-Id: <email address hidden>

diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index 4961e6119e24..f6022fd70493 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -2331,14 +2331,13 @@ static void pgb_reserved_va(const char *image_name, abi_ulong guest_loaddr,
     assert(guest_base != 0);
     test = g2h(0);
     addr = mmap(test, reserved_va, PROT_NONE, flags, -1, 0);
-    if (addr == MAP_FAILED) {
+    if (addr == MAP_FAILED || addr != test) {
         error_report("Unable to reserve 0x%lx bytes of virtual address "
-                     "space (%s) for use as guest address space (check your "
-                     "virtual memory ulimit setting or reserve less "
-                     "using -R option)", reserved_va, strerror(errno));
+                     "space at %p (%s) for use as guest address space (check your"
+                     "virtual memory ulimit setting, min_mmap_addr or reserve less "
+                     "using -R option)", reserved_va, test, strerror(errno));
         exit(EXIT_FAILURE);
     }
-    assert(addr == test);
 }
 
 void probe_guest_base(const char *image_name, abi_ulong guest_loaddr,
-- 
2.20.1



https://git.qemu.org/?p=qemu.git;a=commitdiff;h=fb730c8683807d549c4a

Released with QEMU v5.2.0.