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Date: Sun, 02 May 2021 13:39:16 -0500
From: ebiederm@...ssion.com (Eric W. Biederman)
To: Marco Elver <elver@...gle.com>
Cc: Arnd Bergmann <arnd@...db.de>, Florian Weimer <fweimer@...hat.com>,
"David S. Miller" <davem@...emloft.net>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...nel.org>,
Thomas Gleixner <tglx@...utronix.de>,
Peter Collingbourne <pcc@...gle.com>,
Dmitry Vyukov <dvyukov@...gle.com>,
Alexander Potapenko <glider@...gle.com>,
sparclinux <sparclinux@...r.kernel.org>,
linux-arch <linux-arch@...r.kernel.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Linux API <linux-api@...r.kernel.org>,
kasan-dev <kasan-dev@...glegroups.com>
Subject: Re: [PATCH 7/3] signal: Deliver all of the perf_data in si_perf
Marco Elver <elver@...gle.com> writes:
> On Sat, 1 May 2021 at 01:44, Eric W. Biederman <ebiederm@...ssion.com> wrote:
>>
>> Don't abuse si_errno and deliver all of the perf data in si_perf.
>>
>> Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com>
>> ---
>
> Thank you for the fix, this looks cleaner.
>
> Just note that this patch needs to include updates to
> tools/testing/selftests/perf_events. This should do it:
>> sed -i 's/si_perf/si_perf.data/g; s/si_errno/si_perf.type/g' tools/testing/selftests/perf_events/*.c
>
> Subject: s/perf_data/perf data/ ?
>
> For uapi, need to switch to __u32, see below.
Good point.
The one thing that this doesn't do is give you a 64bit field
on 32bit architectures.
On 32bit builds the layout is:
int si_signo;
int si_errno;
int si_code;
void __user *_addr;
So I believe if the first 3 fields were moved into the _sifields union
si_perf could define a 64bit field as it's first member and it would not
break anything else.
Given that the data field is 64bit that seems desirable.
Eric
>> fs/signalfd.c | 3 ++-
>> include/linux/compat.h | 5 ++++-
>> include/uapi/asm-generic/siginfo.h | 5 ++++-
>> include/uapi/linux/signalfd.h | 4 ++--
>> kernel/signal.c | 18 +++++++++++-------
>> 5 files changed, 23 insertions(+), 12 deletions(-)
>>
>> diff --git a/fs/signalfd.c b/fs/signalfd.c
>> index 83130244f653..9686af56f073 100644
>> --- a/fs/signalfd.c
>> +++ b/fs/signalfd.c
>> @@ -134,7 +134,8 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
>> break;
>> case SIL_FAULT_PERF_EVENT:
>> new.ssi_addr = (long) kinfo->si_addr;
>> - new.ssi_perf = kinfo->si_perf;
>> + new.ssi_perf_type = kinfo->si_perf.type;
>> + new.ssi_perf_data = kinfo->si_perf.data;
>> break;
>> case SIL_CHLD:
>> new.ssi_pid = kinfo->si_pid;
>> diff --git a/include/linux/compat.h b/include/linux/compat.h
>> index 24462ed63af4..0726f9b3a57c 100644
>> --- a/include/linux/compat.h
>> +++ b/include/linux/compat.h
>> @@ -235,7 +235,10 @@ typedef struct compat_siginfo {
>> u32 _pkey;
>> } _addr_pkey;
>> /* used when si_code=TRAP_PERF */
>> - compat_ulong_t _perf;
>> + struct {
>> + compat_ulong_t data;
>> + u32 type;
>> + } _perf;
>> };
>> } _sigfault;
>>
>> diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
>> index 2abdf1d19aad..19b6310021a3 100644
>> --- a/include/uapi/asm-generic/siginfo.h
>> +++ b/include/uapi/asm-generic/siginfo.h
>> @@ -90,7 +90,10 @@ union __sifields {
>> __u32 _pkey;
>> } _addr_pkey;
>> /* used when si_code=TRAP_PERF */
>> - unsigned long _perf;
>> + struct {
>> + unsigned long data;
>> + u32 type;
>
> This needs to be __u32.
>
>
>> + } _perf;
>> };
>> } _sigfault;
>>
>> diff --git a/include/uapi/linux/signalfd.h b/include/uapi/linux/signalfd.h
>> index 7e333042c7e3..e78dddf433fc 100644
>> --- a/include/uapi/linux/signalfd.h
>> +++ b/include/uapi/linux/signalfd.h
>> @@ -39,8 +39,8 @@ struct signalfd_siginfo {
>> __s32 ssi_syscall;
>> __u64 ssi_call_addr;
>> __u32 ssi_arch;
>> - __u32 __pad3;
>> - __u64 ssi_perf;
>> + __u32 ssi_perf_type;
>> + __u64 ssi_perf_data;
>>
>> /*
>> * Pad strcture to 128 bytes. Remember to update the
>> diff --git a/kernel/signal.c b/kernel/signal.c
>> index 5b1ad7f080ab..cb3574b7319c 100644
>> --- a/kernel/signal.c
>> +++ b/kernel/signal.c
>> @@ -1758,11 +1758,13 @@ int force_sig_perf(void __user *pending_addr, u32 type, u64 sig_data)
>> struct kernel_siginfo info;
>>
>> clear_siginfo(&info);
>> - info.si_signo = SIGTRAP;
>> - info.si_errno = type;
>> - info.si_code = TRAP_PERF;
>> - info.si_addr = pending_addr;
>> - info.si_perf = sig_data;
>> + info.si_signo = SIGTRAP;
>> + info.si_errno = 0;
>> + info.si_code = TRAP_PERF;
>> + info.si_addr = pending_addr;
>> + info.si_perf.data = sig_data;
>> + info.si_perf.type = type;
>> +
>> return force_sig_info(&info);
>> }
>>
>> @@ -3379,7 +3381,8 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
>> break;
>> case SIL_FAULT_PERF_EVENT:
>> to->si_addr = ptr_to_compat(from->si_addr);
>> - to->si_perf = from->si_perf;
>> + to->si_perf.data = from->si_perf.data;
>> + to->si_perf.type = from->si_perf.type;
>> break;
>> case SIL_CHLD:
>> to->si_pid = from->si_pid;
>> @@ -3455,7 +3458,8 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
>> break;
>> case SIL_FAULT_PERF_EVENT:
>> to->si_addr = compat_ptr(from->si_addr);
>> - to->si_perf = from->si_perf;
>> + to->si_perf.data = from->si_perf.data;
>> + to->si_perf.type = from->si_perf.type;
>> break;
>> case SIL_CHLD:
>> to->si_pid = from->si_pid;
>> --
>> 2.30.1
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