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Date: Tue, 20 Apr 2021 23:26:17 +0200
From: Marek Szyprowski <m.szyprowski@...sung.com>
To: Marco Elver <elver@...gle.com>, peterz@...radead.org,
alexander.shishkin@...ux.intel.com, acme@...nel.org,
mingo@...hat.com, jolsa@...hat.com, mark.rutland@....com,
namhyung@...nel.org, tglx@...utronix.de
Cc: glider@...gle.com, viro@...iv.linux.org.uk, arnd@...db.de,
christian@...uner.io, dvyukov@...gle.com, jannh@...gle.com,
axboe@...nel.dk, mascasa@...gle.com, pcc@...gle.com,
irogers@...gle.com, oleg@...hat.com, kasan-dev@...glegroups.com,
linux-arch@...r.kernel.org, linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org, x86@...nel.org,
linux-kselftest@...r.kernel.org,
Geert Uytterhoeven <geert@...ux-m68k.org>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Subject: Re: [PATCH v4 05/10] signal: Introduce TRAP_PERF si_code and
si_perf to siginfo
Hi Marco,
On 08.04.2021 12:36, Marco Elver wrote:
> Introduces the TRAP_PERF si_code, and associated siginfo_t field
> si_perf. These will be used by the perf event subsystem to send signals
> (if requested) to the task where an event occurred.
>
> Acked-by: Geert Uytterhoeven <geert@...ux-m68k.org> # m68k
> Acked-by: Arnd Bergmann <arnd@...db.de> # asm-generic
> Signed-off-by: Marco Elver <elver@...gle.com>
This patch landed in linux-next as commit fb6cc127e0b6 ("signal:
Introduce TRAP_PERF si_code and si_perf to siginfo"). It causes
regression on my test systems (arm 32bit and 64bit). Most systems fails
to boot in the given time frame. I've observed that there is a timeout
waiting for udev to populate /dev and then also during the network
interfaces configuration. Reverting this commit, together with
97ba62b27867 ("perf: Add support for SIGTRAP on perf events") to let it
compile, on top of next-20210420 fixes the issue.
> ---
> arch/m68k/kernel/signal.c | 3 +++
> arch/x86/kernel/signal_compat.c | 5 ++++-
> fs/signalfd.c | 4 ++++
> include/linux/compat.h | 2 ++
> include/linux/signal.h | 1 +
> include/uapi/asm-generic/siginfo.h | 6 +++++-
> include/uapi/linux/signalfd.h | 4 +++-
> kernel/signal.c | 11 +++++++++++
> 8 files changed, 33 insertions(+), 3 deletions(-)
>
> diff --git a/arch/m68k/kernel/signal.c b/arch/m68k/kernel/signal.c
> index 349570f16a78..a4b7ee1df211 100644
> --- a/arch/m68k/kernel/signal.c
> +++ b/arch/m68k/kernel/signal.c
> @@ -622,6 +622,9 @@ static inline void siginfo_build_tests(void)
> /* _sigfault._addr_pkey */
> BUILD_BUG_ON(offsetof(siginfo_t, si_pkey) != 0x12);
>
> + /* _sigfault._perf */
> + BUILD_BUG_ON(offsetof(siginfo_t, si_perf) != 0x10);
> +
> /* _sigpoll */
> BUILD_BUG_ON(offsetof(siginfo_t, si_band) != 0x0c);
> BUILD_BUG_ON(offsetof(siginfo_t, si_fd) != 0x10);
> diff --git a/arch/x86/kernel/signal_compat.c b/arch/x86/kernel/signal_compat.c
> index a5330ff498f0..0e5d0a7e203b 100644
> --- a/arch/x86/kernel/signal_compat.c
> +++ b/arch/x86/kernel/signal_compat.c
> @@ -29,7 +29,7 @@ static inline void signal_compat_build_tests(void)
> BUILD_BUG_ON(NSIGFPE != 15);
> BUILD_BUG_ON(NSIGSEGV != 9);
> BUILD_BUG_ON(NSIGBUS != 5);
> - BUILD_BUG_ON(NSIGTRAP != 5);
> + BUILD_BUG_ON(NSIGTRAP != 6);
> BUILD_BUG_ON(NSIGCHLD != 6);
> BUILD_BUG_ON(NSIGSYS != 2);
>
> @@ -138,6 +138,9 @@ static inline void signal_compat_build_tests(void)
> BUILD_BUG_ON(offsetof(siginfo_t, si_pkey) != 0x20);
> BUILD_BUG_ON(offsetof(compat_siginfo_t, si_pkey) != 0x14);
>
> + BUILD_BUG_ON(offsetof(siginfo_t, si_perf) != 0x18);
> + BUILD_BUG_ON(offsetof(compat_siginfo_t, si_perf) != 0x10);
> +
> CHECK_CSI_OFFSET(_sigpoll);
> CHECK_CSI_SIZE (_sigpoll, 2*sizeof(int));
> CHECK_SI_SIZE (_sigpoll, 4*sizeof(int));
> diff --git a/fs/signalfd.c b/fs/signalfd.c
> index 456046e15873..040a1142915f 100644
> --- a/fs/signalfd.c
> +++ b/fs/signalfd.c
> @@ -134,6 +134,10 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
> #endif
> new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;
> break;
> + case SIL_PERF_EVENT:
> + new.ssi_addr = (long) kinfo->si_addr;
> + new.ssi_perf = kinfo->si_perf;
> + break;
> case SIL_CHLD:
> new.ssi_pid = kinfo->si_pid;
> new.ssi_uid = kinfo->si_uid;
> diff --git a/include/linux/compat.h b/include/linux/compat.h
> index 6e65be753603..c8821d966812 100644
> --- a/include/linux/compat.h
> +++ b/include/linux/compat.h
> @@ -236,6 +236,8 @@ typedef struct compat_siginfo {
> char _dummy_pkey[__COMPAT_ADDR_BND_PKEY_PAD];
> u32 _pkey;
> } _addr_pkey;
> + /* used when si_code=TRAP_PERF */
> + compat_u64 _perf;
> };
> } _sigfault;
>
> diff --git a/include/linux/signal.h b/include/linux/signal.h
> index 205526c4003a..1e98548d7cf6 100644
> --- a/include/linux/signal.h
> +++ b/include/linux/signal.h
> @@ -43,6 +43,7 @@ enum siginfo_layout {
> SIL_FAULT_MCEERR,
> SIL_FAULT_BNDERR,
> SIL_FAULT_PKUERR,
> + SIL_PERF_EVENT,
> SIL_CHLD,
> SIL_RT,
> SIL_SYS,
> diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h
> index d2597000407a..d0bb9125c853 100644
> --- a/include/uapi/asm-generic/siginfo.h
> +++ b/include/uapi/asm-generic/siginfo.h
> @@ -91,6 +91,8 @@ union __sifields {
> char _dummy_pkey[__ADDR_BND_PKEY_PAD];
> __u32 _pkey;
> } _addr_pkey;
> + /* used when si_code=TRAP_PERF */
> + __u64 _perf;
> };
> } _sigfault;
>
> @@ -155,6 +157,7 @@ typedef struct siginfo {
> #define si_lower _sifields._sigfault._addr_bnd._lower
> #define si_upper _sifields._sigfault._addr_bnd._upper
> #define si_pkey _sifields._sigfault._addr_pkey._pkey
> +#define si_perf _sifields._sigfault._perf
> #define si_band _sifields._sigpoll._band
> #define si_fd _sifields._sigpoll._fd
> #define si_call_addr _sifields._sigsys._call_addr
> @@ -253,7 +256,8 @@ typedef struct siginfo {
> #define TRAP_BRANCH 3 /* process taken branch trap */
> #define TRAP_HWBKPT 4 /* hardware breakpoint/watchpoint */
> #define TRAP_UNK 5 /* undiagnosed trap */
> -#define NSIGTRAP 5
> +#define TRAP_PERF 6 /* perf event with sigtrap=1 */
> +#define NSIGTRAP 6
>
> /*
> * There is an additional set of SIGTRAP si_codes used by ptrace
> diff --git a/include/uapi/linux/signalfd.h b/include/uapi/linux/signalfd.h
> index 83429a05b698..7e333042c7e3 100644
> --- a/include/uapi/linux/signalfd.h
> +++ b/include/uapi/linux/signalfd.h
> @@ -39,6 +39,8 @@ struct signalfd_siginfo {
> __s32 ssi_syscall;
> __u64 ssi_call_addr;
> __u32 ssi_arch;
> + __u32 __pad3;
> + __u64 ssi_perf;
>
> /*
> * Pad strcture to 128 bytes. Remember to update the
> @@ -49,7 +51,7 @@ struct signalfd_siginfo {
> * comes out of a read(2) and we really don't want to have
> * a compat on read(2).
> */
> - __u8 __pad[28];
> + __u8 __pad[16];
> };
>
>
> diff --git a/kernel/signal.c b/kernel/signal.c
> index f2718350bf4b..7061e4957650 100644
> --- a/kernel/signal.c
> +++ b/kernel/signal.c
> @@ -1199,6 +1199,7 @@ static inline bool has_si_pid_and_uid(struct kernel_siginfo *info)
> case SIL_FAULT_MCEERR:
> case SIL_FAULT_BNDERR:
> case SIL_FAULT_PKUERR:
> + case SIL_PERF_EVENT:
> case SIL_SYS:
> ret = false;
> break;
> @@ -2531,6 +2532,7 @@ static void hide_si_addr_tag_bits(struct ksignal *ksig)
> case SIL_FAULT_MCEERR:
> case SIL_FAULT_BNDERR:
> case SIL_FAULT_PKUERR:
> + case SIL_PERF_EVENT:
> ksig->info.si_addr = arch_untagged_si_addr(
> ksig->info.si_addr, ksig->sig, ksig->info.si_code);
> break;
> @@ -3341,6 +3343,10 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
> #endif
> to->si_pkey = from->si_pkey;
> break;
> + case SIL_PERF_EVENT:
> + to->si_addr = ptr_to_compat(from->si_addr);
> + to->si_perf = from->si_perf;
> + break;
> case SIL_CHLD:
> to->si_pid = from->si_pid;
> to->si_uid = from->si_uid;
> @@ -3421,6 +3427,10 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to,
> #endif
> to->si_pkey = from->si_pkey;
> break;
> + case SIL_PERF_EVENT:
> + to->si_addr = compat_ptr(from->si_addr);
> + to->si_perf = from->si_perf;
> + break;
> case SIL_CHLD:
> to->si_pid = from->si_pid;
> to->si_uid = from->si_uid;
> @@ -4601,6 +4611,7 @@ static inline void siginfo_buildtime_checks(void)
> CHECK_OFFSET(si_lower);
> CHECK_OFFSET(si_upper);
> CHECK_OFFSET(si_pkey);
> + CHECK_OFFSET(si_perf);
>
> /* sigpoll */
> CHECK_OFFSET(si_band);
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
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