From: Jakub Kicinski <jakub.kicinski@netronome.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Jiong Wang <jiong.wang@netronome.com>,
daniel@iogearbox.net, bpf@vger.kernel.org,
netdev@vger.kernel.org, oss-drivers@netronome.com
Subject: Re: [PATCH v4 bpf-next 02/15] bpf: mark lo32 writes that should be zero extended into hi32
Date: Fri, 19 Apr 2019 14:33:10 -0700 [thread overview]
Message-ID: <20190419143310.6c749160@cakuba.netronome.com> (raw)
In-Reply-To: <20190419211403.6iovh26bu6cg2x36@ast-mbp.dhcp.thefacebook.com>
On Fri, 19 Apr 2019 14:14:05 -0700, Alexei Starovoitov wrote:
> > This reminds me, I'm not entirely clear on the need to propagate the
> > zext through stack slots... Pointers are guaranteed to be 64bit, we
> > don't save parentage on scalars (AFAICT),
>
> scalars have parentage chain too.
> we don't track them precisely when they're spilled to stack.
> That actually caused an issue recently when valid program was rejected,
> so we might add a feature to track full contents of scalars in the stack.
Interesting..
> > why not pass REG_LIVE_READ
> > or READ64 to mark_reg_read() from stack_read?
>
> can we agree on only two states first ? ;)
Yess, the LIVE_READ was thought to be more of a mask for those accesses
that only care about "any read" being set, to be honest. As you said
read64 is a strict superset of read32. Keeping the name REG_LIVE_READ,
rather than REG_LIVE_READ_ANY or _MASK let us leave some of the
existing code untouched.
Jiong's original idea was to add a read32, and have read mean read64.
I think you said we should have read32 and read64 flags, but clear
read32 once read64 gets set? SGTM!
next prev parent reply other threads:[~2019-04-19 21:33 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-15 17:26 [PATCH v4 bpf-next 00/15] bpf: eliminate zero extensions for sub-register writes Jiong Wang
2019-04-15 17:26 ` [PATCH v4 bpf-next 01/15] bpf: split read liveness into REG_LIVE_READ64 and REG_LIVE_READ32 Jiong Wang
2019-04-15 23:03 ` Jakub Kicinski
2019-04-16 1:26 ` Alexei Starovoitov
2019-04-16 7:39 ` Jiong Wang
2019-04-16 16:20 ` Alexei Starovoitov
2019-04-16 20:19 ` Jiong Wang
2019-04-15 17:26 ` [PATCH v4 bpf-next 02/15] bpf: mark lo32 writes that should be zero extended into hi32 Jiong Wang
2019-04-18 23:57 ` Alexei Starovoitov
2019-04-19 20:40 ` Jakub Kicinski
2019-04-19 21:14 ` Alexei Starovoitov
2019-04-19 21:33 ` Jakub Kicinski [this message]
2019-04-19 21:41 ` Alexei Starovoitov
2019-04-19 23:27 ` Jiong Wang
2019-04-19 23:28 ` Alexei Starovoitov
2019-04-15 17:26 ` [PATCH v4 bpf-next 03/15] bpf: reduce false alarm by refining helper call arg types Jiong Wang
2019-04-15 17:26 ` [PATCH v4 bpf-next 04/15] bpf: insert explicit zero extension insn when hardware doesn't do it implicitly Jiong Wang
2019-04-15 17:26 ` [PATCH v4 bpf-next 05/15] bpf: introduce new bpf prog load flags "BPF_F_TEST_RND_HI32" Jiong Wang
2019-04-15 17:26 ` [PATCH v4 bpf-next 06/15] bpf: randomize high 32-bit when BPF_F_TEST_RND_HI32 is set Jiong Wang
2019-04-15 17:26 ` [PATCH v4 bpf-next 07/15] libbpf: add "prog_flags" to bpf_program/bpf_prog_load_attr/bpf_load_program_attr Jiong Wang
2019-04-15 17:26 ` [PATCH v4 bpf-next 08/15] selftests: enable hi32 randomization for all tests Jiong Wang
2019-04-15 17:26 ` [PATCH v4 bpf-next 09/15] arm: bpf: eliminate zero extension code-gen Jiong Wang
2019-04-15 17:26 ` [PATCH v4 bpf-next 10/15] powerpc: " Jiong Wang
2019-04-15 17:26 ` [PATCH v4 bpf-next 11/15] s390: " Jiong Wang
2019-04-15 17:26 ` [PATCH v4 bpf-next 12/15] sparc: " Jiong Wang
2019-04-15 17:26 ` [PATCH v4 bpf-next 13/15] x32: " Jiong Wang
2019-04-15 17:26 ` [PATCH v4 bpf-next 14/15] riscv: " Jiong Wang
2019-04-17 7:55 ` Björn Töpel
2019-04-15 17:26 ` [PATCH v4 bpf-next 15/15] nfp: " Jiong Wang
2019-04-24 16:31 ` kbuild test robot
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