From: Paul Walmsley <pjw@kernel.org>
To: Deepak Gupta <debug@rivosinc.com>
Cc: "Thomas Gleixner" <tglx@linutronix.de>,
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"Zong Li" <zong.li@sifive.com>,
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"Andy Chiu" <andybnac@gmail.com>
Subject: Re: [PATCH v19 00/27] riscv control-flow integrity for usermode
Date: Wed, 24 Sep 2025 08:36:11 -0600 (MDT) [thread overview]
Message-ID: <f953ee7b-91b3-f6f5-6955-b4a138f16dbc@kernel.org> (raw)
In-Reply-To: <20250731-v5_user_cfi_series-v19-0-09b468d7beab@rivosinc.com>
Hi,
On Thu, 31 Jul 2025, Deepak Gupta wrote:
[ ... ]
> vDSO related Opens (in the flux)
> =================================
>
> I am listing these opens for laying out plan and what to expect in future
> patch sets. And of course for the sake of discussion.
>
[ ... ]
> How many vDSOs
> ---------------
> Shadow stack instructions are carved out of zimop (may be operations) and if CPU
> doesn't implement zimop, they're illegal instructions. Kernel could be running on
> a CPU which may or may not implement zimop. And thus kernel will have to carry 2
> different vDSOs and expose the appropriate one depending on whether CPU implements
> zimop or not.
If we merge this series without this, then when CFI is enabled in the
Kconfig, we'll wind up with a non-portable kernel that won't run on older
hardware. We go to great lengths to enable kernel binary portability
across the presence or absence of other RISC-V extensions, and I think
these CFI extensions should be no different.
So before considering this for merging, I'd like to see at least an
attempt to implement the dual-vDSO approach (or something equivalent)
where the same kernel binary with CFI enabled can run on both pre-Zimop
and post-Zimop hardware, with the existing userspaces that are common
today.
thanks Deepak,
- Paul
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next prev parent reply other threads:[~2025-09-24 14:36 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-31 23:19 [PATCH v19 00/27] riscv control-flow integrity for usermode Deepak Gupta
2025-07-31 23:19 ` [PATCH v19 01/27] mm: VM_SHADOW_STACK definition for riscv Deepak Gupta
2025-07-31 23:19 ` [PATCH v19 02/27] dt-bindings: riscv: zicfilp and zicfiss in dt-bindings (extensions.yaml) Deepak Gupta
2025-07-31 23:19 ` [PATCH v19 03/27] riscv: zicfiss / zicfilp enumeration Deepak Gupta
2025-07-31 23:19 ` [PATCH v19 04/27] riscv: zicfiss / zicfilp extension csr and bit definitions Deepak Gupta
2025-07-31 23:19 ` [PATCH v19 05/27] riscv: usercfi state for task and save/restore of CSR_SSP on trap entry/exit Deepak Gupta
2025-07-31 23:19 ` [PATCH v19 06/27] riscv/mm : ensure PROT_WRITE leads to VM_READ | VM_WRITE Deepak Gupta
2025-07-31 23:19 ` [PATCH v19 07/27] riscv/mm: manufacture shadow stack pte Deepak Gupta
2025-07-31 23:19 ` [PATCH v19 08/27] riscv/mm: teach pte_mkwrite to manufacture shadow stack PTEs Deepak Gupta
2025-07-31 23:19 ` [PATCH v19 09/27] riscv/mm: write protect and shadow stack Deepak Gupta
2025-07-31 23:19 ` [PATCH v19 10/27] riscv/mm: Implement map_shadow_stack() syscall Deepak Gupta
2025-07-31 23:19 ` [PATCH v19 11/27] riscv/shstk: If needed allocate a new shadow stack on clone Deepak Gupta
2025-07-31 23:19 ` [PATCH v19 12/27] riscv: Implements arch agnostic shadow stack prctls Deepak Gupta
2025-07-31 23:19 ` [PATCH v19 13/27] prctl: arch-agnostic prctl for indirect branch tracking Deepak Gupta
2025-07-31 23:19 ` [PATCH v19 14/27] riscv: Implements arch agnostic indirect branch tracking prctls Deepak Gupta
2025-07-31 23:19 ` [PATCH v19 15/27] riscv/traps: Introduce software check exception and uprobe handling Deepak Gupta
2025-07-31 23:19 ` [PATCH v19 16/27] riscv: signal: abstract header saving for setup_sigcontext Deepak Gupta
2025-07-31 23:19 ` [PATCH v19 17/27] riscv/signal: save and restore of shadow stack for signal Deepak Gupta
2025-07-31 23:19 ` [PATCH v19 18/27] riscv/kernel: update __show_regs to print shadow stack register Deepak Gupta
2025-07-31 23:19 ` [PATCH v19 19/27] riscv/ptrace: riscv cfi status and state via ptrace and in core files Deepak Gupta
2025-07-31 23:19 ` [PATCH v19 20/27] riscv/hwprobe: zicfilp / zicfiss enumeration in hwprobe Deepak Gupta
2025-07-31 23:19 ` [PATCH v19 21/27] riscv: kernel command line option to opt out of user cfi Deepak Gupta
2025-07-31 23:19 ` [PATCH v19 22/27] riscv: enable kernel access to shadow stack memory via FWFT sbi call Deepak Gupta
2025-07-31 23:19 ` [PATCH v19 23/27] arch/riscv: compile vdso with landing pad and shadow stack note Deepak Gupta
2025-07-31 23:19 ` [PATCH v19 24/27] riscv: create a config for shadow stack and landing pad instr support Deepak Gupta
2025-07-31 23:19 ` [PATCH v19 25/27] riscv: Documentation for landing pad / indirect branch tracking Deepak Gupta
2025-07-31 23:19 ` [PATCH v19 26/27] riscv: Documentation for shadow stack on riscv Deepak Gupta
2025-07-31 23:19 ` [PATCH v19 27/27] kselftest/riscv: kselftest for user mode cfi Deepak Gupta
2025-08-01 1:09 ` [PATCH v19 00/27] riscv control-flow integrity for usermode Benjamin LaHaise
2025-08-06 17:15 ` patchwork-bot+linux-riscv
2025-08-07 12:28 ` Mark Brown
2025-08-08 8:23 ` Deepak Gupta
2025-08-08 11:48 ` Mark Brown
2025-08-08 17:20 ` Deepak Gupta
2025-09-24 14:36 ` Paul Walmsley [this message]
2025-09-24 18:40 ` Deepak Gupta
2025-09-25 12:30 ` Andy Chiu
2025-09-25 14:30 ` Deepak Gupta
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