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Peter Anvin" , Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Lorenzo Stoakes , Paul Walmsley , Palmer Dabbelt , Albert Ou , Conor Dooley , Rob Herring , Krzysztof Kozlowski , Arnd Bergmann , Christian Brauner , Peter Zijlstra , Oleg Nesterov , Eric Biederman , Kees Cook , Jonathan Corbet , Shuah Khan , Jann Horn , Conor Dooley , Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , =?utf-8?Q?Bj=C3=B6?= =?utf-8?Q?rn?= Roy Baron , Andreas Hindborg , Alice Ryhl , Trevor Gross , Benno Lossin , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-riscv@lists.infradead.org, devicetree@vger.kernel.org, linux-arch@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, alistair.francis@wdc.com, richard.henderson@linaro.org, jim.shu@sifive.com, andybnac@gmail.com, kito.cheng@sifive.com, charlie@rivosinc.com, atishp@rivosinc.com, evan@rivosinc.com, cleger@rivosinc.com, alexghiti@rivosinc.com, samitolvanen@google.com, broonie@kernel.org, rick.p.edgecombe@intel.com, rust-for-linux@vger.kernel.org, Zong Li Subject: Re: [PATCH v23 06/28] riscv/mm : ensure PROT_WRITE leads to VM_READ | VM_WRITE In-Reply-To: (Deepak Gupta's message of "Mon, 1 Jun 2026 09:22:17 -0700") References: <20251112-v5_user_cfi_series-v23-0-b55691eacf4f@rivosinc.com> <20251112-v5_user_cfi_series-v23-6-b55691eacf4f@rivosinc.com> <87jyslndo4.fsf@igel.home> <875x44o9hj.fsf@igel.home> Date: Mon, 01 Jun 2026 19:10:36 +0200 Message-ID: <871peqgp9v.fsf@igel.home> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Rspamd-Queue-Id: 0BAE440012 X-Stat-Signature: w3c19pa6usobz5bn1xdbh8mkkg3wcocu X-Rspamd-Server: rspam03 X-Rspam-User: X-HE-Tag: 1780333846-772000 X-HE-Meta: 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 yma/JvWL FLHMTI7EtZt9sUPczrwJu8rdlvSc9rWsbeHhjJlQ2dsNDHsiRyR4AVDltYmDY8oyUvvNa8tVSIT2KAX/81ZctkHwFtUcktHVQA8rGTKQ9f9u6mzmE59+m/wemJEO1houuf6KliYq7LPoklma2COICjIs8Uh8qX2lyes3EH91RDhYtC65ZbWBOY+PvPUVIVpTzcQKejRQIbu1a3fJkMgrheMNUeXet+Bj2qA+KqoFyBGpUpmdHBVqdVTYkso+E3BFBQvPE7OgTlwF9On3LS6xcAfjcHbwo/f11RquZJDII9KbESVfFLQDB51Pe7Ph6ARzNIiRCyy4OUmw+1Cem/TUPtaDR4TLkKm484Q4xF4gofMT53fN30KP/XTFreDMytRhT6Bm3ZRWVoJOActgq27q3t+4i4hPCbcbBI+3I8qIqXT/lG9KB2mmIs0TC4/rRIgqvDVLf Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Jun 01 2026, Deepak Gupta wrote: > This was settled when x86 introduced shadow stack. Instead of having > new `PROT_`, it was agreed to create a new syscall for mapping shadow > stack memory (syscall: `map_shadow_stack`). Scenarios like `clone3` or > co-routines required manufacturing a shadow stack, thus necessitating a > new mechanism to create shadow stack style memory in demand. Instead > of having a new PROT_ flag, a new syscall was created. So what prevents riscv from making use of VM_SHADOW_STACK similar as x86, without the user visible effects? -- Andreas Schwab, schwab@linux-m68k.org GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510 2552 DF73 E780 A9DA AEC1 "And now for something completely different."