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Fri, 25 Jul 2025 10:01:31 -0700 (PDT) Date: Fri, 25 Jul 2025 10:01:28 -0700 From: Deepak Gupta To: Sami Tolvanen Cc: Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Masahiro Yamada , Nathan Chancellor , Nicolas Schier , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Nick Desaulniers , Bill Wendling , Monk Chiang , Kito Cheng , Justin Stitt , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org, linux-mm@kvack.org, llvm@lists.linux.dev, rick.p.edgecombe@intel.com, broonie@kernel.org, cleger@rivosinc.com, apatel@ventanamicro.com, ajones@ventanamicro.com, conor.dooley@microchip.com, charlie@rivosinc.com, samuel.holland@sifive.com, bjorn@rivosinc.com, fweimer@redhat.com, jeffreyalaw@gmail.com, heinrich.schuchardt@canonical.com, andrew@sifive.com, ved@rivosinc.com Subject: Re: [PATCH 01/11] riscv: add landing pad for asm routines. Message-ID: References: <20250724-riscv_kcfi-v1-0-04b8fa44c98c@rivosinc.com> <20250724-riscv_kcfi-v1-1-04b8fa44c98c@rivosinc.com> <20250725152745.GA1724026@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20250725152745.GA1724026@google.com> X-Rspamd-Queue-Id: 7633E12001B X-Rspam-User: X-Rspamd-Server: rspam09 X-Stat-Signature: 7at5afd96ibrpfz9udk9zrxci95qo7ut X-HE-Tag: 1753462893-952042 X-HE-Meta: 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 /22ytqKE 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Jul 25, 2025 at 03:27:45PM +0000, Sami Tolvanen wrote: >On Thu, Jul 24, 2025 at 04:36:54PM -0700, Deepak Gupta wrote: >> SYM_* macros are used to define assembly routines. In this patch series, >> re-define those macros in risc-v arch specific include file to include >> a landing pad instruction at the beginning. This is done only when the >> compiler flag for landing pad is enabled (i.e. __riscv_zicfilp). >> >> TODO: Update `lpad 0` with `lpad %lpad_hash(name)` after toolchain >> support. > >I glanced through the proposed signature based landing pad labeling >scheme, but didn't see any mentions of lpad_hash for labeling assembly >functions. Is there more information somewhere about how this is going >to be implemented? Take a look here for generation of type string https://github.com/sifive/riscv-gcc/blob/f26ae78e21e591f78802a975b68dbde9a224a192/gcc/config/riscv/riscv-func-sig.cc For hash scheme, take a look here https://github.com/sifive/riscv-binutils-gdb/commit/1d027fd590c8ad79eba997bcf9b979872ff38eef `riscv_lpad_hash` function has detail about how 20bit hash is extracted. > >Sami