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b=r7r3HpYQ6nFiS0E8RoFspK8YNTCn1wvgAKmlggqCij/FXkbh7szpgdlp50MnvnkyP lk96Jv8sQ1JdQGAURqqmqgYkF3mGapE5gySL9ZwhZHyzkL0O/RbIQf5t1nWm3gYpbq uEpL9PSB2RTnOFLn1B9HaIE/diUnPoc6ZmU/M8wQ2SoiNmWWCQToS5x4OihQModqbL wQp9NYpGP/8mk1FlFPEVNiGZQBNpmOaQ1CBof6I+gHZEt/zViTgmR/oZTmy5m+cXoj Tt5QDTjkEbUg1MEvU+IXwpfYnYqHcejQQSHvHq4OyuZGU6Xkki5E+LhnslG0zaaCc7 s1wPnD7FtE6tA== Date: Thu, 18 Apr 2024 13:23:55 +0300 From: Mike Rapoport To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, Andrew Morton , Andy Lutomirski , Arnd Bergmann , Catalin Marinas , Christoph Hellwig , Helge Deller , Lorenzo Stoakes , Luis Chamberlain , Mark Rutland , Masami Hiramatsu , Mathieu Desnoyers , Michael Ellerman , Palmer Dabbelt , Russell King , Song Liu , Steven Rostedt , Thomas Gleixner , Uladzislau Rezki , Will Deacon , bpf@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-modules@vger.kernel.org, linux-parisc@vger.kernel.org, linux-riscv@lists.infradead.org, linux-trace-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, x86@kernel.org Subject: Re: [RFC PATCH 6/7] execmem: add support for cache of large ROX pages Message-ID: References: <20240411160526.2093408-1-rppt@kernel.org> <20240411160526.2093408-7-rppt@kernel.org> <20240415104750.GJ40213@noisy.programming.kicks-ass.net> <20240416075234.GA31647@noisy.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240416075234.GA31647@noisy.programming.kicks-ass.net> X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 66D2240019 X-Rspam-User: X-Stat-Signature: wqeokxa45oab4g3413pbawbro45w8uc7 X-HE-Tag: 1713435913-625438 X-HE-Meta: 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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 Tue, Apr 16, 2024 at 09:52:34AM +0200, Peter Zijlstra wrote: > On Mon, Apr 15, 2024 at 08:00:26PM +0300, Mike Rapoport wrote: > > On Mon, Apr 15, 2024 at 12:47:50PM +0200, Peter Zijlstra wrote: > > > On Thu, Apr 11, 2024 at 07:05:25PM +0300, Mike Rapoport wrote: > > > > > > > To populate the cache, a writable large page is allocated from vmalloc with > > > > VM_ALLOW_HUGE_VMAP, filled with invalid instructions and then remapped as > > > > ROX. > > > > > > > +static void execmem_invalidate(void *ptr, size_t size, bool writable) > > > > +{ > > > > + if (execmem_info->invalidate) > > > > + execmem_info->invalidate(ptr, size, writable); > > > > + else > > > > + memset(ptr, 0, size); > > > > +} > > > > > > +static void execmem_invalidate(void *ptr, size_t size, bool writeable) > > > +{ > > > + /* fill memory with INT3 instructions */ > > > + if (writeable) > > > + memset(ptr, 0xcc, size); > > > + else > > > + text_poke_set(ptr, 0xcc, size); > > > +} > > > > > > Thing is, 0xcc (aka INT3_INSN_OPCODE) is not an invalid instruction. > > > It raises #BP not #UD. > > > > Do you mean that _invalidate is a poor name choice or that it's necessary > > to use an instruction that raises #UD? > > Poor naming, mostly. #BP handler will still scream bloody murder if the > site is otherwise unclaimed. > > It just isn't an invalid instruction. Well, execmem_fill_with_insns_screaming_bloody_murder seems too long, how about execmem_fill_trapping_insns? -- Sincerely yours, Mike.