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b=JQhmkrbxlkokAIFsbHYvCZlDdyYFqLoERLQD9UjXNswKquLP0xtcV1u+YOoMVBYzN Sb7LZUsXfhw2SSDicmJPXX6wJEySR7qXgqeF6WRCMsTmaxb6dTEEvdKVJ2QF8xV73M zWVAeo2j5d2mIhRamGxbmxaN76CTvh0ZT5e287zxh62+7uCraDbeX1crXvejWzPawj XA+nSfS1WF1QUSKZ+OwNWlmE2LS69a8cbAEH8Ow0G8h8jNNt9mOeOurVvGxQejJFIq lJWV1cL3Cak0wByUAJkuz9CCwdQLw1/FNbKBb/4i5MFAWn2PKkhEyDcE8g7rJ9Kbjc EpnrFltAXi4ng== Date: Mon, 15 Apr 2024 20:00:26 +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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240415104750.GJ40213@noisy.programming.kicks-ass.net> X-Rspamd-Queue-Id: D6F24A0003 X-Rspam-User: X-Stat-Signature: 5ck9bwskzw7hayi6bqs1mw1yg9paca7s X-Rspamd-Server: rspam03 X-HE-Tag: 1713200501-814273 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 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? -- Sincerely yours, Mike.