From: Pratyush Anand <panand@redhat.com> To: Catalin Marinas <catalin.marinas@arm.com> Cc: Mark Rutland <mark.rutland@arm.com>, srikar@linux.vnet.ibm.com, Will Deacon <will.deacon@arm.com>, open list <linux-kernel@vger.kernel.org>, Vladimir Murzin <vladimir.murzin@arm.com>, Russell King - ARM Linux <linux@arm.linux.org.uk>, vijaya.kumar@caviumnetworks.com, Dave Long <dave.long@linaro.org>, Shi Yang <yang.shi@linaro.org>, Jungseok Lee <jungseoklee85@gmail.com>, Steve Capper <steve.capper@linaro.org>, "Suzuki K. Poulose" <suzuki.poulose@arm.com>, Andre Przywara <andre.przywara@arm.com>, Shaokun Zhang <zhangshaokun@hisilicon.com>, Ashok Kumar <ashoks@broadcom.com>, Sandeepa Prabhu <sandeepa.s.prabhu@gmail.com>, Will Cohen <wcohen@redhat.com>, linux-arm-kernel <linux-arm-kernel@lists.infradead.org>, Ard Biesheuvel <ard.biesheuvel@linaro.org>, Oleg Nesterov <oleg@redhat.com>, James Morse <james.morse@arm.com>, Masami Hiramatsu <mhiramat@kernel.org>, Robin Murphy <robin.murphy@arm.com>, "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Subject: Re: [PATCH 5/5] arm64: Add uprobe support Date: Sun, 25 Sep 2016 22:32:28 +0530 [thread overview] Message-ID: <CAHB_GupuUYPNFoYQeX8EhAcesvqKVVuphuxneudZ5kL2cxm-7g@mail.gmail.com> (raw) In-Reply-To: <20160923130528.GE2161@e104818-lin.cambridge.arm.com> On Fri, Sep 23, 2016 at 6:35 PM, Catalin Marinas <catalin.marinas@arm.com> wrote: > On Fri, Sep 23, 2016 at 09:42:30AM +0530, Pratyush Anand wrote: >> On 22/09/2016:05:50:30 PM, Catalin Marinas wrote: >> > On Thu, Sep 22, 2016 at 08:53:28AM +0530, Pratyush Anand wrote: >> > > On 21/09/2016:06:04:04 PM, Catalin Marinas wrote: >> > As a quick workaround you could check mm->task_size > TASK_SIZE_32 in >> > the arch_uprobe_analyze_insn() function. >> >> It would be doable. TASK_SIZE_32 is defined only for COMPAT. So, may be I can >> return -EINVAL when mm->task_size < TASK_SIZE_64. > > That's just a temporary workaround. If we ever merge ILP32, this test > would no longer be enough (as the ISA is AArch64 but with TASK_SIZE_32). OK.. So what about doing something similar what x86 is doing. We can have a flag for task Type in arch specific mm_context_t. We also set this flag in COMPAT_SET_PERSONALITY() along with setting thread_info flag, and we clear them in SET_PERSONALITY(). > > Looking at prepare_uprobe(), we have a weak is_trap_insn() function. > This check is meaningless without knowing which instruction set we > target. A false positive here, however, is not that bad as we wouldn't > end up inserting the wrong breakpoint in the executable. But it looks to > me like the core uprobe code needs to pass some additional information > like the type of task or ELF format to the arch code to make a useful > choice of breakpoint type. It seems that 'strtle r0, [r0], #160' would have the closest matching aarch32 instruction wrt BRK64_OPCODE_UPROBES(0xd42000A0). But that too seems a bad instruction. So, may be we can use still weak is_trap_insn(). ~Pratyush
WARNING: multiple messages have this Message-ID (diff)
From: panand@redhat.com (Pratyush Anand) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH 5/5] arm64: Add uprobe support Date: Sun, 25 Sep 2016 22:32:28 +0530 [thread overview] Message-ID: <CAHB_GupuUYPNFoYQeX8EhAcesvqKVVuphuxneudZ5kL2cxm-7g@mail.gmail.com> (raw) In-Reply-To: <20160923130528.GE2161@e104818-lin.cambridge.arm.com> On Fri, Sep 23, 2016 at 6:35 PM, Catalin Marinas <catalin.marinas@arm.com> wrote: > On Fri, Sep 23, 2016 at 09:42:30AM +0530, Pratyush Anand wrote: >> On 22/09/2016:05:50:30 PM, Catalin Marinas wrote: >> > On Thu, Sep 22, 2016 at 08:53:28AM +0530, Pratyush Anand wrote: >> > > On 21/09/2016:06:04:04 PM, Catalin Marinas wrote: >> > As a quick workaround you could check mm->task_size > TASK_SIZE_32 in >> > the arch_uprobe_analyze_insn() function. >> >> It would be doable. TASK_SIZE_32 is defined only for COMPAT. So, may be I can >> return -EINVAL when mm->task_size < TASK_SIZE_64. > > That's just a temporary workaround. If we ever merge ILP32, this test > would no longer be enough (as the ISA is AArch64 but with TASK_SIZE_32). OK.. So what about doing something similar what x86 is doing. We can have a flag for task Type in arch specific mm_context_t. We also set this flag in COMPAT_SET_PERSONALITY() along with setting thread_info flag, and we clear them in SET_PERSONALITY(). > > Looking at prepare_uprobe(), we have a weak is_trap_insn() function. > This check is meaningless without knowing which instruction set we > target. A false positive here, however, is not that bad as we wouldn't > end up inserting the wrong breakpoint in the executable. But it looks to > me like the core uprobe code needs to pass some additional information > like the type of task or ELF format to the arch code to make a useful > choice of breakpoint type. It seems that 'strtle r0, [r0], #160' would have the closest matching aarch32 instruction wrt BRK64_OPCODE_UPROBES(0xd42000A0). But that too seems a bad instruction. So, may be we can use still weak is_trap_insn(). ~Pratyush
next prev parent reply other threads:[~2016-09-25 17:02 UTC|newest] Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-08-02 5:30 [PATCH 0/5] ARM64: Uprobe support added Pratyush Anand 2016-08-02 5:30 ` Pratyush Anand 2016-08-02 5:30 ` [PATCH 1/5] arm64: kprobe: protect/rename few definitions to be reused by uprobe Pratyush Anand 2016-08-02 5:30 ` Pratyush Anand 2016-08-02 5:30 ` [PATCH 2/5] arm64: kgdb_step_brk_fn: ignore other's exception Pratyush Anand 2016-08-02 5:30 ` Pratyush Anand 2016-08-02 5:30 ` [PATCH 3/5] arm64: Handle TRAP_HWBRKPT for user mode as well Pratyush Anand 2016-08-02 5:30 ` Pratyush Anand 2016-09-06 16:11 ` Catalin Marinas 2016-09-06 16:11 ` Catalin Marinas 2016-09-06 21:36 ` David Long 2016-09-06 21:36 ` David Long 2016-09-07 4:47 ` Pratyush Anand 2016-09-07 4:47 ` Pratyush Anand 2016-09-07 13:41 ` Catalin Marinas 2016-09-07 13:41 ` Catalin Marinas 2016-08-02 5:30 ` [PATCH 4/5] arm64: Handle TRAP_BRKPT " Pratyush Anand 2016-08-02 5:30 ` Pratyush Anand 2016-09-06 16:34 ` Catalin Marinas 2016-09-06 16:34 ` Catalin Marinas 2016-08-02 5:30 ` [PATCH 5/5] arm64: Add uprobe support Pratyush Anand 2016-08-02 5:30 ` Pratyush Anand 2016-08-09 18:49 ` Oleg Nesterov 2016-08-09 18:49 ` Oleg Nesterov 2016-08-24 7:13 ` Pratyush Anand 2016-08-24 7:13 ` Pratyush Anand 2016-08-24 15:47 ` Oleg Nesterov 2016-08-24 15:47 ` Oleg Nesterov 2016-08-24 15:56 ` Will Deacon 2016-08-24 15:56 ` Will Deacon 2016-08-25 13:33 ` Oleg Nesterov 2016-08-25 13:33 ` Oleg Nesterov 2016-09-20 16:59 ` Catalin Marinas 2016-09-20 16:59 ` Catalin Marinas 2016-09-21 11:00 ` Pratyush Anand 2016-09-21 11:00 ` Pratyush Anand 2016-09-21 17:04 ` Catalin Marinas 2016-09-21 17:04 ` Catalin Marinas 2016-09-22 3:23 ` Pratyush Anand 2016-09-22 3:23 ` Pratyush Anand 2016-09-22 16:50 ` Catalin Marinas 2016-09-22 16:50 ` Catalin Marinas 2016-09-23 4:12 ` Pratyush Anand 2016-09-23 4:12 ` Pratyush Anand 2016-09-23 13:05 ` Catalin Marinas 2016-09-23 13:05 ` Catalin Marinas 2016-09-25 17:02 ` Pratyush Anand [this message] 2016-09-25 17:02 ` Pratyush Anand 2016-09-26 11:01 ` Catalin Marinas 2016-09-26 11:01 ` Catalin Marinas 2016-09-26 13:03 ` Pratyush Anand 2016-09-26 13:03 ` Pratyush Anand 2016-09-27 13:51 ` Catalin Marinas 2016-09-27 13:51 ` Catalin Marinas 2016-09-27 15:03 ` Pratyush Anand 2016-09-27 15:03 ` Pratyush Anand 2016-09-28 17:12 ` Catalin Marinas 2016-09-28 17:12 ` Catalin Marinas 2016-08-24 7:26 ` [PATCH 0/5] ARM64: Uprobe support added Pratyush Anand 2016-08-24 7:26 ` Pratyush Anand 2016-09-20 2:51 ` Pratyush Anand 2016-09-20 2:51 ` Pratyush Anand
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