| Message ID | 20180529133615.26889-1-nixiaoming@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, May 29, 2018 at 09:36:15PM +0800, nixiaoming wrote: > mark_rodata_ro is only called by the function mark_readonly when > CONFIG_STRICT_KERNEL_RWX=y, > if CONFIG_STRICT_KERNEL_RWX is not set > a compile warning may be triggered: unused function How are you achieving this configuration? In our Kconfig we select this unconditionally. Will
Unable to set CONFIG_STRICT_KERNEL_RWX=n by make menuconfig ARCH=arm64 When reading the code, I feel it is more appropriate to add macro control here. -----Original Message----- From: Will Deacon [mailto:will.deacon@arm.com] Sent: Tuesday, May 29, 2018 11:45 PM To: Nixiaoming <nixiaoming@huawei.com> Cc: catalin.marinas@arm.com; ard.biesheuvel@linaro.org; marc.zyngier@arm.com; james.morse@arm.com; kristina.martsenko@arm.com; steve.capper@arm.com; tglx@linutronix.de; mingo@redhat.com; hpa@zytor.com; akpm@linux-foundation.org; vbabka@suse.cz; mhocko@suse.com; dave.hansen@linux.intel.com; dan.j.williams@intel.com; kirill.shutemov@linux.intel.com; zhang.jia@linux.alibaba.com; schwidefsky@de.ibm.com; heiko.carstens@de.ibm.com; gregkh@linuxfoundation.org; linux-kernel@vger.kernel.org; linux-arm-kernel@lists.infradead.org; x86@kernel.org; linux-s390@vger.kernel.org Subject: Re: [PATCH 1/3] arm64:add missing CONFIG_STRICT_KERNEL_RWX for mark_rodata_ro On Tue, May 29, 2018 at 09:36:15PM +0800, nixiaoming wrote: > mark_rodata_ro is only called by the function mark_readonly when > CONFIG_STRICT_KERNEL_RWX=y, > if CONFIG_STRICT_KERNEL_RWX is not set > a compile warning may be triggered: unused function How are you achieving this configuration? In our Kconfig we select this unconditionally. Will
On Wed, May 30, 2018 at 03:31:38AM +0000, Nixiaoming wrote: > Unable to set CONFIG_STRICT_KERNEL_RWX=n by make menuconfig ARCH=arm64 Indeed. Making this mandatory was a deliberate decision, in part because this allows simplification of code (e.g. removal of #ifdef guards). > When reading the code, I feel it is more appropriate to add macro control > here. I must disagree. I do not think it makes sense to add an #ifdef for a configuration option that is mandatory. There are other places in the kernel that should behave differently if CONFIG_STRICT_KERNEL_RWX were disabled, so this wouldn't be sufficient even if we were to make CONFIG_STRICT_KERNEL_RWX optional. i.e. the #ifdef would give the misleading impression that STRICT_KERNEL_RWX *could* be made optional, even though this might not function correctly. Having an #ifdef here makes the code more complicated and confusing, for the benefit of a case which cannot occur. Thanks, Mark. > -----Original Message----- > From: Will Deacon [mailto:will.deacon@arm.com] > Sent: Tuesday, May 29, 2018 11:45 PM > To: Nixiaoming <nixiaoming@huawei.com> > Cc: catalin.marinas@arm.com; ard.biesheuvel@linaro.org; marc.zyngier@arm.com; james.morse@arm.com; kristina.martsenko@arm.com; steve.capper@arm.com; tglx@linutronix.de; mingo@redhat.com; hpa@zytor.com; akpm@linux-foundation.org; vbabka@suse.cz; mhocko@suse.com; dave.hansen@linux.intel.com; dan.j.williams@intel.com; kirill.shutemov@linux.intel.com; zhang.jia@linux.alibaba.com; schwidefsky@de.ibm.com; heiko.carstens@de.ibm.com; gregkh@linuxfoundation.org; linux-kernel@vger.kernel.org; linux-arm-kernel@lists.infradead.org; x86@kernel.org; linux-s390@vger.kernel.org > Subject: Re: [PATCH 1/3] arm64:add missing CONFIG_STRICT_KERNEL_RWX for mark_rodata_ro > > On Tue, May 29, 2018 at 09:36:15PM +0800, nixiaoming wrote: > > mark_rodata_ro is only called by the function mark_readonly when > > CONFIG_STRICT_KERNEL_RWX=y, > > if CONFIG_STRICT_KERNEL_RWX is not set > > a compile warning may be triggered: unused function > > How are you achieving this configuration? In our Kconfig we select this > unconditionally. > > Will
Because CONFIG_STRICT_KERNEL_RWX=n cannot be set by make menuconfig on arm64/x86/s390 architecture So, these three patches should not be necessary Sorry to disturb everyone Thank you for your guidance Thanks -----Original Message----- From: Mark Rutland [mailto:mark.rutland@arm.com] Sent: Wednesday, May 30, 2018 4:08 PM To: Nixiaoming <nixiaoming@huawei.com> Cc: Will Deacon <will.deacon@arm.com>; catalin.marinas@arm.com; ard.biesheuvel@linaro.org; marc.zyngier@arm.com; james.morse@arm.com; kristina.martsenko@arm.com; steve.capper@arm.com; tglx@linutronix.de; mingo@redhat.com; hpa@zytor.com; akpm@linux-foundation.org; vbabka@suse.cz; mhocko@suse.com; dave.hansen@linux.intel.com; dan.j.williams@intel.com; kirill.shutemov@linux.intel.com; zhang.jia@linux.alibaba.com; schwidefsky@de.ibm.com; heiko.carstens@de.ibm.com; gregkh@linuxfoundation.org; linux-kernel@vger.kernel.org; linux-arm-kernel@lists.infradead.org; x86@kernel.org; linux-s390@vger.kernel.org Subject: Re: [PATCH 1/3] arm64:add missing CONFIG_STRICT_KERNEL_RWX for mark_rodata_ro On Wed, May 30, 2018 at 03:31:38AM +0000, Nixiaoming wrote: > Unable to set CONFIG_STRICT_KERNEL_RWX=n by make menuconfig ARCH=arm64 Indeed. Making this mandatory was a deliberate decision, in part because this allows simplification of code (e.g. removal of #ifdef guards). > When reading the code, I feel it is more appropriate to add macro control > here. I must disagree. I do not think it makes sense to add an #ifdef for a configuration option that is mandatory. There are other places in the kernel that should behave differently if CONFIG_STRICT_KERNEL_RWX were disabled, so this wouldn't be sufficient even if we were to make CONFIG_STRICT_KERNEL_RWX optional. i.e. the #ifdef would give the misleading impression that STRICT_KERNEL_RWX *could* be made optional, even though this might not function correctly. Having an #ifdef here makes the code more complicated and confusing, for the benefit of a case which cannot occur. Thanks, Mark. > -----Original Message----- > From: Will Deacon [mailto:will.deacon@arm.com] > Sent: Tuesday, May 29, 2018 11:45 PM > To: Nixiaoming <nixiaoming@huawei.com> > Cc: catalin.marinas@arm.com; ard.biesheuvel@linaro.org; marc.zyngier@arm.com; james.morse@arm.com; kristina.martsenko@arm.com; steve.capper@arm.com; tglx@linutronix.de; mingo@redhat.com; hpa@zytor.com; akpm@linux-foundation.org; vbabka@suse.cz; mhocko@suse.com; dave.hansen@linux.intel.com; dan.j.williams@intel.com; kirill.shutemov@linux.intel.com; zhang.jia@linux.alibaba.com; schwidefsky@de.ibm.com; heiko.carstens@de.ibm.com; gregkh@linuxfoundation.org; linux-kernel@vger.kernel.org; linux-arm-kernel@lists.infradead.org; x86@kernel.org; linux-s390@vger.kernel.org > Subject: Re: [PATCH 1/3] arm64:add missing CONFIG_STRICT_KERNEL_RWX for mark_rodata_ro > > On Tue, May 29, 2018 at 09:36:15PM +0800, nixiaoming wrote: > > mark_rodata_ro is only called by the function mark_readonly when > > CONFIG_STRICT_KERNEL_RWX=y, > > if CONFIG_STRICT_KERNEL_RWX is not set > > a compile warning may be triggered: unused function > > How are you achieving this configuration? In our Kconfig we select this > unconditionally. > > Will
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 2dbb2c9..849f326 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -491,6 +491,7 @@ static void __init map_mem(pgd_t *pgdp) #endif } +#ifdef CONFIG_STRICT_KERNEL_RWX void mark_rodata_ro(void) { unsigned long section_size; @@ -505,6 +506,7 @@ void mark_rodata_ro(void) debug_checkwx(); } +#endif static void __init map_kernel_segment(pgd_t *pgdp, void *va_start, void *va_end, pgprot_t prot, struct vm_struct *vma,
mark_rodata_ro is only called by the function mark_readonly when CONFIG_STRICT_KERNEL_RWX=y, if CONFIG_STRICT_KERNEL_RWX is not set a compile warning may be triggered: unused function Signed-off-by: nixiaoming <nixiaoming@huawei.com> --- arch/arm64/mm/mmu.c | 2 ++ 1 file changed, 2 insertions(+)