| Message ID | 20210306002058.303796-1-ira.weiny@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v5] x86: Remove unnecessary kmap() from sgx_ioc_enclave_init() | expand |
On Fri, Mar 05, 2021 at 04:20:58PM -0800, 'Ira Weiny' wrote: > From: Ira Weiny <ira.weiny@intel.com> > > kmap is inefficient and we are trying to reduce the usage in the kernel. > There is no readily apparent reason why initp_page needs to be allocated > and kmap'ed() but sigstruct needs to be page aligned and token > 512 byte aligned. Friendly ping, maybe I missed a response? Ira > > kmalloc() can give us this alignment but we need to allocate PAGE_SIZE > bytes to do so. Rather than change this kmap() to kmap_local_page() use > kmalloc() instead. > > Remove the alloc_page()/kmap() and replace with kmalloc(PAGE_SIZE, ...) > to get a page aligned kernel address to use. > > In addition add a comment to document the alignment requirements so that > others like myself don't attempt to 'fix' this again. > > Cc: Sean Christopherson <seanjc@google.com> > Cc: Jethro Beekman <jethro@fortanix.com> > Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org> > Acked-by: Dave Hansen <dave.hansen@intel.com> > Signed-off-by: Ira Weiny <ira.weiny@intel.com> > > --- > Changes from v4[4]: > Add Ack and Reviews > Send to the correct maintainers > > Changes from v3[3]: > Remove BUILD_BUG_ONs > > Changes from v2[2]: > When allocating a power of 2 size kmalloc() now guarantees the > alignment of the respective size. So go back to using kmalloc() but > with a PAGE_SIZE allocation to get the alignment. This also follows > the pattern in sgx_ioc_enclave_create() > > Changes from v1[1]: > Use page_address() instead of kcmalloc() to ensure sigstruct is > page aligned > Use BUILD_BUG_ON to ensure token and sigstruct don't collide. > > [1] https://lore.kernel.org/lkml/20210129001459.1538805-1-ira.weiny@intel.com/ > [2] https://lore.kernel.org/lkml/20210202013725.3514671-1-ira.weiny@intel.com/ > [3] https://lore.kernel.org/lkml/20210205050850.GC5033@iweiny-DESK2.sc.intel.com/#t > [4] https://lore.kernel.org/lkml/YCBY02iEKLVyj7Ix@kernel.org/ > > --- > arch/x86/kernel/cpu/sgx/ioctl.c | 13 +++++++------ > 1 file changed, 7 insertions(+), 6 deletions(-) > > diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c > index 90a5caf76939..38e540de5e2a 100644 > --- a/arch/x86/kernel/cpu/sgx/ioctl.c > +++ b/arch/x86/kernel/cpu/sgx/ioctl.c > @@ -604,7 +604,6 @@ static long sgx_ioc_enclave_init(struct sgx_encl *encl, void __user *arg) > { > struct sgx_sigstruct *sigstruct; > struct sgx_enclave_init init_arg; > - struct page *initp_page; > void *token; > int ret; > > @@ -615,11 +614,14 @@ static long sgx_ioc_enclave_init(struct sgx_encl *encl, void __user *arg) > if (copy_from_user(&init_arg, arg, sizeof(init_arg))) > return -EFAULT; > > - initp_page = alloc_page(GFP_KERNEL); > - if (!initp_page) > + /* > + * sigstruct must be on a page boundry and token on a 512 byte boundry > + * kmalloc() gives us this alignment when allocating PAGE_SIZE bytes > + */ > + sigstruct = kmalloc(PAGE_SIZE, GFP_KERNEL); > + if (!sigstruct) > return -ENOMEM; > > - sigstruct = kmap(initp_page); > token = (void *)((unsigned long)sigstruct + PAGE_SIZE / 2); > memset(token, 0, SGX_LAUNCH_TOKEN_SIZE); > > @@ -645,8 +647,7 @@ static long sgx_ioc_enclave_init(struct sgx_encl *encl, void __user *arg) > ret = sgx_encl_init(encl, sigstruct, token); > > out: > - kunmap(initp_page); > - __free_page(initp_page); > + kfree(sigstruct); > return ret; > } > > -- > 2.28.0.rc0.12.gb6a658bd00c9 >
On Fri, Mar 05, 2021 at 04:20:58PM -0800, ira.weiny@intel.com wrote: > Subject: Re: [PATCH v5] x86: Remove unnecessary kmap() from sgx_ioc_enclave_init() The tip tree preferred format for patch subject prefixes is 'subsys/component:', e.g. 'x86/apic:', 'x86/mm/fault:', 'sched/fair:', 'genirq/core:'. Please do not use file names or complete file paths as prefix. 'git log path/to/file' should give you a reasonable hint in most cases. > From: Ira Weiny <ira.weiny@intel.com> > > kmap is inefficient and we are trying to reduce the usage in the kernel. Please use passive voice in your commit message: no "we" or "I", etc, and describe your changes in imperative mood. Also, pls read section "2) Describe your changes" in Documentation/process/submitting-patches.rst for more details. Bottom line is: personal pronouns are ambiguous in text, especially with so many parties/companies/etc developing the kernel so let's avoid them please. > @@ -615,11 +614,14 @@ static long sgx_ioc_enclave_init(struct sgx_encl *encl, void __user *arg) > if (copy_from_user(&init_arg, arg, sizeof(init_arg))) > return -EFAULT; > > - initp_page = alloc_page(GFP_KERNEL); > - if (!initp_page) > + /* > + * sigstruct must be on a page boundry and token on a 512 byte boundry > + * kmalloc() gives us this alignment when allocating PAGE_SIZE bytes Please integrate scripts/checkpatch.pl into your patch creation workflow. Some of the warnings/errors *actually* make sense. WARNING: 'boundry' may be misspelled - perhaps 'boundary'? #90: FILE: arch/x86/kernel/cpu/sgx/ioctl.c:618: + * sigstruct must be on a page boundry and token on a 512 byte boundry ^^^^^^^ WARNING: 'boundry' may be misspelled - perhaps 'boundary'? #90: FILE: arch/x86/kernel/cpu/sgx/ioctl.c:618: + * sigstruct must be on a page boundry and token on a 512 byte boundry ^^^^^^^ Also, do you see how other comments in this file are proper sentences? Please formulate yours this way too. The change itself looks ok. Thx.
On Wed, Mar 24, 2021 at 10:47:20AM +0100, Borislav Petkov wrote: > On Fri, Mar 05, 2021 at 04:20:58PM -0800, ira.weiny@intel.com wrote: > > > Subject: Re: [PATCH v5] x86: Remove unnecessary kmap() from sgx_ioc_enclave_init() > > The tip tree preferred format for patch subject prefixes is > 'subsys/component:', e.g. 'x86/apic:', 'x86/mm/fault:', 'sched/fair:', > 'genirq/core:'. Please do not use file names or complete file paths as > prefix. 'git log path/to/file' should give you a reasonable hint in most > cases. Fixed. > > > From: Ira Weiny <ira.weiny@intel.com> > > > > kmap is inefficient and we are trying to reduce the usage in the kernel. > > Please use passive voice in your commit message: no "we" or "I", etc, > and describe your changes in imperative mood. > > Also, pls read section "2) Describe your changes" in > Documentation/process/submitting-patches.rst for more details. > > Bottom line is: personal pronouns are ambiguous in text, especially with > so many parties/companies/etc developing the kernel so let's avoid them > please. Fixed. > > > @@ -615,11 +614,14 @@ static long sgx_ioc_enclave_init(struct sgx_encl *encl, void __user *arg) > > if (copy_from_user(&init_arg, arg, sizeof(init_arg))) > > return -EFAULT; > > > > - initp_page = alloc_page(GFP_KERNEL); > > - if (!initp_page) > > + /* > > + * sigstruct must be on a page boundry and token on a 512 byte boundry > > + * kmalloc() gives us this alignment when allocating PAGE_SIZE bytes > > Please integrate scripts/checkpatch.pl into your patch creation > workflow. Some of the warnings/errors *actually* make sense. > > WARNING: 'boundry' may be misspelled - perhaps 'boundary'? > #90: FILE: arch/x86/kernel/cpu/sgx/ioctl.c:618: > + * sigstruct must be on a page boundry and token on a 512 byte boundry > ^^^^^^^ > > WARNING: 'boundry' may be misspelled - perhaps 'boundary'? > #90: FILE: arch/x86/kernel/cpu/sgx/ioctl.c:618: > + * sigstruct must be on a page boundry and token on a 512 byte boundry > ^^^^^^^ > > Also, do you see how other comments in this file are proper sentences? > Please formulate yours this way too. Thanks fixed. > > The change itself looks ok. Thanks, new version 5 sent. Ira > > Thx. > > -- > Regards/Gruss, > Boris. > > https://people.kernel.org/tglx/notes-about-netiquette
diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c index 90a5caf76939..38e540de5e2a 100644 --- a/arch/x86/kernel/cpu/sgx/ioctl.c +++ b/arch/x86/kernel/cpu/sgx/ioctl.c @@ -604,7 +604,6 @@ static long sgx_ioc_enclave_init(struct sgx_encl *encl, void __user *arg) { struct sgx_sigstruct *sigstruct; struct sgx_enclave_init init_arg; - struct page *initp_page; void *token; int ret; @@ -615,11 +614,14 @@ static long sgx_ioc_enclave_init(struct sgx_encl *encl, void __user *arg) if (copy_from_user(&init_arg, arg, sizeof(init_arg))) return -EFAULT; - initp_page = alloc_page(GFP_KERNEL); - if (!initp_page) + /* + * sigstruct must be on a page boundry and token on a 512 byte boundry + * kmalloc() gives us this alignment when allocating PAGE_SIZE bytes + */ + sigstruct = kmalloc(PAGE_SIZE, GFP_KERNEL); + if (!sigstruct) return -ENOMEM; - sigstruct = kmap(initp_page); token = (void *)((unsigned long)sigstruct + PAGE_SIZE / 2); memset(token, 0, SGX_LAUNCH_TOKEN_SIZE); @@ -645,8 +647,7 @@ static long sgx_ioc_enclave_init(struct sgx_encl *encl, void __user *arg) ret = sgx_encl_init(encl, sigstruct, token); out: - kunmap(initp_page); - __free_page(initp_page); + kfree(sigstruct); return ret; }