From: Borislav Petkov <bp@alien8.de>
To: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
linux-sgx@vger.kernel.org, akpm@linux-foundation.org,
dave.hansen@intel.com, sean.j.christopherson@intel.com,
nhorman@redhat.com, npmccallum@redhat.com, serge.ayoun@intel.com,
shay.katz-zamir@intel.com, haitao.huang@intel.com,
andriy.shevchenko@linux.intel.com, tglx@linutronix.de,
kai.svahn@intel.com, josh@joshtriplett.org, luto@kernel.org,
kai.huang@intel.com, rientjes@google.com, cedric.xing@intel.com
Subject: Re: [PATCH v22 09/24] x86/sgx: Add functions to allocate and free EPC pages
Date: Sat, 5 Oct 2019 18:44:08 +0200 [thread overview]
Message-ID: <20191005164408.GB25699@zn.tnic> (raw)
In-Reply-To: <20190903142655.21943-10-jarkko.sakkinen@linux.intel.com>
On Tue, Sep 03, 2019 at 05:26:40PM +0300, Jarkko Sakkinen wrote:
> Add functions for grabbing EPC pages into use:
>
> * sgx_alloc_page(): Iterate the EPC sections and return the first free
> page, or ERR_PTR(-ENOMEM) when no free pages are available.
> * __sgx_free_page(): Return the page into uninitialized state and move
> it back to the corresponding EPC section structure. Issues WARN()
> when EREMOVE fails.
> * sgx_free_page(): Return the page into uninitialized state and move
> it back to the corresponding EPC section structure. Returns
> ENCLS[EREMOVE] error code back to the caller.
>
> [1] Intel SDM: 40.3 INTEL® SGX SYSTEM LEAF FUNCTION REFERENCE
>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> Co-developed-by: Sean Christopherson <sean.j.christopherson@intel.com>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> ---
> arch/x86/kernel/cpu/sgx/main.c | 90 ++++++++++++++++++++++++++++++++++
> arch/x86/kernel/cpu/sgx/sgx.h | 4 ++
> 2 files changed, 94 insertions(+)
>
> diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
> index e2317f6e4374..6b4727df72ca 100644
> --- a/arch/x86/kernel/cpu/sgx/main.c
> +++ b/arch/x86/kernel/cpu/sgx/main.c
> @@ -9,6 +9,7 @@
> #include <linux/sched/signal.h>
> #include <linux/slab.h>
> #include "arch.h"
> +#include "encls.h"
> #include "sgx.h"
>
> struct sgx_epc_section sgx_epc_sections[SGX_MAX_EPC_SECTIONS];
> @@ -16,6 +17,95 @@ EXPORT_SYMBOL_GPL(sgx_epc_sections);
>
> int sgx_nr_epc_sections;
>
> +static struct sgx_epc_page *sgx_section_get_page(
That fits into 80 cols (oh well, 81) and even if not, a trailing opening
arg brace is ugly.
> + struct sgx_epc_section *section)
> +{
> + struct sgx_epc_page *page;
> +
> + if (!section->free_cnt)
> + return NULL;
> +
> + page = list_first_entry(§ion->page_list,
> + struct sgx_epc_page, list);
That fits in 80-cols too. Why break it?
> + list_del_init(&page->list);
> + section->free_cnt--;
> + return page;
> +}
> +
> +/**
> + * sgx_alloc_page - Allocate an EPC page
> + *
> + * Try to grab a page from the free EPC page list.
> + *
> + * Return:
> + * a pointer to a &struct sgx_epc_page instance,
> + * -errno on error
> + */
> +struct sgx_epc_page *sgx_alloc_page(void)
> +{
> + struct sgx_epc_section *section;
> + struct sgx_epc_page *page;
> + int i;
> +
> + for (i = 0; i < sgx_nr_epc_sections; i++) {
> + section = &sgx_epc_sections[i];
> + spin_lock(§ion->lock);
> + page = sgx_section_get_page(section);
> + spin_unlock(§ion->lock);
> +
> + if (page)
> + return page;
> + }
> +
> + return ERR_PTR(-ENOMEM);
> +}
> +EXPORT_SYMBOL_GPL(sgx_alloc_page);
That export gets removed later too. But you know already...
> +
> +/**
> + * __sgx_free_page - Free an EPC page
> + * @page: pointer a previously allocated EPC page
> + *
> + * EREMOVE an EPC page and insert it back to the list of free pages.
> + *
> + * Return:
> + * 0 on success
> + * SGX error code if EREMOVE fails
> + */
> +int __sgx_free_page(struct sgx_epc_page *page)
> +{
> + struct sgx_epc_section *section = sgx_epc_section(page);
> + int ret;
Shouldn't you be grabbing the lock here already?
Or nothing can happen to that page from another thread after you
ENCLS[EREMOVE] it and before it is added to the ->page_list of the
section?
> +
> + ret = __eremove(sgx_epc_addr(page));
> + if (ret)
> + return ret;
> +
> + spin_lock(§ion->lock);
> + list_add_tail(&page->list, §ion->page_list);
> + section->free_cnt++;
> + spin_unlock(§ion->lock);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(__sgx_free_page);
> +
> +/**
> + * sgx_free_page - Free an EPC page and WARN on failure
> + * @page: pointer to a previously allocated EPC page
> + *
> + * EREMOVE an EPC page and insert it back to the list of free pages, and WARN
> + * if EREMOVE fails. For use when the call site cannot (or chooses not to)
> + * handle failure, i.e. the page is leaked on failure.
> + */
> +void sgx_free_page(struct sgx_epc_page *page)
> +{
> + int ret;
> +
> + ret = __sgx_free_page(page);
> + WARN(ret > 0, "sgx: EREMOVE returned %d (0x%x)", ret, ret);
That will potentially flood dmesg. Why are we even accommodating such
callers? They either handle the error or they don't get to alloc EPC
pages. There's also __must_check with which you can enforce the error
code checking or we simply don't allow not handling failure. Fullstop.
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2019-10-05 16:44 UTC|newest]
Thread overview: 102+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-03 14:26 [PATCH v22 00/24] Intel SGX foundations Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 01/24] x86/cpufeatures: x86/msr: Add Intel SGX hardware bits Jarkko Sakkinen
2019-09-24 15:28 ` Borislav Petkov
2019-09-24 16:11 ` Sean Christopherson
2019-09-24 16:25 ` Borislav Petkov
2019-09-03 14:26 ` [PATCH v22 02/24] x86/cpufeatures: x86/msr: Intel SGX Launch Control " Jarkko Sakkinen
2019-09-24 15:52 ` Borislav Petkov
2019-09-24 20:22 ` Sean Christopherson
2019-09-25 8:51 ` Borislav Petkov
2019-09-25 17:18 ` Sean Christopherson
2019-09-25 18:31 ` Borislav Petkov
2019-09-25 19:08 ` Sean Christopherson
2019-09-27 16:11 ` Jarkko Sakkinen
2019-09-25 14:09 ` Jarkko Sakkinen
2019-09-25 14:10 ` Jarkko Sakkinen
2019-09-25 14:38 ` Jarkko Sakkinen
2019-09-25 15:19 ` Borislav Petkov
2019-09-25 16:49 ` Sean Christopherson
2019-09-25 17:28 ` Borislav Petkov
2019-09-25 18:18 ` Sean Christopherson
2019-09-03 14:26 ` [PATCH v22 03/24] x86/mm: x86/sgx: Signal SIGSEGV with PF_SGX Jarkko Sakkinen
2019-09-24 16:04 ` Borislav Petkov
2019-09-25 14:16 ` Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 04/24] x86/cpu/intel: Detect SGX supprt Jarkko Sakkinen
2019-09-24 16:13 ` Borislav Petkov
2019-09-24 17:43 ` Sean Christopherson
2019-09-24 18:21 ` Borislav Petkov
2019-09-25 14:46 ` Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 05/24] x86/sgx: Add ENCLS architectural error codes Jarkko Sakkinen
2019-09-27 10:20 ` Borislav Petkov
2019-09-27 16:08 ` Jarkko Sakkinen
2019-09-27 17:20 ` Sean Christopherson
2019-10-01 20:23 ` Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 06/24] x86/sgx: Add SGX microarchitectural data structures Jarkko Sakkinen
2019-09-27 16:27 ` Borislav Petkov
2019-10-01 19:10 ` Jarkko Sakkinen
2019-10-01 20:39 ` Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 07/24] x86/sgx: Add wrappers for ENCLS leaf functions Jarkko Sakkinen
2019-10-04 9:45 ` Borislav Petkov
2019-10-04 18:56 ` Jarkko Sakkinen
2019-10-08 4:04 ` Sean Christopherson
2019-10-08 7:18 ` Borislav Petkov
2019-10-08 13:35 ` Sean Christopherson
2019-10-08 14:56 ` Borislav Petkov
2019-09-03 14:26 ` [PATCH v22 08/24] x86/sgx: Enumerate and track EPC sections Jarkko Sakkinen
2019-10-05 9:26 ` Borislav Petkov
2019-10-07 11:58 ` Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 09/24] x86/sgx: Add functions to allocate and free EPC pages Jarkko Sakkinen
2019-10-05 16:44 ` Borislav Petkov [this message]
2019-10-07 14:50 ` Sean Christopherson
2019-10-08 9:09 ` Borislav Petkov
2019-10-08 13:31 ` Sean Christopherson
2019-10-07 17:55 ` Jarkko Sakkinen
2019-10-07 18:09 ` Borislav Petkov
2019-09-03 14:26 ` [PATCH v22 10/24] x86/sgx: Add sgx_einit() for wrapping ENCLS[EINIT] Jarkko Sakkinen
2019-10-08 17:30 ` Borislav Petkov
2019-10-08 17:45 ` Sean Christopherson
2019-10-08 17:46 ` Sean Christopherson
2019-10-08 17:53 ` Borislav Petkov
2019-09-03 14:26 ` [PATCH v22 11/24] mm: Introduce vm_ops->may_mprotect() Jarkko Sakkinen
2019-10-08 17:41 ` Borislav Petkov
2019-09-03 14:26 ` [PATCH v22 12/24] x86/sgx: Linux Enclave Driver Jarkko Sakkinen
2019-10-08 17:59 ` Borislav Petkov
2019-10-08 18:17 ` Sean Christopherson
2019-10-08 19:19 ` Borislav Petkov
2019-09-03 14:26 ` [PATCH v22 13/24] x86/sgx: Add provisioning Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 14/24] x86/sgx: Add a page reclaimer Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 15/24] x86/sgx: ptrace() support for the SGX driver Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 16/24] x86/vdso: Add support for exception fixup in vDSO functions Jarkko Sakkinen
2019-10-02 23:18 ` Jarkko Sakkinen
2019-10-02 23:45 ` Jarkko Sakkinen
2019-10-04 0:03 ` Sean Christopherson
2019-10-04 18:49 ` Jarkko Sakkinen
2019-10-04 0:15 ` Sean Christopherson
2019-10-04 18:52 ` Jarkko Sakkinen
2019-10-05 15:54 ` Sean Christopherson
2019-10-07 7:57 ` Jarkko Sakkinen
2019-10-07 8:10 ` Jarkko Sakkinen
2019-10-07 12:04 ` Jarkko Sakkinen
2019-10-08 4:54 ` Sean Christopherson
2019-10-05 18:39 ` Sean Christopherson
2019-10-07 8:01 ` Jarkko Sakkinen
2019-10-06 23:38 ` Jarkko Sakkinen
2019-10-06 23:40 ` Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 17/24] x86/fault: Add helper function to sanitize error code Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 18/24] x86/traps: Attempt to fixup exceptions in vDSO before signaling Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 19/24] x86/vdso: Add __vdso_sgx_enter_enclave() to wrap SGX enclave transitions Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 20/24] selftests/x86: Add a selftest for SGX Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 21/24] selftests/x86: Recurse into subdirectories Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 22/24] x86/sgx: Update MAINTAINERS Jarkko Sakkinen
2019-09-03 14:26 ` [PATCH v22 23/24] docs: x86/sgx: Document microarchitecture Jarkko Sakkinen
2019-09-27 18:15 ` Randy Dunlap
2019-09-03 14:26 ` [PATCH v22 24/24] docs: x86/sgx: Document kernel internals Jarkko Sakkinen
2019-09-27 17:07 ` Randy Dunlap
2019-10-01 19:34 ` Jarkko Sakkinen
2019-09-13 20:38 ` [PATCH v22 00/24] Intel SGX foundations Dave Hansen
2019-09-14 13:41 ` Jarkko Sakkinen
2019-09-14 15:32 ` Dave Hansen
2019-09-16 5:23 ` Jarkko Sakkinen
2019-09-24 17:20 ` Andy Lutomirski
2019-09-25 14:32 ` Jarkko Sakkinen
2019-10-02 23:42 ` Jarkko Sakkinen
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