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Subject[PATCH v20 18/28] x86/sgx: ptrace() support for the SGX driver
Date
Add VMA callbacks for ptrace() that can be used with debug enclaves.
With debug enclaves data can be read and write the memory word at a time
by using ENCLS(EDBGRD) and ENCLS(EDBGWR) leaf instructions.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
---
arch/x86/kernel/cpu/sgx/encl.c | 97 ++++++++++++++++++++++++++++++++++
1 file changed, 97 insertions(+)

diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
index 16e8524687c1..7216bdf07bd0 100644
--- a/arch/x86/kernel/cpu/sgx/encl.c
+++ b/arch/x86/kernel/cpu/sgx/encl.c
@@ -273,10 +273,107 @@ static unsigned int sgx_vma_fault(struct vm_fault *vmf)
return ret;
}

+static int sgx_edbgrd(struct sgx_encl *encl, struct sgx_encl_page *page,
+ unsigned long addr, void *data)
+{
+ unsigned long offset;
+ int ret;
+
+ offset = addr & ~PAGE_MASK;
+
+ if ((page->desc & SGX_ENCL_PAGE_TCS) &&
+ offset > offsetof(struct sgx_tcs, gs_limit))
+ return -ECANCELED;
+
+ ret = __edbgrd(sgx_epc_addr(page->epc_page) + offset, data);
+ if (ret)
+ return -EIO;
+
+ return 0;
+}
+
+static int sgx_edbgwr(struct sgx_encl *encl, struct sgx_encl_page *page,
+ unsigned long addr, void *data)
+{
+ unsigned long offset;
+ int ret;
+
+ offset = addr & ~PAGE_MASK;
+
+ /* Writing anything else than flags will cause #GP */
+ if ((page->desc & SGX_ENCL_PAGE_TCS) &&
+ offset != offsetof(struct sgx_tcs, flags))
+ return -ECANCELED;
+
+ ret = __edbgwr(sgx_epc_addr(page->epc_page) + offset, data);
+ if (ret)
+ return -EIO;
+
+ return 0;
+}
+
+static int sgx_vma_access(struct vm_area_struct *vma, unsigned long addr,
+ void *buf, int len, int write)
+{
+ struct sgx_encl *encl = vma->vm_private_data;
+ struct sgx_encl_page *entry = NULL;
+ unsigned long align;
+ char data[sizeof(unsigned long)];
+ int offset;
+ int cnt;
+ int ret = 0;
+ int i;
+
+ /* If process was forked, VMA is still there but vm_private_data is set
+ * to NULL.
+ */
+ if (!encl)
+ return -EFAULT;
+
+ if (!(encl->flags & SGX_ENCL_DEBUG) ||
+ !(encl->flags & SGX_ENCL_INITIALIZED) ||
+ (encl->flags & SGX_ENCL_DEAD))
+ return -EFAULT;
+
+ for (i = 0; i < len; i += cnt) {
+ entry = sgx_encl_reserve_page(encl, (addr + i) & PAGE_MASK);
+ if (IS_ERR(entry)) {
+ ret = PTR_ERR(entry);
+ break;
+ }
+
+ align = ALIGN_DOWN(addr + i, sizeof(unsigned long));
+ offset = (addr + i) & (sizeof(unsigned long) - 1);
+ cnt = sizeof(unsigned long) - offset;
+ cnt = min(cnt, len - i);
+
+ ret = sgx_edbgrd(encl, entry, align, data);
+ if (ret)
+ goto out;
+
+ if (write) {
+ memcpy(data + offset, buf + i, cnt);
+ ret = sgx_edbgwr(encl, entry, align, data);
+ if (ret)
+ goto out;
+ } else
+ memcpy(buf + i, data + offset, cnt);
+
+out:
+ mutex_unlock(&encl->lock);
+
+ if (ret)
+ break;
+ }
+
+ return ret < 0 ? ret : i;
+}
+
const struct vm_operations_struct sgx_vm_ops = {
.close = sgx_vma_close,
.open = sgx_vma_open,
.fault = sgx_vma_fault,
+ .access = sgx_vma_access,
};
EXPORT_SYMBOL_GPL(sgx_vm_ops);

--
2.19.1
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