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SubjectRe: [PATCH v38 17/24] x86/sgx: ptrace() support for the SGX driver

> Subject: Re: [PATCH v38 17/24] x86/sgx: ptrace() support for the SGX driver
... x86/sgx: Add ptrace() support...

subject needs a verb.

On Tue, Sep 15, 2020 at 02:28:35PM +0300, Jarkko Sakkinen wrote:
> 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

I think you wanna say here

"... data can be read and/or written a memory word at a time by using..."

> by using ENCLS(EDBGRD) and ENCLS(EDBGWR) leaf instructions.
>
> Acked-by: Jethro Beekman <jethro@fortanix.com>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> ---
> arch/x86/kernel/cpu/sgx/encl.c | 87 ++++++++++++++++++++++++++++++++++
> 1 file changed, 87 insertions(+)
>
> diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
> index 11ec2df59b54..7f8df2c8ef35 100644
> --- a/arch/x86/kernel/cpu/sgx/encl.c
> +++ b/arch/x86/kernel/cpu/sgx/encl.c
> @@ -333,10 +333,97 @@ static int sgx_vma_mprotect(struct vm_area_struct *vma,
> return mprotect_fixup(vma, pprev, start, end, newflags);
> }
>
> +static int sgx_edbgrd(struct sgx_encl *encl, struct sgx_encl_page *page,
> + unsigned long addr, void *data)
> +{
> + unsigned long offset = addr & ~PAGE_MASK;
> + int ret;
> +
> +
> + ret = __edbgrd(sgx_get_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 = addr & ~PAGE_MASK;
> + int ret;
> +
> + ret = __edbgwr(sgx_get_epc_addr(page->epc_page) + offset, data);
> + if (ret)
> + return -EIO;
> +
> + return 0;
> +}

I know those are supposed to correspond to the ENCLS leafs but the
function names are totally unreadable. I guess you could name them

sgx_encl_dbg_read
sgx_encl_dbg_write

and leave the lowlevel helpers like the insn names.

> +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;
> + char data[sizeof(unsigned long)];
> + unsigned long align;
> + unsigned int flags;
> + 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.
> + */

Kernel comments style is:

/*
* A sentence ending with a full-stop.
* Another sentence. ...
* More sentences. ...
*/

> + if (!encl)
> + return -EFAULT;
> +
> + flags = atomic_read(&encl->flags);
> +
> + if (!(flags & SGX_ENCL_DEBUG) || !(flags & SGX_ENCL_INITIALIZED) ||
> + (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

} else {

> + memcpy(buf + i, data + offset, cnt);

}

Put the else branch in {} too.

--
Regards/Gruss,
Boris.

https://people.kernel.org/tglx/notes-about-netiquette

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