Re: [PATCH v22 8/8] x86/vdso: Add ENDBR64 to __vdso_sgx_enter_enclave
From: Yu, Yu-cheng <hidden>
Date: 2021-03-10 22:57:02
Also in:
linux-arch, linux-doc, linux-mm, lkml
On 3/10/2021 2:39 PM, Jarkko Sakkinen wrote:
On Wed, Mar 10, 2021 at 02:05:19PM -0800, Yu-cheng Yu wrote:quoted
When CET is enabled, __vdso_sgx_enter_enclave() needs an endbr64 in the beginning of the function.OK. What you should do is to explain what it does and why it's needed.
The endbr marks a branch target. Without the "no-track" prefix, if an indirect call/jmp reaches a non-endbr opcode, a control-protection fault is raised. Usually endbr's are inserted by the compiler. For assembly, these have to be put in manually. I will add this in the commit log if there is another revision. Thanks! -- Yu-cheng
quoted
Signed-off-by: Yu-cheng Yu <redacted> Cc: Andy Lutomirski <luto@kernel.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Jarkko Sakkinen <jarkko@kernel.org> --- arch/x86/entry/vdso/vsgx.S | 3 +++ 1 file changed, 3 insertions(+)diff --git a/arch/x86/entry/vdso/vsgx.S b/arch/x86/entry/vdso/vsgx.S index 86a0e94f68df..a70d4d09f713 100644 --- a/arch/x86/entry/vdso/vsgx.S +++ b/arch/x86/entry/vdso/vsgx.S@@ -27,6 +27,9 @@ SYM_FUNC_START(__vdso_sgx_enter_enclave) /* Prolog */ .cfi_startproc +#ifdef CONFIG_X86_CET + endbr64 +#endif push %rbp .cfi_adjust_cfa_offset 8 .cfi_rel_offset %rbp, 0-- 2.21.0/Jarkko