Subject: Re: [PATCH 06/18] add support for Clang's Shadow Call Stack (SCS)

From: Joe Perches <[email-masked]>
Date: Fri, 18 Oct 2019 09:58:14 -0700

On Fri, 2019-10-18 at 09:10 -0700, Sami Tolvanen wrote:
> This change adds generic support for Clang's Shadow Call Stack, which
> uses a shadow stack to protect return addresses from being overwritten
> by an attacker
[]
> .diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h
[]
> @@ -42,3 +42,5 @@
>   * compilers, like ICC.
>   */
>  #define barrier() __asm__ __volatile__("" : : : "memory")
> +
> +#define __noscs		__attribute__((no_sanitize("shadow-call-stack")))

trivia:

This should likely use the __ prefix and suffix form:

#define __noscs		__attribute__((__no_sanitize__("shadow-call-stack")))

as should the __no_sanitize_address above this

> diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
[]
> @@ -202,6 +202,10 @@ struct ftrace_likely_data {
>  # define randomized_struct_fields_end
>  #endif
>  
> +#ifndef __noscs
> +# define __noscs
> +#endif
> +
>  #ifndef asm_volatile_goto
>  #define asm_volatile_goto(x...) asm goto(x)
>  #endif

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