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From: Mark Rutland <mark.rutland@arm.com>
To: Sami Tolvanen <samitolvanen@google.com>
Cc: Kees Cook <keescook@chromium.org>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Will Deacon <will@kernel.org>, Jessica Yu <jeyu@kernel.org>,
	Arnd Bergmann <arnd@arndb.de>, Tejun Heo <tj@kernel.org>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Christoph Hellwig <hch@infradead.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Sedat Dilek <sedat.dilek@gmail.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	bpf@vger.kernel.org, linux-hardening@vger.kernel.org,
	linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kbuild@vger.kernel.org, linux-pci@vger.kernel.org,
	linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com
Subject: Re: [PATCH v5 16/18] arm64: ftrace: use function_nocfi for ftrace_call
Date: Tue, 6 Apr 2021 12:58:36 +0100	[thread overview]
Message-ID: <20210406115836.GF96480@C02TD0UTHF1T.local> (raw)
In-Reply-To: <20210401233216.2540591-17-samitolvanen@google.com>

On Thu, Apr 01, 2021 at 04:32:14PM -0700, Sami Tolvanen wrote:
> With CONFIG_CFI_CLANG, the compiler replaces function pointers with
> jump table addresses, which breaks dynamic ftrace as the address of
> ftrace_call is replaced with the address of ftrace_call.cfi_jt. Use
> function_nocfi() to get the address of the actual function instead.
> 
> Suggested-by: Ben Dai <ben.dai@unisoc.com>
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> ---
>  arch/arm64/kernel/ftrace.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
> index 86a5cf9bc19a..b5d3ddaf69d9 100644
> --- a/arch/arm64/kernel/ftrace.c
> +++ b/arch/arm64/kernel/ftrace.c
> @@ -55,7 +55,7 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
>  	unsigned long pc;
>  	u32 new;
>  
> -	pc = (unsigned long)&ftrace_call;
> +	pc = (unsigned long)function_nocfi(ftrace_call);

Acked-by: Mark Rutland <mark.rutland@arm.com>

Thanks,
Mark.

>  	new = aarch64_insn_gen_branch_imm(pc, (unsigned long)func,
>  					  AARCH64_INSN_BRANCH_LINK);
>  
> -- 
> 2.31.0.208.g409f899ff0-goog
> 

WARNING: multiple messages have this Message-ID (diff)
From: Mark Rutland <mark.rutland@arm.com>
To: Sami Tolvanen <samitolvanen@google.com>
Cc: Kees Cook <keescook@chromium.org>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Will Deacon <will@kernel.org>, Jessica Yu <jeyu@kernel.org>,
	Arnd Bergmann <arnd@arndb.de>, Tejun Heo <tj@kernel.org>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Christoph Hellwig <hch@infradead.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Sedat Dilek <sedat.dilek@gmail.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	bpf@vger.kernel.org, linux-hardening@vger.kernel.org,
	linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	linux-kbuild@vger.kernel.org, linux-pci@vger.kernel.org,
	linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com
Subject: Re: [PATCH v5 16/18] arm64: ftrace: use function_nocfi for ftrace_call
Date: Tue, 6 Apr 2021 12:58:36 +0100	[thread overview]
Message-ID: <20210406115836.GF96480@C02TD0UTHF1T.local> (raw)
In-Reply-To: <20210401233216.2540591-17-samitolvanen@google.com>

On Thu, Apr 01, 2021 at 04:32:14PM -0700, Sami Tolvanen wrote:
> With CONFIG_CFI_CLANG, the compiler replaces function pointers with
> jump table addresses, which breaks dynamic ftrace as the address of
> ftrace_call is replaced with the address of ftrace_call.cfi_jt. Use
> function_nocfi() to get the address of the actual function instead.
> 
> Suggested-by: Ben Dai <ben.dai@unisoc.com>
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> ---
>  arch/arm64/kernel/ftrace.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
> index 86a5cf9bc19a..b5d3ddaf69d9 100644
> --- a/arch/arm64/kernel/ftrace.c
> +++ b/arch/arm64/kernel/ftrace.c
> @@ -55,7 +55,7 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
>  	unsigned long pc;
>  	u32 new;
>  
> -	pc = (unsigned long)&ftrace_call;
> +	pc = (unsigned long)function_nocfi(ftrace_call);

Acked-by: Mark Rutland <mark.rutland@arm.com>

Thanks,
Mark.

>  	new = aarch64_insn_gen_branch_imm(pc, (unsigned long)func,
>  					  AARCH64_INSN_BRANCH_LINK);
>  
> -- 
> 2.31.0.208.g409f899ff0-goog
> 

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  reply	other threads:[~2021-04-06 11:58 UTC|newest]

Thread overview: 60+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-01 23:31 [PATCH v5 00/18] Add support for Clang CFI Sami Tolvanen
2021-04-01 23:31 ` Sami Tolvanen
2021-04-01 23:31 ` [PATCH v5 01/18] add " Sami Tolvanen
2021-04-01 23:31   ` Sami Tolvanen
2021-04-01 23:32 ` [PATCH v5 02/18] cfi: add __cficanonical Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-01 23:32 ` [PATCH v5 03/18] mm: add generic function_nocfi macro Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-02  6:37   ` Christoph Hellwig
2021-04-02  6:37     ` Christoph Hellwig
2021-04-06 11:27   ` Mark Rutland
2021-04-06 11:27     ` Mark Rutland
2021-04-01 23:32 ` [PATCH v5 04/18] module: ensure __cfi_check alignment Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-01 23:32 ` [PATCH v5 05/18] workqueue: use WARN_ON_FUNCTION_MISMATCH Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-01 23:32 ` [PATCH v5 06/18] kthread: " Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-01 23:32 ` [PATCH v5 07/18] kallsyms: strip ThinLTO hashes from static functions Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-01 23:32 ` [PATCH v5 08/18] bpf: disable CFI in dispatcher functions Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-01 23:32 ` [PATCH v5 09/18] treewide: Change list_sort to use const pointers Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-01 23:32 ` [PATCH v5 10/18] lkdtm: use function_nocfi Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-01 23:32 ` [PATCH v5 11/18] psci: use function_nocfi for cpu_resume Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-06 11:27   ` Mark Rutland
2021-04-06 11:27     ` Mark Rutland
2021-04-01 23:32 ` [PATCH v5 12/18] arm64: implement function_nocfi Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-06 11:36   ` Mark Rutland
2021-04-06 11:36     ` Mark Rutland
2021-04-06 17:02     ` Sami Tolvanen
2021-04-06 17:02       ` Sami Tolvanen
2021-04-01 23:32 ` [PATCH v5 13/18] arm64: use function_nocfi with __pa_symbol Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-06 11:41   ` Mark Rutland
2021-04-06 11:41     ` Mark Rutland
2021-04-01 23:32 ` [PATCH v5 14/18] arm64: add __nocfi to functions that jump to a physical address Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-06 11:53   ` Mark Rutland
2021-04-06 11:53     ` Mark Rutland
2021-04-06 12:59     ` Ard Biesheuvel
2021-04-06 12:59       ` Ard Biesheuvel
2021-04-06 17:43     ` Sami Tolvanen
2021-04-06 17:43       ` Sami Tolvanen
2021-04-01 23:32 ` [PATCH v5 15/18] arm64: add __nocfi to __apply_alternatives Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-01 23:32 ` [PATCH v5 16/18] arm64: ftrace: use function_nocfi for ftrace_call Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-06 11:58   ` Mark Rutland [this message]
2021-04-06 11:58     ` Mark Rutland
2021-04-01 23:32 ` [PATCH v5 17/18] KVM: arm64: Disable CFI for nVHE Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-01 23:32 ` [PATCH v5 18/18] arm64: allow CONFIG_CFI_CLANG to be selected Sami Tolvanen
2021-04-01 23:32   ` Sami Tolvanen
2021-04-02 19:58 ` [PATCH v5 00/18] Add support for Clang CFI Nathan Chancellor
2021-04-02 19:58   ` Nathan Chancellor

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