From: Mark Rutland <mark.rutland@arm.com>
To: guoren@kernel.org
Cc: arnd@arndb.de, palmer@rivosinc.com, tglx@linutronix.de,
peterz@infradead.org, luto@kernel.org,
conor.dooley@microchip.com, heiko@sntech.de, jszhang@kernel.org,
lazyparser@gmail.com, falcon@tinylab.org, chenhuacai@kernel.org,
apatel@ventanamicro.com, atishp@atishpatra.org,
ben@decadent.org.uk, bjorn@kernel.org,
linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-riscv@lists.infradead.org,
"Guo Ren" <guoren@linux.alibaba.com>,
"Björn Töpel" <bjorn@rivosinc.com>
Subject: Re: [PATCH -next V12 3/7] riscv: entry: Add noinstr to prevent instrumentation inserted
Date: Wed, 4 Jan 2023 11:55:35 +0000 [thread overview]
Message-ID: <Y7VpN/fFjqGJbxPu@FVFF77S0Q05N> (raw)
In-Reply-To: <20230103033531.2011112-4-guoren@kernel.org>
On Mon, Jan 02, 2023 at 10:35:27PM -0500, guoren@kernel.org wrote:
> From: Guo Ren <guoren@linux.alibaba.com>
>
> Without noinstr the compiler is free to insert instrumentation (think
> all the k*SAN, KCov, GCov, ftrace etc..) which can call code we're not
> yet ready to run this early in the entry path, for instance it could
> rely on RCU which isn't on yet, or expect lockdep state. (by peterz)
That's generally true, and makes sense to me, but ....
> Link: https://lore.kernel.org/linux-riscv/YxcQ6NoPf3AH0EXe@hirez.programming.kicks-ass.net/
> Reviewed-by: Björn Töpel <bjorn@rivosinc.com>
> Suggested-by: Peter Zijlstra <peterz@infradead.org>
> Tested-by: Jisheng Zhang <jszhang@kernel.org>
> Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
> Signed-off-by: Guo Ren <guoren@kernel.org>
> ---
> arch/riscv/kernel/traps.c | 4 ++--
> arch/riscv/mm/fault.c | 2 +-
> 2 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c
> index 549bde5c970a..96ec76c54ff2 100644
> --- a/arch/riscv/kernel/traps.c
> +++ b/arch/riscv/kernel/traps.c
> @@ -95,9 +95,9 @@ static void do_trap_error(struct pt_regs *regs, int signo, int code,
> }
>
> #if defined(CONFIG_XIP_KERNEL) && defined(CONFIG_RISCV_ALTERNATIVE)
> -#define __trap_section __section(".xip.traps")
> +#define __trap_section __noinstr_section(".xip.traps")
> #else
> -#define __trap_section
> +#define __trap_section noinstr
> #endif
> #define DO_ERROR_INFO(name, signo, code, str) \
> asmlinkage __visible __trap_section void name(struct pt_regs *regs) \
> diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c
> index d86f7cebd4a7..b26f68eac61c 100644
> --- a/arch/riscv/mm/fault.c
> +++ b/arch/riscv/mm/fault.c
> @@ -204,7 +204,7 @@ static inline bool access_error(unsigned long cause, struct vm_area_struct *vma)
> * This routine handles page faults. It determines the address and the
> * problem, and then passes it off to one of the appropriate routines.
> */
> -asmlinkage void do_page_fault(struct pt_regs *regs)
> +asmlinkage void noinstr do_page_fault(struct pt_regs *regs)
... why do you need that for do_page_fault? That doesn't (currently) do any
entry/exit logic, so this seems unnecessary per the commit description.
Thanks,
Mark.
> {
> struct task_struct *tsk;
> struct vm_area_struct *vma;
> --
> 2.36.1
>
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next prev parent reply other threads:[~2023-01-04 15:11 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-03 3:35 [PATCH -next V12 0/7] riscv: Add GENERIC_ENTRY support guoren
2023-01-03 3:35 ` [PATCH -next V12 1/7] compiler_types.h: Add __noinstr_section() for noinstr guoren
2023-01-03 3:35 ` [PATCH -next V12 2/7] riscv: ptrace: Remove duplicate operation guoren
2023-01-03 3:35 ` [PATCH -next V12 3/7] riscv: entry: Add noinstr to prevent instrumentation inserted guoren
2023-01-03 9:11 ` Alexandre Ghiti
2023-01-04 1:40 ` Guo Ren
2023-01-04 12:03 ` Mark Rutland
2023-01-07 11:48 ` Guo Ren
2023-01-04 11:55 ` Mark Rutland [this message]
2023-01-07 11:49 ` Guo Ren
2023-01-03 3:35 ` [PATCH -next V12 4/7] riscv: entry: Convert to generic entry guoren
2023-01-03 3:35 ` [PATCH -next V12 5/7] riscv: entry: Remove extra level wrappers of trace_hardirqs_{on,off} guoren
2023-01-03 3:35 ` [PATCH -next V12 6/7] riscv: entry: Consolidate ret_from_kernel_thread into ret_from_fork guoren
2023-01-03 3:35 ` [PATCH -next V12 7/7] riscv: entry: Consolidate general regs saving/restoring guoren
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