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From: Mark Rutland <mark.rutland@arm.com>
To: Will Deacon <will.deacon@arm.com>
Cc: catalin.marinas@arm.com, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 08/10] arm64: debug: Remove redundant user_mode(regs) checks from debug handlers
Date: Fri, 1 Mar 2019 14:13:22 +0000	[thread overview]
Message-ID: <20190301141322.GI15517@lakrids.cambridge.arm.com> (raw)
In-Reply-To: <20190301132809.24653-9-will.deacon@arm.com>

On Fri, Mar 01, 2019 at 01:28:07PM +0000, Will Deacon wrote:
> Now that the debug hook dispatching code takes the triggering exception
> level into account, there's no need for the hooks themselves to poke
> around with user_mode(regs).
> 
> Signed-off-by: Will Deacon <will.deacon@arm.com>

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

Mark.

> ---
>  arch/arm64/kernel/kgdb.c           |  8 +-------
>  arch/arm64/kernel/probes/kprobes.c |  6 ------
>  arch/arm64/kernel/probes/uprobes.c | 12 ++++--------
>  arch/arm64/kernel/traps.c          |  6 ------
>  4 files changed, 5 insertions(+), 27 deletions(-)
> 
> diff --git a/arch/arm64/kernel/kgdb.c b/arch/arm64/kernel/kgdb.c
> index 4c01f299aeb2..30853d5b7859 100644
> --- a/arch/arm64/kernel/kgdb.c
> +++ b/arch/arm64/kernel/kgdb.c
> @@ -244,9 +244,6 @@ int kgdb_arch_handle_exception(int exception_vector, int signo,
>  
>  static int kgdb_brk_fn(struct pt_regs *regs, unsigned int esr)
>  {
> -	if (user_mode(regs))
> -		return DBG_HOOK_ERROR;
> -
>  	kgdb_handle_exception(1, SIGTRAP, 0, regs);
>  	return DBG_HOOK_HANDLED;
>  }
> @@ -254,9 +251,6 @@ NOKPROBE_SYMBOL(kgdb_brk_fn)
>  
>  static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int esr)
>  {
> -	if (user_mode(regs))
> -		return DBG_HOOK_ERROR;
> -
>  	compiled_break = 1;
>  	kgdb_handle_exception(1, SIGTRAP, 0, regs);
>  
> @@ -266,7 +260,7 @@ NOKPROBE_SYMBOL(kgdb_compiled_brk_fn);
>  
>  static int kgdb_step_brk_fn(struct pt_regs *regs, unsigned int esr)
>  {
> -	if (user_mode(regs) || !kgdb_single_step)
> +	if (!kgdb_single_step)
>  		return DBG_HOOK_ERROR;
>  
>  	kgdb_handle_exception(1, SIGTRAP, 0, regs);
> diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c
> index 3066ffd70cf5..30502a3c8cf0 100644
> --- a/arch/arm64/kernel/probes/kprobes.c
> +++ b/arch/arm64/kernel/probes/kprobes.c
> @@ -450,9 +450,6 @@ kprobe_single_step_handler(struct pt_regs *regs, unsigned int esr)
>  	struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
>  	int retval;
>  
> -	if (user_mode(regs))
> -		return DBG_HOOK_ERROR;
> -
>  	/* return error if this is not our step */
>  	retval = kprobe_ss_hit(kcb, instruction_pointer(regs));
>  
> @@ -473,9 +470,6 @@ static struct step_hook kprobes_step_hook = {
>  static int __kprobes
>  kprobe_breakpoint_handler(struct pt_regs *regs, unsigned int esr)
>  {
> -	if (user_mode(regs))
> -		return DBG_HOOK_ERROR;
> -
>  	kprobe_handler(regs);
>  	return DBG_HOOK_HANDLED;
>  }
> diff --git a/arch/arm64/kernel/probes/uprobes.c b/arch/arm64/kernel/probes/uprobes.c
> index 7d6ea88796a6..f37ab9567676 100644
> --- a/arch/arm64/kernel/probes/uprobes.c
> +++ b/arch/arm64/kernel/probes/uprobes.c
> @@ -171,7 +171,7 @@ int arch_uprobe_exception_notify(struct notifier_block *self,
>  static int uprobe_breakpoint_handler(struct pt_regs *regs,
>  		unsigned int esr)
>  {
> -	if (user_mode(regs) && uprobe_pre_sstep_notifier(regs))
> +	if (uprobe_pre_sstep_notifier(regs))
>  		return DBG_HOOK_HANDLED;
>  
>  	return DBG_HOOK_ERROR;
> @@ -182,13 +182,9 @@ static int uprobe_single_step_handler(struct pt_regs *regs,
>  {
>  	struct uprobe_task *utask = current->utask;
>  
> -	if (user_mode(regs)) {
> -		WARN_ON(utask &&
> -			(instruction_pointer(regs) != utask->xol_vaddr + 4));
> -
> -		if (uprobe_post_sstep_notifier(regs))
> -			return DBG_HOOK_HANDLED;
> -	}
> +	WARN_ON(utask && (instruction_pointer(regs) != utask->xol_vaddr + 4));
> +	if (uprobe_post_sstep_notifier(regs))
> +		return DBG_HOOK_HANDLED;
>  
>  	return DBG_HOOK_ERROR;
>  }
> diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
> index 4be52bdcede6..3bcd56dd94fa 100644
> --- a/arch/arm64/kernel/traps.c
> +++ b/arch/arm64/kernel/traps.c
> @@ -943,9 +943,6 @@ int is_valid_bugaddr(unsigned long addr)
>  
>  static int bug_handler(struct pt_regs *regs, unsigned int esr)
>  {
> -	if (user_mode(regs))
> -		return DBG_HOOK_ERROR;
> -
>  	switch (report_bug(regs->pc, regs)) {
>  	case BUG_TRAP_TYPE_BUG:
>  		die("Oops - BUG", regs, 0);
> @@ -984,9 +981,6 @@ static int kasan_handler(struct pt_regs *regs, unsigned int esr)
>  	u64 addr = regs->regs[0];
>  	u64 pc = regs->pc;
>  
> -	if (user_mode(regs))
> -		return DBG_HOOK_ERROR;
> -
>  	kasan_report(addr, size, write, pc);
>  
>  	/*
> -- 
> 2.11.0
> 

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  reply	other threads:[~2019-03-01 14:13 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-01 13:27 [PATCH 00/10] Rework debug exception handling code Will Deacon
2019-03-01 13:28 ` [PATCH 01/10] arm64: debug: Don't propagate UNKNOWN FAR into si_code for debug signals Will Deacon
2019-03-01 13:28   ` Will Deacon
2019-03-01 13:45   ` Mark Rutland
2019-03-01 13:45     ` Mark Rutland
2019-03-05 13:35   ` Sasha Levin
2019-03-01 13:28 ` [PATCH 02/10] arm64: debug: Ensure debug handlers check triggering exception level Will Deacon
2019-03-01 13:28   ` Will Deacon
2019-03-01 13:46   ` Mark Rutland
2019-03-01 13:46     ` Mark Rutland
2019-03-05 13:35   ` Sasha Levin
2019-03-01 13:28 ` [PATCH 03/10] arm64: debug: Remove unused return value from do_debug_exception() Will Deacon
2019-03-01 13:48   ` Mark Rutland
2019-03-01 13:28 ` [PATCH 04/10] arm64: debug: Rename addr parameter for non-watchpoint exception hooks Will Deacon
2019-03-01 13:49   ` Mark Rutland
2019-03-01 13:28 ` [PATCH 05/10] arm64: debug: Remove meaningless comment Will Deacon
2019-03-01 14:08   ` Mark Rutland
2019-03-01 13:28 ` [PATCH 06/10] arm64: debug: Separate debug hooks based on target exception level Will Deacon
2019-03-01 14:07   ` Mark Rutland
2019-03-01 13:28 ` [PATCH 07/10] arm64: kprobes: Avoid calling kprobes debug handlers explicitly Will Deacon
2019-03-01 14:12   ` Mark Rutland
2019-03-01 13:28 ` [PATCH 08/10] arm64: debug: Remove redundant user_mode(regs) checks from debug handlers Will Deacon
2019-03-01 14:13   ` Mark Rutland [this message]
2019-03-01 13:28 ` [PATCH 09/10] arm64: probes: Move magic BRK values into brk-imm.h Will Deacon
2019-03-01 14:16   ` Mark Rutland
2019-03-01 13:28 ` [PATCH 10/10] arm64: debug: Clean up brk_handler() Will Deacon
2019-03-01 14:17   ` Mark Rutland
2019-03-01 16:24 ` [PATCH 00/10] Rework debug exception handling code Catalin Marinas

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