Re: [PATCH v11 10/14] tracing, arm64: untag user pointers in seq_print_user_ip

From: Steven Rostedt <rostedt@goodmis.org>
To: Andrey Konovalov <andreyknvl@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Robin Murphy <robin.murphy@arm.com>,
	Kees Cook <keescook@chromium.org>,
	Kate Stewart <kstewart@linuxfoundation.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Ingo Molnar <mingo@kernel.org>,
	"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
	Shuah Khan <shuah@kernel.org>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Eric Dumazet <edumazet@google.com>,
	"David S. Miller" <davem@davemloft.net>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org,
	linux-mm@kvack.org, linux-arch@vger.kernel.org,
	netdev@vger.kernel.org, bpf@vger.kernel.org,
	linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org,
	Dmitry Vyukov <dvyukov@google.com>,
	Kostya Serebryany <kcc@google.com>,
	Evgeniy Stepanov <eugenis@google.com>,
	Lee Smith <Lee.Smith@arm.com>,
	Ramana Radhakrishnan <Ramana.Radhakrishnan@arm.com>,
	Jacob Bramley <Jacob.Bramley@arm.com>,
	Ruben Ayrapetyan <Ruben.Ayrapetyan@arm.com>,
	Chintan Pandya <cpandya@codeaurora.org>,
	Luc Van Oostenryck <luc.vanoostenryck@gmail.com>,
	Dave Martin <Dave.Martin@arm.com>,
	Kevin Brodsky <kevin.brodsky@arm.com>,
	Szabolcs Nagy <Szabolcs.Nagy@arm.com>
Subject: Re: [PATCH v11 10/14] tracing, arm64: untag user pointers in seq_print_user_ip
Date: Fri, 15 Mar 2019 16:14:14 -0400	[thread overview]
Message-ID: <20190315161414.4b31fb03@gandalf.local.home> (raw)
In-Reply-To: <355e7c0dadaa2bb79d22e0b7aac7e4efc1114d49.1552679409.git.andreyknvl@google.com>

On Fri, 15 Mar 2019 20:51:34 +0100
Andrey Konovalov <andreyknvl@google.com> wrote:

> This patch is a part of a series that extends arm64 kernel ABI to allow to
> pass tagged user pointers (with the top byte set to something else other
> than 0x00) as syscall arguments.
> 
> seq_print_user_ip() uses provided user pointers for vma lookups, which
> can only by done with untagged pointers.
> 
> Untag user pointers in this function.
> 
> Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
> ---
>  kernel/trace/trace_output.c |  5 +++--
>  p                           | 45 +++++++++++++++++++++++++++++++++++++
>  2 files changed, 48 insertions(+), 2 deletions(-)
>  create mode 100644 p
> 
> diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
> index 54373d93e251..6376bee93c84 100644
> --- a/kernel/trace/trace_output.c
> +++ b/kernel/trace/trace_output.c
> @@ -370,6 +370,7 @@ static int seq_print_user_ip(struct trace_seq *s, struct mm_struct *mm,
>  {
>  	struct file *file = NULL;
>  	unsigned long vmstart = 0;
> +	unsigned long untagged_ip = untagged_addr(ip);
>  	int ret = 1;
>  
>  	if (s->full)
> @@ -379,7 +380,7 @@ static int seq_print_user_ip(struct trace_seq *s, struct mm_struct *mm,
>  		const struct vm_area_struct *vma;
>  
>  		down_read(&mm->mmap_sem);
> -		vma = find_vma(mm, ip);
> +		vma = find_vma(mm, untagged_ip);
>  		if (vma) {
>  			file = vma->vm_file;
>  			vmstart = vma->vm_start;
> @@ -388,7 +389,7 @@ static int seq_print_user_ip(struct trace_seq *s, struct mm_struct *mm,
>  			ret = trace_seq_path(s, &file->f_path);
>  			if (ret)
>  				trace_seq_printf(s, "[+0x%lx]",
> -						 ip - vmstart);
> +						 untagged_ip - vmstart);
>  		}
>  		up_read(&mm->mmap_sem);
>  	}
> diff --git a/p b/p
> new file mode 100644
> index 000000000000..9d6fa5386e55
> --- /dev/null
> +++ b/p
> @@ -0,0 +1,45 @@
> +commit 1fa6fadf644859e8a6a8ecce258444b49be8c7ee
> +Author: Andrey Konovalov <andreyknvl@google.com>
> +Date:   Mon Mar 4 17:20:32 2019 +0100
> +
> +    kasan: fix coccinelle warnings in kasan_p*_table
> +    
> +    kasan_p4d_table, kasan_pmd_table and kasan_pud_table are declared as
> +    returning bool, but return 0 instead of false, which produces a coccinelle
> +    warning. Fix it.
> +    
> +    Fixes: 0207df4fa1a8 ("kernel/memremap, kasan: make ZONE_DEVICE with work with KASAN")
> +    Reported-by: kbuild test robot <lkp@intel.com>
> +    Signed-off-by: Andrey Konovalov <andreyknvl@google.com>

Did you mean to append this commit to this patch?

-- Steve

> +
> +diff --git a/mm/kasan/init.c b/mm/kasan/init.c
> +index 45a1b5e38e1e..fcaa1ca03175 100644
> +--- a/mm/kasan/init.c
> ++++ b/mm/kasan/init.c
> +@@ -42,7 +42,7 @@ static inline bool kasan_p4d_table(pgd_t pgd)
> + #else
> + static inline bool kasan_p4d_table(pgd_t pgd)
> + {
> +-	return 0;
> ++	return false;
> + }
> + #endif
> + #if CONFIG_PGTABLE_LEVELS > 3
> +@@ -54,7 +54,7 @@ static inline bool kasan_pud_table(p4d_t p4d)
> + #else
> + static inline bool kasan_pud_table(p4d_t p4d)
> + {
> +-	return 0;
> ++	return false;
> + }
> + #endif
> + #if CONFIG_PGTABLE_LEVELS > 2
> +@@ -66,7 +66,7 @@ static inline bool kasan_pmd_table(pud_t pud)
> + #else
> + static inline bool kasan_pmd_table(pud_t pud)
> + {
> +-	return 0;
> ++	return false;
> + }
> + #endif
> + pte_t kasan_early_shadow_pte[PTRS_PER_PTE] __page_aligned_bss;