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Date: Wed, 30 May 2018 16:08:31 -0500
From: Rob Herring <robh+dt@...nel.org>
To: Jaewon Kim <jaewon31.kim@...sung.com>
Cc: Marek Szyprowski <m.szyprowski@...sung.com>,
Mitchel Humpherys <mitchelh@...eaurora.org>,
Frank Rowand <frowand.list@...il.com>,
devicetree@...r.kernel.org, linux-mm@...ck.org,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Jaewon Kim <jaewon31.kim@...il.com>
Subject: Re: [PATCH] drivers: of: of_reserved_mem: detect count overflow or
range overlap
On Wed, May 30, 2018 at 12:21 AM, Jaewon Kim <jaewon31.kim@...sung.com> wrote:
> During development, number of reserved memory region could be increased
> and a new region could be unwantedly overlapped. In that case the new
> region may work well but one of exisiting region could be affected so
> that it would not be defined properly. It may require time consuming
> work to find reason that there is a newly added region.
>
> If a newly added region invoke kernel panic, it will be helpful. This
> patch records if there is count overflow or range overlap, and invoke
> panic if that case.
>
> These are test example based on v4.9.
>
> Case 1 - out of region count
> <3>[ 0.000000] [0: swapper: 0] OF: reserved mem: not enough space all defined regions.
> <0>[ 1.688695] [6: swapper/0: 1] Kernel panic - not syncing: overflow on reserved memory, check the latest change
> <4>[ 1.688743] [6: swapper/0: 1] CPU: 6 PID: 1 Comm: swapper/0 Not tainted 4.9.65+ #10
> <4>[ 1.688836] [6: swapper/0: 1] Call trace:
> <4>[ 1.688869] [6: swapper/0: 1] [<ffffff8008095748>] dump_backtrace+0x0/0x248
> <4>[ 1.688913] [6: swapper/0: 1] [<ffffff8008095b48>] show_stack+0x18/0x28
> <4>[ 1.688958] [6: swapper/0: 1] [<ffffff8008446e84>] dump_stack+0x98/0xc0
> <4>[ 1.689001] [6: swapper/0: 1] [<ffffff80081cf784>] panic+0x1e0/0x404
> <4>[ 1.689046] [6: swapper/0: 1] [<ffffff8008ddcdb8>] check_reserved_mem+0x40/0x50
> <4>[ 1.689091] [6: swapper/0: 1] [<ffffff8008090190>] do_one_initcall+0x54/0x214
> <4>[ 1.689138] [6: swapper/0: 1] [<ffffff8009eacf98>] kernel_init_freeable+0x198/0x24c
> <4>[ 1.689187] [6: swapper/0: 1] [<ffffff8009396950>] kernel_init+0x18/0x144
> <4>[ 1.689229] [6: swapper/0: 1] [<ffffff800808fa50>] ret_from_fork+0x10/0x40
>
> Case 2 - overlapped region
> <3>[ 0.000000] [0: swapper: 0] OF: reserved mem: OVERLAP DETECTED!
> <0>[ 2.309331] [2: swapper/0: 1] Kernel panic - not syncing: reserved memory overlap, check the latest change
> <4>[ 2.309398] [2: swapper/0: 1] CPU: 2 PID: 1 Comm: swapper/0 Not tainted 4.9.65+ #14
> <4>[ 2.309508] [2: swapper/0: 1] Call trace:
> <4>[ 2.309546] [2: swapper/0: 1] [<ffffff8008121748>] dump_backtrace+0x0/0x248
> <4>[ 2.309599] [2: swapper/0: 1] [<ffffff8008121b48>] show_stack+0x18/0x28
> <4>[ 2.309652] [2: swapper/0: 1] [<ffffff80084d2e84>] dump_stack+0x98/0xc0
> <4>[ 2.309701] [2: swapper/0: 1] [<ffffff800825b784>] panic+0x1e0/0x404
> <4>[ 2.309751] [2: swapper/0: 1] [<ffffff8008e68dc4>] check_reserved_mem+0x4c/0x50
> <4>[ 2.309802] [2: swapper/0: 1] [<ffffff800811c190>] do_one_initcall+0x54/0x214
> <4>[ 2.309856] [2: swapper/0: 1] [<ffffff8009f38f98>] kernel_init_freeable+0x198/0x24c
> <4>[ 2.309913] [2: swapper/0: 1] [<ffffff8009422950>] kernel_init+0x18/0x144
> <4>[ 2.309961] [2: swapper/0: 1] [<ffffff800811ba50>] ret_from_fork+0x10/0x40
>
> Signed-off-by: Jaewon Kim <jaewon31.kim@...sung.com>
> ---
> drivers/of/of_reserved_mem.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
> index 9a4f4246231d..e97d5c5dcc9a 100644
> --- a/drivers/of/of_reserved_mem.c
> +++ b/drivers/of/of_reserved_mem.c
> @@ -65,6 +65,7 @@ int __init __weak early_init_dt_alloc_reserved_memory_arch(phys_addr_t size,
> }
> #endif
>
> +static bool rmem_overflow;
> /**
> * res_mem_save_node() - save fdt node for second pass initialization
> */
> @@ -75,6 +76,7 @@ void __init fdt_reserved_mem_save_node(unsigned long node, const char *uname,
>
> if (reserved_mem_count == ARRAY_SIZE(reserved_mem)) {
> pr_err("not enough space all defined regions.\n");
> + rmem_overflow = true;
> return;
> }
>
> @@ -221,6 +223,7 @@ static int __init __rmem_cmp(const void *a, const void *b)
> return 0;
> }
>
> +static bool rmem_overlap;
> static void __init __rmem_check_for_overlap(void)
> {
> int i;
> @@ -245,6 +248,7 @@ static void __init __rmem_check_for_overlap(void)
> pr_err("OVERLAP DETECTED!\n%s (%pa--%pa) overlaps with %s (%pa--%pa)\n",
> this->name, &this->base, &this_end,
> next->name, &next->base, &next_end);
> + rmem_overlap = true;
> }
> }
> }
> @@ -419,3 +423,13 @@ struct reserved_mem *of_reserved_mem_lookup(struct device_node *np)
> return NULL;
> }
> EXPORT_SYMBOL_GPL(of_reserved_mem_lookup);
> +
> +static int check_reserved_mem(void)
> +{
> + if (rmem_overflow)
> + panic("overflow on reserved memory, check the latest change");
> + if (rmem_overlap)
> + panic("overlap on reserved memory, check the latest change");
> + return 0;
> +}
> +late_initcall(check_reserved_mem);
Just use WARN and avoid this dance you are doing to panic after your
console is up.
Rob
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