Hi,
thanks for picking this up!
On 01/02/18 23:04, Andrew F. Davis (by way of Andre Przywara
<andre@xxxxxxxxx>) wrote:
> From: Benjamin Fair <b-fair@xxxxxx>
>
> This patch extends the capability of libfdt to parse the contents of device
> trees in a similar manner to fdt_address_cells and fdt_size_cells.
>
> It adds a helper function which reads the address and size of a device from
> the reg property and performs basic sanity checks.
>
> It does not perform translation to a physical address using the ranges
> properties of parents, but this enhancement may be added as a separate
> function in the future.
Ignoring Rob's answer for a moment, there is something I noticed when I
quickly hacked an older version of this into the ARM port
of the Xen related Mini-OS, see below ...
> Signed-off-by: Benjamin Fair <b-fair@xxxxxx>
> Reviewed-by: Simon Glass <sjg@xxxxxxxxxxxx>
> Signed-off-by: Dave Gerlach <d-gerlach@xxxxxx>
> Signed-off-by: Andrew F. Davis <afd@xxxxxx>
> ---
>
> Changes from v4:
> - Removed unneeded #defines
> - Return status in parameter to avoid unsafe conversion to unsigned
> - Added error code translation for NOTFOUND -> BADNCELLS
> - Check for cell sizes being larger than the types they go into
> - Added tests for failure cases
>
> The only comment from the last posting I didn't agree on was
> converting the type of the parameters into uint64_t. This
> helper function is designed to be used to get the size and
> address for instant use. If we have to cast them later we need
> extra checks for size correctness in the caller, who can't do
> that as they would then have to check the cells sizes themselves,
> which defeats the whole point of this function.
>
> To make this intentional behavior more clear we add checks for
> miss-sized types and return appropriate errors for that. We even
> add some test cases for platforms with different sized types to
> check the same.
>
> libfdt/fdt_addresses.c | 72 ++++++++++++++++++++++++++++++++++++++
> libfdt/libfdt.h | 33 ++++++++++++++++++
> libfdt/version.lds | 1 +
> tests/.gitignore | 1 +
> tests/Makefile.tests | 2 +-
> tests/addr_size.c | 93 ++++++++++++++++++++++++++++++++++++++++++++++++++
> tests/addresses.dts | 20 +++++++++++
> tests/run_tests.sh | 1 +
> 8 files changed, 222 insertions(+), 1 deletion(-)
> create mode 100644 tests/addr_size.c
>
> diff --git a/libfdt/fdt_addresses.c b/libfdt/fdt_addresses.c
> index eff4dbc..41d3c5d 100644
> --- a/libfdt/fdt_addresses.c
> +++ b/libfdt/fdt_addresses.c
> @@ -94,3 +94,75 @@ int fdt_size_cells(const void *fdt, int nodeoffset)
>
> return val;
> }
> +
> +static uint64_t _fdt_read_cells(const fdt32_t *cells, unsigned int n, int *res)
> +{
> + int i;
> + uint64_t value;
> +
> + if (n > 2) {
> + *res = -FDT_ERR_BADNCELLS;
> + return 0;
> + }
> +
> + value = 0;
> + for (i = 0; i < n; i++) {
> + value <<= (sizeof(*cells) * 8);
> + value |= fdt32_to_cpu(cells[i]);
> + }
> +
> + *res = 0;
> + return value;
> +}
> +
> +int fdt_simple_addr_size(const void *fdt, int nodeoffset, int idx,
> + uintptr_t *addrp, size_t *sizep)
I believe this was mentioned in previous reviews:
I don't think that those types are the right ones to use here.
There is no correlation between the address size used in a DT and the
(current) size of pointers or addressable memory.
So you might end up in 32-bit code reading a DT with 64-bit addresses.
MMIO addresses might be under 4GB underway, or you are running using
LPAE, where physical addresses can be 40 bits long.
So I think we should use uint64_t* here, this would also avoid the
checks below.
Cheers,
Andre.
> +{
> + int parent;
> + int ac, sc, reg_stride;
> + int res;
> + const fdt32_t *reg;
> +
> + reg = fdt_getprop(fdt, nodeoffset, "reg", &res);
> + if (res < 0)
> + return res;
> +
> + parent = fdt_parent_offset(fdt, nodeoffset);
> + if (parent == -FDT_ERR_NOTFOUND) /* an node without a parent does
> + * not have _any_ number of cells */
> + return -FDT_ERR_BADNCELLS;
> + if (parent < 0)
> + return parent;
> +
> + ac = fdt_address_cells(fdt, parent);
> + if (ac < 0)
> + return ac;
> + if (ac * sizeof(fdt32_t) > sizeof(*addrp))
> + return -FDT_ERR_BADNCELLS;
> +
> + sc = fdt_size_cells(fdt, parent);
> + if (sc < 0)
> + return sc;
> + if (sc * sizeof(fdt32_t) > sizeof(*sizep))
> + return -FDT_ERR_BADNCELLS;
> +
> + reg_stride = ac + sc;
> +
> + /* res is the number of bytes read and must be an even multiple of the
> + * sum of address cells and size cells */
> + if ((res % (reg_stride * sizeof(*reg))) != 0)
> + return -FDT_ERR_BADVALUE;
> +
> + if (addrp) {
> + *addrp = (uintptr_t) _fdt_read_cells(®[reg_stride * idx], ac, &res);
> + if (res < 0)
> + return res;
> + }
> + if (sizep) {
> + *sizep = (size_t) _fdt_read_cells(®[ac + reg_stride * idx], sc, &res);
> + if (res < 0)
> + return res;
> + }
> +
> + return 0;
> +}
> diff --git a/libfdt/libfdt.h b/libfdt/libfdt.h
> index c8c00fa..73f2fea 100644
> --- a/libfdt/libfdt.h
> +++ b/libfdt/libfdt.h
> @@ -1101,6 +1101,39 @@ int fdt_address_cells(const void *fdt, int nodeoffset);
> */
> int fdt_size_cells(const void *fdt, int nodeoffset);
>
> +/**
> + *
> + * fdt_simple_addr_size - read address and/or size from the reg property of a
> + * device node.
> + * @fdt: pointer to the device tree blob
> + * @nodeoffset: offset of the node to find the address and/or size from
> + * @idx: which address/size pair to read
> + * @addrp: pointer to where address will be stored (will be overwritten) or NULL
> + * @sizep: pointer to where size will be stored (will be overwritten) or NULL
> + *
> + * When the node has a valid reg property, returns the address and/or size
> + * values stored there. It does not perform any type of translation based on
> + * the parent bus(es).
> + *
> + * NOTE: This function is expensive, as it must scan the device tree
> + * structure from the start to nodeoffset, *twice*, with fdt_parent_offset.
> + *
> + * returns:
> + * 0, on success
> + * -FDT_ERR_BADVALUE, if there is an unexpected number of entries in the
> + * reg property
> + * -FDT_ERR_NOTFOUND, if the node does not have a reg property
> + * -FDT_ERR_BADNCELLS, if the number of address or size cells is invalid
> + * or greater than 2 (which is the maximum currently supported)
> + * -FDT_ERR_BADMAGIC,
> + * -FDT_ERR_BADSTATE,
> + * -FDT_ERR_BADSTRUCTURE,
> + * -FDT_ERR_BADVERSION,
> + * -FDT_ERR_TRUNCATED, standard meanings
> + */
> +
> +int fdt_simple_addr_size(const void *fdt, int nodeoffset, int idx,
> + uintptr_t *addrp, size_t *sizep);
>
> /**********************************************************************/
> /* Write-in-place functions */
> diff --git a/libfdt/version.lds b/libfdt/version.lds
> index 18fb69f..1f19341 100644
> --- a/libfdt/version.lds
> +++ b/libfdt/version.lds
> @@ -59,6 +59,7 @@ LIBFDT_1.2 {
> fdt_next_subnode;
> fdt_address_cells;
> fdt_size_cells;
> + fdt_simple_addr_size;
> fdt_stringlist_contains;
> fdt_stringlist_count;
> fdt_stringlist_search;
> diff --git a/tests/.gitignore b/tests/.gitignore
> index 9e209d5..acb9335 100644
> --- a/tests/.gitignore
> +++ b/tests/.gitignore
> @@ -43,6 +43,7 @@ tmp.*
> /path_offset
> /path_offset_aliases
> /phandle_format
> +/addr_size
> /property_iterate
> /propname_escapes
> /references
> diff --git a/tests/Makefile.tests b/tests/Makefile.tests
> index 262944a..1e326ea 100644
> --- a/tests/Makefile.tests
> +++ b/tests/Makefile.tests
> @@ -8,7 +8,7 @@ LIB_TESTS_L = get_mem_rsv \
> char_literal \
> sized_cells \
> notfound \
> - addr_size_cells \
> + addr_size_cells addr_size \
> stringlist \
> setprop_inplace nop_property nop_node \
> sw_tree1 \
> diff --git a/tests/addr_size.c b/tests/addr_size.c
> new file mode 100644
> index 0000000..10275f4
> --- /dev/null
> +++ b/tests/addr_size.c
> @@ -0,0 +1,93 @@
> +/*
> + * libfdt - Flat Device Tree manipulation
> + * Testcase for address and size handling
> + * Copyright (C) 2016-2018 Texas Instruments Incorporated - http://www.ti.com/
> + *
> + * Based on addr_size_cells.c by David Gibson, <david@xxxxxxxxxxxxxxxxxxxxx>
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU Lesser General Public License as published by
> + * the Free Software Foundation; either version 2.1 of the License, or (at
> + * your option) any later version.
> + *
> + * This program is distributed "as is" WITHOUT ANY WARRANTY of any kind,
> + * whether express or implied; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + * Lesser General Public License for more details.
> + */
> +
> +#include <stdlib.h>
> +#include <stdio.h>
> +#include <string.h>
> +#include <stdint.h>
> +
> +#include <libfdt.h>
> +
> +#include "tests.h"
> +#include "testdata.h"
> +
> +static void check_node(const void *fdt, const char *path, int err,
> + int idx, uintptr_t addr, size_t size)
> +{
> + int offset, res;
> + uintptr_t xaddr;
> + size_t xsize;
> +
> + offset = fdt_path_offset(fdt, path);
> + if (offset < 0)
> + FAIL("Couldn't find path %s", path);
> +
> + res = fdt_simple_addr_size(fdt, offset, idx, &xaddr, &xsize);
> + if (res != err)
> + FAIL("fdt_simple_addr_size returned %s instead of %s",
> + fdt_strerror(res), fdt_strerror(err));
> + if (res < 0)
> + return;
> +
> + if (xaddr != addr)
> + FAIL("Physical address for %s is %p instead of %p\n",
> + path, (void *) xaddr, (void *) addr);
> +
> + if (xsize != size)
> + FAIL("Size for %s is %zx instead of %zx\n",
> + path, xsize, size);
> +}
> +
> +int main(int argc, char *argv[])
> +{
> + void *fdt;
> +
> + if (argc != 2)
> + CONFIG("Usage: %s <dtb file>\n", argv[0]);
> +
> + test_init(argc, argv);
> + fdt = load_blob(argv[1]);
> +
> + if (sizeof(uintptr_t) == 4 && sizeof(size_t) == 4) {
> + /* 32-bit address , 32-bit size */
> + check_node(fdt, "/identity-bus@0/id-device@400",
> + -FDT_ERR_BADNCELLS, 0, 0x0, 0x0);
> + check_node(fdt, "/simple-bus@1000000/sb-device@8000000800",
> + -FDT_ERR_BADNCELLS, 0, 0x0, 0x0);
> + }
> + else if (sizeof(uintptr_t) == 8 && sizeof(size_t) == 8) {
> + /* 64-bit uintptr_t , 64-bit size_t */
> + check_node(fdt, "/identity-bus@0/id-device@400",
> + 0, 0,0x400, 0x100);
> + check_node(fdt, "/simple-bus@1000000/sb-device@8000000800",
> + 0, 0, 0x8000000800, 0x200);
> + check_node(fdt, "/identity-bus@0/id-device@400",
> + 0, 1, 0x400000000, 0x100000030);
> + check_node(fdt, "/simple-bus@1000000/sb-device@8000000800",
> + 0, 1, 0x70000000, 0x700);
> + check_node(fdt, "/simple-bus@1000000/sb-device@8000000800",
> + 0, 2, 0x1050000000, 0x20);
> + }
> +
> + check_node(fdt, "/identity-bus@0",
> + -FDT_ERR_NOTFOUND, 0, 0x0, 0x0);
> + check_node(fdt, "/narrow-bus@2000000/sb-device@80000000",
> + 0, 0, 0x00000800, 0x200);
> +
> + PASS();
> +}
> diff --git a/tests/addresses.dts b/tests/addresses.dts
> index a2faaf5..747c291 100644
> --- a/tests/addresses.dts
> +++ b/tests/addresses.dts
> @@ -6,10 +6,30 @@
> #size-cells = <2>;
>
> identity-bus@0 {
> + #address-cells = <2>;
> + #size-cells = <2>;
> + id-device@400 {
> + reg = <0x0 0x00000400 0x0 0x00000100>,
> + <0x4 0x00000000 0x1 0x00000030>;
> + };
> };
>
> simple-bus@1000000 {
> #address-cells = <2>;
> #size-cells = <1>;
> + sb-device@8000000800 {
> + reg = <0x80 0x00000800 0x200>,
> + <0x00 0x70000000 0x700>,
> + <0x10 0x50000000 0x020>;
> + };
> + };
> +
> + narrow-bus@2000000 {
> + #address-cells = <1>;
> + #size-cells = <1>;
> + sb-device@80000000 {
> + reg = <0x00000800 0x200>,
> + <0x50000000 0x020>;
> + };
> };
> };
> diff --git a/tests/run_tests.sh b/tests/run_tests.sh
> index 0d30edf..c195d0d 100755
> --- a/tests/run_tests.sh
> +++ b/tests/run_tests.sh
> @@ -311,6 +311,7 @@ libfdt_tests () {
>
> run_dtc_test -I dts -O dtb -o addresses.test.dtb addresses.dts
> run_test addr_size_cells addresses.test.dtb
> + run_test addr_size addresses.test.dtb
>
> run_dtc_test -I dts -O dtb -o stringlist.test.dtb stringlist.dts
> run_test stringlist stringlist.test.dtb
>
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