binman: Support accessing binman tables at run time
Binman construct images consisting of multiple binary files. These files
sometimes need to know (at run timme) where their peers are located. For
example, SPL may want to know where U-Boot is located in the image, so
that it can jump to U-Boot correctly on boot.
In general the positions where the binaries end up after binman has
finished packing them cannot be known at compile time. One reason for
this is that binman does not know the size of the binaries until
everything is compiled, linked and converted to binaries with objcopy.
To make this work, we add a feature to binman which checks each binary
for symbol names starting with '_binman'. These are then decoded to figure
out which entry and property they refer to. Then binman writes the value
of this symbol into the appropriate binary. With this, the symbol will
have the correct value at run time.
Macros are used to make this easier to use. As an example, this declares
a symbol that will access the 'u-boot-spl' entry to find the 'pos' value
(i.e. the position of SPL in the image):
binman_sym_declare(unsigned long, u_boot_spl, pos);
This converts to a symbol called '_binman_u_boot_spl_prop_pos' in any
binary that includes it. Binman then updates the value in that binary,
ensuring that it can be accessed at runtime with:
ulong u_boot_pos = binman_sym(ulong, u_boot_spl, pos);
This assigns the variable u_boot_pos to the position of SPL in the image.
Signed-off-by: Simon Glass <sjg@chromium.org>
2017-11-14 01:55:01 +00:00
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/dts-v1/;
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/ {
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#address-cells = <1>;
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#size-cells = <1>;
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binman {
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pad-byte = <0xff>;
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u-boot-spl {
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};
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u-boot {
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spl: binman: Check at runtime if binman symbols were filled in
Binman lets us declare symbols in SPL/TPL that refer to other entries in
the same binman image as them. These symbols are filled in with the
correct values while binman assembles the images, but this is done
in-memory only. Symbols marked as optional can be filled with
BINMAN_SYM_MISSING as an error value if their referred entry is missing.
However, the unmodified SPL/TPL binaries are still available on disk,
and can be used by people. For these files, nothing ensures that the
symbols are set to this error value, and they will be considered valid
when they are not.
Empirically, all symbols show up as zero in a sandbox_vpl build when we
run e.g. tpl/u-boot-tpl directly. On the other hand, zero is a perfectly
fine value for a binman-written symbol, so we cannot say the symbols
have wrong values based on that.
Declare a magic symbol that binman always fills in with a fixed value.
Check this value as an indicator that symbols were filled in correctly.
Return the error value for all symbols when this magic symbol has the
wrong value.
For binman tests, we need to make room for the new symbol in the mocked
SPL/TPL data by extending them by four bytes. This messes up some test
image layouts. Fix the affected values, and check the magic symbol
wherever it makes sense.
Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>
2022-06-18 12:13:11 +00:00
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offset = <0x1c>;
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binman: Support accessing binman tables at run time
Binman construct images consisting of multiple binary files. These files
sometimes need to know (at run timme) where their peers are located. For
example, SPL may want to know where U-Boot is located in the image, so
that it can jump to U-Boot correctly on boot.
In general the positions where the binaries end up after binman has
finished packing them cannot be known at compile time. One reason for
this is that binman does not know the size of the binaries until
everything is compiled, linked and converted to binaries with objcopy.
To make this work, we add a feature to binman which checks each binary
for symbol names starting with '_binman'. These are then decoded to figure
out which entry and property they refer to. Then binman writes the value
of this symbol into the appropriate binary. With this, the symbol will
have the correct value at run time.
Macros are used to make this easier to use. As an example, this declares
a symbol that will access the 'u-boot-spl' entry to find the 'pos' value
(i.e. the position of SPL in the image):
binman_sym_declare(unsigned long, u_boot_spl, pos);
This converts to a symbol called '_binman_u_boot_spl_prop_pos' in any
binary that includes it. Binman then updates the value in that binary,
ensuring that it can be accessed at runtime with:
ulong u_boot_pos = binman_sym(ulong, u_boot_spl, pos);
This assigns the variable u_boot_pos to the position of SPL in the image.
Signed-off-by: Simon Glass <sjg@chromium.org>
2017-11-14 01:55:01 +00:00
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};
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u-boot-spl2 {
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type = "u-boot-spl";
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};
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};
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};
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