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LD: Assert when CONFIG_PRIVILEGED_STACK_TEXT_AREA is too small

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The error message is obscure when CONFIG_PRIVILEGED_STACK_TEXT_AREA is
configured incorrectly. It looks like this:

zephyr/linker.cmd:73 cannot move location counter backwards (from
0000000000069bfc to 0000000000069bd8)

This patch re-writes the linker script mechanism in a (believed and
tested) semantically equivalent way such that it is possible to use an
assertion.

The assertion's error message now looks like this:

Memory region         Used Size  Region Size  %age Used
           FLASH:      503012 B         1 MB     47.97%
            SRAM:       53760 B       256 KB     20.51%
        IDT_LIST:         120 B         2 KB      5.86
real-ld: The configuration system has incorrectly set
'CONFIG_PRIVILEGED_STACK_TEXT_AREA' to
128, which is not big enough. You must
through Kconfig either disable 'CONFIG_USERSPACE', or set
'CONFIG_PRIVILEGED_STACK_TEXT_AREA' to a value larger than
128 .
collect2: error: ld returned 1 exit status

Signed-off-by: Sebastian Bøe <sebastian.boe@nordicsemi.no>
This commit is contained in:
Sebastian Bøe 2019-01-28 17:48:26 +01:00 • committed by Anas Nashif
commit ed85b76093
1 changed files with 21 additions and 5 deletions
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26
include/linker/priv_stacks-text.ld
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@ -7,16 +7,32 @@
/* We need to reserve room for the gperf generated hash functions.
* Fortunately, unlike the data tables, the size of the code is
* reasonably predictable.
*
* The linker will error out complaining that the location pointer
* is moving backwards if the reserved room isn't large enough.
*/
_priv_stacks_text_area_start = .;
*(".priv_stacks.text*")
_priv_stacks_text_area_end = .;
_priv_stacks_text_area_used = _priv_stacks_text_area_end - _priv_stacks_text_area_start;
#ifndef LINKER_PASS2
PROVIDE(_k_priv_stack_find = .);
#endif
. += CONFIG_PRIVILEGED_STACK_TEXT_AREA - (_priv_stacks_text_area_end - _priv_stacks_text_area_start);
#endif /* CONFIG_USERSPACE */
/* In a valid build the MAX function will always evaluate to the
second argument below, but to give the user a good error message
when the area overflows we need to temporarily corrupt the
location counter, and then detect the overflow with an assertion
later on. */
. = MAX(., _priv_stacks_text_area_start + CONFIG_PRIVILEGED_STACK_TEXT_AREA);
ASSERT(
CONFIG_PRIVILEGED_STACK_TEXT_AREA >= _priv_stacks_text_area_used,
"The configuration system has incorrectly set
'CONFIG_PRIVILEGED_STACK_TEXT_AREA' to
CONFIG_PRIVILEGED_STACK_TEXT_AREA, which is not big enough. You must
through Kconfig either disable 'CONFIG_USERSPACE', or set
'CONFIG_PRIVILEGED_STACK_TEXT_AREA' to a value larger than
CONFIG_PRIVILEGED_STACK_TEXT_AREA."
);
#endif /* CONFIG_USERSPACE */