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Define and use no_ret macro where no return is expected

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There are many instances in ARM Trusted Firmware where control is
transferred to functions from which return isn't expected. Such jumps
are made using 'bl' instruction to provide the callee with the location
from which it was jumped to. Additionally, debuggers infer the caller by
examining where 'lr' register points to. If a 'bl' of the nature
described above falls at the end of an assembly function, 'lr' will be
left pointing to a location outside of the function range. This misleads
the debugger back trace.

This patch defines a 'no_ret' macro to be used when jumping to functions
from which return isn't expected. The macro ensures to use 'bl'
instruction for the jump, and also, for debug builds, places a 'nop'
instruction immediately thereafter (unless instructed otherwise) so as
to leave 'lr' pointing within the function range.

Change-Id: Ib34c69fc09197cfd57bc06e147cc8252910e01b0
Co-authored-by: Douglas Raillard <douglas.raillard@arm.com>
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>
This commit is contained in:
Jeenu Viswambharan 2016-11-30 15:21:11 +00:00
parent c59428b150
commit a806dad58c
19 changed files with 122 additions and 78 deletions
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2
lib/psci/aarch32/psci_helpers.S
View file

@ -176,5 +176,5 @@ endfunc do_stack_maintenance
func psci_power_down_wfi
dsb sy // ensure write buffer empty
wfi
bl plat_panic_handler
no_ret plat_panic_handler
endfunc psci_power_down_wfi

2
lib/psci/aarch64/psci_helpers.S
View file

@ -167,7 +167,7 @@ endfunc psci_do_pwrup_cache_maintenance
func psci_power_down_wfi
dsb sy // ensure write buffer empty
wfi
bl plat_panic_handler
no_ret plat_panic_handler
endfunc psci_power_down_wfi
/* -----------------------------------------------------------------------