From a806dad58c4cf752238d7bbffbc9a1ce17f63cea Mon Sep 17 00:00:00 2001 From: Jeenu Viswambharan Date: Wed, 30 Nov 2016 15:21:11 +0000 Subject: Define and use no_ret macro where no return is expected 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 Signed-off-by: Jeenu Viswambharan --- bl2/aarch32/bl2_entrypoint.S | 2 +- bl2/aarch64/bl2_entrypoint.S | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) (limited to 'bl2') diff --git a/bl2/aarch32/bl2_entrypoint.S b/bl2/aarch32/bl2_entrypoint.S index 6c620e22..bb0b7f31 100644 --- a/bl2/aarch32/bl2_entrypoint.S +++ b/bl2/aarch32/bl2_entrypoint.S @@ -140,6 +140,6 @@ func bl2_entrypoint * Should never reach this point. * --------------------------------------------- */ - bl plat_panic_handler + no_ret plat_panic_handler endfunc bl2_entrypoint diff --git a/bl2/aarch64/bl2_entrypoint.S b/bl2/aarch64/bl2_entrypoint.S index 476efe85..25363ace 100644 --- a/bl2/aarch64/bl2_entrypoint.S +++ b/bl2/aarch64/bl2_entrypoint.S @@ -131,6 +131,6 @@ func bl2_entrypoint * Should never reach this point. * --------------------------------------------- */ - bl plat_panic_handler + no_ret plat_panic_handler endfunc bl2_entrypoint -- cgit v1.2.3