When building with -mbranch-protection=bti, which affects the compiler
codegen only, ensure that the assembler based codegen is aligned with
this, by emitting the BTI C opcode at the start of each exported
function. While most exported functions are not in fact ever called
indirectly, whether or not this is the case is a property of the caller
so annotating every exported function is a reasonable default.
While at it, fix two occurrences in ArmPkg of exported functions that
did not use the ASM_FUNC() macro.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Leif Lindholm <quic_llindhol@quicinc.com>
Reviewed-by: Oliver Smith-Denny <osd@smith-denny.com>
The Arm SMC calling convention standard v1.2 allows 8 input and output
parameter registers. The FF-A specification relies on this
communication. This patch extends the number of output registers
returned by ArmCallSvc() to match this convention.
Signed-off-by: Achin Gupta <achin.gupta@arm.com>
Reviewed-by: Sami Mujawar <sami.mujawar@arm.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Supervisor Call instruction (SVC) is used by the Arm Standalone MM
environment to request services from the privileged software (such as
ARM Trusted Firmware running in EL3) and also return back to the
non-secure caller via EL3. Some Arm CPUs speculatively executes the
instructions after the SVC instruction without crossing the privilege
level (S-EL0). Although the results of this execution are
architecturally discarded, adversary running on the non-secure side can
manipulate the contents of the general purpose registers to leak the
secure work memory through spectre like micro-architectural side channel
attacks. This behavior is demonstrated by the SafeSide project [1] and
[2]. Add barrier instructions after SVC to prevent speculative execution
to mitigate such attacks.
[1]: https://github.com/google/safeside/blob/master/demos/eret_hvc_smc_wrapper.cc
[2]: https://github.com/google/safeside/blob/master/kernel_modules/kmod_eret_hvc_smc/eret_hvc_smc_module.c
Signed-off-by: Vijayenthiran Subramaniam <vijayenthiran.subramaniam@arm.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@arm.com>
This patch adds a library that enables invocation of SVCs from Exception
Level EL0. It will be used by the Standalone MM environment to request
services from a software running in a privileged EL e.g. ARM Trusted
Firmware. The library is derived directly from Arm SMC Library.
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Achin Gupta <achin.gupta@arm.com>
Signed-off-by: Supreeth Venkatesh <supreeth.venkatesh@arm.com>
[ardb: assign frame pointer (AArch64)
keep stack alignment (ARM)]
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Ard Biesheuvel
Achin Gupta
Vijayenthiran Subramaniam
Michael D Kinney
Supreeth Venkatesh