Hi Julien,
Julien Grall writes: > Hi Roman, > > On 06/01/2021 11:26, Roman Skakun wrote: >> This patch added additional sanity and increases an understanding for >> getting proper value from the first argument for SMC call on aarch64 >> according to SMCC Convention. > > I would suggest the following commit message: > > "xen/arm: optee: The function identifier is always 32-bit > > Per the SMCCC specification (see section 3.1 in ARM DEN 0028D), the > function identifier is only stored in the least significant > 32-bits. The most significant 32-bits should be ignored. > > The function optee_handle_call() is now updated to ignore the most > significant 32-bits. > > " > > Note that I used the version D rather than B because the latter has > buggy wording (it seems to suggest that the least significants bits > should be ignored). > > Furthermore, I checked vsmc.c (the layer that dispatch the SMC) and it > was already handled properly thanks to commit 7f4217cc6057 "xen/arm: > vsmc: The function identifier is always 32-bit". > >> [0] ARM DEN0028B, page 12 >> Signed-off-by: Roman Skakun <roman_ska...@epam.com> >> --- >> xen/arch/arm/tee/optee.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> diff --git a/xen/arch/arm/tee/optee.c b/xen/arch/arm/tee/optee.c >> index ee85359742..87060b52b8 100644 >> --- a/xen/arch/arm/tee/optee.c >> +++ b/xen/arch/arm/tee/optee.c >> @@ -1643,7 +1643,8 @@ static bool optee_handle_call(struct cpu_user_regs >> *regs) >> if ( !ctx ) >> return false; >> - switch ( get_user_reg(regs, 0) ) >> + /* Only least 32 bits are significant (see ARM DEN 0028B, page 12) */ > > I would suggest: > > /* The function identifier is always stored in the least significant > 32-bit (see section ARM DEN 0028D) */ > > I can update it while committing, if both Volodymyr and you are happy > with changes. I'm totally fine with the proposed changes. Thank you for tidying this up. -- Volodymyr Babchuk at EPAM
