diff options
| author | Soby Mathew <soby.mathew@arm.com> | 2014-04-30 15:36:37 +0100 |
|---|---|---|
| committer | Soby Mathew <soby.mathew@arm.com> | 2014-05-08 12:01:23 +0100 |
| commit | c3260f9b82c5017ca078f090c03cd7135ee8f8c9 (patch) | |
| tree | 066308ed69c8a6bd421f5ad43458f3fe184f59f3 /services | |
| parent | e404d7f44a190b82332bb96daffa0c6239732218 (diff) | |
Preserve x19-x29 across world switch for exception handling
Previously exception handlers in BL3-1, X19-X29 were not saved
and restored on every SMC/trap into EL3. Instead these registers
were 'saved as needed' as a side effect of the A64 ABI used by the C
compiler.
That approach failed when world switching but was not visible
with the TSP/TSPD code because the TSP is 64-bit, did not
clobber these registers when running and did not support pre-emption
by normal world interrupts. These scenarios showed
that the values in these registers can be passed through a world
switch, which broke the normal and trusted world assumptions
about these registers being preserved.
The Ideal solution saves and restores these registers when a
world switch occurs - but that type of implementation is more complex.
So this patch always saves and restores these registers on entry and
exit of EL3.
Fixes ARM-software/tf-issues#141
Change-Id: I9a727167bbc594454e81cf78a97ca899dfb11c27
Diffstat (limited to 'services')
| -rw-r--r-- | services/std_svc/psci/psci_entry.S | 1 |
1 files changed, 0 insertions, 1 deletions
diff --git a/services/std_svc/psci/psci_entry.S b/services/std_svc/psci/psci_entry.S index e2c690d..50f74a6 100644 --- a/services/std_svc/psci/psci_entry.S +++ b/services/std_svc/psci/psci_entry.S @@ -104,7 +104,6 @@ psci_aff_common_finish_entry: mov x0, x19 bl platform_set_stack - zero_callee_saved_regs b el3_exit _panic: b _panic |