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aarch64: Fix stack pointer maintenance on EA handling path

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EA handlers for exceptions taken from lower ELs at the end invokes
el3_exit function. However there was a bug with sp maintenance which
resulted in el3_exit setting runtime stack to context. This in turn
caused memory corruption on consecutive EL3 entries.

Signed-off-by: Jan Dabros <jsd@semihalf.com>
Change-Id: I0424245c27c369c864506f4baa719968890ce659
This commit is contained in:
Jan Dabros 2019-12-02 13:30:03 +01:00
parent 0d35873c8f
commit bb9549babc
2 changed files with 17 additions and 4 deletions
bl31/aarch64
ea_delegate.S
lib/el3_runtime/aarch64
context.S

13
bl31/aarch64/ea_delegate.S
View file

@ -102,9 +102,11 @@ func enter_lower_el_sync_ea
/* Setup exception class and syndrome arguments for platform handler */
mov x0, #ERROR_EA_SYNC
mrs x1, esr_el3
adr x30, el3_exit
b delegate_sync_ea
bl delegate_sync_ea
/* el3_exit assumes SP_EL0 on entry */
msr spsel, #MODE_SP_EL0
b el3_exit
2:
ldp x0, x1, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X0]
ldp x2, x3, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X2]
@ -146,8 +148,11 @@ func enter_lower_el_async_ea
/* Setup exception class and syndrome arguments for platform handler */
mov x0, #ERROR_EA_ASYNC
mrs x1, esr_el3
adr x30, el3_exit
b delegate_async_ea
bl delegate_async_ea
/* el3_exit assumes SP_EL0 on entry */
msr spsel, #MODE_SP_EL0
b el3_exit
endfunc enter_lower_el_async_ea

8
lib/el3_runtime/aarch64/context.S
View file

@ -6,6 +6,7 @@
#include <arch.h>
#include <asm_macros.S>
#include <assert_macros.S>
#include <context.h>
.global el1_sysregs_context_save
@ -477,6 +478,13 @@ endfunc restore_gp_pmcr_pauth_regs
* ------------------------------------------------------------------
*/
func el3_exit
#if ENABLE_ASSERTIONS
/* el3_exit assumes SP_EL0 on entry */
mrs x17, spsel
cmp x17, #MODE_SP_EL0
ASM_ASSERT(eq)
#endif
/* ----------------------------------------------------------
* Save the current SP_EL0 i.e. the EL3 runtime stack which
* will be used for handling the next SMC.