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authorJeenu Viswambharan <jeenu.viswambharan@arm.com>2014-05-12 15:28:47 +0100
committerJeenu Viswambharan <jeenu.viswambharan@arm.com>2014-05-16 17:11:31 +0100
commit2da8d8bfc0877b9c723514133554dfee4c0638f1 (patch)
tree5178aafe28b80e33b6581663bee66b9d2194688a /bl31/aarch64
parentc3c1e9b0abe1a879dad4400421ad00849231eb3c (diff)
downloadarm-trusted-firmware-2da8d8bfc0877b9c723514133554dfee4c0638f1.tar.gz
Add build configuration for timer save/restore
At present, non-secure timer register contents are saved and restored as part of world switch by BL3-1. This effectively means that the non-secure timer stops, and non-secure timer interrupts are prevented from asserting until BL3-1 switches back, introducing latency for non-secure services. Often, secure world might depend on alternate sources for secure interrupts (secure timer or platform timer) instead of non-secure timers, in which case this save and restore is unnecessary. This patch introduces a boolean build-time configuration NS_TIMER_SWITCH to choose whether or not to save and restore non-secure timer registers upon world switch. The default choice is made not to save and restore them. Fixes ARM-software/tf-issues#148 Change-Id: I1b9d623606acb9797c3e0b02fb5ec7c0a414f37e
Diffstat (limited to 'bl31/aarch64')
-rw-r--r--bl31/aarch64/context.S14
1 files changed, 12 insertions, 2 deletions
diff --git a/bl31/aarch64/context.S b/bl31/aarch64/context.S
index 45d4a22..d0bca64 100644
--- a/bl31/aarch64/context.S
+++ b/bl31/aarch64/context.S
@@ -172,6 +172,8 @@ func el1_sysregs_context_save
mrs x9, vbar_el1
stp x17, x9, [x0, #CTX_CONTEXTIDR_EL1]
+ /* Save NS timer registers if the build has instructed so */
+#if NS_TIMER_SWITCH
mrs x10, cntp_ctl_el0
mrs x11, cntp_cval_el0
stp x10, x11, [x0, #CTX_CNTP_CTL_EL0]
@@ -181,8 +183,11 @@ func el1_sysregs_context_save
stp x12, x13, [x0, #CTX_CNTV_CTL_EL0]
mrs x14, cntkctl_el1
+ str x14, [x0, #CTX_CNTKCTL_EL1]
+#endif
+
mrs x15, fpexc32_el2
- stp x14, x15, [x0, #CTX_CNTKCTL_EL1]
+ str x15, [x0, #CTX_FP_FPEXC32_EL2]
ret
@@ -253,6 +258,8 @@ func el1_sysregs_context_restore
msr contextidr_el1, x17
msr vbar_el1, x9
+ /* Restore NS timer registers if the build has instructed so */
+#if NS_TIMER_SWITCH
ldp x10, x11, [x0, #CTX_CNTP_CTL_EL0]
msr cntp_ctl_el0, x10
msr cntp_cval_el0, x11
@@ -261,8 +268,11 @@ func el1_sysregs_context_restore
msr cntv_ctl_el0, x12
msr cntv_cval_el0, x13
- ldp x14, x15, [x0, #CTX_CNTKCTL_EL1]
+ ldr x14, [x0, #CTX_CNTKCTL_EL1]
msr cntkctl_el1, x14
+#endif
+
+ ldr x15, [x0, #CTX_FP_FPEXC32_EL2]
msr fpexc32_el2, x15
/* No explict ISB required here as ERET covers it */