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authorMax Filippov <jcmvbkbc@gmail.com>2022-05-13 08:11:14 -0700
committerMax Filippov <jcmvbkbc@gmail.com>2022-05-17 03:35:43 -0700
commit5cc5f19f884a75f0bf96b95b4292fcc81effd755 (patch)
treea751a2cec798c43780f333a1bd2d4d2583833c07 /arch/xtensa
parentd74862007e0849fad8ba86447e6f05928f920640 (diff)
downloadlinux-5cc5f19f884a75f0bf96b95b4292fcc81effd755.tar.bz2
xtensa: improve call0 ABI probing
When call0 userspace ABI support by probing is enabled instructions that cause illegal instruction exception when PS.WOE is clear are retried with PS.WOE set before calling c-level exception handler. Record user pc at which PS.WOE was set in the fast exception handler and clear PS.WOE in the c-level exception handler if we get there from the same address. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Diffstat (limited to 'arch/xtensa')
-rw-r--r--arch/xtensa/include/asm/thread_info.h4
-rw-r--r--arch/xtensa/kernel/asm-offsets.c3
-rw-r--r--arch/xtensa/kernel/entry.S5
-rw-r--r--arch/xtensa/kernel/traps.c12
4 files changed, 24 insertions, 0 deletions
diff --git a/arch/xtensa/include/asm/thread_info.h b/arch/xtensa/include/asm/thread_info.h
index 52974317a6b6..326db1c1d5d8 100644
--- a/arch/xtensa/include/asm/thread_info.h
+++ b/arch/xtensa/include/asm/thread_info.h
@@ -56,6 +56,10 @@ struct thread_info {
/* result of the most recent exclusive store */
unsigned long atomctl8;
#endif
+#ifdef CONFIG_USER_ABI_CALL0_PROBE
+ /* Address where PS.WOE was enabled by the ABI probing code */
+ unsigned long ps_woe_fix_addr;
+#endif
/*
* If i-th bit is set then coprocessor state is loaded into the
diff --git a/arch/xtensa/kernel/asm-offsets.c b/arch/xtensa/kernel/asm-offsets.c
index 9a1db6ffcbf4..da38de20ae59 100644
--- a/arch/xtensa/kernel/asm-offsets.c
+++ b/arch/xtensa/kernel/asm-offsets.c
@@ -88,6 +88,9 @@ int main(void)
OFFSET(TI_STSTUS, thread_info, status);
OFFSET(TI_CPU, thread_info, cpu);
OFFSET(TI_PRE_COUNT, thread_info, preempt_count);
+#ifdef CONFIG_USER_ABI_CALL0_PROBE
+ OFFSET(TI_PS_WOE_FIX_ADDR, thread_info, ps_woe_fix_addr);
+#endif
/* struct thread_info (offset from start_struct) */
DEFINE(THREAD_RA, offsetof (struct task_struct, thread.ra));
diff --git a/arch/xtensa/kernel/entry.S b/arch/xtensa/kernel/entry.S
index 3224b4ceca34..e3eae648ba2e 100644
--- a/arch/xtensa/kernel/entry.S
+++ b/arch/xtensa/kernel/entry.S
@@ -1056,6 +1056,11 @@ ENTRY(fast_illegal_instruction_user)
movi a3, PS_WOE_MASK
or a0, a0, a3
wsr a0, ps
+#ifdef CONFIG_USER_ABI_CALL0_PROBE
+ GET_THREAD_INFO(a3, a2)
+ rsr a0, epc1
+ s32i a0, a3, TI_PS_WOE_FIX_ADDR
+#endif
l32i a3, a2, PT_AREG3
l32i a0, a2, PT_AREG0
rsr a2, depc
diff --git a/arch/xtensa/kernel/traps.c b/arch/xtensa/kernel/traps.c
index 2b75b252b626..f97d43a8d13d 100644
--- a/arch/xtensa/kernel/traps.c
+++ b/arch/xtensa/kernel/traps.c
@@ -317,6 +317,18 @@ static bool check_div0(struct pt_regs *regs)
static void do_illegal_instruction(struct pt_regs *regs)
{
+#ifdef CONFIG_USER_ABI_CALL0_PROBE
+ /*
+ * When call0 application encounters an illegal instruction fast
+ * exception handler will attempt to set PS.WOE and retry failing
+ * instruction.
+ * If we get here we know that that instruction is also illegal
+ * with PS.WOE set, so it's not related to the windowed option
+ * hence PS.WOE may be cleared.
+ */
+ if (regs->pc == current_thread_info()->ps_woe_fix_addr)
+ regs->ps &= ~PS_WOE_MASK;
+#endif
if (check_div0(regs)) {
do_div0(regs);
return;