diff options
| author |   Max Filippov <jcmvbkbc@gmail.com> | 2022-05-13 08:11:14 -0700 |
|---|---|---|
| committer | Max Filippov <jcmvbkbc@gmail.com> | 2022-05-17 03:35:43 -0700 |
| commit | 5cc5f19f884a75f0bf96b95b4292fcc81effd755 (patch) | |
| tree | a751a2cec798c43780f333a1bd2d4d2583833c07 /arch/xtensa | |
| parent | xtensa: support artificial division by 0 exception (diff) | |
| download | linux-dev-5cc5f19f884a75f0bf96b95b4292fcc81effd755.tar.xz linux-dev-5cc5f19f884a75f0bf96b95b4292fcc81effd755.zip | |
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.h | 4 | ||||
| -rw-r--r-- | arch/xtensa/kernel/asm-offsets.c | 3 | ||||
| -rw-r--r-- | arch/xtensa/kernel/entry.S | 5 | ||||
| -rw-r--r-- | arch/xtensa/kernel/traps.c | 12 |
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; |