diff options
| -rw-r--r-- | arch/xtensa/Kconfig | 48 | ||||
| -rw-r--r-- | arch/xtensa/include/asm/processor.h | 9 | ||||
| -rw-r--r-- | arch/xtensa/kernel/entry.S | 34 | ||||
| -rw-r--r-- | arch/xtensa/kernel/signal.c | 26 | ||||
| -rw-r--r-- | arch/xtensa/kernel/stacktrace.c | 5 | ||||
| -rw-r--r-- | arch/xtensa/kernel/traps.c | 4 |
6 files changed, 117 insertions, 9 deletions
diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig index ebc135bda921..fb64469ca8f0 100644 --- a/arch/xtensa/Kconfig +++ b/arch/xtensa/Kconfig @@ -385,6 +385,54 @@ config FAST_SYSCALL_SPILL_REGISTERS If unsure, say N. +config USER_ABI_CALL0 + bool + +choice + prompt "Userspace ABI" + default USER_ABI_DEFAULT + help + Select supported userspace ABI. + + If unsure, choose the default ABI. + +config USER_ABI_DEFAULT + bool "Default ABI only" + help + Assume default userspace ABI. For XEA2 cores it is windowed ABI. + call0 ABI binaries may be run on such kernel, but signal delivery + will not work correctly for them. + +config USER_ABI_CALL0_ONLY + bool "Call0 ABI only" + select USER_ABI_CALL0 + help + Select this option to support only call0 ABI in userspace. + Windowed ABI binaries will crash with a segfault caused by + an illegal instruction exception on the first 'entry' opcode. + + Choose this option if you're planning to run only user code + built with call0 ABI. + +config USER_ABI_CALL0_PROBE + bool "Support both windowed and call0 ABI by probing" + select USER_ABI_CALL0 + help + Select this option to support both windowed and call0 userspace + ABIs. When enabled all processes are started with PS.WOE disabled + and a fast user exception handler for an illegal instruction is + used to turn on PS.WOE bit on the first 'entry' opcode executed by + the userspace. + + This option should be enabled for the kernel that must support + both call0 and windowed ABIs in userspace at the same time. + + Note that Xtensa ISA does not guarantee that entry opcode will + raise an illegal instruction exception on cores with XEA2 when + PS.WOE is disabled, check whether the target core supports it. + +endchoice + endmenu config XTENSA_CALIBRATE_CCOUNT diff --git a/arch/xtensa/include/asm/processor.h b/arch/xtensa/include/asm/processor.h index 0b4efec9e19e..7495520d7a3e 100644 --- a/arch/xtensa/include/asm/processor.h +++ b/arch/xtensa/include/asm/processor.h @@ -176,14 +176,21 @@ struct thread_struct { /* * Do necessary setup to start up a newly executed thread. - * Note: We set-up ps as if we did a call4 to the new pc. + * Note: When windowed ABI is used for userspace we set-up ps + * as if we did a call4 to the new pc. * set_thread_state in signal.c depends on it. */ +#if IS_ENABLED(CONFIG_USER_ABI_CALL0) +#define USER_PS_VALUE ((USER_RING << PS_RING_SHIFT) | \ + (1 << PS_UM_BIT) | \ + (1 << PS_EXCM_BIT)) +#else #define USER_PS_VALUE (PS_WOE_MASK | \ (1 << PS_CALLINC_SHIFT) | \ (USER_RING << PS_RING_SHIFT) | \ (1 << PS_UM_BIT) | \ (1 << PS_EXCM_BIT)) +#endif /* Clearing a0 terminates the backtrace. */ #define start_thread(regs, new_pc, new_sp) \ diff --git a/arch/xtensa/kernel/entry.S b/arch/xtensa/kernel/entry.S index 9afe8f612f23..9e3676879168 100644 --- a/arch/xtensa/kernel/entry.S +++ b/arch/xtensa/kernel/entry.S @@ -1003,7 +1003,41 @@ ENTRY(fast_alloca) 4: j _WindowUnderflow4 ENDPROC(fast_alloca) +#ifdef CONFIG_USER_ABI_CALL0_PROBE /* + * fast illegal instruction handler. + * + * This is used to fix up user PS.WOE on the exception caused + * by the first opcode related to register window. If PS.WOE is + * already set it goes directly to the common user exception handler. + * + * Entry condition: + * + * a0: trashed, original value saved on stack (PT_AREG0) + * a1: a1 + * a2: new stack pointer, original in DEPC + * a3: a3 + * depc: a2, original value saved on stack (PT_DEPC) + * excsave_1: dispatch table + */ + +ENTRY(fast_illegal_instruction_user) + + rsr a0, ps + bbsi.l a0, PS_WOE_BIT, user_exception + s32i a3, a2, PT_AREG3 + movi a3, PS_WOE_MASK + or a0, a0, a3 + wsr a0, ps + l32i a3, a2, PT_AREG3 + l32i a0, a2, PT_AREG0 + rsr a2, depc + rfe + +ENDPROC(fast_illegal_instruction_user) +#endif + + /* * fast system calls. * * WARNING: The kernel doesn't save the entire user context before diff --git a/arch/xtensa/kernel/signal.c b/arch/xtensa/kernel/signal.c index fbedf2aba09d..dae83cddd6ca 100644 --- a/arch/xtensa/kernel/signal.c +++ b/arch/xtensa/kernel/signal.c @@ -335,7 +335,8 @@ static int setup_frame(struct ksignal *ksig, sigset_t *set, { struct rt_sigframe *frame; int err = 0, sig = ksig->sig; - unsigned long sp, ra, tp; + unsigned long sp, ra, tp, ps; + unsigned int base; sp = regs->areg[1]; @@ -385,17 +386,26 @@ static int setup_frame(struct ksignal *ksig, sigset_t *set, /* Set up registers for signal handler; preserve the threadptr */ tp = regs->threadptr; + ps = regs->ps; start_thread(regs, (unsigned long) ksig->ka.sa.sa_handler, (unsigned long) frame); - /* Set up a stack frame for a call4 - * Note: PS.CALLINC is set to one by start_thread - */ - regs->areg[4] = (((unsigned long) ra) & 0x3fffffff) | 0x40000000; - regs->areg[6] = (unsigned long) sig; - regs->areg[7] = (unsigned long) &frame->info; - regs->areg[8] = (unsigned long) &frame->uc; + /* Set up a stack frame for a call4 if userspace uses windowed ABI */ + if (ps & PS_WOE_MASK) { + base = 4; + regs->areg[base] = + (((unsigned long) ra) & 0x3fffffff) | 0x40000000; + ps = (ps & ~(PS_CALLINC_MASK | PS_OWB_MASK)) | + (1 << PS_CALLINC_SHIFT); + } else { + base = 0; + regs->areg[base] = (unsigned long) ra; + } + regs->areg[base + 2] = (unsigned long) sig; + regs->areg[base + 3] = (unsigned long) &frame->info; + regs->areg[base + 4] = (unsigned long) &frame->uc; regs->threadptr = tp; + regs->ps = ps; pr_debug("SIG rt deliver (%s:%d): signal=%d sp=%p pc=%08lx\n", current->comm, current->pid, sig, frame, regs->pc); diff --git a/arch/xtensa/kernel/stacktrace.c b/arch/xtensa/kernel/stacktrace.c index b9f82510c650..c822abb93d20 100644 --- a/arch/xtensa/kernel/stacktrace.c +++ b/arch/xtensa/kernel/stacktrace.c @@ -44,6 +44,11 @@ void xtensa_backtrace_user(struct pt_regs *regs, unsigned int depth, if (pc == 0 || pc >= TASK_SIZE || ufn(&frame, data)) return; + if (IS_ENABLED(CONFIG_USER_ABI_CALL0_ONLY) || + (IS_ENABLED(CONFIG_USER_ABI_CALL0_PROBE) && + !(regs->ps & PS_WOE_MASK))) + return; + /* Two steps: * * 1. Look through the register window for the diff --git a/arch/xtensa/kernel/traps.c b/arch/xtensa/kernel/traps.c index f060348c1b23..4a6c495ce9b6 100644 --- a/arch/xtensa/kernel/traps.c +++ b/arch/xtensa/kernel/traps.c @@ -51,6 +51,7 @@ extern void kernel_exception(void); extern void user_exception(void); +extern void fast_illegal_instruction_user(void); extern void fast_syscall_user(void); extern void fast_alloca(void); extern void fast_unaligned(void); @@ -87,6 +88,9 @@ typedef struct { static dispatch_init_table_t __initdata dispatch_init_table[] = { +#ifdef CONFIG_USER_ABI_CALL0_PROBE +{ EXCCAUSE_ILLEGAL_INSTRUCTION, USER, fast_illegal_instruction_user }, +#endif { EXCCAUSE_ILLEGAL_INSTRUCTION, 0, do_illegal_instruction}, { EXCCAUSE_SYSTEM_CALL, USER, fast_syscall_user }, { EXCCAUSE_SYSTEM_CALL, 0, system_call }, |