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
/*
* 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) \
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
{
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];
/* 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);
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
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);
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 },