diff options
| -rw-r--r-- | arch/xtensa/Kconfig.debug | 11 | ||||
| -rw-r--r-- | arch/xtensa/include/asm/regs.h | 4 | ||||
| -rw-r--r-- | arch/xtensa/kernel/setup.c | 120 |
3 files changed, 135 insertions, 0 deletions
diff --git a/arch/xtensa/Kconfig.debug b/arch/xtensa/Kconfig.debug index be5fb4c6243f..a34010e0e51c 100644 --- a/arch/xtensa/Kconfig.debug +++ b/arch/xtensa/Kconfig.debug @@ -13,4 +13,15 @@ config LD_NO_RELAX Enabling this option improves the link time but increases the code size, and possibly execution time. +config S32C1I_SELFTEST + bool "Perform S32C1I instruction self-test at boot" + default y + help + Enable this option to test S32C1I instruction behavior at boot. + Correct operation of this instruction requires some cooperation from hardware + external to the processor (such as bus bridge, bus fabric, or memory controller). + It is easy to make wrong hardware configuration, this test should catch it early. + + Say 'N' on stable hardware. + endmenu diff --git a/arch/xtensa/include/asm/regs.h b/arch/xtensa/include/asm/regs.h index 8a8aa61ccc8d..6aaf6d6a5fc4 100644 --- a/arch/xtensa/include/asm/regs.h +++ b/arch/xtensa/include/asm/regs.h @@ -52,6 +52,10 @@ #define EXCCAUSE_SPECULATION 7 #define EXCCAUSE_PRIVILEGED 8 #define EXCCAUSE_UNALIGNED 9 +#define EXCCAUSE_INSTR_DATA_ERROR 12 +#define EXCCAUSE_LOAD_STORE_DATA_ERROR 13 +#define EXCCAUSE_INSTR_ADDR_ERROR 14 +#define EXCCAUSE_LOAD_STORE_ADDR_ERROR 15 #define EXCCAUSE_ITLB_MISS 16 #define EXCCAUSE_ITLB_MULTIHIT 17 #define EXCCAUSE_ITLB_PRIVILEGE 18 diff --git a/arch/xtensa/kernel/setup.c b/arch/xtensa/kernel/setup.c index e53a94b3edbc..45217617c60d 100644 --- a/arch/xtensa/kernel/setup.c +++ b/arch/xtensa/kernel/setup.c @@ -42,6 +42,7 @@ #include <asm/page.h> #include <asm/setup.h> #include <asm/param.h> +#include <asm/traps.h> #include <platform/hardware.h> @@ -235,6 +236,123 @@ extern char _UserExceptionVector_text_end; extern char _DoubleExceptionVector_literal_start; extern char _DoubleExceptionVector_text_end; + +#ifdef CONFIG_S32C1I_SELFTEST +#if XCHAL_HAVE_S32C1I + +static int __initdata rcw_word, rcw_probe_pc, rcw_exc; + +/* + * Basic atomic compare-and-swap, that records PC of S32C1I for probing. + * + * If *v == cmp, set *v = set. Return previous *v. + */ +static inline int probed_compare_swap(int *v, int cmp, int set) +{ + int tmp; + + __asm__ __volatile__( + " movi %1, 1f\n" + " s32i %1, %4, 0\n" + " wsr %2, scompare1\n" + "1: s32c1i %0, %3, 0\n" + : "=a" (set), "=&a" (tmp) + : "a" (cmp), "a" (v), "a" (&rcw_probe_pc), "0" (set) + : "memory" + ); + return set; +} + +/* Handle probed exception */ + +void __init do_probed_exception(struct pt_regs *regs, unsigned long exccause) +{ + if (regs->pc == rcw_probe_pc) { /* exception on s32c1i ? */ + regs->pc += 3; /* skip the s32c1i instruction */ + rcw_exc = exccause; + } else { + do_unhandled(regs, exccause); + } +} + +/* Simple test of S32C1I (soc bringup assist) */ + +void __init check_s32c1i(void) +{ + int n, cause1, cause2; + void *handbus, *handdata, *handaddr; /* temporarily saved handlers */ + + rcw_probe_pc = 0; + handbus = trap_set_handler(EXCCAUSE_LOAD_STORE_ERROR, + do_probed_exception); + handdata = trap_set_handler(EXCCAUSE_LOAD_STORE_DATA_ERROR, + do_probed_exception); + handaddr = trap_set_handler(EXCCAUSE_LOAD_STORE_ADDR_ERROR, + do_probed_exception); + + /* First try an S32C1I that does not store: */ + rcw_exc = 0; + rcw_word = 1; + n = probed_compare_swap(&rcw_word, 0, 2); + cause1 = rcw_exc; + + /* took exception? */ + if (cause1 != 0) { + /* unclean exception? */ + if (n != 2 || rcw_word != 1) + panic("S32C1I exception error"); + } else if (rcw_word != 1 || n != 1) { + panic("S32C1I compare error"); + } + + /* Then an S32C1I that stores: */ + rcw_exc = 0; + rcw_word = 0x1234567; + n = probed_compare_swap(&rcw_word, 0x1234567, 0xabcde); + cause2 = rcw_exc; + + if (cause2 != 0) { + /* unclean exception? */ + if (n != 0xabcde || rcw_word != 0x1234567) + panic("S32C1I exception error (b)"); + } else if (rcw_word != 0xabcde || n != 0x1234567) { + panic("S32C1I store error"); + } + + /* Verify consistency of exceptions: */ + if (cause1 || cause2) { + pr_warn("S32C1I took exception %d, %d\n", cause1, cause2); + /* If emulation of S32C1I upon bus error gets implemented, + we can get rid of this panic for single core (not SMP) */ + panic("S32C1I exceptions not currently supported"); + } + if (cause1 != cause2) + panic("inconsistent S32C1I exceptions"); + + trap_set_handler(EXCCAUSE_LOAD_STORE_ERROR, handbus); + trap_set_handler(EXCCAUSE_LOAD_STORE_DATA_ERROR, handdata); + trap_set_handler(EXCCAUSE_LOAD_STORE_ADDR_ERROR, handaddr); +} + +#else /* XCHAL_HAVE_S32C1I */ + +/* This condition should not occur with a commercially deployed processor. + Display reminder for early engr test or demo chips / FPGA bitstreams */ +void __init check_s32c1i(void) +{ + pr_warn("Processor configuration lacks atomic compare-and-swap support!\n"); +} + +#endif /* XCHAL_HAVE_S32C1I */ +#else /* CONFIG_S32C1I_SELFTEST */ + +void __init check_s32c1i(void) +{ +} + +#endif /* CONFIG_S32C1I_SELFTEST */ + + void __init setup_arch(char **cmdline_p) { extern int mem_reserve(unsigned long, unsigned long, int); @@ -244,6 +362,8 @@ void __init setup_arch(char **cmdline_p) boot_command_line[COMMAND_LINE_SIZE-1] = '\0'; *cmdline_p = command_line; + check_s32c1i(); + /* Reserve some memory regions */ #ifdef CONFIG_BLK_DEV_INITRD |