From: Ovidiu Panait Date: Sun, 13 Feb 2022 08:09:22 +0000 (+0200) Subject: microblaze: exception: fix return address for delay slot exceptions X-Git-Url: http://git.dujemihanovic.xyz/login.html?a=commitdiff_plain;h=ee8161f7d182e57ea828f77a6b246c884c70b7cd;p=u-boot.git microblaze: exception: fix return address for delay slot exceptions According to the MicroBlaze reference manual (xilinx2021.2/ug984/page-37): """ If an exception is caused by an instruction in a delay slot (that is, ESR[DS]=1), the exception handler should return execution to the address stored in BTR instead of the normal exception return address stored in R17. """ Adjust the code to print the proper return address for delay slot exceptions. Signed-off-by: Ovidiu Panait Link: https://lore.kernel.org/r/20220213080925.1548411-4-ovidiu.panait@windriver.com Signed-off-by: Michal Simek --- diff --git a/arch/microblaze/cpu/exception.c b/arch/microblaze/cpu/exception.c index 64d5fe4a80..f79e465e1f 100644 --- a/arch/microblaze/cpu/exception.c +++ b/arch/microblaze/cpu/exception.c @@ -20,11 +20,17 @@ void _hw_exception_handler (void) MFS(state, resr); printf("Hardware exception at 0x%x address\n", address); R17(address); - printf("Return address from exception 0x%x\n", address); if (CONFIG_IS_ENABLED(XILINX_MICROBLAZE0_DELAY_SLOT_EXCEP) && - (state & 0x1000)) + (state & 0x1000)) { + /* + * For exceptions in delay slots, the return address is stored + * in the Branch Target Register (BTR), rather than R17. + */ + MFS(address, rbtr); + puts("Exception in delay slot\n"); + } switch (state & 0x1f) { /* mask on exception cause */ case 0x1: @@ -49,6 +55,8 @@ void _hw_exception_handler (void) puts("Undefined cause\n"); break; } + + printf("Return address from exception 0x%x\n", address); printf("Unaligned %sword access\n", ((state & 0x800) ? "" : "half")); printf("Unaligned %s access\n", ((state & 0x400) ? "store" : "load")); printf("Register R%x\n", (state & 0x3E) >> 5);