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target/nios2: Create EXCP_SEMIHOST for semi-hosting 

Decode 'break 1' during translation, rather than doing
it again during exception processing.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220421151735.31996-32-richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2022-04-21 08:17:02 -07:00
parent bdb307b4d8
commit 24ca31346e
3 changed files with 23 additions and 9 deletions
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1
target/nios2/cpu.h
View File

@ -156,6 +156,7 @@ FIELD(CR_TLBMISC, EE, 24, 1)
/* Exceptions */
#define EXCP_BREAK 0x1000
#define EXCP_SEMIHOST 0x1001
#define EXCP_RESET 0
#define EXCP_PRESET 1
#define EXCP_IRQ 2

14
target/nios2/helper.c
View File

@ -152,14 +152,6 @@ void nios2_cpu_do_interrupt(CPUState *cs)
case EXCP_BREAK:
qemu_log_mask(CPU_LOG_INT, "BREAK exception at pc=%x\n", env->pc);
/* The semihosting instruction is "break 1". */
if (semihosting_enabled() &&
cpu_ldl_code(env, env->pc) == 0x003da07a) {
qemu_log_mask(CPU_LOG_INT, "Entering semihosting\n");
env->pc += 4;
do_nios2_semihosting(env);
break;
}
if ((env->ctrl[CR_STATUS] & CR_STATUS_EH) == 0) {
env->ctrl[CR_BSTATUS] = env->ctrl[CR_STATUS];
@ -176,6 +168,12 @@ void nios2_cpu_do_interrupt(CPUState *cs)
env->pc = cpu->exception_addr;
break;
case EXCP_SEMIHOST:
qemu_log_mask(CPU_LOG_INT, "BREAK semihosting at pc=%x\n", env->pc);
env->pc += 4;
do_nios2_semihosting(env);
break;
default:
cpu_abort(cs, "unhandled exception type=%d\n",
cs->exception_index);

17
target/nios2/translate.c
View File

@ -33,6 +33,7 @@
#include "exec/translator.h"
#include "qemu/qemu-print.h"
#include "exec/gen-icount.h"
#include "semihosting/semihost.h"
/* is_jmp field values */
#define DISAS_JUMP DISAS_TARGET_0 /* only pc was modified dynamically */
@ -686,6 +687,20 @@ static void trap(DisasContext *dc, uint32_t code, uint32_t flags)
t_gen_helper_raise_exception(dc, EXCP_TRAP);
}
static void gen_break(DisasContext *dc, uint32_t code, uint32_t flags)
{
#ifndef CONFIG_USER_ONLY
/* The semihosting instruction is "break 1". */
R_TYPE(instr, code);
if (semihosting_enabled() && instr.imm5 == 1) {
t_gen_helper_raise_exception(dc, EXCP_SEMIHOST);
return;
}
#endif
t_gen_helper_raise_exception(dc, EXCP_BREAK);
}
static const Nios2Instruction r_type_instructions[] = {
INSTRUCTION_ILLEGAL(),
INSTRUCTION(eret), /* eret */
@ -739,7 +754,7 @@ static const Nios2Instruction r_type_instructions[] = {
INSTRUCTION(add), /* add */
INSTRUCTION_ILLEGAL(),
INSTRUCTION_ILLEGAL(),
INSTRUCTION_FLG(gen_excp, EXCP_BREAK), /* break */
INSTRUCTION(gen_break), /* break */
INSTRUCTION_ILLEGAL(),
INSTRUCTION(nop), /* nop */
INSTRUCTION_ILLEGAL(),