[v6] Hexagon: add PC alignment check and exception

The Hexagon Programmer's Reference Manual says that the exception 0x1e
should be raised upon an unaligned program counter. Let's implement that
and also add some tests.

Signed-off-by: Matheus Tavares Bernardino <quic_mathbern@quicinc.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Taylor Simpson <ltaylorsimpson@gmail.com>
---
Changes in v6:
- The multi COF test defines a new section for the unaligned label to
  make it more robust.
- Instead of a nop in the undesired test branch, we use a trap for
  SYS_EXIT

 target/hexagon/cpu.h              |   7 ++
 target/hexagon/cpu_bits.h         |   4 ++
 target/hexagon/macros.h           |   3 -
 linux-user/hexagon/cpu_loop.c     |   4 ++
 target/hexagon/op_helper.c        |   9 ++-
 tests/tcg/hexagon/unaligned_pc.c  | 107 ++++++++++++++++++++++++++++++
 tests/tcg/hexagon/Makefile.target |   2 +
 7 files changed, 128 insertions(+), 8 deletions(-)
 create mode 100644 tests/tcg/hexagon/unaligned_pc.c

> -----Original Message-----
> From: Matheus Bernardino (QUIC) <quic_mathbern@quicinc.com>
> Sent: Friday, May 3, 2024 11:53 AM
> To: qemu-devel@nongnu.org
> Cc: Brian Cain <bcain@quicinc.com>; Sid Manning <sidneym@quicinc.com>;
> ale@rev.ng; anjo@rev.ng; ltaylorsimpson@gmail.com;
> richard.henderson@linaro.org; Laurent Vivier <laurent@vivier.eu>
> Subject: [PATCH v6] Hexagon: add PC alignment check and exception
> 
> The Hexagon Programmer's Reference Manual says that the exception 0x1e
> should be raised upon an unaligned program counter. Let's implement that
> and also add some tests.
> 
> Signed-off-by: Matheus Tavares Bernardino <quic_mathbern@quicinc.com>
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
> Reviewed-by: Taylor Simpson <ltaylorsimpson@gmail.com>
> ---
> Changes in v6:
> - The multi COF test defines a new section for the unaligned label to
>   make it more robust.
> - Instead of a nop in the undesired test branch, we use a trap for
>   SYS_EXIT
> 

Reviewed-by: Brian Cain <bcain@quicinc.com>

>  target/hexagon/cpu.h              |   7 ++
>  target/hexagon/cpu_bits.h         |   4 ++
>  target/hexagon/macros.h           |   3 -
>  linux-user/hexagon/cpu_loop.c     |   4 ++
>  target/hexagon/op_helper.c        |   9 ++-
>  tests/tcg/hexagon/unaligned_pc.c  | 107 ++++++++++++++++++++++++++++++
>  tests/tcg/hexagon/Makefile.target |   2 +
>  7 files changed, 128 insertions(+), 8 deletions(-)
>  create mode 100644 tests/tcg/hexagon/unaligned_pc.c
> 
> diff --git a/target/hexagon/cpu.h b/target/hexagon/cpu.h
> index 3eef58fe8f..764f3c38cc 100644
> --- a/target/hexagon/cpu.h
> +++ b/target/hexagon/cpu.h
> @@ -134,6 +134,10 @@ struct ArchCPU {
> 
>  FIELD(TB_FLAGS, IS_TIGHT_LOOP, 0, 1)
> 
> +G_NORETURN void hexagon_raise_exception_err(CPUHexagonState *env,
> +                                            uint32_t exception,
> +                                            uintptr_t pc);
> +
>  static inline void cpu_get_tb_cpu_state(CPUHexagonState *env, vaddr *pc,
>                                          uint64_t *cs_base, uint32_t *flags)
>  {
> @@ -144,6 +148,9 @@ static inline void
> cpu_get_tb_cpu_state(CPUHexagonState *env, vaddr *pc,
>          hex_flags = FIELD_DP32(hex_flags, TB_FLAGS, IS_TIGHT_LOOP, 1);
>      }
>      *flags = hex_flags;
> +    if (*pc & PCALIGN_MASK) {
> +        hexagon_raise_exception_err(env, HEX_EXCP_PC_NOT_ALIGNED, 0);
> +    }
>  }
> 
>  typedef HexagonCPU ArchCPU;
> diff --git a/target/hexagon/cpu_bits.h b/target/hexagon/cpu_bits.h
> index 96fef71729..4279281a71 100644
> --- a/target/hexagon/cpu_bits.h
> +++ b/target/hexagon/cpu_bits.h
> @@ -20,9 +20,13 @@
> 
>  #include "qemu/bitops.h"
> 
> +#define PCALIGN 4
> +#define PCALIGN_MASK (PCALIGN - 1)
> +
>  #define HEX_EXCP_FETCH_NO_UPAGE  0x012
>  #define HEX_EXCP_INVALID_PACKET  0x015
>  #define HEX_EXCP_INVALID_OPCODE  0x015
> +#define HEX_EXCP_PC_NOT_ALIGNED  0x01e
>  #define HEX_EXCP_PRIV_NO_UREAD   0x024
>  #define HEX_EXCP_PRIV_NO_UWRITE  0x025
> 
> diff --git a/target/hexagon/macros.h b/target/hexagon/macros.h
> index 1376d6ccc1..f375471a98 100644
> --- a/target/hexagon/macros.h
> +++ b/target/hexagon/macros.h
> @@ -22,9 +22,6 @@
>  #include "hex_regs.h"
>  #include "reg_fields.h"
> 
> -#define PCALIGN 4
> -#define PCALIGN_MASK (PCALIGN - 1)
> -
>  #define GET_FIELD(FIELD, REGIN) \
>      fEXTRACTU_BITS(REGIN, reg_field_info[FIELD].width, \
>                     reg_field_info[FIELD].offset)
> diff --git a/linux-user/hexagon/cpu_loop.c b/linux-user/hexagon/cpu_loop.c
> index 7f1499ed28..d41159e52a 100644
> --- a/linux-user/hexagon/cpu_loop.c
> +++ b/linux-user/hexagon/cpu_loop.c
> @@ -60,6 +60,10 @@ void cpu_loop(CPUHexagonState *env)
>                  env->gpr[0] = ret;
>              }
>              break;
> +        case HEX_EXCP_PC_NOT_ALIGNED:
> +            force_sig_fault(TARGET_SIGBUS, TARGET_BUS_ADRALN,
> +                            env->gpr[HEX_REG_R31]);
> +            break;
>          case EXCP_ATOMIC:
>              cpu_exec_step_atomic(cs);
>              break;
> diff --git a/target/hexagon/op_helper.c b/target/hexagon/op_helper.c
> index da10ac5847..ae5a605513 100644
> --- a/target/hexagon/op_helper.c
> +++ b/target/hexagon/op_helper.c
> @@ -36,10 +36,9 @@
>  #define SF_MANTBITS    23
> 
>  /* Exceptions processing helpers */
> -static G_NORETURN
> -void do_raise_exception_err(CPUHexagonState *env,
> -                            uint32_t exception,
> -                            uintptr_t pc)
> +G_NORETURN void hexagon_raise_exception_err(CPUHexagonState *env,
> +                                            uint32_t exception,
> +                                            uintptr_t pc)
>  {
>      CPUState *cs = env_cpu(env);
>      qemu_log_mask(CPU_LOG_INT, "%s: %d\n", __func__, exception);
> @@ -49,7 +48,7 @@ void do_raise_exception_err(CPUHexagonState *env,
> 
>  G_NORETURN void HELPER(raise_exception)(CPUHexagonState *env, uint32_t
> excp)
>  {
> -    do_raise_exception_err(env, excp, 0);
> +    hexagon_raise_exception_err(env, excp, 0);
>  }
> 
>  void log_store32(CPUHexagonState *env, target_ulong addr,
> diff --git a/tests/tcg/hexagon/unaligned_pc.c
> b/tests/tcg/hexagon/unaligned_pc.c
> new file mode 100644
> index 0000000000..e9dc7cb8b5
> --- /dev/null
> +++ b/tests/tcg/hexagon/unaligned_pc.c
> @@ -0,0 +1,107 @@
> +#include <stdio.h>
> +#include <signal.h>
> +#include <setjmp.h>
> +#include <stdlib.h>
> +
> +/* will be changed in signal handler */
> +volatile sig_atomic_t completed_tests;
> +static jmp_buf after_test;
> +static int nr_tests;
> +
> +void __attribute__((naked)) test_return(void)
> +{
> +    asm volatile(
> +        "allocframe(#0x8)\n"
> +        "r0 = #0xffffffff\n"
> +        "framekey = r0\n"
> +        "dealloc_return\n"
> +        :
> +        :
> +        : "r0", "r29", "r30", "r31", "framekey");
> +}
> +
> +void test_endloop(void)
> +{
> +    asm volatile(
> +        "loop0(1f, #2)\n"
> +        "1: r0 = #0x3\n"
> +        "sa0 = r0\n"
> +        "{ nop }:endloop0\n"
> +        :
> +        :
> +        : "r0", "sa0", "lc0", "usr");
> +}
> +
> +asm(
> +    ".pushsection .text.unaligned\n"
> +    ".org 0x3\n"
> +    ".global test_multi_cof_unaligned\n"
> +    "test_multi_cof_unaligned:\n"
> +    "   jumpr r31\n"
> +    ".popsection\n"
> +);
> +
> +#define SYS_EXIT 94
> +
> +void test_multi_cof(void)
> +{
> +    asm volatile(
> +        "p0 = cmp.eq(r0, r0)\n"
> +        "{\n"
> +        "    if (p0) jump test_multi_cof_unaligned\n"
> +        "    if (!p0) jump 1f\n"
> +        "}\n"
> +        "1:"
> +        "  r0 = #1\n"
> +        "  r6 = #%0\n"
> +        "  trap0(#1)\n"
> +        :
> +        : "i"(SYS_EXIT)
> +        : "p0", "r0", "r6");
> +}
> +
> +void sigbus_handler(int signum)
> +{
> +    /* retore framekey after test_return */
> +    asm volatile(
> +        "r0 = #0\n"
> +        "framekey = r0\n"
> +        :
> +        :
> +        : "r0", "framekey");
> +    printf("Test %d complete\n", completed_tests);
> +    completed_tests++;
> +    siglongjmp(after_test, 1);
> +}
> +
> +void test_done(void)
> +{
> +    int err = (completed_tests != nr_tests);
> +    puts(err ? "FAIL" : "PASS");
> +    exit(err);
> +}
> +
> +typedef void (*test_fn)(void);
> +
> +int main()
> +{
> +    test_fn tests[] = { test_return, test_endloop, test_multi_cof, test_done };
> +    nr_tests = (sizeof(tests) / sizeof(tests[0])) - 1;
> +
> +    struct sigaction sa = {
> +        .sa_sigaction = sigbus_handler,
> +        .sa_flags = SA_SIGINFO
> +    };
> +
> +    if (sigaction(SIGBUS, &sa, NULL) < 0) {
> +        perror("sigaction");
> +        return EXIT_FAILURE;
> +    }
> +
> +    sigsetjmp(after_test, 1);
> +    tests[completed_tests]();
> +
> +    /* should never get here */
> +    puts("FAIL");
> +    return 1;
> +}
> diff --git a/tests/tcg/hexagon/Makefile.target
> b/tests/tcg/hexagon/Makefile.target
> index f839b2c0d5..e5182c01d8 100644
> --- a/tests/tcg/hexagon/Makefile.target
> +++ b/tests/tcg/hexagon/Makefile.target
> @@ -51,6 +51,7 @@ HEX_TESTS += scatter_gather
>  HEX_TESTS += hvx_misc
>  HEX_TESTS += hvx_histogram
>  HEX_TESTS += invalid-slots
> +HEX_TESTS += unaligned_pc
> 
>  run-and-check-exception = $(call run-test,$2,$3 2>$2.stderr; \
>  	test $$? -eq 1 && grep -q "exception $(strip $1)" $2.stderr)
> @@ -107,6 +108,7 @@ overflow: overflow.c hex_test.h
>  preg_alias: preg_alias.c hex_test.h
>  read_write_overlap: read_write_overlap.c hex_test.h
>  reg_mut: reg_mut.c hex_test.h
> +unaligned_pc: unaligned_pc.c
> 
>  # This test has to be compiled for the -mv67t target
>  usr: usr.c hex_test.h
> --
> 2.37.2