radv: add an option to configure the trap handler exceptions

This introduces RADV_TRAP_HANDLER_EXCP to configure the various
shader exceptions.

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/31902>

docs/envvars.rst

@@ -1492,6 +1492,20 @@ RADV driver environment variables
    enable/disable the experimental trap handler for debugging GPU hangs on GFX8
    (disabled by default)
 
+.. envvar:: RADV_TRAP_HANDLER_EXCP
+
+  a comma-separated list of named flags to configure the trap handler
+  exceptions, see the list below:
+
+  ``mem_viol``
+    enable memory violation exception
+  ``float_div_by_zero``
+    enable floating point division by zero exception
+  ``float_overflow``
+    enable floating point overflow exception
+  ``float_underflow``
+    enable floating point underflow exception
+
 .. envvar:: RADV_RRA_TRACE_VALIDATE
 
    enable validation of captured acceleration structures. Can be

src/amd/vulkan/radv_debug.h

@@ -81,6 +81,13 @@ enum {
    RADV_PERFTEST_VIDEO_ENCODE = 1u << 16,
 };
 
+enum {
+   RADV_TRAP_EXCP_MEM_VIOL = 1u << 0,
+   RADV_TRAP_EXCP_FLOAT_DIV_BY_ZERO = 1u << 1,
+   RADV_TRAP_EXCP_FLOAT_OVERFLOW = 1u << 2,
+   RADV_TRAP_EXCP_FLOAT_UNDERFLOW = 1u << 3,
+};
+
 bool radv_init_trace(struct radv_device *device);
 void radv_finish_trace(struct radv_device *device);
 

src/amd/vulkan/radv_instance.c

@@ -100,6 +100,14 @@ static const struct debug_control radv_perftest_options[] = {{"localbos", RADV_P
                                                              {"video_encode", RADV_PERFTEST_VIDEO_ENCODE},
                                                              {NULL, 0}};
 
+static const struct debug_control radv_trap_excp_options[] = {
+   {"mem_viol", RADV_PERFTEST_LOCAL_BOS},
+   {"float_div_by_zero", RADV_PERFTEST_DCC_MSAA},
+   {"float_overflow", RADV_PERFTEST_BO_LIST},
+   {"float_underflow", RADV_PERFTEST_CS_WAVE_32},
+   {NULL, 0},
+};
+
 const char *
 radv_get_perftest_option_name(int id)
 {
@@ -343,6 +351,7 @@ radv_CreateInstance(const VkInstanceCreateInfo *pCreateInfo, const VkAllocationC
 
    instance->debug_flags = parse_debug_string(getenv("RADV_DEBUG"), radv_debug_options);
    instance->perftest_flags = parse_debug_string(getenv("RADV_PERFTEST"), radv_perftest_options);
+   instance->trap_excp_flags = parse_debug_string(getenv("RADV_TRAP_HANDLER_EXCP"), radv_trap_excp_options);
    instance->profile_pstate = radv_parse_pstate(debug_get_option("RADV_PROFILE_PSTATE", "peak"));
 
    /* When RADV_FORCE_FAMILY is set, the driver creates a null

src/amd/vulkan/radv_instance.h

@@ -42,6 +42,7 @@ struct radv_instance {
 
    uint64_t debug_flags;
    uint64_t perftest_flags;
+   uint64_t trap_excp_flags;
    enum radeon_ctx_pstate profile_pstate;
 
    struct {

src/amd/vulkan/radv_shader.c

@@ -1889,6 +1889,7 @@ radv_postprocess_binary_config(struct radv_device *device, struct radv_shader_bi
                                const struct radv_shader_args *args)
 {
    const struct radv_physical_device *pdev = radv_device_physical(device);
+   const struct radv_instance *instance = radv_physical_device_instance(pdev);
    struct ac_shader_config *config = &binary->config;
 
    if (binary->type == RADV_BINARY_TYPE_RTLD) {
@@ -1940,6 +1941,7 @@ radv_postprocess_binary_config(struct radv_device *device, struct radv_shader_bi
           (pdev->info.gfx_level < GFX10 && num_shared_vgprs == 0));
    unsigned num_shared_vgpr_blocks = num_shared_vgprs / 8;
    unsigned excp_en = 0, excp_en_msb = 0;
+   bool dx10_clamp = pdev->info.gfx_level < GFX12;
 
    config->num_vgprs = num_vgprs;
    config->num_sgprs = num_sgprs;
@@ -1949,11 +1951,24 @@ radv_postprocess_binary_config(struct radv_device *device, struct radv_shader_bi
                    S_00B12C_TRAP_PRESENT(trap_enabled);
 
    if (trap_enabled) {
-      /* Configure the shader exceptions like memory violation, etc.
+      /* Configure the shader exceptions like memory violation, etc. */
-       * TODO: Enable (and validate) more exceptions.
+      if (instance->trap_excp_flags & RADV_TRAP_EXCP_MEM_VIOL) {
-       */
+         excp_en |= 1 << 8;     /* for the graphics stages */
-      excp_en = 1 << 8;     /* mem_viol for the graphics stages */
+         excp_en_msb |= 1 << 1; /* for the compute stage */
-      excp_en_msb = 1 << 1; /* mem_viol for the compute stage */
+      }
+
+      if (instance->trap_excp_flags & RADV_TRAP_EXCP_FLOAT_DIV_BY_ZERO)
+         excp_en |= 1 << 2;
+      if (instance->trap_excp_flags & RADV_TRAP_EXCP_FLOAT_OVERFLOW)
+         excp_en |= 1 << 3;
+      if (instance->trap_excp_flags & RADV_TRAP_EXCP_FLOAT_UNDERFLOW)
+         excp_en |= 1 << 4;
+
+      if (instance->trap_excp_flags &
+          (RADV_TRAP_EXCP_FLOAT_DIV_BY_ZERO | RADV_TRAP_EXCP_FLOAT_OVERFLOW | RADV_TRAP_EXCP_FLOAT_UNDERFLOW)) {
+         /* It seems needed to disable DX10_CLAMP, otherwise the float exceptions aren't thrown. */
+         dx10_clamp = false;
+      }
    }
 
    if (!pdev->use_ngg_streamout) {
@@ -1962,8 +1977,8 @@ radv_postprocess_binary_config(struct radv_device *device, struct radv_shader_bi
                        S_00B12C_SO_EN(!!info->so.num_outputs);
    }
 
-   config->rsrc1 = S_00B848_VGPRS((num_vgprs - 1) / (info->wave_size == 32 ? 8 : 4)) |
+   config->rsrc1 = S_00B848_VGPRS((num_vgprs - 1) / (info->wave_size == 32 ? 8 : 4)) | S_00B848_DX10_CLAMP(dx10_clamp) |
-                   S_00B848_DX10_CLAMP(pdev->info.gfx_level < GFX12) | S_00B848_FLOAT_MODE(config->float_mode);
+                   S_00B848_FLOAT_MODE(config->float_mode);
 
    if (pdev->info.gfx_level >= GFX10) {
       config->rsrc2 |= S_00B22C_USER_SGPR_MSB_GFX10(args->num_user_sgprs >> 5);