[Mesa-dev] [PATCH 1/3] gallium/radeon: Add query for symbol specific config information

[Tom Stellard]

This adds a query which allows drivers to access the config
information of a specific function within the LLVM generated ELF
binary.  This makes it possible for the driver to handle ELF
binaries with multiple kernels / global functions.
---
 src/gallium/drivers/radeon/r600_pipe_common.h |  8 ++++
 src/gallium/drivers/radeon/radeon_elf_util.c  | 68 +++++++++++++++++++++++++++
 src/gallium/drivers/radeon/radeon_elf_util.h  | 10 ++++
 3 files changed, 86 insertions(+)

diff --git a/src/gallium/drivers/radeon/r600_pipe_common.h b/src/gallium/drivers/radeon/r600_pipe_common.h
index 4651bf8..2ff2eda 100644
--- a/src/gallium/drivers/radeon/r600_pipe_common.h
+++ b/src/gallium/drivers/radeon/r600_pipe_common.h
@@ -120,11 +120,19 @@ struct radeon_shader_binary {
 	unsigned char *config;
 	unsigned config_size;
 
+	/** The number of bytes of config information for each global symbol.
+	 */
+	unsigned config_size_per_symbol;
+
 	/** Constant data accessed by the shader.  This will be uploaded
 	 * into a constant buffer. */
 	unsigned char *rodata;
 	unsigned rodata_size;
 
+	/** List of symbol offsets for the shader */
+	uint64_t *global_symbol_offsets;
+	unsigned global_symbol_count;
+
 	/** Set to 1 if the disassembly for this binary has been dumped to
 	 *  stderr. */
 	int disassembled;
diff --git a/src/gallium/drivers/radeon/radeon_elf_util.c b/src/gallium/drivers/radeon/radeon_elf_util.c
index 7c5f93e..ec39a89 100644
--- a/src/gallium/drivers/radeon/radeon_elf_util.c
+++ b/src/gallium/drivers/radeon/radeon_elf_util.c
@@ -33,6 +33,48 @@
 #include <libelf.h>
 #include <stdio.h>
 
+static void parse_symbol_table(Elf_Data *symbol_table_data,
+				const GElf_Shdr *symbol_table_header,
+				struct radeon_shader_binary *binary)
+{
+	GElf_Sym symbol;
+	unsigned i = 0;
+	unsigned symbol_count =
+		symbol_table_header->sh_size / symbol_table_header->sh_entsize;
+
+	/* We are over allocating this list, because symbol_count gives the
+ 	 * total number of symbols, and we will only be filling the list
+ 	 * with offsets of global symbols.  The memory savings from
+ 	 * allocating the correct size of this list will be small, and
+ 	 * I don't think it is worth the cost of pre-computing the number
+ 	 * of global symbols.
+ 	 */
+	binary->global_symbol_offsets = CALLOC(symbol_count, sizeof(uint64_t));
+
+	while (gelf_getsym(symbol_table_data, i++, &symbol)) {
+		unsigned i;
+		if (GELF_ST_BIND(symbol.st_info) != STB_GLOBAL) {
+			continue;
+		}
+
+		binary->global_symbol_offsets[binary->global_symbol_count] =
+					symbol.st_value;
+
+		/* Sort the list using bubble sort.  This list will usually
+		 * be small. */
+		for (i = binary->global_symbol_count; i > 0; --i) {
+			uint64_t lhs = binary->global_symbol_offsets[i - 1];
+			uint64_t rhs = binary->global_symbol_offsets[i];
+			if (lhs < rhs) {
+				break;
+			}
+			binary->global_symbol_offsets[i] = lhs;
+			binary->global_symbol_offsets[i - 1] = rhs;
+		}
+		++binary->global_symbol_count;
+	}
+}
+
 void radeon_elf_read(const char *elf_data, unsigned elf_size,
 					struct radeon_shader_binary *binary,
 					unsigned debug)
@@ -85,6 +127,9 @@ void radeon_elf_read(const char *elf_data, unsigned elf_size,
 			binary->rodata_size = section_data->d_size;
 			binary->rodata = MALLOC(binary->rodata_size * sizeof(unsigned char));
 			memcpy(binary->rodata, section_data->d_buf, binary->rodata_size);
+		} else if (!strncmp(name, ".symtab", 7)) {
+			section_data = elf_getdata(section, section_data);
+			parse_symbol_table(section_data, &section_header, binary);
 		}
 	}
 
@@ -92,4 +137,27 @@ void radeon_elf_read(const char *elf_data, unsigned elf_size,
 		elf_end(elf);
 	}
 	FREE(elf_buffer);
+
+	/* Cache the config size per symbol */
+	if (binary->global_symbol_count) {
+		binary->config_size_per_symbol =
+			binary->config_size / binary->global_symbol_count;
+	} else {
+		binary->global_symbol_count = 1;
+		binary->config_size_per_symbol = binary->config_size;
+	}
+}
+
+const unsigned char *radeon_shader_binary_config_start(
+	const struct radeon_shader_binary *binary,
+	uint64_t symbol_offset)
+{
+	unsigned i;
+	for (i = 0; i < binary->global_symbol_count; ++i) {
+		if (binary->global_symbol_offsets[i] == symbol_offset) {
+			unsigned offset = i * binary->config_size_per_symbol;
+			return binary->config + offset;
+		}
+	}
+	return binary->config;
 }
diff --git a/src/gallium/drivers/radeon/radeon_elf_util.h b/src/gallium/drivers/radeon/radeon_elf_util.h
index 60dae42..8095e2f 100644
--- a/src/gallium/drivers/radeon/radeon_elf_util.h
+++ b/src/gallium/drivers/radeon/radeon_elf_util.h
@@ -27,6 +27,8 @@
 #ifndef RADEON_ELF_UTIL_H
 #define RADEON_ELF_UTIL_H
 
+#include <stdint.h>
+
 struct radeon_shader_binary;
 
 /*
@@ -36,4 +38,12 @@ struct radeon_shader_binary;
 void radeon_elf_read(const char *elf_data, unsigned elf_size,
 		struct radeon_shader_binary *binary, unsigned debug);
 
+/**
+ * @returns A pointer to the start of the configuration information for
+ * the function starting at \p symbol_offset of the binary.
+ */
+const unsigned char *radeon_shader_binary_config_start(
+	const struct radeon_shader_binary *binary,
+	uint64_t symbol_offset);
+
 #endif /* RADEON_ELF_UTIL_H */
-- 
1.8.5.5