Setup initial PC according executable entry form ELF file if it is non zero.

Signed-off-by: Pavel Pisa <pisa@cmp.felk.cvut.cz>

3 files changed, 12 insertions, 2 deletions

diff --git a/qtmips_machine/programloader.cpp b/qtmips_machine/programloader.cpp
index 5a907c8..7722774 100644
--- a/qtmips_machine/programloader.cpp
+++ b/qtmips_machine/programloader.cpp
@@ -44,6 +44,7 @@
 using namespace machine;
 
 ProgramLoader::ProgramLoader(const char *file) {
+    const GElf_Ehdr *elf_ehdr;
     // Initialize elf library
     if (elf_version(EV_CURRENT) == EV_NONE)
         throw QTMIPS_EXCEPTION(Input, "Elf library initialization failed", elf_errmsg(-1));
@@ -57,8 +58,10 @@ ProgramLoader::ProgramLoader(const char *file) {
     if (elf_kind(this->elf) != ELF_K_ELF)
         throw QTMIPS_EXCEPTION(Input, "Invalid input file elf format, plain elf file expected", "");
 
-    if (!gelf_getehdr(this->elf, &this->hdr))
+    elf_ehdr = gelf_getehdr(this->elf, &this->hdr);
+    if (!elf_ehdr)
         throw QTMIPS_EXCEPTION(Input, "Getting elf file header failed", elf_errmsg(-1));
+    executable_entry = elf_ehdr->e_entry;
     // Check elf file format, executable expected, nothing else.
     if (this->hdr.e_type != ET_EXEC)
         throw QTMIPS_EXCEPTION(Input, "Invalid input file type", "");
@@ -119,3 +122,7 @@ std::uint32_t ProgramLoader::end() {
     }
     return last + 0x10; // We add offset so we are sure that also pipeline is empty
 }
+
+std::uint32_t ProgramLoader::get_executable_entry() {
+    return executable_entry;
+}
diff --git a/qtmips_machine/programloader.h b/qtmips_machine/programloader.h
index 686f64c..607bdb0 100644
--- a/qtmips_machine/programloader.h
+++ b/qtmips_machine/programloader.h
@@ -54,6 +54,7 @@ public:
 
     void to_memory(Memory *mem); // Writes all loaded sections to memory
     std::uint32_t end(); // Return address after which there is no more code for sure
+    std::uint32_t get_executable_entry();
 private:
     int fd;
     Elf *elf;
@@ -61,6 +62,7 @@ private:
     size_t n_secs; // number of sections in elf program header
     Elf32_Phdr *phdrs; // program section headers
     QVector<size_t> map; // external index to phdrs index
+    std::uint32_t executable_entry;
 };
 
 }
diff --git a/qtmips_machine/qtmipsmachine.cpp b/qtmips_machine/qtmipsmachine.cpp
index ea14701..51e5580 100644
--- a/qtmips_machine/qtmipsmachine.cpp
+++ b/qtmips_machine/qtmipsmachine.cpp
@@ -45,8 +45,9 @@ QtMipsMachine::QtMipsMachine(const MachineConfig &cc) : QObject(), mcnf(&cc) {
     mem_program_only = new Memory();
     program.to_memory(mem_program_only);
     program_end = program.end();
-
     regs = new Registers();
+    if (program.get_executable_entry())
+        regs->pc_abs_jmp(program.get_executable_entry());
     mem = new Memory(*mem_program_only);
     cch_program = new Cache(mem, &cc.cache_program(), cc.memory_access_time_read(), cc.memory_access_time_write());
     cch_data = new Cache(mem, &cc.cache_data(), cc.memory_access_time_read(), cc.memory_access_time_write());