elfloader, RISC-V: Move the elfloader during boot

The SBI implementation usually loads the elfloader where the kernel would prefer to also be loaded. Allow the elfloader to move itself to a higher address before loading the kernel and user images. Signed-off-by: Kent McLeod <[email protected]>
seL4 · Feb 1, 2022 · 52f3510 · 52f3510
1 parent 3a3c02f
commit 52f3510
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diff --git a/cmake-tool/helpers/application_settings.cmake b/cmake-tool/helpers/application_settings.cmake
@@ -49,9 +49,6 @@ function(ApplyData61ElfLoaderSettings kernel_platform kernel_sel4_arch)
     if(KernelPlatformZynqmp AND KernelSel4ArchAarch32)
         set(IMAGE_START_ADDR 0x8000000 CACHE INTERNAL "" FORCE)
     endif()
-    if(KernelPlatformSpike AND KernelSel4ArchRiscV32)
-        set(IMAGE_START_ADDR 0x80400000 CACHE INTERNAL "" FORCE)
-    endif()
 endfunction()
 
 function(ApplyCommonSimulationSettings kernel_sel4_arch)

diff --git a/elfloader-tool/src/arch-riscv/crt0.S b/elfloader-tool/src/arch-riscv/crt0.S
@@ -54,10 +54,25 @@ _start:
   mv s0, a0 /* preserve a0 (hart id) in s0 */
   mv s2, a1 /* preserve a1 (dtb) in s2 */
 
-#ifdef CONFIG_IMAGE_BINARY
+  /* Set a stack so that we can call into C functions */
+  la sp, (elfloader_stack_alloc + BIT(12))
+  /*
+   * Binary images may not be loaded in the correct location.
+   * Try and move ourselves so we're in the right place.
+   */
+  jal fixup_image_base
+  /* fixup_image_base returns 0 if no need to move */
+  beqz     a0, 1f
+
+  /* otherwise, restore args and jump to the start of the new elfloader */
+  mv a2, a0
+  mv a0, s0
+  mv a1, s2
+  jr a2
+
 /* Clear the BSS before we get to do anything more specific */
+1:
   jal clear_bss
-#endif
 
   /* Check if the Heart State Management (HSM) extension exists, so it can be
    * used to switch harts if we are not running on hart CONFIG_FIRST_HART_ID.