[PATCH v5 19/22] riscv: linker script: create separate PT_LOAD segments for text, rodata, and data

[Sascha Hauer]

Fix the linker script to generate three distinct PT_LOAD segments with
correct permissions instead of combining .rodata with .data.

Before this fix, the linker auto-generated only two PT_LOAD segments:
1. Text segment (PF_R|PF_X)
2. Data segment (PF_R|PF_W) - containing .rodata, .data, .bss, etc.

With explicit PHDRS directives, we now generate three segments:
1. text segment (PF_R|PF_X): .text and related code sections
2. rodata segment (PF_R): .rodata and related read-only sections
3. data segment (PF_R|PF_W): .data, .bss, and related sections

With this we can setup the MMU properly from outside the ELF binary.

Reviewed-by: Ahmad Fatoum <a.fat...@pengutronix.de>
Signed-off-by: Sascha Hauer <s.ha...@pengutronix.de>
---
 arch/riscv/lib/barebox.lds.S | 38 +++++++++++++++++++++++++-------------
 1 file changed, 25 insertions(+), 13 deletions(-)

diff --git a/arch/riscv/lib/barebox.lds.S b/arch/riscv/lib/barebox.lds.S
index 03b3a96719..0cfa4bff57 100644
--- a/arch/riscv/lib/barebox.lds.S
+++ b/arch/riscv/lib/barebox.lds.S
@@ -16,14 +16,23 @@
 OUTPUT_ARCH(BAREBOX_OUTPUT_ARCH)
 ENTRY(start)
 OUTPUT_FORMAT(BAREBOX_OUTPUT_FORMAT)
+
+PHDRS
+{
+       text PT_LOAD FLAGS(5);          /* PF_R | PF_X */
+       rodata PT_LOAD FLAGS(4);        /* PF_R */
+       dynamic PT_DYNAMIC FLAGS(4);    /* PF_R */
+       data PT_LOAD FLAGS(6);          /* PF_R | PF_W */
+}
+
 SECTIONS
 {
        . = 0x0;
 
-       .image_start : { *(.__image_start) }
+       .image_start : { *(.__image_start) } :text
 
        . = ALIGN(4);
-       ._text : { *(._text) }
+       ._text : { *(._text) } :text
        .text      :
        {
                _stext = .;
@@ -35,44 +44,47 @@ SECTIONS
                KEEP(*(.text_exceptions*))
                __exceptions_stop = .;
                *(.text*)
-       }
+       } :text
        BAREBOX_BARE_INIT_SIZE
 
-       . = ALIGN(4);
+       . = ALIGN(4096);
        __start_rodata = .;
        .rodata : {
                *(.rodata*)
                RO_DATA_SECTION
-       }
+       } :rodata
+
+       .dynamic : { *(.dynamic) } :rodata :dynamic
 
        __end_rodata = .;
        _etext = .;
        _sdata = .;
 
-       . = ALIGN(4);
-       .data : { *(.data*) }
+       . = ALIGN(4096);
+
+       .data : { *(.data*) } :data
 
        /DISCARD/ : { *(.rela.plt*) }
        .rela.dyn : {
                __rel_dyn_start = .;
                *(.rel*)
                __rel_dyn_end = .;
-       }
+       } :data
 
        .dynsym : {
                __dynsym_start = .;
                *(.dynsym)
                __dynsym_end = .;
-       }
+       } :data
 
        _edata = .;
 
-       .image_end : { *(.__image_end) }
+       .image_end : { *(.__image_end) } :data
 
        . = ALIGN(4);
-       .__bss_start :  { *(.__bss_start) }
-       .bss : { *(.bss*) }
-       .__bss_stop :  { *(.__bss_stop) }
+       .__bss_start :  { *(.__bss_start) } :data
+       .bss : { *(.bss*) } :data
+       .__bss_stop :  { *(.__bss_stop) } :data
        _end = .;
        _barebox_image_size = __bss_start;
 }

-- 
2.47.3