[PATCH master 1/2] ARM: document PBL barebox memory layout

[PATCH master 1/2] ARM: document PBL barebox memory layout

[Ahmad Fatoum]

Apparently, we have an overlap between ramoops/barebox proper
and the early malloc area. Before fixing that, let's add a diagram
explaining the current state of affairs.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 arch/arm/include/asm/barebox-arm.h | 36 ++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/arch/arm/include/asm/barebox-arm.h b/arch/arm/include/asm/barebox-arm.h
index 4d70360b9121..30834233fb96 100644
--- a/arch/arm/include/asm/barebox-arm.h
+++ b/arch/arm/include/asm/barebox-arm.h
@@ -52,6 +52,42 @@ static inline void arm_fixup_vectors(void)
 
 void *barebox_arm_boot_dtb(void);
 
+/*
+ *  ----------------------------- endmem ------------------------------
+ *                                   ↑
+ *	        OPTEE_SIZE (depends on CONFIG_OPTEE_SIZE)
+ *                                   ↓
+ *  ------------------------- arm_mem_optee() -------------------------
+ *                                   ↑
+ *                                 SZ_32K
+ *                                   ↓
+ *  ------------------------ arm_mem_scratch() ------------------------
+ *                                   ↑
+ *                               STACK_SIZE
+ *                                   ↓
+ *  ------------------------- arm_mem_stack() -------------------------
+ *                                   ↑
+ *            PAGE_SIZE (depends on CONFIG_STACK_GUARD_PAGE)
+ *                                   ↓
+ *  ----------------------- arm_mem_guard_page() ----------------------
+ *                                   ↑
+ *                       ARM_EARLY_PAGETABLE_SIZE
+ *                                   ↓
+ *  ------------ arm_mem_ttb() / arm_mem_early_malloc_end() ------------
+ *                                   ↑                          ↑
+ *                     CONFIG_FS_PSTORE_RAMOOPS_SIZE         SZ_128K
+ *                     (depends on FS_PSTORE_RAMOOPS)           |
+ *                                   |                          ↓
+ *                                   | ------ arm_mem_early_malloc() ---
+ *                                   ↓
+ *  ------------------------- arm_mem_ramoops() ------------------------
+ *                                   ↑
+ *                   (barebox uncompressed image size
+ *                       + BSS) rounded to SZ_1M
+ *                                   ↓
+ *  ---------------------- arm_mem_barebox_image() ---------------------
+ */
+
 static inline unsigned long arm_mem_optee(unsigned long endmem)
 {
 	return endmem - OPTEE_SIZE;
-- 
2.39.2

[PATCH master 2/2] ARM: fix overlap between ramoops area and early malloc area

[Ahmad Fatoum]

ramoops is usually a few megabytes and the early malloc area is just
128K, so the effect of this overlap was likely limited, but depending on
size of the data stored to pstore, this could still lead to problems.

Avoid this by locating the early malloc area before the barebox binary.
That way that space is reclaimed in barebox proper for the non-early
malloc region.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 arch/arm/cpu/uncompress.c          |  4 ++--
 arch/arm/include/asm/barebox-arm.h | 24 +++++++++---------------
 2 files changed, 11 insertions(+), 17 deletions(-)

diff --git a/arch/arm/cpu/uncompress.c b/arch/arm/cpu/uncompress.c
index aa1a49bfc96a..612a5b65ff4c 100644
--- a/arch/arm/cpu/uncompress.c
+++ b/arch/arm/cpu/uncompress.c
@@ -66,8 +66,8 @@ void __noreturn barebox_pbl_start(unsigned long membase, unsigned long memsize,
 	if (IS_ENABLED(CONFIG_MMU))
 		mmu_early_enable(membase, memsize);
 
-	free_mem_ptr = arm_mem_early_malloc(endmem);
-	free_mem_end_ptr = arm_mem_early_malloc_end(endmem);
+	free_mem_ptr = barebox_base - ARM_MEM_EARLY_MALLOC_SIZE;
+	free_mem_end_ptr = barebox_base;
 
 	pr_debug("uncompressing barebox binary at 0x%p (size 0x%08x) to 0x%08lx (uncompressed size: 0x%08x)\n",
 			pg_start, pg_len, barebox_base, uncompressed_len);
diff --git a/arch/arm/include/asm/barebox-arm.h b/arch/arm/include/asm/barebox-arm.h
index 30834233fb96..c64e74f8f03a 100644
--- a/arch/arm/include/asm/barebox-arm.h
+++ b/arch/arm/include/asm/barebox-arm.h
@@ -73,12 +73,10 @@ void *barebox_arm_boot_dtb(void);
  *                                   ↑
  *                       ARM_EARLY_PAGETABLE_SIZE
  *                                   ↓
- *  ------------ arm_mem_ttb() / arm_mem_early_malloc_end() ------------
- *                                   ↑                          ↑
- *                     CONFIG_FS_PSTORE_RAMOOPS_SIZE         SZ_128K
- *                     (depends on FS_PSTORE_RAMOOPS)           |
- *                                   |                          ↓
- *                                   | ------ arm_mem_early_malloc() ---
+ *  --------------------------- arm_mem_ttb() -------------------------
+ *                                   ↑
+ *                     CONFIG_FS_PSTORE_RAMOOPS_SIZE
+ *                     (depends on FS_PSTORE_RAMOOPS)
  *                                   ↓
  *  ------------------------- arm_mem_ramoops() ------------------------
  *                                   ↑
@@ -86,6 +84,10 @@ void *barebox_arm_boot_dtb(void);
  *                       + BSS) rounded to SZ_1M
  *                                   ↓
  *  ---------------------- arm_mem_barebox_image() ---------------------
+ *                                   ↑
+ *                                SZ_128K
+ *                                   ↓
+ *  ------------------------ arm_mem_early_malloc ----------------------
  */
 
 static inline unsigned long arm_mem_optee(unsigned long endmem)
@@ -121,15 +123,7 @@ static inline unsigned long arm_mem_ttb(unsigned long endmem)
 	return endmem;
 }
 
-static inline unsigned long arm_mem_early_malloc(unsigned long endmem)
-{
-	return arm_mem_ttb(endmem) - SZ_128K;
-}
-
-static inline unsigned long arm_mem_early_malloc_end(unsigned long endmem)
-{
-	return arm_mem_ttb(endmem);
-}
+#define ARM_MEM_EARLY_MALLOC_SIZE	SZ_128K
 
 static inline unsigned long arm_mem_ramoops(unsigned long endmem)
 {
-- 
2.39.2

Re: [PATCH master 1/2] ARM: document PBL barebox memory layout

[Sascha Hauer]

On Fri, 17 May 2024 08:10:56 +0200, Ahmad Fatoum wrote:
> Apparently, we have an overlap between ramoops/barebox proper
> and the early malloc area. Before fixing that, let's add a diagram
> explaining the current state of affairs.
> 
> 

Applied, thanks!

[1/2] ARM: document PBL barebox memory layout
      https://git.pengutronix.de/cgit/barebox/commit/?id=c9af0d2b5e57 (link may not be stable)
[2/2] ARM: fix overlap between ramoops area and early malloc area
      https://git.pengutronix.de/cgit/barebox/commit/?id=d1cc8a4045a0 (link may not be stable)

Best regards,
-- 
Sascha Hauer <s.hauer@pengutronix.de>