[XS] Change in coreboot[main]: libpayload: Move ttb_buffer to a standalone section

[Martin L Roth (Code Review)]

Martin L Roth has submitted this change. ( https://review.coreboot.org/c/coreboot/+/79078?usp=email )

(

8 is the latest approved patch-set.
No files were changed between the latest approved patch-set and the submitted one.
 )Change subject: libpayload: Move ttb_buffer to a standalone section
......................................................................

libpayload: Move ttb_buffer to a standalone section

When cleaning the sensitive data in the memory, we will want to prevent
zero out the content of tbb_buffer. Move the ttb_buffer to a standalone
section will simplify the problem.

BUG=b:248610274
TEST=emerge-cherry libpayload
BRANCH=none

Change-Id: I610276cbe30552263d791860c15e5ad9a201c744
Signed-off-by: Yi Chou 
Reviewed-on: https://review.coreboot.org/c/coreboot/+/79078
Reviewed-by: Julius Werner 
Tested-by: build bot (Jenkins) 
---
M payloads/libpayload/arch/arm64/libpayload.ldscript
M payloads/libpayload/arch/arm64/mmu.c
2 files changed, 4 insertions(+), 1 deletion(-)

Approvals:
  Julius Werner: Looks good to me, approved
  build bot (Jenkins): Verified

diff --git a/payloads/libpayload/arch/arm64/libpayload.ldscript b/payloads/libpayload/arch/arm64/libpayload.ldscript
index f9fb771..e225aa8 100644
--- a/payloads/libpayload/arch/arm64/libpayload.ldscript
+++ b/payloads/libpayload/arch/arm64/libpayload.ldscript
@@ -58,6 +58,8 @@
    _edata = .;

.bss : {
+		*(.ttb_buffer)
+
    	*(.sbss)
    	*(.sbss.*)
    	*(.bss)
diff --git a/payloads/libpayload/arch/arm64/mmu.c b/payloads/libpayload/arch/arm64/mmu.c
index 4c8f8c1..bb79544 100644
--- a/payloads/libpayload/arch/arm64/mmu.c
+++ b/payloads/libpayload/arch/arm64/mmu.c
@@ -41,7 +41,8 @@
 static uint64_t *xlat_addr;

static int free_idx;
-static uint8_t ttb_buffer[TTB_DEFAULT_SIZE] __attribute__((aligned(GRANULE_SIZE)));
+static uint8_t ttb_buffer[TTB_DEFAULT_SIZE] __aligned(GRANULE_SIZE)
+	__attribute__((__section__(".ttb_buffer")));

static const char * const tag_to_string[] = {
    [TYPE_NORMAL_MEM] = "normal",