[PATCH master 3/3] RISC-V: add compiler barriers around unrelocated accesses

[Ahmad Fatoum]

We observed on ARM miscompilation because get_runtime_offset() was
cached before relocation, while address computation of symbol happened
after, effectively adding the base address twice to the symbol offset.

New get_unrelocated() hides origin of the symbol going into the address
calculation and thereby thwarts this optimization. Employ it in RISC-V
code as well to avoid such issues as experienced on ARM.

Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
---
 arch/riscv/boot/uncompress.c      | 4 ++--
 arch/riscv/include/asm/sections.h | 2 +-
 arch/riscv/lib/reloc.c            | 6 +++---
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/riscv/boot/uncompress.c b/arch/riscv/boot/uncompress.c
index ee24f81e0159..eab51c8d52bc 100644
--- a/arch/riscv/boot/uncompress.c
+++ b/arch/riscv/boot/uncompress.c
@@ -36,8 +36,8 @@ void __noreturn barebox_pbl_start(unsigned long membase, unsigned long memsize,
 	irq_init_vector(riscv_mode());
 
 	/* piggy data is not relocated, so determine the bounds now */
-	pg_start = input_data + get_runtime_offset();
-	pg_end = input_data_end + get_runtime_offset();
+	pg_start = get_unrelocated(input_data);
+	pg_end = get_unrelocated(input_data_end);
 	pg_len = pg_end - pg_start;
 	uncompressed_len = input_data_len();
 
diff --git a/arch/riscv/include/asm/sections.h b/arch/riscv/include/asm/sections.h
index 6673648bcd58..b90f4d6d2ad5 100644
--- a/arch/riscv/include/asm/sections.h
+++ b/arch/riscv/include/asm/sections.h
@@ -19,7 +19,7 @@ unsigned long get_runtime_offset(void);
 
 static inline unsigned int input_data_len(void)
 {
-	return get_unaligned((const u32 *)(input_data_end + get_runtime_offset() - 4));
+	return get_unaligned((const u32 *)get_unrelocated(input_data_end) - 1);
 }
 
 #endif
diff --git a/arch/riscv/lib/reloc.c b/arch/riscv/lib/reloc.c
index 13118a9ac54f..1dddf627d0b9 100644
--- a/arch/riscv/lib/reloc.c
+++ b/arch/riscv/lib/reloc.c
@@ -42,9 +42,9 @@ void relocate_to_current_adr(void)
 	if (!offset)
 		return;
 
-	dstart = __rel_dyn_start + offset;
-	dend = __rel_dyn_end + offset;
-	dynsym = (void *)__dynsym_start + offset;
+	dstart = get_unrelocated(__rel_dyn_start);
+	dend = get_unrelocated(__rel_dyn_end);
+	dynsym = get_unrelocated(__dynsym_start) + offset;
 
 	for (rela = dstart; (void *)rela < dend; rela++) {
 		unsigned long *fixup;
-- 
2.30.2