From: Ziqiao Kong <ziqiaok...@gmail.com>
On big endian systems, pte and updated_pte hold big endian host data
while pte_pa points to little endian target data. This means the branch
at cpu_helper.c:1669 will be always satisfied and restart translation,
causing an endless translation loop.
The correctness of this patch can be deduced by:
old_pte will hold value either from cpu_to_le32/64(pte) or
cpu_to_le32/64(updated_pte), both of wich is litte endian. After that,
an in-place conversion by le32/64_to_cpu(old_pte) ensures that old_pte
now is in native endian, same with pte. Therefore, the endianness of the
both side of if (old_pte != pte) is correct.
Signed-off-by: Ziqiao Kong <ziqiaok...@gmail.com>
Reviewed-by: Alistair Francis <alistair.fran...@wdc.com>
Reviewed-by: Richard Henderson <richard.hender...@linaro.org>
Message-ID: <20250415080254.3667878-2-ziqiaok...@gmail.com>
Signed-off-by: Alistair Francis <alistair.fran...@wdc.com>
Cc: qemu-sta...@nongnu.org
---
target/riscv/cpu_helper.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
index d5039f69a9..2ed69d7c2d 100644
--- a/target/riscv/cpu_helper.c
+++ b/target/riscv/cpu_helper.c
@@ -1566,9 +1566,11 @@ static int get_physical_address(CPURISCVState *env,
hwaddr *physical,
target_ulong *pte_pa = qemu_map_ram_ptr(mr->ram_block, addr1);
target_ulong old_pte;
if (riscv_cpu_sxl(env) == MXL_RV32) {
- old_pte = qatomic_cmpxchg((uint32_t *)pte_pa, pte,
updated_pte);
+ old_pte = qatomic_cmpxchg((uint32_t *)pte_pa,
cpu_to_le32(pte), cpu_to_le32(updated_pte));
+ old_pte = le32_to_cpu(old_pte);
} else {
- old_pte = qatomic_cmpxchg(pte_pa, pte, updated_pte);
+ old_pte = qatomic_cmpxchg(pte_pa, cpu_to_le64(pte),
cpu_to_le64(updated_pte));
+ old_pte = le64_to_cpu(old_pte);
}
if (old_pte != pte) {
goto restart;
--
2.49.0
