On 11/03/2022 02:38, Guo Ren wrote:

Hi Arnd,

On Mon, Feb 28, 2022 at 12:30 AM [off-list ref] wrote:

quoted

From: Guo Ren <redacted>

If the current task is in COMPAT mode, set SR_UXL_32 in status for
returning userspace. We need CONFIG _COMPAT to prevent compiling
errors with rv32 defconfig.

Signed-off-by: Guo Ren <redacted>
Signed-off-by: Guo Ren <guoren@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
---
  arch/riscv/kernel/process.c | 5 +++++
  1 file changed, 5 insertions(+)

diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c
index 03ac3aa611f5..54787ca9806a 100644
--- a/arch/riscv/kernel/process.c
+++ b/arch/riscv/kernel/process.c

@@ -97,6 +97,11 @@ void start_thread(struct pt_regs *regs, unsigned long pc,
         }
         regs->epc = pc;
         regs->sp = sp;
+

FIxup:

+ #ifdef CONFIG_COMPAT

quoted

+       if (is_compat_task())
+               regs->status = (regs->status & ~SR_UXL) | SR_UXL_32;
+       else
+               regs->status = (regs->status & ~SR_UXL) | SR_UXL_64;

+ #endif

We still need "#ifdef CONFIG_COMPAT" here, because for rv32 we can't
set SR_UXL at all. SR_UXL is BIT[32, 33].

would an if (IS_ENABLED(CONFIG_COMPAT)) { } around the lot be better
than an #ifdef here?

quoted

  }

  void flush_thread(void)
--
2.25.1

-- 
Ben Dooks				http://www.codethink.co.uk/
Senior Engineer				Codethink - Providing Genius

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