Re: [PATCH RFC v2 1/2] m68k: Handle __generic_copy_to_user faults more carefully

[Finn Thain <fthain@linux-m68k.org>]

On Fri, 26 Apr 2024, Michael Schmitz wrote:

> Not sure you noticed this - the 040 passed __clear_user without fault. 
> We managed to test this one without meaning to. Exception handling in 
> there appears to work OK (for the cases we're testing).
> 
> No idea why you have the __clear_user call occur within 
> __generic_copy_to_user - it does not appear in my disassembly.
> 

I'm afraid I neglected to mention that I added the patch below in order to 
exercise that code path.

diff --git a/arch/m68k/lib/uaccess.c b/arch/m68k/lib/uaccess.c
index ef761fc10981..1c9a24a0b554 100644
--- a/arch/m68k/lib/uaccess.c
+++ b/arch/m68k/lib/uaccess.c
@@ -58,6 +58,8 @@ unsigned long __generic_copy_to_user(void __user *to, const void *from,
 {
 	unsigned long tmp, res;
 
+	__clear_user(to, n);
+
 	asm volatile ("\n"
 		"	tst.l	%0\n"
 		"	jeq	5f\n"