Re: [PATCH v3 27/37] x86/shstk: Introduce routines modifying shstk
From: Peter Zijlstra <peterz@infradead.org>
Date: 2022-11-15 19:44:04
Also in:
linux-arch, linux-doc, linux-mm, lkml
On Fri, Nov 04, 2022 at 03:35:54PM -0700, Rick Edgecombe wrote:
+#ifdef CONFIG_X86_USER_SHADOW_STACK
+static inline int write_user_shstk_64(u64 __user *addr, u64 val)
+{
+ asm_volatile_goto("1: wrussq %[val], (%[addr])\n"
+ _ASM_EXTABLE(1b, %l[fail])
+ :: [addr] "r" (addr), [val] "r" (val)
+ :: fail);
+ return 0;
+fail:
+ return -EFAULT;
+}
+#endif /* CONFIG_X86_USER_SHADOW_STACK */Why isn't this modelled after put_user() ? Should you write a 64bit value even if the task receiving a signal is 32bit ?