Patch "riscv: Fix syscall wrapper for >word-size arguments" has been added to the 6.7-stable tree

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This is a note to let you know that I've just added the patch titled

    riscv: Fix syscall wrapper for >word-size arguments

to the 6.7-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     riscv-fix-syscall-wrapper-for-word-size-arguments.patch
and it can be found in the queue-6.7 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 793aeac1c9174dce5a1dc22c8ea70324b497342c
Author: Sami Tolvanen <samitolvanen@xxxxxxxxxx>
Date:   Mon Mar 11 19:31:44 2024 +0000

    riscv: Fix syscall wrapper for >word-size arguments
    
    [ Upstream commit a9ad73295cc1e3af0253eee7d08943b2419444c4 ]
    
    The current syscall wrapper macros break 64-bit arguments on
    rv32 because they only guarantee the first N input registers are
    passed to syscalls that accept N arguments. According to the
    calling convention, values twice the word size reside in register
    pairs and as a result, syscall arguments don't always have a
    direct register mapping on rv32.
    
    Instead of using `__MAP(x,__SC_LONG,__VA_ARGS__)` to declare the
    type of the `__se(_compat)_sys_*` functions on rv32, change the
    function declarations to accept `ulong` arguments and alias them
    to the actual syscall implementations, similarly to the existing
    macros in include/linux/syscalls.h. This matches previous
    behavior and ensures registers are passed to syscalls as-is, no
    matter which argument types they expect.
    
    Fixes: 08d0ce30e0e4 ("riscv: Implement syscall wrappers")
    Reported-by: Khem Raj <raj.khem@xxxxxxxxx>
    Signed-off-by: Sami Tolvanen <samitolvanen@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/20240311193143.2981310-2-samitolvanen@xxxxxxxxxx
    Signed-off-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/arch/riscv/include/asm/syscall_wrapper.h b/arch/riscv/include/asm/syscall_wrapper.h
index eeec04b7dae67..980094c2e9761 100644
--- a/arch/riscv/include/asm/syscall_wrapper.h
+++ b/arch/riscv/include/asm/syscall_wrapper.h
@@ -12,25 +12,51 @@
 
 asmlinkage long __riscv_sys_ni_syscall(const struct pt_regs *);
 
-#define SC_RISCV_REGS_TO_ARGS(x, ...)				\
-	__MAP(x,__SC_ARGS					\
-	      ,,regs->orig_a0,,regs->a1,,regs->a2		\
+#ifdef CONFIG_64BIT
+
+#define __SYSCALL_SE_DEFINEx(x, prefix, name, ...)					\
+	static long __se_##prefix##name(__MAP(x,__SC_LONG,__VA_ARGS__));		\
+	static long __se_##prefix##name(__MAP(x,__SC_LONG,__VA_ARGS__))
+
+#define SC_RISCV_REGS_TO_ARGS(x, ...)							\
+	__MAP(x,__SC_ARGS								\
+	      ,,regs->orig_a0,,regs->a1,,regs->a2					\
 	      ,,regs->a3,,regs->a4,,regs->a5,,regs->a6)
 
+#else
+/*
+ * Use type aliasing to ensure registers a0-a6 are correctly passed to the syscall
+ * implementation when >word-size arguments are used.
+ */
+#define __SYSCALL_SE_DEFINEx(x, prefix, name, ...)					\
+	__diag_push();									\
+	__diag_ignore(GCC, 8, "-Wattribute-alias",					\
+			"Type aliasing is used to sanitize syscall arguments");		\
+	static long __se_##prefix##name(ulong, ulong, ulong, ulong, ulong, ulong, 	\
+					ulong)						\
+			__attribute__((alias(__stringify(___se_##prefix##name))));	\
+	__diag_pop();									\
+	static long noinline ___se_##prefix##name(__MAP(x,__SC_LONG,__VA_ARGS__));	\
+	static long ___se_##prefix##name(__MAP(x,__SC_LONG,__VA_ARGS__))
+
+#define SC_RISCV_REGS_TO_ARGS(x, ...) \
+	regs->orig_a0,regs->a1,regs->a2,regs->a3,regs->a4,regs->a5,regs->a6
+
+#endif /* CONFIG_64BIT */
+
 #ifdef CONFIG_COMPAT
 
 #define COMPAT_SYSCALL_DEFINEx(x, name, ...)						\
 	asmlinkage long __riscv_compat_sys##name(const struct pt_regs *regs);		\
 	ALLOW_ERROR_INJECTION(__riscv_compat_sys##name, ERRNO);				\
-	static long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__));		\
 	static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));	\
-	asmlinkage long __riscv_compat_sys##name(const struct pt_regs *regs)		\
+	__SYSCALL_SE_DEFINEx(x, compat_sys, name, __VA_ARGS__)				\
 	{										\
-		return __se_compat_sys##name(SC_RISCV_REGS_TO_ARGS(x,__VA_ARGS__));	\
+		return __do_compat_sys##name(__MAP(x,__SC_DELOUSE,__VA_ARGS__));	\
 	}										\
-	static long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__))		\
+	asmlinkage long __riscv_compat_sys##name(const struct pt_regs *regs)		\
 	{										\
-		return __do_compat_sys##name(__MAP(x,__SC_DELOUSE,__VA_ARGS__));	\
+		return __se_compat_sys##name(SC_RISCV_REGS_TO_ARGS(x,__VA_ARGS__));	\
 	}										\
 	static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))
 
@@ -51,19 +77,18 @@ asmlinkage long __riscv_sys_ni_syscall(const struct pt_regs *);
 #define __SYSCALL_DEFINEx(x, name, ...)						\
 	asmlinkage long __riscv_sys##name(const struct pt_regs *regs);		\
 	ALLOW_ERROR_INJECTION(__riscv_sys##name, ERRNO);			\
-	static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__));		\
 	static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));	\
-	asmlinkage long __riscv_sys##name(const struct pt_regs *regs)		\
-	{									\
-		return __se_sys##name(SC_RISCV_REGS_TO_ARGS(x,__VA_ARGS__));	\
-	}									\
-	static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__))		\
+	__SYSCALL_SE_DEFINEx(x, sys, name, __VA_ARGS__)				\
 	{									\
 		long ret = __do_sys##name(__MAP(x,__SC_CAST,__VA_ARGS__));	\
 		__MAP(x,__SC_TEST,__VA_ARGS__);					\
 		__PROTECT(x, ret,__MAP(x,__SC_ARGS,__VA_ARGS__));		\
 		return ret;							\
 	}									\
+	asmlinkage long __riscv_sys##name(const struct pt_regs *regs)		\
+	{									\
+		return __se_sys##name(SC_RISCV_REGS_TO_ARGS(x,__VA_ARGS__));	\
+	}									\
 	static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))
 
 #define SYSCALL_DEFINE0(sname)							\




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