Unverified Commit a9ad7329 authored by Sami Tolvanen's avatar Sami Tolvanen Committed by Palmer Dabbelt
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riscv: Fix syscall wrapper for >word-size arguments 



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: 08d0ce30 ("riscv: Implement syscall wrappers")
Reported-by: default avatarKhem Raj <raj.khem@gmail.com>
Signed-off-by: default avatarSami Tolvanen <samitolvanen@google.com>
Link: https://lore.kernel.org/r/20240311193143.2981310-2-samitolvanen@google.com


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent eeb7a893

arch/riscv/include/asm/syscall_wrapper.h

+39 −14
Original line number Diff line number Diff line
@@ -12,25 +12,51 @@ 


asmlinkage long __riscv_sys_ni_syscall(const struct pt_regs *);



#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)							\