diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2025-10-27 09:43:42 +0100 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2025-11-03 15:26:09 +0100 |
| commit | 44c5b6768e3a1385fdf3b10893404bc5a2c1248a (patch) | |
| tree | a29ea8d66f7f391c227c75517327a1e88ff763b4 | |
| parent | 6146a0f1dfae5d37442a9ddcba012add260bceb0 (diff) | |
ARM: uaccess: Implement missing __get_user_asm_dword()
When CONFIG_CPU_SPECTRE=n then get_user() is missing the 8 byte ASM variant
for no real good reason. This prevents using get_user(u64) in generic code.
Implement it as a sequence of two 4-byte reads with LE/BE awareness and
make the unsigned long (or long long) type for the intermediate variable to
read into dependend on the the target type.
The __long_type() macro and idea was lifted from PowerPC. Thanks to
Christophe for pointing it out.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202509120155.pFgwfeUD-lkp@intel.com/
Link: https://patch.msgid.link/20251027083745.168468637@linutronix.de
| -rw-r--r-- | arch/arm/include/asm/uaccess.h | 26 |
1 files changed, 25 insertions, 1 deletions
diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h index f90be312418e..d6ae80b5df36 100644 --- a/arch/arm/include/asm/uaccess.h +++ b/arch/arm/include/asm/uaccess.h @@ -283,10 +283,17 @@ extern int __put_user_8(void *, unsigned long long); __gu_err; \ }) +/* + * This is a type: either unsigned long, if the argument fits into + * that type, or otherwise unsigned long long. + */ +#define __long_type(x) \ + __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL)) + #define __get_user_err(x, ptr, err, __t) \ do { \ unsigned long __gu_addr = (unsigned long)(ptr); \ - unsigned long __gu_val; \ + __long_type(x) __gu_val; \ unsigned int __ua_flags; \ __chk_user_ptr(ptr); \ might_fault(); \ @@ -295,6 +302,7 @@ do { \ case 1: __get_user_asm_byte(__gu_val, __gu_addr, err, __t); break; \ case 2: __get_user_asm_half(__gu_val, __gu_addr, err, __t); break; \ case 4: __get_user_asm_word(__gu_val, __gu_addr, err, __t); break; \ + case 8: __get_user_asm_dword(__gu_val, __gu_addr, err, __t); break; \ default: (__gu_val) = __get_user_bad(); \ } \ uaccess_restore(__ua_flags); \ @@ -353,6 +361,22 @@ do { \ #define __get_user_asm_word(x, addr, err, __t) \ __get_user_asm(x, addr, err, "ldr" __t) +#ifdef __ARMEB__ +#define __WORD0_OFFS 4 +#define __WORD1_OFFS 0 +#else +#define __WORD0_OFFS 0 +#define __WORD1_OFFS 4 +#endif + +#define __get_user_asm_dword(x, addr, err, __t) \ + ({ \ + unsigned long __w0, __w1; \ + __get_user_asm(__w0, addr + __WORD0_OFFS, err, "ldr" __t); \ + __get_user_asm(__w1, addr + __WORD1_OFFS, err, "ldr" __t); \ + (x) = ((u64)__w1 << 32) | (u64) __w0; \ +}) + #define __put_user_switch(x, ptr, __err, __fn) \ do { \ const __typeof__(*(ptr)) __user *__pu_ptr = (ptr); \ |