From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops There's some internal state that ftrace_ops needs to have set, but since it can be declared outside of the ftrace.c code, it calls ftrace_ops_init() on the ops in every global function. The issue is that if two tasks call it on the same ops at the same time it is possible to have the initialization of one corrupt the initialization of the other call. Create a ops_mutex to use to synchronize every initialization of the ftrace_ops. The mutex is taken within checking the ftrace_ops flag that states it was initializied but the flag is checked again after the mutex has been taken. Checking first outside the mutex allows it to shortcut having to take the mutex. But then the check needs to be done again after the mute is taken in case of races. Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock") Reported-by: sashiko-bot@kernel.org Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/ Signed-off-by: Steven Rostedt --- arch/xtensa/lib/mulsi3.S | 134 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 134 insertions(+) create mode 100644 arch/xtensa/lib/mulsi3.S (limited to 'arch/xtensa/lib/mulsi3.S') diff --git a/arch/xtensa/lib/mulsi3.S b/arch/xtensa/lib/mulsi3.S new file mode 100644 index 000000000..c6b4fd46b --- /dev/null +++ b/arch/xtensa/lib/mulsi3.S @@ -0,0 +1,134 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later WITH GCC-exception-2.0 */ +#include +#include +#include + + .macro do_addx2 dst, as, at, tmp +#if XCHAL_HAVE_ADDX + addx2 \dst, \as, \at +#else + slli \tmp, \as, 1 + add \dst, \tmp, \at +#endif + .endm + + .macro do_addx4 dst, as, at, tmp +#if XCHAL_HAVE_ADDX + addx4 \dst, \as, \at +#else + slli \tmp, \as, 2 + add \dst, \tmp, \at +#endif + .endm + + .macro do_addx8 dst, as, at, tmp +#if XCHAL_HAVE_ADDX + addx8 \dst, \as, \at +#else + slli \tmp, \as, 3 + add \dst, \tmp, \at +#endif + .endm + +ENTRY(__mulsi3) + + abi_entry_default + +#if XCHAL_HAVE_MUL32 + mull a2, a2, a3 + +#elif XCHAL_HAVE_MUL16 + or a4, a2, a3 + srai a4, a4, 16 + bnez a4, .LMUL16 + mul16u a2, a2, a3 + abi_ret_default +.LMUL16: + srai a4, a2, 16 + srai a5, a3, 16 + mul16u a7, a4, a3 + mul16u a6, a5, a2 + mul16u a4, a2, a3 + add a7, a7, a6 + slli a7, a7, 16 + add a2, a7, a4 + +#elif XCHAL_HAVE_MAC16 + mul.aa.hl a2, a3 + mula.aa.lh a2, a3 + rsr a5, ACCLO + umul.aa.ll a2, a3 + rsr a4, ACCLO + slli a5, a5, 16 + add a2, a4, a5 + +#else /* !MUL32 && !MUL16 && !MAC16 */ + + /* Multiply one bit at a time, but unroll the loop 4x to better + exploit the addx instructions and avoid overhead. + Peel the first iteration to save a cycle on init. */ + + /* Avoid negative numbers. */ + xor a5, a2, a3 /* Top bit is 1 if one input is negative. */ + do_abs a3, a3, a6 + do_abs a2, a2, a6 + + /* Swap so the second argument is smaller. */ + sub a7, a2, a3 + mov a4, a3 + movgez a4, a2, a7 /* a4 = max (a2, a3) */ + movltz a3, a2, a7 /* a3 = min (a2, a3) */ + + movi a2, 0 + extui a6, a3, 0, 1 + movnez a2, a4, a6 + + do_addx2 a7, a4, a2, a7 + extui a6, a3, 1, 1 + movnez a2, a7, a6 + + do_addx4 a7, a4, a2, a7 + extui a6, a3, 2, 1 + movnez a2, a7, a6 + + do_addx8 a7, a4, a2, a7 + extui a6, a3, 3, 1 + movnez a2, a7, a6 + + bgeui a3, 16, .Lmult_main_loop + neg a3, a2 + movltz a2, a3, a5 + abi_ret_default + + .align 4 +.Lmult_main_loop: + srli a3, a3, 4 + slli a4, a4, 4 + + add a7, a4, a2 + extui a6, a3, 0, 1 + movnez a2, a7, a6 + + do_addx2 a7, a4, a2, a7 + extui a6, a3, 1, 1 + movnez a2, a7, a6 + + do_addx4 a7, a4, a2, a7 + extui a6, a3, 2, 1 + movnez a2, a7, a6 + + do_addx8 a7, a4, a2, a7 + extui a6, a3, 3, 1 + movnez a2, a7, a6 + + bgeui a3, 16, .Lmult_main_loop + + neg a3, a2 + movltz a2, a3, a5 + +#endif /* !MUL32 && !MUL16 && !MAC16 */ + + abi_ret_default + +ENDPROC(__mulsi3) +EXPORT_SYMBOL(__mulsi3) -- cgit v1.3.1