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/arm64/lib/mte.S | 177 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 177 insertions(+) create mode 100644 arch/arm64/lib/mte.S (limited to 'arch/arm64/lib/mte.S') diff --git a/arch/arm64/lib/mte.S b/arch/arm64/lib/mte.S new file mode 100644 index 000000000..5018ac03b --- /dev/null +++ b/arch/arm64/lib/mte.S @@ -0,0 +1,177 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2020 ARM Ltd. + */ +#include + +#include +#include +#include +#include +#include + + .arch armv8.5-a+memtag + +/* + * multitag_transfer_size - set \reg to the block size that is accessed by the + * LDGM/STGM instructions. + */ + .macro multitag_transfer_size, reg, tmp + mrs_s \reg, SYS_GMID_EL1 + ubfx \reg, \reg, #GMID_EL1_BS_SHIFT, #GMID_EL1_BS_WIDTH + mov \tmp, #4 + lsl \reg, \tmp, \reg + .endm + +/* + * Clear the tags in a page + * x0 - address of the page to be cleared + */ +SYM_FUNC_START(mte_clear_page_tags) + multitag_transfer_size x1, x2 +1: stgm xzr, [x0] + add x0, x0, x1 + tst x0, #(PAGE_SIZE - 1) + b.ne 1b + ret +SYM_FUNC_END(mte_clear_page_tags) + +/* + * Zero the page and tags at the same time + * + * Parameters: + * x0 - address to the beginning of the page + */ +SYM_FUNC_START(mte_zero_clear_page_tags) + and x0, x0, #(1 << MTE_TAG_SHIFT) - 1 // clear the tag + mrs x1, dczid_el0 + tbnz x1, #4, 2f // Branch if DC GZVA is prohibited + and w1, w1, #0xf + mov x2, #4 + lsl x1, x2, x1 + +1: dc gzva, x0 + add x0, x0, x1 + tst x0, #(PAGE_SIZE - 1) + b.ne 1b + ret + +2: stz2g x0, [x0], #(MTE_GRANULE_SIZE * 2) + tst x0, #(PAGE_SIZE - 1) + b.ne 2b + ret +SYM_FUNC_END(mte_zero_clear_page_tags) + +/* + * Copy the tags from the source page to the destination one + * x0 - address of the destination page + * x1 - address of the source page + */ +SYM_FUNC_START(mte_copy_page_tags) + mov x2, x0 + mov x3, x1 + multitag_transfer_size x5, x6 +1: ldgm x4, [x3] + stgm x4, [x2] + add x2, x2, x5 + add x3, x3, x5 + tst x2, #(PAGE_SIZE - 1) + b.ne 1b + ret +SYM_FUNC_END(mte_copy_page_tags) + +/* + * Read tags from a user buffer (one tag per byte) and set the corresponding + * tags at the given kernel address. Used by PTRACE_POKEMTETAGS. + * x0 - kernel address (to) + * x1 - user buffer (from) + * x2 - number of tags/bytes (n) + * Returns: + * x0 - number of tags read/set + */ +SYM_FUNC_START(mte_copy_tags_from_user) + mov x3, x1 + cbz x2, 2f +1: +USER(2f, ldtrb w4, [x1]) + lsl x4, x4, #MTE_TAG_SHIFT + stg x4, [x0], #MTE_GRANULE_SIZE + add x1, x1, #1 + subs x2, x2, #1 + b.ne 1b + + // exception handling and function return +2: sub x0, x1, x3 // update the number of tags set + ret +SYM_FUNC_END(mte_copy_tags_from_user) + +/* + * Get the tags from a kernel address range and write the tag values to the + * given user buffer (one tag per byte). Used by PTRACE_PEEKMTETAGS. + * x0 - user buffer (to) + * x1 - kernel address (from) + * x2 - number of tags/bytes (n) + * Returns: + * x0 - number of tags read/set + */ +SYM_FUNC_START(mte_copy_tags_to_user) + mov x3, x0 + cbz x2, 2f +1: + ldg x4, [x1] + ubfx x4, x4, #MTE_TAG_SHIFT, #MTE_TAG_SIZE +USER(2f, sttrb w4, [x0]) + add x0, x0, #1 + add x1, x1, #MTE_GRANULE_SIZE + subs x2, x2, #1 + b.ne 1b + + // exception handling and function return +2: sub x0, x0, x3 // update the number of tags copied + ret +SYM_FUNC_END(mte_copy_tags_to_user) + +/* + * Save the tags in a page + * x0 - page address + * x1 - tag storage, MTE_PAGE_TAG_STORAGE bytes + */ +SYM_FUNC_START(mte_save_page_tags) + multitag_transfer_size x7, x5 +1: + mov x2, #0 +2: + ldgm x5, [x0] + orr x2, x2, x5 + add x0, x0, x7 + tst x0, #0xFF // 16 tag values fit in a register, + b.ne 2b // which is 16*16=256 bytes + + str x2, [x1], #8 + + tst x0, #(PAGE_SIZE - 1) + b.ne 1b + + ret +SYM_FUNC_END(mte_save_page_tags) + +/* + * Restore the tags in a page + * x0 - page address + * x1 - tag storage, MTE_PAGE_TAG_STORAGE bytes + */ +SYM_FUNC_START(mte_restore_page_tags) + multitag_transfer_size x7, x5 +1: + ldr x2, [x1], #8 +2: + stgm x2, [x0] + add x0, x0, x7 + tst x0, #0xFF + b.ne 2b + + tst x0, #(PAGE_SIZE - 1) + b.ne 1b + + ret +SYM_FUNC_END(mte_restore_page_tags) -- cgit v1.3.1