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/alpha/lib/stacktrace.c | 103 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 103 insertions(+) create mode 100644 arch/alpha/lib/stacktrace.c (limited to 'arch/alpha/lib/stacktrace.c') diff --git a/arch/alpha/lib/stacktrace.c b/arch/alpha/lib/stacktrace.c new file mode 100644 index 000000000..2b1176dd5 --- /dev/null +++ b/arch/alpha/lib/stacktrace.c @@ -0,0 +1,103 @@ +// SPDX-License-Identifier: GPL-2.0 +#include + +typedef unsigned int instr; + +#define MAJOR_OP 0xfc000000 +#define LDA_OP 0x20000000 +#define STQ_OP 0xb4000000 +#define BR_OP 0xc0000000 + +#define STK_ALLOC_1 0x23de8000 /* lda $30,-X($30) */ +#define STK_ALLOC_1M 0xffff8000 +#define STK_ALLOC_2 0x43c0153e /* subq $30,X,$30 */ +#define STK_ALLOC_2M 0xffe01fff + +#define MEM_REG 0x03e00000 +#define MEM_BASE 0x001f0000 +#define MEM_OFF 0x0000ffff +#define MEM_OFF_SIGN 0x00008000 +#define BASE_SP 0x001e0000 + +#define STK_ALLOC_MATCH(INSTR) \ + (((INSTR) & STK_ALLOC_1M) == STK_ALLOC_1 \ + || ((INSTR) & STK_ALLOC_2M) == STK_ALLOC_2) +#define STK_PUSH_MATCH(INSTR) \ + (((INSTR) & (MAJOR_OP | MEM_BASE | MEM_OFF_SIGN)) == (STQ_OP | BASE_SP)) +#define MEM_OP_OFFSET(INSTR) \ + (((long)((INSTR) & MEM_OFF) << 48) >> 48) +#define MEM_OP_REG(INSTR) \ + (((INSTR) & MEM_REG) >> 22) + +/* Branches, jumps, PAL calls, and illegal opcodes end a basic block. */ +#define BB_END(INSTR) \ + (((instr)(INSTR) >= BR_OP) | ((instr)(INSTR) < LDA_OP) | \ + ((((instr)(INSTR) ^ 0x60000000) < 0x20000000) & \ + (((instr)(INSTR) & 0x0c000000) != 0))) + +#define IS_KERNEL_TEXT(PC) ((unsigned long)(PC) > START_ADDR) + +static char reg_name[][4] = { + "v0 ", "t0 ", "t1 ", "t2 ", "t3 ", "t4 ", "t5 ", "t6 ", "t7 ", + "s0 ", "s1 ", "s2 ", "s3 ", "s4 ", "s5 ", "s6 ", "a0 ", "a1 ", + "a2 ", "a3 ", "a4 ", "a5 ", "t8 ", "t9 ", "t10", "t11", "ra ", + "pv ", "at ", "gp ", "sp ", "0" +}; + + +static instr * +display_stored_regs(instr * pro_pc, unsigned char * sp) +{ + instr * ret_pc = 0; + int reg; + unsigned long value; + + printk("Prologue [<%p>], Frame %p:\n", pro_pc, sp); + while (!BB_END(*pro_pc)) + if (STK_PUSH_MATCH(*pro_pc)) { + reg = (*pro_pc & MEM_REG) >> 21; + value = *(unsigned long *)(sp + (*pro_pc & MEM_OFF)); + if (reg == 26) + ret_pc = (instr *)value; + printk("\t\t%s / 0x%016lx\n", reg_name[reg], value); + } + return ret_pc; +} + +static instr * +seek_prologue(instr * pc) +{ + while (!STK_ALLOC_MATCH(*pc)) + --pc; + while (!BB_END(*(pc - 1))) + --pc; + return pc; +} + +static long +stack_increment(instr * prologue_pc) +{ + while (!STK_ALLOC_MATCH(*prologue_pc)) + ++prologue_pc; + + /* Count the bytes allocated. */ + if ((*prologue_pc & STK_ALLOC_1M) == STK_ALLOC_1M) + return -(((long)(*prologue_pc) << 48) >> 48); + else + return (*prologue_pc >> 13) & 0xff; +} + +void +stacktrace(void) +{ + instr * ret_pc; + instr * prologue = (instr *)stacktrace; + unsigned char *sp = (unsigned char *)current_stack_pointer; + + printk("\tstack trace:\n"); + do { + ret_pc = display_stored_regs(prologue, sp); + sp += stack_increment(prologue); + prologue = seek_prologue(ret_pc); + } while (IS_KERNEL_TEXT(ret_pc)); +} -- cgit v1.3.1