From 9cc63f8bcd560c760d0b12e15bba8f81c86237cf Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Fri, 14 Aug 2026 15:43:51 -0700 Subject: Merge branches 'expcb.2026.07.24a', 'misc.2026.07.30a', 'rcu-tasks.2026.07.30a', 'srcu.2026.08.11a' and 'torture.2026.08.14a' into HEAD Changes: Make expedited grace periods expedite normal RCU callbacks Miscellaneous fixes: * Improve diagnostic output with character task states. * Mark accesses to inform KCSAN of concurrency design. * Move from kmalloc() to kmalloc_obj(). * Documentation updates. * Improve handling of RCU deferred quiescent states. * Clean up unused function arguments and structure fields. * Reduce show_rcu_gp_kthreads() stack space. Tasks RCU updates: * Clean up after SRCU re-implementation of Tasks Trace RCU. * Mark accesses to inform KCSAN of concurrency design. * Add ->lazy_timer status to diagnostic output. * Remove an unnecessary memory barrier. * Fix a data race, courtesy of KCSAN. * Documentation updates. * Convert cond_resched_tasks_rcu_qs() from macro to static inline function. SRCU updates: * Add Rust helpers for SRCU. * Avoid losing queued work at cleanup_srcu_struct() time. Torture-test updates: * Preparation work for immediate RCU priority deboosting. * Test RCU readers from real interrupt handlers (as opposed to softirq). * Simplify code through use of cpumask_next_wrap(). * Improve diagnostic output with character task states. * Add rcutorture.nwriters parameter to allow lightweight stall testing, and rcutorture.stall_only to make doing so easier. * Test an RCU Tasks Trace grace period implying an RCU grace period. * Make RCU Tasks Trace torturing track reader batches. * Fix a data race, courtesy of KCSAN. * Plug a shuffle_tmp_mask memory leak on kthread spawn failure. --- arch/arm/lib/backtrace.S | 131 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 131 insertions(+) create mode 100644 arch/arm/lib/backtrace.S (limited to 'arch/arm/lib/backtrace.S') diff --git a/arch/arm/lib/backtrace.S b/arch/arm/lib/backtrace.S new file mode 100644 index 000000000..293a2716b --- /dev/null +++ b/arch/arm/lib/backtrace.S @@ -0,0 +1,131 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * linux/arch/arm/lib/backtrace.S + * + * Copyright (C) 1995, 1996 Russell King + * + * 27/03/03 Ian Molton Clean up CONFIG_CPU + */ +#include +#include +#include + .text + +@ fp is 0 or stack frame + +#define frame r4 +#define sv_fp r5 +#define sv_pc r6 +#define mask r7 +#define offset r8 +#define loglvl r9 + +ENTRY(c_backtrace) + +#if !defined(CONFIG_FRAME_POINTER) || !defined(CONFIG_PRINTK) + ret lr +ENDPROC(c_backtrace) +#else + stmfd sp!, {r4 - r9, lr} @ Save an extra register so we have a location... + movs frame, r0 @ if frame pointer is zero + beq no_frame @ we have no stack frames + mov loglvl, r2 + + tst r1, #0x10 @ 26 or 32-bit mode? + ARM( moveq mask, #0xfc000003 ) + THUMB( moveq mask, #0xfc000000 ) + THUMB( orreq mask, #0x03 ) + movne mask, #0 @ mask for 32-bit + +1: stmfd sp!, {pc} @ calculate offset of PC stored + ldr r0, [sp], #4 @ by stmfd for this CPU + adr r1, 1b + sub offset, r0, r1 + +/* + * Stack frame layout: + * optionally saved caller registers (r4 - r10) + * saved fp + * saved sp + * saved lr + * frame => saved pc + * optionally saved arguments (r0 - r3) + * saved sp => + * + * Functions start with the following code sequence: + * mov ip, sp + * stmfd sp!, {r0 - r3} (optional) + * corrected pc => stmfd sp!, {..., fp, ip, lr, pc} + */ +for_each_frame: tst frame, mask @ Check for address exceptions + bne no_frame + +1001: ldr sv_pc, [frame, #0] @ get saved pc +1002: ldr sv_fp, [frame, #-12] @ get saved fp + + sub sv_pc, sv_pc, offset @ Correct PC for prefetching + bic sv_pc, sv_pc, mask @ mask PC/LR for the mode + +1003: ldr r2, [sv_pc, #-4] @ if stmfd sp!, {args} exists, + ldr r3, .Ldsi+4 @ adjust saved 'pc' back one + teq r3, r2, lsr #11 @ instruction + subne r0, sv_pc, #4 @ allow for mov + subeq r0, sv_pc, #8 @ allow for mov + stmia + + ldr r1, [frame, #-4] @ get saved lr + mov r2, frame + bic r1, r1, mask @ mask PC/LR for the mode + mov r3, loglvl + bl dump_backtrace_entry + + ldr r1, [sv_pc, #-4] @ if stmfd sp!, {args} exists, + ldr r3, .Ldsi+4 + teq r3, r1, lsr #11 + ldreq r0, [frame, #-8] @ get sp + subeq r0, r0, #4 @ point at the last arg + mov r2, loglvl + bleq dump_backtrace_stm @ dump saved registers + +1004: ldr r1, [sv_pc, #0] @ if stmfd sp!, {..., fp, ip, lr, pc} + ldr r3, .Ldsi @ instruction exists, + teq r3, r1, lsr #11 + subeq r0, frame, #16 + mov r2, loglvl + bleq dump_backtrace_stm @ dump saved registers + + teq sv_fp, #0 @ zero saved fp means + beq no_frame @ no further frames + + cmp sv_fp, frame @ next frame must be + mov frame, sv_fp @ above the current frame +#ifdef CONFIG_IRQSTACKS + @ + @ Kernel stacks may be discontiguous in memory. If the next + @ frame is below the previous frame, accept it as long as it + @ lives in kernel memory. + @ + cmpls sv_fp, #PAGE_OFFSET +#endif + bhi for_each_frame + +1006: adr r0, .Lbad + mov r1, loglvl + mov r2, frame + bl _printk +no_frame: ldmfd sp!, {r4 - r9, pc} +ENDPROC(c_backtrace) + + .pushsection __ex_table,"a" + .align 3 + .long 1001b, 1006b + .long 1002b, 1006b + .long 1003b, 1006b + .long 1004b, 1006b + .popsection + +.Lbad: .asciz "%sBacktrace aborted due to bad frame pointer <%p>\n" + .align +.Ldsi: .word 0xe92dd800 >> 11 @ stmfd sp!, {... fp, ip, lr, pc} + .word 0xe92d0000 >> 11 @ stmfd sp!, {} + +#endif -- cgit v1.3.1