From 4022918876f9a28fe5379e2d7b7840e84f7b56ed Mon Sep 17 00:00:00 2001 From: Brendan Jackman Date: Thu, 20 Feb 2025 12:23:40 +0000 Subject: scripts/gdb: add $lx_per_cpu_ptr() We currently have $lx_per_cpu() which works fine for stuff that kernel code would access via per_cpu(). But this doesn't work for stuff that kernel code accesses via per_cpu_ptr(): (gdb) p $lx_per_cpu(node_data[1].node_zones[2]->per_cpu_pageset) Cannot access memory at address 0xffff11105fbd6c28 This is because we take the address of the pointer and use that as the offset, instead of using the stored value. Add a GDB version that mirrors the kernel API, which uses the pointer value. To be consistent with per_cpu_ptr(), we need to return the pointer value instead of dereferencing it for the user. Therefore, move the existing dereference out of the per_cpu() Python helper and do that only in the $lx_per_cpu() implementation. Link: https://lkml.kernel.org/r/20250220-lx-per-cpu-ptr-v2-1-945dee8d8d38@google.com Signed-off-by: Brendan Jackman Reviewed-by: Jan Kiszka Cc: Florian Rommel Cc: Kieran Bingham Signed-off-by: Andrew Morton --- scripts/gdb/linux/cpus.py | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-) (limited to 'scripts/gdb/linux/cpus.py') diff --git a/scripts/gdb/linux/cpus.py b/scripts/gdb/linux/cpus.py index 13eb8b3901b8..1a50a4195def 100644 --- a/scripts/gdb/linux/cpus.py +++ b/scripts/gdb/linux/cpus.py @@ -46,7 +46,7 @@ def per_cpu(var_ptr, cpu): # !CONFIG_SMP case offset = 0 pointer = var_ptr.cast(utils.get_long_type()) + offset - return pointer.cast(var_ptr.type).dereference() + return pointer.cast(var_ptr.type) cpu_mask = {} @@ -149,11 +149,29 @@ Note that VAR has to be quoted as string.""" super(PerCpu, self).__init__("lx_per_cpu") def invoke(self, var, cpu=-1): - return per_cpu(var.address, cpu) + return per_cpu(var.address, cpu).dereference() PerCpu() + +class PerCpuPtr(gdb.Function): + """Return per-cpu pointer. + +$lx_per_cpu_ptr("VAR"[, CPU]): Return the per-cpu pointer called VAR for the +given CPU number. If CPU is omitted, the CPU of the current context is used. +Note that VAR has to be quoted as string.""" + + def __init__(self): + super(PerCpuPtr, self).__init__("lx_per_cpu_ptr") + + def invoke(self, var, cpu=-1): + return per_cpu(var, cpu) + + +PerCpuPtr() + + def get_current_task(cpu): task_ptr_type = task_type.get_type().pointer() -- cgit v1.2.3