From 526940e3962620f1a24d5e30c3dac7358194d963 Mon Sep 17 00:00:00 2001 From: Barry Song Date: Thu, 6 May 2021 18:05:09 -0700 Subject: scripts/gdb: add lx_current support for arm64 arm64 uses SP_EL0 to save the current task_struct address. While running in EL0, SP_EL0 is clobbered by userspace. So if the upper bit is not 1 (not TTBR1), the current address is invalid. This patch checks the upper bit of SP_EL0, if the upper bit is 1, lx_current() of arm64 will return the derefrence of current task. Otherwise, lx_current() will tell users they are running in userspace(EL0). While arm64 is running in EL0, it is actually pointless to print current task as the memory of kernel space is not accessible in EL0. Link: https://lkml.kernel.org/r/20210314203444.15188-3-song.bao.hua@hisilicon.com Signed-off-by: Barry Song Cc: Jan Kiszka Cc: Jonathan Corbet Cc: Kieran Bingham Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/dev-tools/gdb-kernel-debugging.rst | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'Documentation/dev-tools') diff --git a/Documentation/dev-tools/gdb-kernel-debugging.rst b/Documentation/dev-tools/gdb-kernel-debugging.rst index 1586901b683c..8e0f1fe8d17a 100644 --- a/Documentation/dev-tools/gdb-kernel-debugging.rst +++ b/Documentation/dev-tools/gdb-kernel-debugging.rst @@ -114,7 +114,7 @@ Examples of using the Linux-provided gdb helpers [ 0.000000] BIOS-e820: [mem 0x000000000009fc00-0x000000000009ffff] reserved .... -- Examine fields of the current task struct(supported by x86 only):: +- Examine fields of the current task struct(supported by x86 and arm64 only):: (gdb) p $lx_current().pid $1 = 4998 -- cgit