Patch "riscv: fix kprobe __user string arg print fault issue" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    riscv: fix kprobe __user string arg print fault issue

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     riscv-fix-kprobe-__user-string-arg-print-fault-issue.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 396e5e547dba6d21c546b1a9f0eb76d621b117c8
Author: Ruan Jinjie <ruanjinjie@xxxxxxxxxx>
Date:   Thu May 4 15:29:10 2023 +0800

    riscv: fix kprobe __user string arg print fault issue
    
    [ Upstream commit 99a670b2069c725a7b50318aa681d9cae8f89325 ]
    
    On riscv qemu platform, when add kprobe event on do_sys_open() to show
    filename string arg, it just print fault as follow:
    
    echo 'p:myprobe do_sys_open dfd=$arg1 filename=+0($arg2):string flags=$arg3
    mode=$arg4' > kprobe_events
    
    bash-166     [000] ...1.   360.195367: myprobe: (do_sys_open+0x0/0x84)
    dfd=0xffffffffffffff9c filename=(fault) flags=0x8241 mode=0x1b6
    
    bash-166     [000] ...1.   360.219369: myprobe: (do_sys_open+0x0/0x84)
    dfd=0xffffffffffffff9c filename=(fault) flags=0x8241 mode=0x1b6
    
    bash-191     [000] ...1.   360.378827: myprobe: (do_sys_open+0x0/0x84)
    dfd=0xffffffffffffff9c filename=(fault) flags=0x98800 mode=0x0
    
    As riscv do not select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE,
    the +0($arg2) addr is processed as a kernel address though it is a
    userspace address, cause the above filename=(fault) print. So select
    ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE to avoid the issue, after that the
    kprobe trace is ok as below:
    
    bash-166     [000] ...1.    96.767641: myprobe: (do_sys_open+0x0/0x84)
    dfd=0xffffffffffffff9c filename="/dev/null" flags=0x8241 mode=0x1b6
    
    bash-166     [000] ...1.    96.793751: myprobe: (do_sys_open+0x0/0x84)
    dfd=0xffffffffffffff9c filename="/dev/null" flags=0x8241 mode=0x1b6
    
    bash-177     [000] ...1.    96.962354: myprobe: (do_sys_open+0x0/0x84)
    dfd=0xffffffffffffff9c filename="/sys/kernel/debug/tracing/events/kprobes/"
    flags=0x98800 mode=0x0
    
    Signed-off-by: Ruan Jinjie <ruanjinjie@xxxxxxxxxx>
    Acked-by: Björn Töpel <bjorn@xxxxxxxxxxxx>
    Fixes: 0ebeea8ca8a4 ("bpf: Restrict bpf_probe_read{, str}() only to archs where they work")
    Link: https://lore.kernel.org/r/20230504072910.3742842-1-ruanjinjie@xxxxxxxxxx
    Signed-off-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index bf602e38962fa..8dd7f01ee031d 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -23,6 +23,7 @@ config RISCV
 	select ARCH_HAS_GIGANTIC_PAGE
 	select ARCH_HAS_KCOV
 	select ARCH_HAS_MMIOWB
+	select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
 	select ARCH_HAS_PTE_SPECIAL
 	select ARCH_HAS_SET_DIRECT_MAP if MMU
 	select ARCH_HAS_SET_MEMORY if MMU