linux-toradex.git/kernel/entry, branch v6.13-rc7

sched: Add TIF_NEED_RESCHED_LAZY infrastructure

2024-11-05T11:55:37+00:00

Add the basic infrastructure to split the TIF_NEED_RESCHED bit in two.
Either bit will cause a resched on return-to-user, but only
TIF_NEED_RESCHED will drive IRQ preemption.

No behavioural change intended.

Suggested-by: Thomas Gleixner 
Signed-off-by: Peter Zijlstra (Intel) 
Reviewed-by: Sebastian Andrzej Siewior 
Link: https://lkml.kernel.org/r/20241007075055.219540785@infradead.org

treewide: context_tracking: Rename CONTEXT_* into CT_STATE_*

2024-07-29T02:03:10+00:00

Context tracking state related symbols currently use a mix of the
CONTEXT_ (e.g. CONTEXT_KERNEL) and CT_SATE_ (e.g. CT_STATE_MASK) prefixes.

Clean up the naming and make the ctx_state enum use the CT_STATE_ prefix.

Suggested-by: Frederic Weisbecker 
Signed-off-by: Valentin Schneider 
Acked-by: Frederic Weisbecker 
Acked-by: Thomas Gleixner 
Signed-off-by: Neeraj Upadhyay

entry: Respect changes to system call number by trace_sys_enter()

2024-03-12T12:23:32+00:00

When a probe is registered at the trace_sys_enter() tracepoint, and that
probe changes the system call number, the old system call still gets
executed.  This worked correctly until commit b6ec41346103 ("core/entry:
Report syscall correctly for trace and audit"), which removed the
re-evaluation of the syscall number after the trace point.

Restore the original semantics by re-evaluating the system call number
after trace_sys_enter(). 

The performance impact of this re-evaluation is minimal because it only
takes place when a trace point is active, and compared to the actual trace
point overhead the read from a cache hot variable is negligible.

Fixes: b6ec41346103 ("core/entry: Report syscall correctly for trace and audit")
Signed-off-by: André Rösti 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/r/20240311211704.7262-1-an.roesti@gmail.com

entry: Move syscall_enter_from_user_mode() to header file

2023-12-21T22:12:18+00:00

To allow inlining of syscall_enter_from_user_mode(), move it
to entry-common.h.

Signed-off-by: Sven Schnelle 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/r/20231218074520.1998026-4-svens@linux.ibm.com

entry: Move enter_from_user_mode() to header file

2023-12-21T22:12:18+00:00

To allow inlining of enter_from_user_mode(), move it to
entry-common.h.

Signed-off-by: Sven Schnelle 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/r/20231218074520.1998026-3-svens@linux.ibm.com

entry: Move exit to usermode functions to header file

2023-12-21T22:12:18+00:00

To allow inlining, move exit_to_user_mode() to
entry-common.h.

Signed-off-by: Sven Schnelle 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/r/20231218074520.1998026-2-svens@linux.ibm.com

entry: Remove empty addr_limit_user_check()

2023-08-23T08:32:39+00:00

Back when set_fs() was a generic API for altering the address limit,
addr_limit_user_check() was a safety measure to prevent userspace being
able to issue syscalls with an unbound limit.

With the the removal of set_fs() as a generic API, the last user of
addr_limit_user_check() was removed in commit:

  b5a5a01d8e9a44ec ("arm64: uaccess: remove addr_limit_user_check()")

... as since that commit, no architecture defines TIF_FSCHECK, and hence
addr_limit_user_check() always expands to nothing.

Remove addr_limit_user_check(), updating the comment in
exit_to_user_mode_prepare() to no longer refer to it. At the same time,
the comment is reworded to be a little more generic so as to cover
kmap_assert_nomap() in addition to lockdep_sys_exit().

No functional change.

Signed-off-by: Mark Rutland 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/r/20230821163526.2319443-1-mark.rutland@arm.com

ptrace: Provide set/get interface for syscall user dispatch

2023-04-16T12:23:07+00:00

The syscall user dispatch configuration can only be set by the task itself,
but lacks a ptrace set/get interface which makes it impossible to implement
checkpoint/restore for it.

Add the required ptrace requests and the get/set functions in the syscall
user dispatch code to make that possible.

Signed-off-by: Gregory Price 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Oleg Nesterov 
Link: https://lore.kernel.org/r/20230407171834.3558-4-gregory.price@memverge.com

syscall_user_dispatch: Untag selector address before access_ok()

2023-04-16T12:23:07+00:00

To support checkpoint/restart, ptrace must be able to set the selector
of the tracee.  The selector is a user pointer that may be subject to
memory tagging extensions on some architectures (namely ARM MTE).

access_ok() clears memory tags for tagged addresses if the current task has
memory tagging enabled.

This obviously fails when ptrace modifies the selector of a tracee when
tracer and tracee do not have the same memory tagging enabled state.

Solve this by untagging the selector address before handing it to
access_ok(), like other ptrace functions which modify tracee pointers do.

Obviously a tracer can set an invalid selector address for the tracee, but
that's independent of tagging and a general capability of the tracer.

Suggested-by: Catalin Marinas 
Signed-off-by: Gregory Price 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Catalin Marinas 
Acked-by: Oleg Nesterov 
Link: https://lore.kernel.org/all/ZCWXE04nLZ4pXEtM@arm.com/
Link: https://lore.kernel.org/r/20230407171834.3558-3-gregory.price@memverge.com

syscall_user_dispatch: Split up set_syscall_user_dispatch()

2023-04-16T12:23:07+00:00

syscall user dispatch configuration is not covered by checkpoint/restore.

To prepare for ptrace access to the syscall user dispatch configuration,
move the inner working of set_syscall_user_dispatch() into a helper
function. Make the helper function task pointer based and let
set_syscall_user_dispatch() invoke it with task=current.

No functional change.

Signed-off-by: Gregory Price 
Signed-off-by: Thomas Gleixner 
Reviewed-by: Oleg Nesterov 
Link: https://lore.kernel.org/r/20230407171834.3558-2-gregory.price@memverge.com