| Age | Commit message (Collapse) | Author |
|---|
|
It can be easy to miss that the notifier mechanism invokes the callbacks
in an atomic context, so add some comments to that effect on the two
handlers we register here.
Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230829063457.54157-4-bgray@linux.ibm.com
|
|
thread_change_pc() uses CPU local data, so must be protected from
swapping CPUs while it is reading the breakpoint struct.
The error is more noticeable after 1e60f3564bad ("powerpc/watchpoints:
Track perf single step directly on the breakpoint"), which added an
unconditional __this_cpu_read() call in thread_change_pc(). However the
existing __this_cpu_read() that runs if a breakpoint does need to be
re-inserted has the same issue.
Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230829063457.54157-2-bgray@linux.ibm.com
|
|
ptrace and perf watchpoints were considered incompatible in
commit 29da4f91c0c1 ("powerpc/watchpoint: Don't allow concurrent perf
and ptrace events"), but the logic in that commit doesn't really apply.
Ptrace doesn't automatically single step; the ptracer must request this
explicitly. And the ptracer can do so regardless of whether a
ptrace/perf watchpoint triggered or not: it could single step every
instruction if it wanted to. Whatever stopped the ptracee before
executing the instruction that would trigger the perf watchpoint is no
longer relevant by this point.
To get correct behaviour when perf and ptrace are watching the same
data we must ignore the perf watchpoint. After all, ptrace has
before-execute semantics, and perf is after-execute, so perf doesn't
actually care about the watchpoint trigger at this point in time.
Pausing before execution does not mean we will actually end up executing
the instruction.
Importantly though, we don't remove the perf watchpoint yet. This is
key.
The ptracer is free to do whatever it likes right now. E.g., it can
continue the process, single step. or even set the child PC somewhere
completely different.
If it does try to execute the instruction though, without reinserting
the watchpoint (in which case we go back to the start of this example),
the perf watchpoint would immediately trigger. This time there is no
ptrace watchpoint, so we can safely perform a single step and increment
the perf counter. Upon receiving the single step exception, the existing
code already handles propagating or consuming it based on whether
another subsystem (e.g. ptrace) requested a single step. Again, this is
needed with or without perf/ptrace exclusion, because ptrace could be
single stepping this instruction regardless of if a watchpoint is
involved.
Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230801011744.153973-6-bgray@linux.ibm.com
|
|
We only remove watchpoints when they have the perf_single_step flag set,
so we can reinsert them during the first iteration.
Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230801011744.153973-5-bgray@linux.ibm.com
|
|
There is a bug in the current watchpoint tracking logic, where the
teardown in arch_unregister_hw_breakpoint() uses bp->ctx->task, which it
does not have a reference of and parallel threads may be in the process
of destroying. This was partially addressed in commit fb822e6076d9
("powerpc/hw_breakpoint: Fix oops when destroying hw_breakpoint event"),
but the underlying issue of accessing a struct member in an unknown
state still remained. Syzkaller managed to trigger a null pointer
derefernce due to the race between the task destructor and checking the
pointer and dereferencing it in the loop.
While this null pointer dereference could be fixed by using READ_ONCE
to access the task up front, that just changes the error to manipulating
possbily freed memory.
Instead, the breakpoint logic needs to be reworked to remove any
dependency on a context or task struct during breakpoint removal.
The reason we have this currently is to clear thread.last_hit_ubp. This
member is used to differentiate the perf DAWR single-step sequence from
other causes of single-step, such as userspace just calling
ptrace(PTRACE_SINGLESTEP, ...). We need to differentiate them because,
when the single step interrupt is received, we need to know whether to
re-insert the DAWR breakpoint (perf) or not (ptrace / other).
arch_unregister_hw_breakpoint() needs to clear this information to
prevent dangling pointers to possibly freed memory. These pointers are
dereferenced in single_step_dabr_instruction() without a way to check
their validity.
This patch moves the tracking of this information to the breakpoint
itself. This means we no longer have to do anything special to clean up.
Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230801011744.153973-4-bgray@linux.ibm.com
|
|
info is cheap to retrieve, and is likely optimised by the compiler
anyway. On the other hand, propagating it across the functions makes it
possible to be inconsistent and adds needless complexity.
Remove it, and invoke counter_arch_bp() when we need to work with it.
As we don't persist it, we just use the local bp array to track whether
we are ignoring a breakpoint.
Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230801011744.153973-3-bgray@linux.ibm.com
|
|
The behaviour of the thread_change_pc() function is a bit cryptic
without being more familiar with how the watchpoint logic handles
perf's after-execute semantics.
Expand the comment to explain why we can re-insert the breakpoint and
unset the perf_single_step flag.
Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230801011744.153973-2-bgray@linux.ibm.com
|
|
In hw_breakpoint_handler(), ea is set by wp_get_instr_detail() except
for 8xx, leading the variable to be passed uninitialised to
wp_check_constraints(). This is safe as wp_check_constraints() returns
early without using ea, so just set it to make the compiler happy.
Signed-off-by: Russell Currey <ruscur@russell.cc>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221024041346.103608-1-ruscur@russell.cc
|
|
Internal data structures (cpu_bps, task_bps) of powerpc's hw_breakpoint
implementation have relied on nr_bp_mutex serializing access to them.
Before overhauling synchronization of kernel/events/hw_breakpoint.c,
introduce 2 spinlocks to synchronize cpu_bps and task_bps respectively,
thus avoiding reliance on callers synchronizing powerpc's hw_breakpoint.
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20220829124719.675715-10-elver@google.com
|
|
In order to stop using 'struct ppc_inst' on PPC32,
define a ppc_inst_t typedef.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/fe5baa2c66fea9db05a8b300b3e8d2880a42596c.1638208156.git.christophe.leroy@csgroup.eu
|
|
No functional change in this patch. arch_debugfs_dir is the generic kernel
name declared in linux/debugfs.h for arch-specific debugfs directory.
Architectures like x86/s390 already use the name. Rename powerpc
specific powerpc_debugfs_root to arch_debugfs_dir.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210812132831.233794-2-aneesh.kumar@linux.ibm.com
|
|
When an interrupt is taken, the SRR registers are set to return to where
it left off. Unless they are modified in the meantime, or the return
address or MSR are modified, there is no need to reload these registers
when returning from interrupt.
Introduce per-CPU flags that track the validity of SRR and HSRR
registers. These are cleared when returning from interrupt, when
using the registers for something else (e.g., OPAL calls), when
adjusting the return address or MSR of a context, and when context
switching (which changes the return address and MSR).
This improves the performance of interrupt returns.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Fold in fixup patch from Nick]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210617155116.2167984-5-npiggin@gmail.com
|
|
POWER10 DD1 has an issue where it generates watchpoint exceptions when
it shouldn't. The conditions where this occur are:
- octword op
- ending address of DAWR range is less than starting address of op
- those addresses need to be in the same or in two consecutive 512B
blocks
- 'op address + 64B' generates an address that has a carry into bit
52 (crosses 2K boundary)
Handle such spurious exception by considering them as extraneous and
emulating/single-steeping instruction without generating an event.
[ravi: Fixed build warning reported by lkp@intel.com]
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201106045650.278987-1-ravi.bangoria@linux.ibm.com
|
|
Power10 hw has multiple DAWRs but hw doesn't tell which DAWR caused
the exception. So we have a sw logic to detect that in hw_breakpoint.c.
But hw_breakpoint.c gets compiled only with CONFIG_HAVE_HW_BREAKPOINT=Y.
Move DAWR detection logic outside of hw_breakpoint.c so that it can be
reused when CONFIG_HAVE_HW_BREAKPOINT is not set.
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200902042945.129369-5-ravi.bangoria@linux.ibm.com
|
|
Vector load/store instructions are special because they are always
aligned. Thus unaligned EA needs to be aligned down before comparing
it with watch ranges. Otherwise we might consider valid event as
invalid.
Fixes: 74c6881019b7 ("powerpc/watchpoint: Prepare handler to handle more than one watchpoint")
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200902042945.129369-3-ravi.bangoria@linux.ibm.com
|
|
On p10 predecessors, watchpoint with quadword access is compared at
quadword length. If the watch range is doubleword or less than that
in a first half of quadword aligned 16 bytes, and if there is any
unaligned quadword access which will access only the 2nd half, the
handler should consider it as extraneous and emulate/single-step it
before continuing.
Fixes: 74c6881019b7 ("powerpc/watchpoint: Prepare handler to handle more than one watchpoint")
Reported-by: Pedro Miraglia Franco de Carvalho <pedromfc@linux.ibm.com>
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200902042945.129369-2-ravi.bangoria@linux.ibm.com
|
|
Power10 has removed 512 bytes boundary from match criteria i.e. the watch
range can cross 512 bytes boundary.
Note: ISA 3.1 Book III 9.4 match criteria includes 512 byte limit but that
is a documentation mistake and hopefully will be fixed in the next version
of ISA. Though, ISA 3.1 change log mentions about removal of 512B boundary:
Multiple DEAW:
Added a second Data Address Watchpoint. [H]DAR is
set to the first byte of overlap. 512B boundary is
removed.
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200723090813.303838-11-ravi.bangoria@linux.ibm.com
|
|
'ea' returned by analyse_instr() needs to be aligned down to cache
block size for CACHEOP instructions. analyse_instr() does not set
size for CACHEOP, thus size also needs to be calculated manually.
Fixes: 27985b2a640e ("powerpc/watchpoint: Don't ignore extraneous exceptions blindly")
Fixes: 74c6881019b7 ("powerpc/watchpoint: Prepare handler to handle more than one watchpoint")
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200723090813.303838-4-ravi.bangoria@linux.ibm.com
|
|
Pedro Miraglia Franco de Carvalho noticed that on p8/p9, DAR value is
inconsistent with different type of load/store. Like for byte,word
etc. load/stores, DAR is set to the address of the first byte of
overlap between watch range and real access. But for quadword load/
store it's sometime set to the address of the first byte of real
access whereas sometime set to the address of the first byte of
overlap. This issue has been fixed in p10. In p10(ISA 3.1), DAR is
always set to the address of the first byte of overlap. Commit 27985b2a640e
("powerpc/watchpoint: Don't ignore extraneous exceptions blindly")
wrongly assumes that DAR is set to the address of the first byte of
overlap for all load/stores on p8/p9 as well. Fix that. With the fix,
we now rely on 'ea' provided by analyse_instr(). If analyse_instr()
fails, generate event unconditionally on p8/p9, and on p10 generate
event only if DAR is within a DAWR range.
Note: 8xx is not affected.
Fixes: 27985b2a640e ("powerpc/watchpoint: Don't ignore extraneous exceptions blindly")
Fixes: 74c6881019b7 ("powerpc/watchpoint: Prepare handler to handle more than one watchpoint")
Reported-by: Pedro Miraglia Franco de Carvalho <pedromfc@br.ibm.com>
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200723090813.303838-3-ravi.bangoria@linux.ibm.com
|
|
Milton Miller reported that we are aligning start and end address to
wrong size SZ_512M. It should be SZ_512. Fix that.
While doing this change I also found a case where ALIGN() comparison
fails. Within a given aligned range, ALIGN() of two addresses does not
match when start address is pointing to the first byte and end address
is pointing to any other byte except the first one. But that's not true
for ALIGN_DOWN(). ALIGN_DOWN() of any two addresses within that range
will always point to the first byte. So use ALIGN_DOWN() instead of
ALIGN().
Fixes: e68ef121c1f4 ("powerpc/watchpoint: Use builtin ALIGN*() macros")
Reported-by: Milton Miller <miltonm@us.ibm.com>
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Tested-by: Jordan Niethe <jniethe5@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200723090813.303838-2-ravi.bangoria@linux.ibm.com
|
|
With Book3s DAWR, ptrace and perf watchpoints on powerpc behaves
differently. Ptrace watchpoint works in one-shot mode and generates
signal before executing instruction. It's ptrace user's job to
single-step the instruction and re-enable the watchpoint. OTOH, in
case of perf watchpoint, kernel emulates/single-steps the instruction
and then generates event. If perf and ptrace creates two events with
same or overlapping address ranges, it's ambiguous to decide who
should single-step the instruction. Because of this issue, don't
allow perf and ptrace watchpoint at the same time if their address
range overlaps.
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Michael Neuling <mikey@neuling.org>
Link: https://lore.kernel.org/r/20200514111741.97993-15-ravi.bangoria@linux.ibm.com
|
|
Currently we assume that we have only one watchpoint supported by hw.
Get rid of that assumption and use dynamic loop instead. This should
make supporting more watchpoints very easy.
With more than one watchpoint, exception handler needs to know which
DAWR caused the exception, and hw currently does not provide it. So
we need sw logic for the same. To figure out which DAWR caused the
exception, check all different combinations of user specified range,
DAWR address range, actual access range and DAWRX constrains. For ex,
if user specified range and actual access range overlaps but DAWRX is
configured for readonly watchpoint and the instruction is store, this
DAWR must not have caused exception.
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Reviewed-by: Michael Neuling <mikey@neuling.org>
[mpe: Unsplit multi-line printk() strings, fix some sparse warnings]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200514111741.97993-14-ravi.bangoria@linux.ibm.com
|
|
Currently we calculate hw aligned start and end addresses manually.
Replace them with builtin ALIGN_DOWN() and ALIGN() macros.
So far end_addr was inclusive but this patch makes it exclusive (by
avoiding -1) for better readability.
Suggested-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Michael Neuling <mikey@neuling.org>
Link: https://lore.kernel.org/r/20200514111741.97993-13-ravi.bangoria@linux.ibm.com
|
|
Introduce is_ptrace_bp() function and move the check inside the
function. It will be utilize more in later set of patches.
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Michael Neuling <mikey@neuling.org>
Link: https://lore.kernel.org/r/20200514111741.97993-12-ravi.bangoria@linux.ibm.com
|
|
ptrace_bps is already an array of size HBP_NUM_MAX. But we use
hardcoded index 0 while fetching/updating it. Convert such code
to loop over array.
ptrace interface to use multiple watchpoint remains same. eg:
two PPC_PTRACE_SETHWDEBUG calls will create two watchpoint if
underneath hw supports it.
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Michael Neuling <mikey@neuling.org>
Link: https://lore.kernel.org/r/20200514111741.97993-11-ravi.bangoria@linux.ibm.com
|
|
Introduce new parameter 'nr' to __set_breakpoint() which indicates
which DAWR should be programed. Also convert current_brk variable
to an array.
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Michael Neuling <mikey@neuling.org>
Link: https://lore.kernel.org/r/20200514111741.97993-7-ravi.bangoria@linux.ibm.com
|
|
So far we had only one watchpoint, so we have hardcoded HBP_NUM to 1.
But Power10 is introducing 2nd DAWR and thus kernel should be able to
dynamically find actual number of watchpoints supported by hw it's
running on. Introduce function for the same. Also convert HBP_NUM macro
to HBP_NUM_MAX, which will now represent maximum number of watchpoints
supported by Powerpc.
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Michael Neuling <mikey@neuling.org>
Link: https://lore.kernel.org/r/20200514111741.97993-4-ravi.bangoria@linux.ibm.com
|
|
Define specialised get_user_instr(), __get_user_instr() and
__get_user_instr_inatomic() macros for reading instructions from user
and/or kernel space.
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Reviewed-by: Alistair Popple <alistair@popple.id.au>
[mpe: Squash in addition of get_user_instr() & __user annotations]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200506034050.24806-17-jniethe5@gmail.com
|
|
Currently unsigned ints are used to represent instructions on powerpc.
This has worked well as instructions have always been 4 byte words.
However, ISA v3.1 introduces some changes to instructions that mean
this scheme will no longer work as well. This change is Prefixed
Instructions. A prefixed instruction is made up of a word prefix
followed by a word suffix to make an 8 byte double word instruction.
No matter the endianness of the system the prefix always comes first.
Prefixed instructions are only planned for powerpc64.
Introduce a ppc_inst type to represent both prefixed and word
instructions on powerpc64 while keeping it possible to exclusively
have word instructions on powerpc32.
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
[mpe: Fix compile error in emulate_spe()]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200506034050.24806-12-jniethe5@gmail.com
|
|
In preparation for instructions having a more complex data type start
using a macro, ppc_inst(), for making an instruction out of a u32. A
macro is used so that instructions can be used as initializer elements.
Currently this does nothing, but it will allow for creating a data type
that can represent prefixed instructions.
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
[mpe: Change include guard to _ASM_POWERPC_INST_H]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Alistair Popple <alistair@popple.id.au>
Link: https://lore.kernel.org/r/20200506034050.24806-7-jniethe5@gmail.com
|
|
ptrace_triggered() is declared in asm/hw_breakpoint.h and
only needed when CONFIG_HW_BREAKPOINT is set, so move it
into hw_breakpoint.c
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/8402c516023da1371953a65af7df2008758ea0c4.1582848567.git.christophe.leroy@c-s.fr
|
|
DAR is set to the first byte of overlap between actual access and
watched range at DSI on Book3S processor. But actual access range
might or might not be within user asked range. So for Book3S, it
must not call dar_within_range().
This revert portion of commit 39413ae00967 ("powerpc/hw_breakpoints:
Rewrite 8xx breakpoints to allow any address range size.").
Before patch:
# ./tools/testing/selftests/powerpc/ptrace/perf-hwbreak
...
TESTED: No overlap
FAILED: Partial overlap: 0 != 2
TESTED: Partial overlap
TESTED: No overlap
FAILED: Full overlap: 0 != 2
failure: perf_hwbreak
After patch:
TESTED: No overlap
TESTED: Partial overlap
TESTED: Partial overlap
TESTED: No overlap
TESTED: Full overlap
success: perf_hwbreak
Fixes: 39413ae00967 ("powerpc/hw_breakpoints: Rewrite 8xx breakpoints to allow any address range size.")
Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200222082049.330435-1-ravi.bangoria@linux.ibm.com
|
|
Unlike standard powerpc, Powerpc 8xx doesn't have SPRN_DABR, but
it has a breakpoint support based on a set of comparators which
allow more flexibility.
Commit 4ad8622dc548 ("powerpc/8xx: Implement hw_breakpoint")
implemented breakpoints by emulating the DABR behaviour. It did
this by setting one comparator the match 4 bytes at breakpoint address
and the other comparator to match 4 bytes at breakpoint address + 4.
Rewrite 8xx hw_breakpoint to make breakpoints match all addresses
defined by the breakpoint address and length by making full use of
comparators.
Now, comparator E is set to match any address greater than breakpoint
address minus one. Comparator F is set to match any address lower than
breakpoint address plus breakpoint length. Addresses are aligned
to 32 bits.
When the breakpoint range starts at address 0, the breakpoint is set
to match comparator F only. When the breakpoint range end at address
0xffffffff, the breakpoint is set to match comparator E only.
Otherwise the breakpoint is set to match comparator E and F.
At the same time, use registers bit names instead of hardcoded values.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/05105deeaf63bc02151aea2cdeaf525534e0e9d4.1574790198.git.christophe.leroy@c-s.fr
|
|
On powerpc, watchpoint match range is double-word granular. On a
watchpoint hit, DAR is set to the first byte of overlap between actual
access and watched range. And thus it's quite possible that DAR does
not point inside user specified range. Ex, say user creates a
watchpoint with address range 0x1004 to 0x1007. So hw would be
configured to watch from 0x1000 to 0x1007. If there is a 4 byte access
from 0x1002 to 0x1005, DAR will point to 0x1002 and thus interrupt
handler considers it as extraneous, but it's actually not, because
part of the access belongs to what user has asked.
Instead of blindly ignoring the exception, get actual address range by
analysing an instruction, and ignore only if actual range does not
overlap with user specified range.
Note: The behavior is unchanged for 8xx.
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191017093204.7511-5-ravi.bangoria@linux.ibm.com
|
|
Watchpoint match range is always doubleword(8 bytes) aligned on
powerpc. If the given range is crossing doubleword boundary, we need
to increase the length such that next doubleword also get
covered. Ex,
address len = 6 bytes
|=========.
|------------v--|------v--------|
| | | | | | | | | | | | | | | | |
|---------------|---------------|
<---8 bytes--->
In such case, current code configures hw as:
start_addr = address & ~HW_BREAKPOINT_ALIGN
len = 8 bytes
And thus read/write in last 4 bytes of the given range is ignored.
Fix this by including next doubleword in the length.
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191017093204.7511-3-ravi.bangoria@linux.ibm.com
|
|
We are hadrcoding length everywhere in the watchpoint code. Introduce
macros for the length and use them.
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191017093204.7511-2-ravi.bangoria@linux.ibm.com
|
|
If watchpoint exception is generated by larx/stcx instructions, the
reservation created by larx gets lost while handling exception, and
thus stcx instruction always fails. Generally these instructions are
used in a while(1) loop, for example spinlocks. And because stcx
never succeeds, it loops forever and ultimately hangs the system.
Note that ptrace anyway works in one-shot mode and thus for ptrace
we don't change the behaviour. It's up to ptrace user to take care
of this.
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190910131513.30499-1-ravi.bangoria@linux.ibm.com
|
|
On 8xx, breakpoints stop after executing the instruction, so
stepping/emulation is not needed. Move it into a sub-function and
remove the #ifdefs.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/f8cdc3f1c66ad3c43ebc568abcc6c39ed4676284.1561737231.git.christophe.leroy@c-s.fr
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull powerpc updates from Michael Ellerman:
"Notable changes:
- Removal of the NPU DMA code, used by the out-of-tree Nvidia driver,
as well as some other functions only used by drivers that haven't
(yet?) made it upstream.
- A fix for a bug in our handling of hardware watchpoints (eg. perf
record -e mem: ...) which could lead to register corruption and
kernel crashes.
- Enable HAVE_ARCH_HUGE_VMAP, which allows us to use large pages for
vmalloc when using the Radix MMU.
- A large but incremental rewrite of our exception handling code to
use gas macros rather than multiple levels of nested CPP macros.
And the usual small fixes, cleanups and improvements.
Thanks to: Alastair D'Silva, Alexey Kardashevskiy, Andreas Schwab,
Aneesh Kumar K.V, Anju T Sudhakar, Anton Blanchard, Arnd Bergmann,
Athira Rajeev, Cédric Le Goater, Christian Lamparter, Christophe
Leroy, Christophe Lombard, Christoph Hellwig, Daniel Axtens, Denis
Efremov, Enrico Weigelt, Frederic Barrat, Gautham R. Shenoy, Geert
Uytterhoeven, Geliang Tang, Gen Zhang, Greg Kroah-Hartman, Greg Kurz,
Gustavo Romero, Krzysztof Kozlowski, Madhavan Srinivasan, Masahiro
Yamada, Mathieu Malaterre, Michael Neuling, Nathan Lynch, Naveen N.
Rao, Nicholas Piggin, Nishad Kamdar, Oliver O'Halloran, Qian Cai, Ravi
Bangoria, Sachin Sant, Sam Bobroff, Satheesh Rajendran, Segher
Boessenkool, Shaokun Zhang, Shawn Anastasio, Stewart Smith, Suraj
Jitindar Singh, Thiago Jung Bauermann, YueHaibing"
* tag 'powerpc-5.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (163 commits)
powerpc/powernv/idle: Fix restore of SPRN_LDBAR for POWER9 stop state.
powerpc/eeh: Handle hugepages in ioremap space
ocxl: Update for AFU descriptor template version 1.1
powerpc/boot: pass CONFIG options in a simpler and more robust way
powerpc/boot: add {get, put}_unaligned_be32 to xz_config.h
powerpc/irq: Don't WARN continuously in arch_local_irq_restore()
powerpc/module64: Use symbolic instructions names.
powerpc/module32: Use symbolic instructions names.
powerpc: Move PPC_HA() PPC_HI() and PPC_LO() to ppc-opcode.h
powerpc/module64: Fix comment in R_PPC64_ENTRY handling
powerpc/boot: Add lzo support for uImage
powerpc/boot: Add lzma support for uImage
powerpc/boot: don't force gzipped uImage
powerpc/8xx: Add microcode patch to move SMC parameter RAM.
powerpc/8xx: Use IO accessors in microcode programming.
powerpc/8xx: replace #ifdefs by IS_ENABLED() in microcode.c
powerpc/8xx: refactor programming of microcode CPM params.
powerpc/8xx: refactor printing of microcode patch name.
powerpc/8xx: Refactor microcode write
powerpc/8xx: refactor writing of CPM microcode arrays
...
|
|
If you compile with KVM but without CONFIG_HAVE_HW_BREAKPOINT you fail
at linking with:
arch/powerpc/kvm/book3s_hv_rmhandlers.o:(.text+0x708): undefined reference to `dawr_force_enable'
This was caused by commit c1fe190c0672 ("powerpc: Add force enable of
DAWR on P9 option").
This moves a bunch of code around to fix this. It moves a lot of the
DAWR code in a new file and creates a new CONFIG_PPC_DAWR to enable
compiling it.
Fixes: c1fe190c0672 ("powerpc: Add force enable of DAWR on P9 option")
Signed-off-by: Michael Neuling <mikey@neuling.org>
[mpe: Minor formatting in set_dawr()]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
|
|
In commit c1fe190c0672 ("powerpc: Add force enable of DAWR on P9
option") the following piece of code was added:
smp_call_function((smp_call_func_t)set_dawr, &null_brk, 0);
Since GCC 8 this triggers the following warning about incompatible
function types:
arch/powerpc/kernel/hw_breakpoint.c:408:21: error: cast between incompatible function types from 'int (*)(struct arch_hw_breakpoint *)' to 'void (*)(void *)' [-Werror=cast-function-type]
Since the warning is there for a reason, and should not be hidden behind
a cast, provide an intermediate callback function to avoid the warning.
Fixes: c1fe190c0672 ("powerpc: Add force enable of DAWR on P9 option")
Suggested-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Mathieu Malaterre <malat@debian.org>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
|
|
Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version this program is distributed in the
hope that it will be useful but without any warranty without even
the implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details you
should have received a copy of the gnu general public license along
with this program if not write to the free software foundation inc
59 temple place suite 330 boston ma 02111 1307 usa
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-or-later
has been chosen to replace the boilerplate/reference in 1334 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070033.113240726@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
|
|
This adds a flag so that the DAWR can be enabled on P9 via:
echo Y > /sys/kernel/debug/powerpc/dawr_enable_dangerous
The DAWR was previously force disabled on POWER9 in:
9654153158 powerpc: Disable DAWR in the base POWER9 CPU features
Also see Documentation/powerpc/DAWR-POWER9.txt
This is a dangerous setting, USE AT YOUR OWN RISK.
Some users may not care about a bad user crashing their box
(ie. single user/desktop systems) and really want the DAWR. This
allows them to force enable DAWR.
This flag can also be used to disable DAWR access. Once this is
cleared, all DAWR access should be cleared immediately and your
machine once again safe from crashing.
Userspace may get confused by toggling this. If DAWR is force
enabled/disabled between getting the number of breakpoints (via
PTRACE_GETHWDBGINFO) and setting the breakpoint, userspace will get an
inconsistent view of what's available. Similarly for guests.
For the DAWR to be enabled in a KVM guest, the DAWR needs to be force
enabled in the host AND the guest. For this reason, this won't work on
POWERVM as it doesn't allow the HCALL to work. Writes of 'Y' to the
dawr_enable_dangerous file will fail if the hypervisor doesn't support
writing the DAWR.
To double check the DAWR is working, run this kernel selftest:
tools/testing/selftests/powerpc/ptrace/ptrace-hwbreak.c
Any errors/failures/skips mean something is wrong.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
|
|
Migrate to the new API in order to remove arch_validate_hwbkpt_settings()
that clumsily mixes up architecture validation and commit
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Joel Fernandes <joel.opensrc@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Link: http://lkml.kernel.org/r/1529981939-8231-5-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
|
|
arch_check_bp_in_kernelspace()
We can't pass the breakpoint directly on arch_check_bp_in_kernelspace()
anymore because its architecture internal datas (struct arch_hw_breakpoint)
are not yet filled by the time we call the function, and most
implementation need this backend to be up to date. So arrange the
function to take the probing struct instead.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Joel Fernandes <joel.opensrc@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Link: http://lkml.kernel.org/r/1529981939-8231-3-git-send-email-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
|
|
Back when we first introduced the DAWR, in commit 4ae7ebe9522a
("powerpc: Change hardware breakpoint to allow longer ranges"), we
screwed up the constraint making it a 1024 byte boundary rather than a
512. This makes the check overly permissive. Fortunately GDB is the
only real user and it always did they right thing, so we never
noticed.
This fixes the constraint to 512 bytes.
Fixes: 4ae7ebe9522a ("powerpc: Change hardware breakpoint to allow longer ranges")
Cc: stable@vger.kernel.org # v3.9+
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
|
|
This updates the ptrace code to use ppc_breakpoint_available().
We now advertise via PPC_PTRACE_GETHWDBGINFO zero breakpoints when the
DAWR is missing (ie. POWER9). This results in GDB falling back to
software emulation of the breakpoint (which is slow).
For the features advertised by PPC_PTRACE_GETHWDBGINFO, we keep
advertising DAWR as if we don't GDB assumes 1 breakpoint irrespective
of the number of breakpoints advertised. GDB then fails later when
trying to set this one breakpoint.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/scottwood/linux into next
Freescale updates from Scott:
"Highlights include 8xx breakpoints and perf, t1042rdb display support,
and board updates."
|
|
Currently xmon data-breakpoint feature is broken.
Whenever there is a watchpoint match occurs, hw_breakpoint_handler will
be called by do_break via notifier chains mechanism. If watchpoint is
registered by xmon, hw_breakpoint_handler won't find any associated
perf_event and returns immediately with NOTIFY_STOP. Similarly, do_break
also returns without notifying to xmon.
Solve this by returning NOTIFY_DONE when hw_breakpoint_handler does not
find any perf_event associated with matched watchpoint, rather than
NOTIFY_STOP, which tells the core code to continue calling the other
breakpoint handlers including the xmon one.
Cc: stable@vger.kernel.org
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
|
|
This patch implements HW breakpoint on the 8xx. The 8xx has
capability to manage HW breakpoints, which is slightly different
than BOOK3S:
1/ The breakpoint match doesn't trigger a DSI exception but a
dedicated data breakpoint exception.
2/ The breakpoint happens after the instruction has completed,
no need to single step or emulate the instruction,
3/ Matched address is not set in DAR but in BAR,
4/ DABR register doesn't exist, instead we have registers
LCTRL1, LCTRL2 and CMPx registers,
5/ The match on one comparator is not on a double word but
on a single word.
The patch does:
1/ Prepare the dedicated registers in call to __set_dabr(). In order
to emulate the double word handling of BOOK3S, comparator E is set to
DABR address value and comparator F to address + 4. Then breakpoint 1
is set to match comparator E or F,
2/ Skip the singlestepping stage when compiled for CONFIG_PPC_8xx,
3/ Implement the exception. In that exception, the matched address
is taken from SPRN_BAR and manage as if it was from SPRN_DAR.
4/ I/D TLB error exception routines perform a tlbie on bad TLBs. That
tlbie triggers the breakpoint exception when performed on the
breakpoint address. For this reason, the routine returns if the match
is from one of those two tlbie.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Scott Wood <oss@buserror.net>
|
