Make our stack-walking code KASAN-safe by using __no_sanitize_address.
Generic code, arm64, s390 and x86 all make accesses unchecked for similar
sorts of reasons: when unwinding a stack, we might touch memory that KASAN
has marked as being out-of-bounds. In ppc64 KASAN development, I hit this
sometimes when checking for an exception frame - because we're checking
an arbitrary offset into the stack frame.
See commit 2095574632 ("s390/kasan: avoid false positives during stack
unwind"), commit bcaf669b4b ("arm64: disable kasan when accessing
frame->fp in unwind_frame"), commit 91e08ab0c8 ("x86/dumpstack:
Prevent KASAN false positive warnings") and commit 6e22c83664
("tracing, kasan: Silence Kasan warning in check_stack of stack_tracer").
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210614120907.1952321-1-dja@axtens.net
The "no_handler_test" in ebb selftests attempts to read the PMU
registers twice via helper function "dump_ebb_state". First dump is
just before closing of event and the second invocation is done after
closing of the event. The original intention of second
dump_ebb_state was to dump the state of registers at the end of
the test when the counters are frozen. But this will be achieved
with the first call itself since sample period is set to low value
and PMU will be frozen by then. Hence patch removes the
dump which was done before closing of the event.
Reported-by: Shirisha Ganta <shirisha.ganta1@ibm.com>
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Tested-by: Nageswara R Sastry <rnsastry@linux.ibm.com <mailto:rnsastry@linux.ibm.com>>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1621950703-1532-2-git-send-email-atrajeev@linux.vnet.ibm.com
KUEP implements the update of user segment registers.
Move it into mmu-hash.h in order to use it from other places.
And inline kuep_lock() and kuep_unlock(). Inlining kuep_lock() is
important for system_call_exception(), otherwise system_call_exception()
has to save into stack the system call parameters that are used just
after, and doing that takes more instructions than kuep_lock() itself.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/24591ca480d14a62ef910e38a5273d551262c4a2.1622708530.git.christophe.leroy@csgroup.eu
nip is already an unsigned long, no cast needed.
op_callback_addr and emulate_step_addr are kprobe_opcode_t *.
There value is obtained with ppc_kallsyms_lookup_name() which
returns 'unsigned long', and there values are used create_branch()
which expects 'unsigned long'. So change them to 'unsigned long'
to avoid casting them back and forth.
can_optimize() used p->addr several times as 'unsigned long'.
Use a local 'unsigned long' variable and avoid casting multiple times.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/e03192a6d4123242a275e71ce2ba0bb4d90700c1.1621516826.git.christophe.leroy@csgroup.eu
'struct ppc_inst' is an internal representation of an instruction, but
in-memory instructions are and will remain a table of 'u32' forever.
Replace all 'struct ppc_inst *' used for locating an instruction in
memory by 'u32 *'. This removes a lot of undue casts to 'struct
ppc_inst *'.
It also helps locating ab-use of 'struct ppc_inst' dereference.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
[mpe: Fix ppc_inst_next(), use u32 instead of unsigned int]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/7062722b087228e42cbd896e39bfdf526d6a340a.1621516826.git.christophe.leroy@csgroup.eu
'struct ppc_inst' is an internal structure to represent an instruction,
it is not directly the representation of that instruction in text code.
It is not meant to map and dereference code.
Dereferencing code directly through 'struct ppc_inst' has two main issues:
- On powerpc, structs are expected to be 8 bytes aligned while code is
spread every 4 byte.
- Should a non prefixed instruction lie at the end of the page and the
following page not be mapped, it would generate a page fault.
In-memory code must be accessed with ppc_inst_read().
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/c9a1201dd0a66b4a0f91f0fb46d9385cbf030feb.1621516826.git.christophe.leroy@csgroup.eu
