linux/arch/powerpc/perf
Aneesh Kumar K.V 15759cb054 powerpc/perf/callchain: Use __get_user_pages_fast in read_user_stack_slow
read_user_stack_slow is called with interrupts soft disabled and it copies contents
from the page which we find mapped to a specific address. To convert
userspace address to pfn, the kernel now uses lockless page table walk.

The kernel needs to make sure the pfn value read remains stable and is not released
and reused for another process while the contents are read from the page. This
can only be achieved by holding a page reference.

One of the first approaches I tried was to check the pte value after the kernel
copies the contents from the page. But as shown below we can still get it wrong

CPU0                           CPU1
pte = READ_ONCE(*ptep);
                               pte_clear(pte);
                               put_page(page);
                               page = alloc_page();
                               memcpy(page_address(page), "secret password", nr);
memcpy(buf, kaddr + offset, nb);
                               put_page(page);
                               handle_mm_fault()
                               page = alloc_page();
                               set_pte(pte, page);
if (pte_val(pte) != pte_val(*ptep))

Hence switch to __get_user_pages_fast.

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/20200505071729.54912-8-aneesh.kumar@linux.ibm.com
2020-05-05 21:20:14 +10:00
..
req-gen powerpc: clean the inclusion of stringify.h 2018-07-30 22:48:17 +10:00
8xx-pmu.c powerpc/8xx: Use alternative scratch registers in DTLB miss handler 2020-01-27 22:36:16 +11:00
bhrb.S treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
callchain_32.c powerpc/perf: split callchain.c by bitness 2020-04-03 00:10:00 +11:00
callchain_64.c powerpc/perf/callchain: Use __get_user_pages_fast in read_user_stack_slow 2020-05-05 21:20:14 +10:00
callchain.c powerpc/perf: split callchain.c by bitness 2020-04-03 00:10:00 +11:00
callchain.h powerpc/perf: split callchain.c by bitness 2020-04-03 00:10:00 +11:00
core-book3s.c perf/core: Add new branch sample type for HW index of raw branch records 2020-02-11 13:23:49 +01:00
core-fsl-emb.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
e500-pmu.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
e6500-pmu.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
generic-compat-pmu.c powerpc/perf: Add generic compat mode pmu driver 2019-05-03 02:54:58 +10:00
hv-24x7-catalog.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
hv-24x7-domains.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
hv-24x7.c powerpc updates for 5.3 2019-07-13 16:08:36 -07:00
hv-24x7.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
hv-common.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
hv-common.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
hv-gpci-requests.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
hv-gpci.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
hv-gpci.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
imc-pmu.c powerpc/perf: Implement a global lock to avoid races between trace, core and thread imc events. 2020-04-03 00:09:58 +11:00
internal.h powerpc/perf: Add generic compat mode pmu driver 2019-05-03 02:54:58 +10:00
isa207-common.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
isa207-common.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 138 2019-05-30 11:25:16 -07:00
Makefile powerpc/perf: split callchain.c by bitness 2020-04-03 00:10:00 +11:00
mpc7450-pmu.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
perf_regs.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
power5-pmu.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
power5+-pmu.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
power6-pmu.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
power7-events-list.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
power7-pmu.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
power8-events-list.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
power8-pmu.c powerpc fixes for 5.2 #3 2019-06-02 10:21:04 -07:00
power9-events-list.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
power9-pmu.c powerpc fixes for 5.2 #3 2019-06-02 10:21:04 -07:00
ppc970-pmu.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00