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2024-02-14powerpc/ftrace: Ignore ftrace locations in exit text sectionsNaveen N Rao
Michael reported that we are seeing an ftrace bug on bootup when KASAN is enabled and we are using -fpatchable-function-entry: ftrace: allocating 47780 entries in 18 pages ftrace-powerpc: 0xc0000000020b3d5c: No module provided for non-kernel address ------------[ ftrace bug ]------------ ftrace faulted on modifying [<c0000000020b3d5c>] 0xc0000000020b3d5c Initializing ftrace call sites ftrace record flags: 0 (0) expected tramp: c00000000008cef4 ------------[ cut here ]------------ WARNING: CPU: 0 PID: 0 at kernel/trace/ftrace.c:2180 ftrace_bug+0x3c0/0x424 Modules linked in: CPU: 0 PID: 0 Comm: swapper Not tainted 6.5.0-rc3-00120-g0f71dcfb4aef #860 Hardware name: IBM pSeries (emulated by qemu) POWER9 (raw) 0x4e1202 0xf000005 of:SLOF,HEAD hv:linux,kvm pSeries NIP: c0000000003aa81c LR: c0000000003aa818 CTR: 0000000000000000 REGS: c0000000033cfab0 TRAP: 0700 Not tainted (6.5.0-rc3-00120-g0f71dcfb4aef) MSR: 8000000002021033 <SF,VEC,ME,IR,DR,RI,LE> CR: 28028240 XER: 00000000 CFAR: c0000000002781a8 IRQMASK: 3 ... NIP [c0000000003aa81c] ftrace_bug+0x3c0/0x424 LR [c0000000003aa818] ftrace_bug+0x3bc/0x424 Call Trace: ftrace_bug+0x3bc/0x424 (unreliable) ftrace_process_locs+0x5f4/0x8a0 ftrace_init+0xc0/0x1d0 start_kernel+0x1d8/0x484 With CONFIG_FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY=y and CONFIG_KASAN=y, compiler emits nops in functions that it generates for registering and unregistering global variables (unlike with -pg and -mprofile-kernel where calls to _mcount() are not generated in those functions). Those functions then end up in INIT_TEXT and EXIT_TEXT respectively. We don't expect to see any profiled functions in EXIT_TEXT, so ftrace_init_nop() assumes that all addresses that aren't in the core kernel text belongs to a module. Since these functions do not match that criteria, we see the above bug. Address this by having ftrace ignore all locations in the text exit sections of vmlinux. Fixes: 0f71dcfb4aef ("powerpc/ftrace: Add support for -fpatchable-function-entry") Cc: stable@vger.kernel.org # v6.6+ Reported-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Naveen N Rao <naveen@kernel.org> Reviewed-by: Benjamin Gray <bgray@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/20240213175410.1091313-1-naveen@kernel.org
2024-01-08Merge tag 'powerpc-6.8-1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux Pull powerpc updates from Michael Ellerman: - Add initial support to recognise the HeXin C2000 processor. - Add papr-vpd and papr-sysparm character device drivers for VPD & sysparm retrieval, so userspace tools can be adapted to avoid doing raw firmware calls from userspace. - Sched domains optimisations for shared processor partitions on P9/P10. - A series of optimisations for KVM running as a nested HV under PowerVM. - Other small features and fixes. Thanks to Aditya Gupta, Aneesh Kumar K.V, Arnd Bergmann, Christophe Leroy, Colin Ian King, Dario Binacchi, David Heidelberg, Geoff Levand, Gustavo A. R. Silva, Haoran Liu, Jordan Niethe, Kajol Jain, Kevin Hao, Kunwu Chan, Li kunyu, Li zeming, Masahiro Yamada, Michal Suchánek, Nathan Lynch, Naveen N Rao, Nicholas Piggin, Randy Dunlap, Sathvika Vasireddy, Srikar Dronamraju, Stephen Rothwell, Vaibhav Jain, and Zhao Ke. * tag 'powerpc-6.8-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (96 commits) powerpc/ps3_defconfig: Disable PPC64_BIG_ENDIAN_ELF_ABI_V2 powerpc/86xx: Drop unused CONFIG_MPC8610 powerpc/powernv: Add error handling to opal_prd_range_is_valid selftests/powerpc: Fix spelling mistake "EACCESS" -> "EACCES" powerpc/hvcall: Reorder Nestedv2 hcall opcodes powerpc/ps3: Add missing set_freezable() for ps3_probe_thread() powerpc/mpc83xx: Use wait_event_freezable() for freezable kthread powerpc/mpc83xx: Add the missing set_freezable() for agent_thread_fn() powerpc/fsl: Fix fsl,tmu-calibration to match the schema powerpc/smp: Dynamically build Powerpc topology powerpc/smp: Avoid asym packing within thread_group of a core powerpc/smp: Add __ro_after_init attribute powerpc/smp: Disable MC domain for shared processor powerpc/smp: Enable Asym packing for cores on shared processor powerpc/sched: Cleanup vcpu_is_preempted() powerpc: add cpu_spec.cpu_features to vmcoreinfo powerpc/imc-pmu: Add a null pointer check in update_events_in_group() powerpc/powernv: Add a null pointer check in opal_powercap_init() powerpc/powernv: Add a null pointer check in opal_event_init() powerpc/powernv: Add a null pointer check to scom_debug_init_one() ...
2023-12-13powerpc/ftrace: Remove nops after the call to ftrace_stubNaveen N Rao
ftrace_stub is within the same CU, so there is no need for a subsequent nop instruction. Signed-off-by: Naveen N Rao <naveen@kernel.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/8ee5ec520e37d5523654bb2cd65a17512fb774e2.1702045299.git.naveen@kernel.org
2023-12-05powerpc/ftrace: Fix stack teardown in ftrace_no_traceNaveen N Rao
Commit 41a506ef71eb ("powerpc/ftrace: Create a dummy stackframe to fix stack unwind") added use of a new stack frame on ftrace entry to fix stack unwind. However, the commit missed updating the offset used while tearing down the ftrace stack when ftrace is disabled. Fix the same. In addition, the commit missed saving the correct stack pointer in pt_regs. Update the same. Fixes: 41a506ef71eb ("powerpc/ftrace: Create a dummy stackframe to fix stack unwind") Cc: stable@vger.kernel.org # v6.5+ Signed-off-by: Naveen N Rao <naveen@kernel.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/20231130065947.2188860-1-naveen@kernel.org
2023-08-31Merge tag 'powerpc-6.6-1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux Pull powerpc updates from Michael Ellerman: - Add HOTPLUG_SMT support (/sys/devices/system/cpu/smt) and honour the configured SMT state when hotplugging CPUs into the system - Combine final TLB flush and lazy TLB mm shootdown IPIs when using the Radix MMU to avoid a broadcast TLBIE flush on exit - Drop the exclusion between ptrace/perf watchpoints, and drop the now unused associated arch hooks - Add support for the "nohlt" command line option to disable CPU idle - Add support for -fpatchable-function-entry for ftrace, with GCC >= 13.1 - Rework memory block size determination, and support 256MB size on systems with GPUs that have hotpluggable memory - Various other small features and fixes Thanks to Andrew Donnellan, Aneesh Kumar K.V, Arnd Bergmann, Athira Rajeev, Benjamin Gray, Christophe Leroy, Frederic Barrat, Gautam Menghani, Geoff Levand, Hari Bathini, Immad Mir, Jialin Zhang, Joel Stanley, Jordan Niethe, Justin Stitt, Kajol Jain, Kees Cook, Krzysztof Kozlowski, Laurent Dufour, Liang He, Linus Walleij, Mahesh Salgaonkar, Masahiro Yamada, Michal Suchanek, Nageswara R Sastry, Nathan Chancellor, Nathan Lynch, Naveen N Rao, Nicholas Piggin, Nick Desaulniers, Omar Sandoval, Randy Dunlap, Reza Arbab, Rob Herring, Russell Currey, Sourabh Jain, Thomas Gleixner, Trevor Woerner, Uwe Kleine-König, Vaibhav Jain, Xiongfeng Wang, Yuan Tan, Zhang Rui, and Zheng Zengkai. * tag 'powerpc-6.6-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (135 commits) macintosh/ams: linux/platform_device.h is needed powerpc/xmon: Reapply "Relax frame size for clang" powerpc/mm/book3s64: Use 256M as the upper limit with coherent device memory attached powerpc/mm/book3s64: Fix build error with SPARSEMEM disabled powerpc/iommu: Fix notifiers being shared by PCI and VIO buses powerpc/mpc5xxx: Add missing fwnode_handle_put() powerpc/config: Disable SLAB_DEBUG_ON in skiroot powerpc/pseries: Remove unused hcall tracing instruction powerpc/pseries: Fix hcall tracepoints with JUMP_LABEL=n powerpc: dts: add missing space before { powerpc/eeh: Use pci_dev_id() to simplify the code powerpc/64s: Move CPU -mtune options into Kconfig powerpc/powermac: Fix unused function warning powerpc/pseries: Rework lppaca_shared_proc() to avoid DEBUG_PREEMPT powerpc: Don't include lppaca.h in paca.h powerpc/pseries: Move hcall_vphn() prototype into vphn.h powerpc/pseries: Move VPHN constants into vphn.h cxl: Drop unused detach_spa() powerpc: Drop zalloc_maybe_bootmem() powerpc/powernv: Use struct opal_prd_msg in more places ...
2023-08-22powerpc/ftrace: Add support for -fpatchable-function-entryNaveen N Rao
GCC v13.1 updated support for -fpatchable-function-entry on ppc64le to emit nops after the local entry point, rather than before it. This allows us to use this in the kernel for ftrace purposes. A new script is added under arch/powerpc/tools/ to help detect if nops are emitted after the function local entry point, or before the global entry point. With -fpatchable-function-entry, we no longer have the profiling instructions generated at function entry, so we only need to validate the presence of two nops at the ftrace location in ftrace_init_nop(). We patch the preceding instruction with 'mflr r0' to match the -mprofile-kernel ABI for subsequent ftrace use. This changes the profiling instructions used on ppc32. The default -pg option emits an additional 'stw' instruction after 'mflr r0' and before the branch to _mcount 'bl _mcount'. This is very similar to the original -mprofile-kernel implementation on ppc64le, where an additional 'std' instruction was used to save LR to its save location in the caller's stackframe. Subsequently, this additional store was removed in later compiler versions for performance reasons. The same reasons apply for ppc32 so we only patch in a 'mflr r0'. Signed-off-by: Naveen N Rao <naveen@kernel.org> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/68586d22981a2c3bb45f27a2b621173d10a7d092.1687166935.git.naveen@kernel.org
2023-08-22powerpc/ftrace: Implement ftrace_replace_code()Naveen N Rao
Implement ftrace_replace_code() to consolidate logic from the different ftrace patching routines: ftrace_make_nop(), ftrace_make_call() and ftrace_modify_call(). Note that ftrace_make_call() is still required primarily to handle patching modules during their load time. The other two routines should no longer be called. This lays the groundwork to enable better control in patching ftrace locations, including the ability to nop-out preceding profiling instructions when ftrace is disabled. Signed-off-by: Naveen N Rao <naveen@kernel.org> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/c28f852225646b0561bbf3c1d22d03f041ace8e0.1687166935.git.naveen@kernel.org
2023-08-22powerpc/ftrace: Replace use of ftrace_call_replace() with ↵Naveen N Rao
ftrace_create_branch_inst() ftrace_create_branch_inst() is clearer about its intent than ftrace_call_replace(). Signed-off-by: Naveen N Rao <naveen@kernel.org> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/953513b88fa922ba7a66d772dc1310710efe9177.1687166935.git.naveen@kernel.org
2023-08-22powerpc/ftrace: Simplify ftrace_modify_call()Naveen N Rao
Now that we validate the ftrace location during initialization in ftrace_init_nop(), we can simplify ftrace_modify_call() to patch-in the updated branch instruction without worrying about the instructions surrounding the ftrace location. Note that we continue to ensure we have the expected branch instruction at the ftrace location before patching it with the updated branch destination. Signed-off-by: Naveen N Rao <naveen@kernel.org> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/06275720939f8ee4c2f61c9e9a3e89b1fa3c441d.1687166935.git.naveen@kernel.org
2023-08-22powerpc/ftrace: Simplify ftrace_make_call()Naveen N Rao
Now that we validate the ftrace location during initialization in ftrace_init_nop(), we can simplify ftrace_make_call() to replace the nop without worrying about the instructions surrounding the ftrace location. Note that we continue to ensure that we have a nop at the ftrace location before patching it. Signed-off-by: Naveen N Rao <naveen@kernel.org> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/2d28866d2f556488a663981abe5621511efb207b.1687166935.git.naveen@kernel.org
2023-08-22powerpc/ftrace: Simplify ftrace_make_nop()Naveen N Rao
Now that we validate the ftrace location during initialization in ftrace_init_nop(), we can simplify ftrace_make_nop() to patch-in the nop without worrying about the instructions surrounding the ftrace location. Note that we continue to ensure that we have a bl to ftrace_[regs_]caller at the ftrace location before nop-ing it out. Signed-off-by: Naveen N Rao <naveen@kernel.org> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/e12ccbf28c50c3a07fb614f4d392e55f7098a729.1687166935.git.naveen@kernel.org
2023-08-22powerpc/ftrace: Add separate ftrace_init_nop() with additional validationNaveen N Rao
Currently, we validate instructions around the ftrace location every time we have to enable/disable ftrace. Introduce ftrace_init_nop() to instead perform all the validation during ftrace initialization. This allows us to simply patch the necessary instructions during enabling/disabling ftrace. Signed-off-by: Naveen N Rao <naveen@kernel.org> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/f373684081e8e98be09b7f44d2d93069768324dc.1687166935.git.naveen@kernel.org
2023-08-22powerpc/ftrace: Stop re-purposing linker generated long branches for ftraceNaveen N Rao
Commit 67361cf8071286 ("powerpc/ftrace: Handle large kernel configs") added ftrace support for ppc64 kernel images with a text section larger than 32MB. The patch did two things: 1. Add stubs at the end of .text to branch into ftrace_[regs_]caller for functions that were out of branch range. 2. Re-purpose linker-generated long branches to _mcount to instead branch to ftrace_[regs_]caller. Before that, we only supported kernel .text up to ~32MB. With the above, we now support up to ~96MB: - The first 32MB of kernel text can branch directly into ftrace_[regs_]caller since that symbol is usually at the beginning. - The modified long_branch from (2) above is used by the next 32MB of kernel text. - The next 32MB of kernel text can use the stub at the end of text to branch back to ftrace_[regs_]caller. While re-purposing the long branch works in practice, it still restricts ftrace to kernel text up to ~96MB. The stub at the end of kernel text from (1) already enables us to extend ftrace support for kernel text up to 64MB, which fulfils the original requirement. Further, once we switch to -fpatchable-function-entry, there will not be a long branch that we can use. Stop re-purposing the linker-generated long branches for ftrace to simplify the code. If there are good reasons to support ftrace on kernels beyond 64MB, we can consider adding support by using -fpatchable-function-entry. Signed-off-by: Naveen N Rao <naveen@kernel.org> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/33fa3be97f8e1f2171254ef2e1b0d5c8836c11fd.1687166935.git.naveen@kernel.org
2023-08-22powerpc/ftrace: Refactor ftrace_modify_code()Naveen N Rao
Split up ftrace_modify_code() into a few helpers for future use. Also update error messages accordingly. Signed-off-by: Naveen N Rao <naveen@kernel.org> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/a8daa49712b44ff539e6c22a2ea649a540386798.1687166935.git.naveen@kernel.org
2023-08-22powerpc/ftrace: Consolidate ftrace support into fewer filesNaveen N Rao
ftrace_low.S has just the _mcount stub and return_to_handler(). Merge this back into ftrace_mprofile.S and ftrace_64_pg.S to keep all ftrace code together, and to allow those to evolve independently. ftrace_mprofile.S is also not an entirely accurate name since this also holds ppc32 code. This will be all the more incorrect once support for -fpatchable-function-entry is added. Rename files here to more accurately describe the code: - ftrace_mprofile.S is renamed to ftrace_entry.S - ftrace_pg.c is renamed to ftrace_64_pg.c - ftrace_64_pg.S is rename to ftrace_64_pg_entry.S Signed-off-by: Naveen N Rao <naveen@kernel.org> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/b900c9a8bba9d6c3c295e0f99886acf3e5bf6f7b.1687166935.git.naveen@kernel.org
2023-08-22powerpc/ftrace: Extend ftrace support for large kernels to ppc32Naveen N Rao
Commit 67361cf8071286 ("powerpc/ftrace: Handle large kernel configs") added ftrace support for ppc64 kernel images with a text section larger than 32MB. The approach itself isn't specific to ppc64, so extend the same to also work on ppc32. While at it, reduce the space reserved for the stub from 64 bytes to 32 bytes since the different stub variants are all less than 8 instructions. To reduce use of #ifdef, a stub implementation is provided for kernel_toc_address() and -SZ_2G is cast to 'long long' to prevent errors on ppc32. Signed-off-by: Naveen N Rao <naveen@kernel.org> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/9fa3258cbb9105cf8a0a8135214d44ffbc75fe84.1687166935.git.naveen@kernel.org
2023-08-22powerpc/ftrace: Use FTRACE_REGS_ADDR to identify the correct ftrace trampolineNaveen N Rao
Instead of keying off DYNAMIC_FTRACE_WITH_REGS, use FTRACE_REGS_ADDR to identify the proper ftrace trampoline address to use. Signed-off-by: Naveen N Rao <naveen@kernel.org> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/6045a280a57a7ea937a5bb13ccac747026dbfb07.1687166935.git.naveen@kernel.org
2023-08-22powerpc/ftrace: Simplify function_graph support in ftrace.cNaveen N Rao
Since we now support DYNAMIC_FTRACE_WITH_ARGS across ppc32 and ppc64 ELFv2, we can simplify function_graph tracer support code in ftrace.c Signed-off-by: Naveen N Rao <naveen@kernel.org> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/4dc92c4b1ed444dc62b748ae7327acdb9e096864.1687166935.git.naveen@kernel.org
2023-08-22powerpc64/ftrace: Move ELFv1 and -pg support code into a separate fileNaveen N Rao
ELFv1 support is deprecated and on the way out. Pre -mprofile-kernel ftrace support (-pg only) is very limited and is retained primarily for clang builds. It won't be necessary once clang lands support for -fpatchable-function-entry. Copy the existing ftrace code supporting these into ftrace_pg.c. ftrace.c can then be refactored and enhanced with a focus on ppc32 and ppc64 ELFv2. Signed-off-by: Naveen N Rao <naveen@kernel.org> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/1eb6cc6c3141ddb77a2a25f8a9e83d83ff312b02.1687166935.git.naveen@kernel.org
2023-08-16powerpc: replace #include <asm/export.h> with #include <linux/export.h>Masahiro Yamada
Commit ddb5cdbafaaa ("kbuild: generate KSYMTAB entries by modpost") deprecated <asm/export.h>, which is now a wrapper of <linux/export.h>. Replace #include <asm/export.h> with #include <linux/export.h>. After all the <asm/export.h> lines are converted, <asm/export.h> and <asm-generic/export.h> will be removed. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> [mpe: Fixup selftests that stub asm/export.h] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/20230806150954.394189-2-masahiroy@kernel.org
2023-08-16powerpc: remove unneeded #include <asm/export.h>Masahiro Yamada
There is no EXPORT_SYMBOL line there, hence #include <asm/export.h> is unneeded. Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/20230806150954.394189-1-masahiroy@kernel.org
2023-07-28powerpc/ftrace: Create a dummy stackframe to fix stack unwindNaveen N Rao
With ppc64 -mprofile-kernel and ppc32 -pg, profiling instructions to call into ftrace are emitted right at function entry. The instruction sequence used is minimal to reduce overhead. Crucially, a stackframe is not created for the function being traced. This breaks stack unwinding since the function being traced does not have a stackframe for itself. As such, it never shows up in the backtrace: /sys/kernel/debug/tracing # echo 1 > /proc/sys/kernel/stack_tracer_enabled /sys/kernel/debug/tracing # cat stack_trace Depth Size Location (17 entries) ----- ---- -------- 0) 4144 32 ftrace_call+0x4/0x44 1) 4112 432 get_page_from_freelist+0x26c/0x1ad0 2) 3680 496 __alloc_pages+0x290/0x1280 3) 3184 336 __folio_alloc+0x34/0x90 4) 2848 176 vma_alloc_folio+0xd8/0x540 5) 2672 272 __handle_mm_fault+0x700/0x1cc0 6) 2400 208 handle_mm_fault+0xf0/0x3f0 7) 2192 80 ___do_page_fault+0x3e4/0xbe0 8) 2112 160 do_page_fault+0x30/0xc0 9) 1952 256 data_access_common_virt+0x210/0x220 10) 1696 400 0xc00000000f16b100 11) 1296 384 load_elf_binary+0x804/0x1b80 12) 912 208 bprm_execve+0x2d8/0x7e0 13) 704 64 do_execveat_common+0x1d0/0x2f0 14) 640 160 sys_execve+0x54/0x70 15) 480 64 system_call_exception+0x138/0x350 16) 416 416 system_call_common+0x160/0x2c4 Fix this by having ftrace create a dummy stackframe for the function being traced. With this, backtraces now capture the function being traced: /sys/kernel/debug/tracing # cat stack_trace Depth Size Location (17 entries) ----- ---- -------- 0) 3888 32 _raw_spin_trylock+0x8/0x70 1) 3856 576 get_page_from_freelist+0x26c/0x1ad0 2) 3280 64 __alloc_pages+0x290/0x1280 3) 3216 336 __folio_alloc+0x34/0x90 4) 2880 176 vma_alloc_folio+0xd8/0x540 5) 2704 416 __handle_mm_fault+0x700/0x1cc0 6) 2288 96 handle_mm_fault+0xf0/0x3f0 7) 2192 48 ___do_page_fault+0x3e4/0xbe0 8) 2144 192 do_page_fault+0x30/0xc0 9) 1952 608 data_access_common_virt+0x210/0x220 10) 1344 16 0xc0000000334bbb50 11) 1328 416 load_elf_binary+0x804/0x1b80 12) 912 64 bprm_execve+0x2d8/0x7e0 13) 848 176 do_execveat_common+0x1d0/0x2f0 14) 672 192 sys_execve+0x54/0x70 15) 480 64 system_call_exception+0x138/0x350 16) 416 416 system_call_common+0x160/0x2c4 This results in two additional stores in the ftrace entry code, but produces reliable backtraces. Fixes: 153086644fd1 ("powerpc/ftrace: Add support for -mprofile-kernel ftrace ABI") Cc: stable@vger.kernel.org Signed-off-by: Naveen N Rao <naveen@kernel.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/20230621051349.759567-1-naveen@kernel.org
2023-04-20powerpc/64: vmlinux support building with PCREL addresingNicholas Piggin
PC-Relative or PCREL addressing is an extension to the ELF ABI which uses Power ISA v3.1 PC-relative instructions to calculate addresses, rather than the traditional TOC scheme. Add an option to build vmlinux using pcrel addressing. Modules continue to use TOC addressing. - TOC address helpers and r2 are poisoned with -1 when running vmlinux. r2 could be used for something useful once things are ironed out. - Assembly must call C functions with @notoc annotation, or the linker complains aobut a missing nop after the call. This is done with the CFUNC macro introduced earlier. - Boot: with the exception of prom_init, the execution branches to the kernel virtual address early in boot, before any addresses are generated, which ensures 34-bit pcrel addressing does not miss the high PAGE_OFFSET bits. TOC relative addressing has a similar requirement. prom_init does not go to the virtual address and its addresses should not carry over to the post-prom kernel. - Ftrace trampolines are converted from TOC addressing to pcrel addressing, including module ftrace trampolines that currently use the kernel TOC to find ftrace target functions. - BPF function prologue and function calling generation are converted from TOC to pcrel. - copypage_64.S has an interesting problem, prefixed instructions have alignment restrictions so the linker can add padding, which makes the assembler treat the difference between two local labels as non-constant even if alignment is arranged so padding is not required. This may need toolchain help to solve nicely, for now move the prefix instruction out of the alternate patch section to work around it. This reduces kernel text size by about 6%. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/20230408021752.862660-6-npiggin@gmail.com
2023-04-20powerpc/64: Add support to build with prefixed instructionsNicholas Piggin
Add an option to build kernel and module with prefixed instructions if the CPU and toolchain support it. This is not related to kernel support for userspace execution of prefixed instructions. Building with prefixed instructions breaks some extended inline asm memory addressing, for example it will provide immediates that exceed the range of simple load/store displacement. Whether this is a toolchain or a kernel asm problem remains to be seen. For now, these are replaced with simpler and less efficient direct register addressing when compiling with prefixed. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/20230408021752.862660-4-npiggin@gmail.com
2023-02-10powerpc/kcsan: Add exclusions from instrumentationRohan McLure
Exclude various incompatible compilation units from KCSAN instrumentation. Signed-off-by: Rohan McLure <rmclure@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20230206021801.105268-2-rmclure@linux.ibm.com
2022-12-02powerpc: add definition for pt_regs offset within an interrupt frameNicholas Piggin
This is a common offset that currently uses the overloaded STACK_FRAME_OVERHEAD constant. It's easier to read and more flexible to use a specific regs offset for this. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20221127124942.1665522-8-npiggin@gmail.com
2022-09-28powerpc/64: provide a helper macro to load r2 with the kernel TOCNicholas Piggin
A later change stops the kernel using r2 and loads it with a poison value. Provide a PACATOC loading abstraction which can hide this detail. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20220926034057.2360083-5-npiggin@gmail.com
2022-09-28powerpc/64: asm use consistent global variable declaration and accessNicholas Piggin
Use helper macros to access global variables, and place them in .data sections rather than in .toc. Putting addresses in TOC is not required because the kernel is linked with a single TOC. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20220926034057.2360083-3-npiggin@gmail.com
2022-08-10powerpc64/ftrace: Fix ftrace for clang buildsNaveen N. Rao
Clang doesn't support -mprofile-kernel ABI, so guard the checks against CONFIG_DYNAMIC_FTRACE_WITH_REGS, rather than the elf ABI version. Fixes: 23b44fc248f4 ("powerpc/ftrace: Make __ftrace_make_{nop/call}() common to PPC32 and PPC64") Cc: stable@vger.kernel.org # v5.19+ Reported-by: Nick Desaulniers <ndesaulniers@google.com> Reported-by: Ondrej Mosnacek <omosnacek@gmail.com> Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Tested-by: Ondrej Mosnacek <omosnacek@gmail.com> Acked-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://github.com/llvm/llvm-project/issues/57031 Link: https://github.com/ClangBuiltLinux/linux/issues/1682 Link: https://lore.kernel.org/r/20220809095907.418764-1-naveen.n.rao@linux.vnet.ibm.com
2022-07-25powerpc: Fix all occurences of duplicate wordsMichael Ellerman
Since commit 87c78b612f4f ("powerpc: Fix all occurences of "the the"") fixed "the the", there's now a steady stream of patches fixing other duplicate words. Just fix them all at once, to save the overhead of dealing with individual patches for each case. This leaves a few cases of "that that", which in some contexts is correct. Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20220718095158.326606-1-mpe@ellerman.id.au
2022-06-29powerpc/64: Drop ppc_inst_as_str()Michael Ellerman
The ppc_inst_as_str() macro tries to make printing variable length, aka "prefixed", instructions convenient. It mostly succeeds, but it does hide an on-stack buffer, which triggers stack protector. More problematically it doesn't compile at all with GCC 12, with -Wdangling-pointer, due to the fact that it returns the char buffer declared inside the macro: arch/powerpc/kernel/trace/ftrace.c: In function '__ftrace_modify_call': ./include/linux/printk.h:475:44: error: using a dangling pointer to '__str' [-Werror=dangling-pointer=] 475 | #define printk(fmt, ...) printk_index_wrap(_printk, fmt, ##__VA_ARGS__) ... arch/powerpc/kernel/trace/ftrace.c:567:17: note: in expansion of macro 'pr_err' 567 | pr_err("Not expected bl: opcode is %s\n", ppc_inst_as_str(op)); | ^~~~~~ ./arch/powerpc/include/asm/inst.h:156:14: note: '__str' declared here 156 | char __str[PPC_INST_STR_LEN]; \ | ^~~~~ This could be fixed by having the caller declare the buffer, but in some places there'd need to be two buffers. In all cases where ppc_inst_as_str() is used the output is not really meant for user consumption, it's almost always indicative of a kernel bug. A simpler solution is to just print the value as an unsigned long. For normal instructions the output is identical. For prefixed instructions the value is printed as a single 64-bit quantity, whereas previously the low half was printed first. But that is good enough for debug output, especially as prefixed instructions will be rare in kernel code in practice. Old: c000000000111170 60420000 ori r2,r2,0 c000000000111174 04100001 e580fb00 .long 0xe580fb0004100001 New: c00000000010f90c 60420000 ori r2,r2,0 c00000000010f910 e580fb0004100001 .long 0xe580fb0004100001 Reported-by: Bagas Sanjaya <bagasdotme@gmail.com> Reported-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Tested-by: Bagas Sanjaya <bagasdotme@gmail.com> Link: https://lore.kernel.org/r/20220531065936.3674348-1-mpe@ellerman.id.au
2022-05-22powerpc/ftrace: Remove ftrace init tramp once kernel init is completeNaveen N. Rao
Stop using the ftrace trampoline for init section once kernel init is complete. Fixes: 67361cf8071286 ("powerpc/ftrace: Handle large kernel configs") Cc: stable@vger.kernel.org # v4.20+ Signed-off-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/20220516071422.463738-1-naveen.n.rao@linux.vnet.ibm.com
2022-05-22powerpc/ftrace: Minimise number of #ifdefsChristophe Leroy
A lot of #ifdefs can be replaced by IS_ENABLED() Do so. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> [mpe: Fold in changes suggested by Naveen and Christophe on list] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/18ce6708d6f8c71d87436f9c6019f04df4125128.1652074503.git.christophe.leroy@csgroup.eu
2022-05-22powerpc/ftrace: Simplify expected_nop_sequence()Christophe Leroy
Avoid ifdefs around expected_nop_sequence(). While at it make it a bool. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/305d22472f1f92127fba09692df6bb5d079a8cd0.1652074503.git.christophe.leroy@csgroup.eu
2022-05-22powerpc/ftrace: Use size macro instead of opencodingChristophe Leroy
0x80000000 is SZ_2G. Use it. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> [mpe: Fix comparison against unsigned -SZ_2G] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/bb6626e884acffe87b58736291df57db3deaa9b9.1652074503.git.christophe.leroy@csgroup.eu
2022-05-19powerpc/ftrace: Use PPC_RAW_xxx() macros instead of opencoding.Christophe Leroy
PPC_RAW_xxx() macros are self explanatory and less error prone than open coding. Use them in ftrace.c Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/9292094c9a69cef6d29ee83f435a557b59c45065.1652074503.git.christophe.leroy@csgroup.eu
2022-05-19powerpc/ftrace: Use BRANCH_SET_LINK instead of value 1Christophe Leroy
To make it explicit, use BRANCH_SET_LINK instead of value 1 when calling create_branch(). Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/d57847063ac93660a5af620d4df1847f10edf61a.1652074503.git.christophe.leroy@csgroup.eu
2022-05-19powerpc/ftrace: Remove ftrace_plt_tramps[]Christophe Leroy
ftrace_plt_tramps table is never filled so it is useless. Remove it. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/daeeb618a6619e3a7e3f82f1bd83ca7c25af6330.1652074503.git.christophe.leroy@csgroup.eu
2022-05-19powerpc/ftrace: Use CONFIG_FUNCTION_TRACER instead of CONFIG_DYNAMIC_FTRACEChristophe Leroy
Since commit 0c0c52306f47 ("powerpc: Only support DYNAMIC_FTRACE not static"), CONFIG_DYNAMIC_FTRACE is always selected when CONFIG_FUNCTION_TRACER is selected. To avoid confusion and have the reader wonder what's happen when CONFIG_FUNCTION_TRACER is selected and CONFIG_DYNAMIC_FTRACE is not, use CONFIG_FUNCTION_TRACER in ifdefs instead of CONFIG_DYNAMIC_FTRACE. As CONFIG_FUNCTION_GRAPH_TRACER depends on CONFIG_FUNCTION_TRACER, ftrace.o doesn't need to appear for both symbols in Makefile. Then as ftrace.o is built only when CONFIG_FUNCTION_TRACER is selected ifdef CONFIG_FUNCTION_TRACER is not needed in ftrace.c, and since it implies CONFIG_DYNAMIC_FTRACE, CONFIG_DYNAMIC_FTRACE is not needed in ftrace.c Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/628d357503eb90b4a034f99b7df516caaff4d279.1652074503.git.christophe.leroy@csgroup.eu
2022-05-19powerpc/ftrace: Don't include ftrace.o for CONFIG_FTRACE_SYSCALLSChristophe Leroy
Since commit 7bea7ac0ca01 ("powerpc/syscalls: Fix syscall tracing") ftrace.o is not needed anymore for CONFIG_FTRACE_SYSCALLS. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/275932a5d61543b825ff9a64f61abed6da5d4a2a.1652074503.git.christophe.leroy@csgroup.eu
2022-05-19powerpc/ftrace: Make __ftrace_make_{nop/call}() common to PPC32 and PPC64Christophe Leroy
Since c93d4f6ecf4b ("powerpc/ftrace: Add module_trampoline_target() for PPC32"), __ftrace_make_nop() for PPC32 is very similar to the one for PPC64. Same for __ftrace_make_call(). Make them common. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/96f53c237316dab4b1b8c682685266faa92da816.1652074503.git.christophe.leroy@csgroup.eu
2022-05-19powerpc: Replace PPC64_ELF_ABI_v{1/2} by CONFIG_PPC64_ELF_ABI_V{1/2}Christophe Leroy
Replace all uses of PPC64_ELF_ABI_v1 and PPC64_ELF_ABI_v2 by resp CONFIG_PPC64_ELF_ABI_V1 and CONFIG_PPC64_ELF_ABI_V2. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/ba13d59e8c50bc9aa6328f1c7f0c0d0278e0a3a7.1652074503.git.christophe.leroy@csgroup.eu
2022-05-19powerpc/ftrace: Use patch_instruction() return directlyChristophe Leroy
Instead of returning -EPERM when patch_instruction() fails, just return what patch_instruction returns. That simplifies ftrace_modify_code(): 0: 94 21 ff c0 stwu r1,-64(r1) 4: 93 e1 00 3c stw r31,60(r1) 8: 7c 7f 1b 79 mr. r31,r3 c: 40 80 00 30 bge 3c <ftrace_modify_code+0x3c> 10: 93 c1 00 38 stw r30,56(r1) 14: 7c 9e 23 78 mr r30,r4 18: 7c a4 2b 78 mr r4,r5 1c: 80 bf 00 00 lwz r5,0(r31) 20: 7c 1e 28 40 cmplw r30,r5 24: 40 82 00 34 bne 58 <ftrace_modify_code+0x58> 28: 83 c1 00 38 lwz r30,56(r1) 2c: 7f e3 fb 78 mr r3,r31 30: 83 e1 00 3c lwz r31,60(r1) 34: 38 21 00 40 addi r1,r1,64 38: 48 00 00 00 b 38 <ftrace_modify_code+0x38> 38: R_PPC_REL24 patch_instruction Before: 0: 94 21 ff c0 stwu r1,-64(r1) 4: 93 e1 00 3c stw r31,60(r1) 8: 7c 7f 1b 79 mr. r31,r3 c: 40 80 00 4c bge 58 <ftrace_modify_code+0x58> 10: 93 c1 00 38 stw r30,56(r1) 14: 7c 9e 23 78 mr r30,r4 18: 7c a4 2b 78 mr r4,r5 1c: 80 bf 00 00 lwz r5,0(r31) 20: 7c 08 02 a6 mflr r0 24: 90 01 00 44 stw r0,68(r1) 28: 7c 1e 28 40 cmplw r30,r5 2c: 40 82 00 48 bne 74 <ftrace_modify_code+0x74> 30: 7f e3 fb 78 mr r3,r31 34: 48 00 00 01 bl 34 <ftrace_modify_code+0x34> 34: R_PPC_REL24 patch_instruction 38: 80 01 00 44 lwz r0,68(r1) 3c: 20 63 00 00 subfic r3,r3,0 40: 83 c1 00 38 lwz r30,56(r1) 44: 7c 63 19 10 subfe r3,r3,r3 48: 7c 08 03 a6 mtlr r0 4c: 83 e1 00 3c lwz r31,60(r1) 50: 38 21 00 40 addi r1,r1,64 54: 4e 80 00 20 blr It improves ftrace activation/deactivation duration by about 3%. Modify patch_instruction() return on failure to -EPERM in order to match with ftrace expectations. Other users of patch_instruction() do not care about the exact error value returned. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/49a8597230713e2633e7d9d7b56140787c4a7e20.1652074503.git.christophe.leroy@csgroup.eu
2022-05-19powerpc/ftrace: Inline ftrace_modify_code()Christophe Leroy
Inlining ftrace_modify_code(), it increases a bit the size of ftrace code but brings 5% improvment on ftrace activation. Usually in C files we let gcc decide what to do but here it really help to 'help' gcc to decide to inline, thought we don't want to force it with an __always_inline that would be too much for CONFIG_CC_OPTIMIZE_FOR_SIZE. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/1597a06d57cfc80e6853838c4066e799bf6c7977.1652074503.git.christophe.leroy@csgroup.eu
2022-05-19powerpc/ftrace: Use is_offset_in_branch_range()Christophe Leroy
Use is_offset_in_branch_range() instead of create_branch() to check if a target is within branch range. This patch together with the previous one improves ftrace activation time by 7% Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/912ae51782f5a53c44e435497c8c3fb5cc632387.1652074503.git.christophe.leroy@csgroup.eu
2022-05-19powerpc/ftrace: Remove redundant create_branch() callsChristophe Leroy
Since commit d5937db114e4 ("powerpc/code-patching: Fix patch_branch() return on out-of-range failure") patch_branch() fails with -ERANGE when trying to branch out of range. No need to perform the test twice. Remove redundant create_branch() calls. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/aa45fbad0b4b7493080835d8276c0cb4ce146503.1652074503.git.christophe.leroy@csgroup.eu
2022-05-19powerpc/ftrace: Refactor prepare_ftrace_return()Christophe Leroy
When we have CONFIG_DYNAMIC_FTRACE_WITH_ARGS, prepare_ftrace_return() is called by ftrace_graph_func() otherwise prepare_ftrace_return() is called from assembly. Refactor prepare_ftrace_return() into a static __prepare_ftrace_return() that will be called by both prepare_ftrace_return() and ftrace_graph_func(). It will allow GCC to fold __prepare_ftrace_return() inside ftrace_graph_func(). Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/0d42deafe353980c66cf19d3132638c05ba9f4a9.1652074503.git.christophe.leroy@csgroup.eu
2022-03-08powerpc: Move C prototypes out of asm-prototypes.hChristophe Leroy
We originally added asm-prototypes.h in commit 42f5b4cacd78 ("powerpc: Introduce asm-prototypes.h"). It's purpose was for prototypes of C functions that are only called from asm, in order to fix sparse warnings about missing prototypes. A few months later Nick added a different use case in commit 4efca4ed05cb ("kbuild: modversions for EXPORT_SYMBOL() for asm") for C prototypes for exported asm functions. This is basically the inverse of our original usage. Since then we've added various prototypes to asm-prototypes.h for both reasons, meaning we now need to unstitch it all. Dispatch prototypes of C functions into relevant headers and keep only the prototypes for functions defined in assembly. For the time being, leave prom_init() there because moving it into asm/prom.h or asm/setup.h conflicts with drivers/gpu/drm/nouveau/nvkm/subdev/bios/shadowrom.o This will be fixed later by untaggling asm/pci.h and asm/prom.h or by renaming the function in shadowrom.c Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/62d46904eca74042097acf4cb12c175e3067f3d1.1646413435.git.christophe.leroy@csgroup.eu
2022-03-08powerpc/ftrace: Use STK_GOT in ftrace_mprofile.SChristophe Leroy
Instead of open coding offset value 24, use STK_GOT when accessing got register in stack. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/9042bb30fa972056715fe5b6598a7c8049681293.1645099283.git.christophe.leroy@csgroup.eu
2022-03-08powerpc/ftrace: Regroup PPC64 specific operations in ftrace_mprofile.SChristophe Leroy
CONFIG_MPROFILE_KERNEL is only for PPC64 and ftrace_mprofile.o is build on PPC64 only when CONFIG_MPROFILE_KERNEL is defined. Move saving of r0 inside #ifdef PPC64 Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/619dfb672bf4f1b777a4b3f8b4f14e637fea2716.1645099283.git.christophe.leroy@csgroup.eu