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2024-11-07selftests/powerpc: Lower run time of count_stcx_fail testMichael Ellerman
The count_stcx_fail test runs for close to or just over 2 minutes, which means it sometimes times out. That's overkill for a test that just demonstrates some PMU counters are working. Drop the 64 billion instruction case, to lower the runtime to ~30s. Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/20241106130453.1741013-1-mpe@ellerman.id.au
2024-11-07powerpc/ps3: Mark ps3_setup_uhc_device() __initGeert Uytterhoeven
ps3_setup_uhc_device() is only called from ps3_setup_ehci_device() and ps3_setup_ohci_device(), which are both marked __init. Hence replace the former's __ref marker by __init. Note that before commit bd721ea73e1f9655 ("treewide: replace obsolete _refok by __ref"), the function was marked __init_refok, which probably should have been __init in the first place. Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/31fe9435056fcfbf82c3a01693be278d5ce4ad0f.1730899557.git.geert+renesas@glider.be
2024-11-06powerpc: Add __must_check to set_memory_...()Christophe Leroy
After the following powerpc commits, all calls to set_memory_...() functions check returned value. - Commit 8f17bd2f4196 ("powerpc: Handle error in mark_rodata_ro() and mark_initmem_nx()") - Commit f7f18e30b468 ("powerpc/kprobes: Handle error returned by set_memory_rox()") - Commit 009cf11d4aab ("powerpc: Don't ignore errors from set_memory_{n}p() in __kernel_map_pages()") - Commit 9cbacb834b4a ("powerpc: Don't ignore errors from set_memory_{n}p() in __kernel_map_pages()") - Commit 78cb0945f714 ("powerpc: Handle error in mark_rodata_ro() and mark_initmem_nx()") All calls in core parts of the kernel also always check returned value, can be looked at with following query: $ git grep -w -e set_memory_ro -e set_memory_rw -e set_memory_x -e set_memory_nx -e set_memory_rox `find . -maxdepth 1 -type d | grep -v arch | grep /` It is now possible to flag those functions with __must_check to make sure no new unchecked call it added. Link: https://github.com/KSPP/linux/issues/7 Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/775dae48064a661554802ed24ed5bdffe1784724.1725723351.git.christophe.leroy@csgroup.eu
2024-11-05powerpc: Use str_enabled_disabled() helper functionThorsten Blum
Remove hard-coded strings by using the str_enabled_disabled() helper function. Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev> Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/20241027222219.1173-2-thorsten.blum@linux.dev
2024-11-05powerpc/modules: start/end_opd are only needed for ABI v1Michael Ellerman
The start_opd/end_opd members of struct mod_arch_specific are only needed for kernels built using ELF ABI v1. Guard them with an ifdef to save a little bit of space on ELF ABI v2 kernels. Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/20240812063312.730496-1-mpe@ellerman.id.au
2024-11-05powerpc/ps3: replace open-coded sysfs_emit functionPaulo Miguel Almeida
sysfs_emit() helper function should be used when formatting the value to be returned to user space. This patch replaces open-coded sysfs_emit() in sysfs .show() callbacks Link: https://github.com/KSPP/linux/issues/105 Signed-off-by: Paulo Miguel Almeida <paulo.miguel.almeida.rodenas@gmail.com> Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> Acked-by: Geoff Levand <geoff@infradead.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/ZxMV3YvSulJFZ8rk@mail.google.com
2024-11-04powerpc/vdso: Drop -mstack-protector-guard flags in 32-bit files with clangNathan Chancellor
Under certain conditions, the 64-bit '-mstack-protector-guard' flags may end up in the 32-bit vDSO flags, resulting in build failures due to the structure of clang's argument parsing of the stack protector options, which validates the arguments of the stack protector guard flags unconditionally in the frontend, choking on the 64-bit values when targeting 32-bit: clang: error: invalid value 'r13' in 'mstack-protector-guard-reg=', expected one of: r2 clang: error: invalid value 'r13' in 'mstack-protector-guard-reg=', expected one of: r2 make[3]: *** [arch/powerpc/kernel/vdso/Makefile:85: arch/powerpc/kernel/vdso/vgettimeofday-32.o] Error 1 make[3]: *** [arch/powerpc/kernel/vdso/Makefile:87: arch/powerpc/kernel/vdso/vgetrandom-32.o] Error 1 Remove these flags by adding them to the CC32FLAGSREMOVE variable, which already handles situations similar to this. Additionally, reformat and align a comment better for the expanding CONFIG_CC_IS_CLANG block. Cc: stable@vger.kernel.org # v6.1+ Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/20241030-powerpc-vdso-drop-stackp-flags-clang-v1-1-d95e7376d29c@kernel.org
2024-10-31powerpc64/bpf: Add support for bpf trampolinesNaveen N Rao
Add support for bpf_arch_text_poke() and arch_prepare_bpf_trampoline() for 64-bit powerpc. While the code is generic, BPF trampolines are only enabled on 64-bit powerpc. 32-bit powerpc will need testing and some updates. BPF Trampolines adhere to the existing ftrace ABI utilizing a two-instruction profiling sequence, as well as the newer ABI utilizing a three-instruction profiling sequence enabling return with a 'blr'. The trampoline code itself closely follows x86 implementation. BPF prog JIT is extended to mimic 64-bit powerpc approach for ftrace having a single nop at function entry, followed by the function profiling sequence out-of-line and a separate long branch stub for calls to trampolines that are out of range. A dummy_tramp is provided to simplify synchronization similar to arm64. When attaching a bpf trampoline to a bpf prog, we can patch up to three things: - the nop at bpf prog entry to go to the out-of-line stub - the instruction in the out-of-line stub to either call the bpf trampoline directly, or to branch to the long_branch stub. - the trampoline address before the long_branch stub. We do not need any synchronization here since we always have a valid branch target regardless of the order in which the above stores are seen. dummy_tramp ensures that the long_branch stub goes to a valid destination on other cpus, even when the branch to the long_branch stub is seen before the updated trampoline address. However, when detaching a bpf trampoline from a bpf prog, or if changing the bpf trampoline address, we need synchronization to ensure that other cpus can no longer branch into the older trampoline so that it can be safely freed. bpf_tramp_image_put() uses rcu_tasks to ensure all cpus make forward progress, but we still need to ensure that other cpus execute isync (or some CSI) so that they don't go back into the trampoline again. While here, update the stale comment that describes the redzone usage in ppc64 BPF JIT. Signed-off-by: Naveen N Rao <naveen@kernel.org> Signed-off-by: Hari Bathini <hbathini@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/20241030070850.1361304-18-hbathini@linux.ibm.com
2024-10-31samples/ftrace: Add support for ftrace direct samples on powerpcNaveen N Rao
Add powerpc 32-bit and 64-bit samples for ftrace direct. This serves to show the sample instruction sequence to be used by ftrace direct calls to adhere to the ftrace ABI. On 64-bit powerpc, TOC setup requires some additional work. Signed-off-by: Naveen N Rao <naveen@kernel.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/20241030070850.1361304-17-hbathini@linux.ibm.com
2024-10-31powerpc/ftrace: Add support for DYNAMIC_FTRACE_WITH_DIRECT_CALLSNaveen N Rao
Add support for DYNAMIC_FTRACE_WITH_DIRECT_CALLS similar to the arm64 implementation. ftrace direct calls allow custom trampolines to be called into directly from function ftrace call sites, bypassing the ftrace trampoline completely. This functionality is currently utilized by BPF trampolines to hook into kernel function entries. Since we have limited relative branch range, we support ftrace direct calls through support for DYNAMIC_FTRACE_WITH_CALL_OPS. In this approach, ftrace trampoline is not entirely bypassed. Rather, it is re-purposed into a stub that reads direct_call field from the associated ftrace_ops structure and branches into that, if it is not NULL. For this, it is sufficient if we can ensure that the ftrace trampoline is reachable from all traceable functions. When multiple ftrace_ops are associated with a call site, we utilize a call back to set pt_regs->orig_gpr3 that can then be tested on the return path from the ftrace trampoline to branch into the direct caller. Signed-off-by: Naveen N Rao <naveen@kernel.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/20241030070850.1361304-16-hbathini@linux.ibm.com
2024-10-31powerpc/ftrace: Add support for DYNAMIC_FTRACE_WITH_CALL_OPSNaveen N Rao
Implement support for DYNAMIC_FTRACE_WITH_CALL_OPS similar to the arm64 implementation. This works by patching-in a pointer to an associated ftrace_ops structure before each traceable function. If multiple ftrace_ops are associated with a call site, then a special ftrace_list_ops is used to enable iterating over all the registered ftrace_ops. If no ftrace_ops are associated with a call site, then a special ftrace_nop_ops structure is used to render the ftrace call as a no-op. ftrace trampoline can then read the associated ftrace_ops for a call site by loading from an offset from the LR, and branch directly to the associated function. The primary advantage with this approach is that we don't have to iterate over all the registered ftrace_ops for call sites that have a single ftrace_ops registered. This is the equivalent of implementing support for dynamic ftrace trampolines, which set up a special ftrace trampoline for each registered ftrace_ops and have individual call sites branch into those directly. A secondary advantage is that this gives us a way to add support for direct ftrace callers without having to resort to using stubs. The address of the direct call trampoline can be loaded from the ftrace_ops structure. To support this, we reserve a nop before each function on 32-bit powerpc. For 64-bit powerpc, two nops are reserved before each out-of-line stub. During ftrace activation, we update this location with the associated ftrace_ops pointer. Then, on ftrace entry, we load from this location and call into ftrace_ops->func(). For 64-bit powerpc, we ensure that the out-of-line stub area is doubleword aligned so that ftrace_ops address can be updated atomically. Signed-off-by: Naveen N Rao <naveen@kernel.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/20241030070850.1361304-15-hbathini@linux.ibm.com
2024-10-31powerpc64/ftrace: Support .text larger than 32MB with out-of-line stubsNaveen N Rao
We are restricted to a .text size of ~32MB when using out-of-line function profile sequence. Allow this to be extended up to the previous limit of ~64MB by reserving space in the middle of .text. A new config option CONFIG_PPC_FTRACE_OUT_OF_LINE_NUM_RESERVE is introduced to specify the number of function stubs that are reserved in .text. On boot, ftrace utilizes stubs from this area first before using the stub area at the end of .text. A ppc64le defconfig has ~44k functions that can be traced. A more conservative value of 32k functions is chosen as the default value of PPC_FTRACE_OUT_OF_LINE_NUM_RESERVE so that we do not allot more space than necessary by default. If building a kernel that only has 32k trace-able functions, we won't allot any more space at the end of .text during the pass on vmlinux.o. Otherwise, only the remaining functions get space for stubs at the end of .text. This default value should help cover a .text size of ~48MB in total (including space reserved at the end of .text which can cover up to 32MB), which should be sufficient for most common builds. For a very small kernel build, this can be set to 0. Or, this can be bumped up to a larger value to support vmlinux .text size up to ~64MB. Signed-off-by: Naveen N Rao <naveen@kernel.org> Signed-off-by: Hari Bathini <hbathini@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/20241030070850.1361304-14-hbathini@linux.ibm.com
2024-10-31powerpc64/ftrace: Move ftrace sequence out of lineNaveen N Rao
Function profile sequence on powerpc includes two instructions at the beginning of each function: mflr r0 bl ftrace_caller The call to ftrace_caller() gets nop'ed out during kernel boot and is patched in when ftrace is enabled. Given the sequence, we cannot return from ftrace_caller with 'blr' as we need to keep LR and r0 intact. This results in link stack (return address predictor) imbalance when ftrace is enabled. To address that, we would like to use a three instruction sequence: mflr r0 bl ftrace_caller mtlr r0 Further more, to support DYNAMIC_FTRACE_WITH_CALL_OPS, we need to reserve two instruction slots before the function. This results in a total of five instruction slots to be reserved for ftrace use on each function that is traced. Move the function profile sequence out-of-line to minimize its impact. To do this, we reserve a single nop at function entry using -fpatchable-function-entry=1 and add a pass on vmlinux.o to determine the total number of functions that can be traced. This is then used to generate a .S file reserving the appropriate amount of space for use as ftrace stubs, which is built and linked into vmlinux. On bootup, the stub space is split into separate stubs per function and populated with the proper instruction sequence. A pointer to the associated stub is maintained in dyn_arch_ftrace. For modules, space for ftrace stubs is reserved from the generic module stub space. This is restricted to and enabled by default only on 64-bit powerpc, though there are some changes to accommodate 32-bit powerpc. This is done so that 32-bit powerpc could choose to opt into this based on further tests and benchmarks. As an example, after this patch, kernel functions will have a single nop at function entry: <kernel_clone>: addis r2,r12,467 addi r2,r2,-16028 nop mfocrf r11,8 ... When ftrace is enabled, the nop is converted to an unconditional branch to the stub associated with that function: <kernel_clone>: addis r2,r12,467 addi r2,r2,-16028 b ftrace_ool_stub_text_end+0x11b28 mfocrf r11,8 ... The associated stub: <ftrace_ool_stub_text_end+0x11b28>: mflr r0 bl ftrace_caller mtlr r0 b kernel_clone+0xc ... This change showed an improvement of ~10% in null_syscall benchmark on a Power 10 system with ftrace enabled. Signed-off-by: Naveen N Rao <naveen@kernel.org> Signed-off-by: Hari Bathini <hbathini@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/20241030070850.1361304-13-hbathini@linux.ibm.com
2024-10-31kbuild: Add generic hook for architectures to use before the final vmlinux linkNaveen N Rao
On powerpc, we would like to be able to make a pass on vmlinux.o and generate a new object file to be linked into vmlinux. Add a generic pass in Makefile.vmlinux that architectures can use for this purpose. Architectures need to select CONFIG_ARCH_WANTS_PRE_LINK_VMLINUX and must provide arch/<arch>/tools/Makefile with .arch.vmlinux.o target, which will be invoked prior to the final vmlinux link step. Acked-by: Masahiro Yamada <masahiroy@kernel.org> Signed-off-by: Naveen N Rao <naveen@kernel.org> Signed-off-by: Hari Bathini <hbathini@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/20241030070850.1361304-12-hbathini@linux.ibm.com
2024-10-31powerpc/ftrace: Add a postlink script to validate function tracerNaveen N Rao
Function tracer on powerpc can only work with vmlinux having a .text size of up to ~64MB due to powerpc branch instruction having a limited relative branch range of 32MB. Today, this is only detected on kernel boot when ftrace is init'ed. Add a post-link script to check the size of .text so that we can detect this at build time, and break the build if necessary. We add a dependency on !COMPILE_TEST for CONFIG_HAVE_FUNCTION_TRACER so that allyesconfig and other test builds can continue to work without enabling ftrace. Signed-off-by: Naveen N Rao <naveen@kernel.org> Signed-off-by: Hari Bathini <hbathini@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/20241030070850.1361304-11-hbathini@linux.ibm.com
2024-10-31powerpc64/bpf: Fold bpf_jit_emit_func_call_hlp() into ↵Naveen N Rao
bpf_jit_emit_func_call_rel() Commit 61688a82e047 ("powerpc/bpf: enable kfunc call") enhanced bpf_jit_emit_func_call_hlp() to handle calls out to module region, where bpf progs are generated. The only difference now between bpf_jit_emit_func_call_hlp() and bpf_jit_emit_func_call_rel() is in handling of the initial pass where target function address is not known. Fold that logic into bpf_jit_emit_func_call_hlp() and rename it to bpf_jit_emit_func_call_rel() to simplify bpf function call JIT code. We don't actually need to load/restore TOC across a call out to a different kernel helper or to a different bpf program since they all work with the kernel TOC. We only need to do it if we have to call out to a module function. So, guard TOC load/restore with appropriate conditions. Signed-off-by: Naveen N Rao <naveen@kernel.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/20241030070850.1361304-10-hbathini@linux.ibm.com
2024-10-31powerpc/ftrace: Move ftrace stub used for init text before _einittextNaveen N Rao
Move the ftrace stub used to cover inittext before _einittext so that it is within kernel text, as seen through core_kernel_text(). This is required for a subsequent change to ftrace. Signed-off-by: Naveen N Rao <naveen@kernel.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/20241030070850.1361304-9-hbathini@linux.ibm.com
2024-10-31powerpc/ftrace: Skip instruction patching if the instructions are the sameNaveen N Rao
To simplify upcoming changes to ftrace, add a check to skip actual instruction patching if the old and new instructions are the same. We still validate that the instruction is what we expect, but don't actually patch the same instruction again. Signed-off-by: Naveen N Rao <naveen@kernel.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/20241030070850.1361304-8-hbathini@linux.ibm.com
2024-10-31powerpc/ftrace: Remove pointer to struct module from dyn_arch_ftraceNaveen N Rao
Pointer to struct module is only relevant for ftrace records belonging to kernel modules. Having this field in dyn_arch_ftrace wastes memory for all ftrace records belonging to the kernel. Remove the same in favour of looking up the module from the ftrace record address, similar to other architectures. Reviewed-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Naveen N Rao <naveen@kernel.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/20241030070850.1361304-7-hbathini@linux.ibm.com
2024-10-31powerpc/module_64: Convert #ifdef to IS_ENABLED()Naveen N Rao
Minor refactor for converting #ifdef to IS_ENABLED(). Reviewed-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Naveen N Rao <naveen@kernel.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/20241030070850.1361304-6-hbathini@linux.ibm.com
2024-10-31powerpc32/ftrace: Unify 32-bit and 64-bit ftrace entry codeNaveen N Rao
On 32-bit powerpc, gcc generates a three instruction sequence for function profiling: mflr r0 stw r0, 4(r1) bl _mcount On kernel boot, the call to _mcount() is nop-ed out, to be patched back in when ftrace is actually enabled. The 'stw' instruction therefore is not necessary unless ftrace is enabled. Nop it out during ftrace init. When ftrace is enabled, we want the 'stw' so that stack unwinding works properly. Perform the same within the ftrace handler, similar to 64-bit powerpc. Reviewed-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Naveen N Rao <naveen@kernel.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/20241030070850.1361304-5-hbathini@linux.ibm.com
2024-10-31powerpc64/ftrace: Nop out additional 'std' instruction emitted by gcc v5.xNaveen N Rao
Gcc v5.x emits a 3-instruction sequence for -mprofile-kernel: mflr r0 std r0, 16(r1) bl _mcount Gcc v6.x moved to a simpler 2-instruction sequence by removing the 'std' instruction. The store saved the return address in the LR save area in the caller stack frame for stack unwinding. However, with dynamic ftrace, we no longer have a call to _mcount on kernel boot when ftrace is not enabled. When ftrace is enabled, that store is performed within ftrace_caller(). As such, the additional 'std' instruction is redundant. Nop it out on kernel boot. With this change, we now use the same 2-instruction profiling sequence with both -mprofile-kernel, as well as -fpatchable-function-entry on 64-bit powerpc. Signed-off-by: Naveen N Rao <naveen@kernel.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/20241030070850.1361304-4-hbathini@linux.ibm.com
2024-10-31powerpc/kprobes: Use ftrace to determine if a probe is at function entryNaveen N Rao
Rather than hard-coding the offset into a function to be used to determine if a kprobe is at function entry, use ftrace_location() to determine the ftrace location within the function and categorize all instructions till that offset to be function entry. For functions that cannot be traced, we fall back to using a fixed offset of 8 (two instructions) to categorize a probe as being at function entry for 64-bit elfv2, unless we are using pcrel. Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Signed-off-by: Naveen N Rao <naveen@kernel.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/20241030070850.1361304-3-hbathini@linux.ibm.com
2024-10-31powerpc/trace: Account for -fpatchable-function-entry support by toolchainNaveen N Rao
So far, we have relied on the fact that gcc supports both -mprofile-kernel, as well as -fpatchable-function-entry, and clang supports neither. Our Makefile only checks for CONFIG_MPROFILE_KERNEL to decide which files to build. Clang has a feature request out [*] to implement -fpatchable-function-entry, and is unlikely to support -mprofile-kernel. Update our Makefile checks so that we pick up the correct files to build once clang picks up support for -fpatchable-function-entry. [*] https://github.com/llvm/llvm-project/issues/57031 Signed-off-by: Naveen N Rao <naveen@kernel.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/20241030070850.1361304-2-hbathini@linux.ibm.com
2024-10-29powerpc/64: Remove maple platformMichael Ellerman
The maple platform was added in 2004 [1], to support the "Maple" 970FX evaluation board. It was later used for IBM JS20/JS21 machines, as well as the Bimini machine, aka "Yellow Dog Powerstation". Sadly all those machines have passed into memory, and there's been no evidence for years that anyone is still using any of them. Remove the platform and related code. It can always be reinstated if there's interest. Note that this has no impact on support for 970FX based Power Macs. [1]: https://git.kernel.org/pub/scm/linux/kernel/git/mpe/linux-fullhistory.git/commit/?id=f0d068d65c5e555ffcfbc189de32598f6f00770c Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/20241013102957.548291-1-mpe@ellerman.id.au
2024-10-29powerpc/boot: Remove bogus reference to liloMichael Ellerman
The help text refers to lilo, but the install script does not run lilo and never has. The reference to lilo seems to have come originally from arch/ppc/Makefile, but it was not true there either. Remove it. Reported-by: Thorsten Leemhuis <linux@leemhuis.info> Link: https://fosstodon.org/@kernellogger/113032940928131612 Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/20241009053806.135807-1-mpe@ellerman.id.au
2024-10-29powerpc/pseries: Fix dtl_access_lock to be a rw_semaphoreMichael Ellerman
The dtl_access_lock needs to be a rw_sempahore, a sleeping lock, because the code calls kmalloc() while holding it, which can sleep: # echo 1 > /proc/powerpc/vcpudispatch_stats BUG: sleeping function called from invalid context at include/linux/sched/mm.h:337 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 199, name: sh preempt_count: 1, expected: 0 3 locks held by sh/199: #0: c00000000a0743f8 (sb_writers#3){.+.+}-{0:0}, at: vfs_write+0x324/0x438 #1: c0000000028c7058 (dtl_enable_mutex){+.+.}-{3:3}, at: vcpudispatch_stats_write+0xd4/0x5f4 #2: c0000000028c70b8 (dtl_access_lock){+.+.}-{2:2}, at: vcpudispatch_stats_write+0x220/0x5f4 CPU: 0 PID: 199 Comm: sh Not tainted 6.10.0-rc4 #152 Hardware name: IBM pSeries (emulated by qemu) POWER9 (raw) 0x4e1202 0xf000005 of:SLOF,HEAD hv:linux,kvm pSeries Call Trace: dump_stack_lvl+0x130/0x148 (unreliable) __might_resched+0x174/0x410 kmem_cache_alloc_noprof+0x340/0x3d0 alloc_dtl_buffers+0x124/0x1ac vcpudispatch_stats_write+0x2a8/0x5f4 proc_reg_write+0xf4/0x150 vfs_write+0xfc/0x438 ksys_write+0x88/0x148 system_call_exception+0x1c4/0x5a0 system_call_common+0xf4/0x258 Fixes: 06220d78f24a ("powerpc/pseries: Introduce rwlock to gatekeep DTLB usage") Tested-by: Kajol Jain <kjain@linux.ibm.com> Reviewed-by: Nysal Jan K.A <nysal@linux.ibm.com> Reviewed-by: Kajol Jain <kjain@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/20240819122401.513203-1-mpe@ellerman.id.au
2024-10-29powerpc/machdep: Drop include of dma-mapping.hMichael Ellerman
Drop the include of dma-mapping.h in machdep.h, replace it with forward declarations of struct device and struct pci_dev, and include time64.h and page.h which are required for time64_t and pgprot_t respectively. Add direct includes of some other headers to some files that were getting them via machdep.h. Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/20241009051826.132805-2-mpe@ellerman.id.au
2024-10-29powerpc/machdep: Drop include of seq_file.hMichael Ellerman
Drop the include of seq_file.h in machdep.h, replace it with a forward declaration of struct seq_file, which is all that's required. Add direct includes of seq_file.h to some files that were getting seq_file.h via machdep.h. Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/20241009051826.132805-1-mpe@ellerman.id.au
2024-10-29powerpc/64: Drop IPI_PRIORITY from asm-offsetsMichael Ellerman
The last use of IPI_PRIORITY in asm was removed in commit 37f55d30df2e ("KVM: PPC: Book3S HV: Convert kvmppc_read_intr to a C function"). Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/20241009051701.132282-1-mpe@ellerman.id.au
2024-10-23powerpc: Adjust adding stack protector flags to KBUILD_CLAGS for clangNathan Chancellor
After fixing the HAVE_STACKPROTECTER checks for clang's in-progress per-task stack protector support [1], the build fails during prepare0 because '-mstack-protector-guard-offset' has not been added to KBUILD_CFLAGS yet but the other '-mstack-protector-guard' flags have. clang: error: '-mstack-protector-guard=tls' is used without '-mstack-protector-guard-offset', and there is no default clang: error: '-mstack-protector-guard=tls' is used without '-mstack-protector-guard-offset', and there is no default make[4]: *** [scripts/Makefile.build:229: scripts/mod/empty.o] Error 1 make[4]: *** [scripts/Makefile.build:102: scripts/mod/devicetable-offsets.s] Error 1 Mirror other architectures and add all '-mstack-protector-guard' flags to KBUILD_CFLAGS atomically during stack_protector_prepare, which resolves the issue and allows clang's implementation to fully work with the kernel. Cc: stable@vger.kernel.org # 6.1+ Link: https://github.com/llvm/llvm-project/pull/110928 [1] Reviewed-by: Keith Packard <keithp@keithp.com> Tested-by: Keith Packard <keithp@keithp.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/20241009-powerpc-fix-stackprotector-test-clang-v2-2-12fb86b31857@kernel.org
2024-10-23powerpc: Fix stack protector Kconfig test for clangNathan Chancellor
Clang's in-progress per-task stack protector support [1] does not work with the current Kconfig checks because '-mstack-protector-guard-offset' is not provided, unlike all other architecture Kconfig checks. $ fd Kconfig -x rg -l mstack-protector-guard-offset ./arch/arm/Kconfig ./arch/riscv/Kconfig ./arch/arm64/Kconfig This produces an error from clang, which is interpreted as the flags not being supported at all when they really are. $ clang --target=powerpc64-linux-gnu \ -mstack-protector-guard=tls \ -mstack-protector-guard-reg=r13 \ -c -o /dev/null -x c /dev/null clang: error: '-mstack-protector-guard=tls' is used without '-mstack-protector-guard-offset', and there is no default This argument will always be provided by the build system, so mirror other architectures and use '-mstack-protector-guard-offset=0' for testing support, which fixes the issue for clang and does not regress support with GCC. Even with the first problem addressed, the 32-bit test continues to fail because Kbuild uses the powerpc64le-linux-gnu target for clang and nothing flips the target to 32-bit, resulting in an error about an invalid register valid: $ clang --target=powerpc64le-linux-gnu \ -mstack-protector-guard=tls -mstack-protector-guard-reg=r2 \ -mstack-protector-guard-offset=0 \ -x c -c -o /dev/null /dev/null clang: error: invalid value 'r2' in 'mstack-protector-guard-reg=', expected one of: r13 While GCC allows arbitrary registers, the implementation of '-mstack-protector-guard=tls' in LLVM shares the same code path as the user space thread local storage implementation, which uses a fixed register (2 for 32-bit and 13 for 62-bit), so the command line parsing enforces this limitation. Use the Kconfig macro '$(m32-flag)', which expands to '-m32' when supported, in the stack protector support cc-option call to properly switch the target to a 32-bit one, which matches what happens in Kbuild. While the 64-bit macro does not strictly need it, add the equivalent 64-bit option for symmetry. Cc: stable@vger.kernel.org # 6.1+ Link: https://github.com/llvm/llvm-project/pull/110928 [1] Reviewed-by: Keith Packard <keithp@keithp.com> Tested-by: Keith Packard <keithp@keithp.com> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/20241009-powerpc-fix-stackprotector-test-clang-v2-1-12fb86b31857@kernel.org
2024-10-23book3s64/hash: Early detect debug_pagealloc size requirementRitesh Harjani (IBM)
Add hash_supports_debug_pagealloc() helper to detect whether debug_pagealloc can be supported on hash or not. This checks for both, whether debug_pagealloc config is enabled and the linear map should fit within rma_size/4 region size. This can then be used early during htab_init_page_sizes() to decide linear map pagesize if hash supports either debug_pagealloc or kfence. Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/c33c6691b2a2cf619cc74ac100118ca4dbf21a48.1729271995.git.ritesh.list@gmail.com
2024-10-23book3s64/hash: Disable kfence if not early initRitesh Harjani (IBM)
Enable kfence on book3s64 hash only when early init is enabled. This is because, kfence could cause the kernel linear map to be mapped at PAGE_SIZE level instead of 16M (which I guess we don't want). Also currently there is no way to - 1. Make multiple page size entries for the SLB used for kernel linear map. 2. No easy way of getting the hash slot details after the page table mapping for kernel linear setup. So even if kfence allocate the pool in late init, we won't be able to get the hash slot details in kfence linear map. Thus this patch disables kfence on hash if kfence early init is not enabled. Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/4a6eea8cfd1cd28fccfae067026bff30cbec1d4b.1729271995.git.ritesh.list@gmail.com
2024-10-23book3s64/radix: Refactoring common kfence related functionsRitesh Harjani (IBM)
Both radix and hash on book3s requires to detect if kfence early init is enabled or not. Hash needs to disable kfence if early init is not enabled because with kfence the linear map is mapped using PAGE_SIZE rather than 16M mapping. We don't support multiple page sizes for slb entry used for kernel linear map in book3s64. This patch refactors out the common functions required to detect kfence early init is enabled or not. Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/f4a787224fbe5bb787158ace579780c0257f6602.1729271995.git.ritesh.list@gmail.com
2024-10-23book3s64/hash: Add kfence functionalityRitesh Harjani (IBM)
Now that linear map functionality of debug_pagealloc is made generic, enable kfence to use this generic infrastructure. 1. Define kfence related linear map variables. - u8 *linear_map_kf_hash_slots; - unsigned long linear_map_kf_hash_count; - DEFINE_RAW_SPINLOCK(linear_map_kf_hash_lock); 2. The linear map size allocated in RMA region is quite small (KFENCE_POOL_SIZE >> PAGE_SHIFT) which is 512 bytes by default. 3. kfence pool memory is reserved using memblock_phys_alloc() which has can come from anywhere. (default 255 objects => ((1+255) * 2) << PAGE_SHIFT = 32MB) 4. The hash slot information for kfence memory gets added in linear map in hash_linear_map_add_slot() (which also adds for debug_pagealloc). Reported-by: Pavithra Prakash <pavrampu@linux.vnet.ibm.com> Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/5c2b61941b344077a2b8654dab46efa0322af3af.1729271995.git.ritesh.list@gmail.com
2024-10-23book3s64/hash: Disable debug_pagealloc if it requires more memoryRitesh Harjani (IBM)
Make size of the linear map to be allocated in RMA region to be of ppc64_rma_size / 4. If debug_pagealloc requires more memory than that then do not allocate any memory and disable debug_pagealloc. Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/e1ef66f32a1fe63bcbb89d5c11d86c65beef5ded.1729271995.git.ritesh.list@gmail.com
2024-10-23book3s64/hash: Make kernel_map_linear_page() genericRitesh Harjani (IBM)
Currently kernel_map_linear_page() function assumes to be working on linear_map_hash_slots array. But since in later patches we need a separate linear map array for kfence, hence make kernel_map_linear_page() take a linear map array and lock in it's function argument. This is needed to separate out kfence from debug_pagealloc infrastructure. Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/5b67df7b29e68d7c78d6fc1f42d41137299bac6b.1729271995.git.ritesh.list@gmail.com
2024-10-23book3s64/hash: Refactor hash__kernel_map_pages() functionRitesh Harjani (IBM)
This refactors hash__kernel_map_pages() function to call hash_debug_pagealloc_map_pages(). This will come useful when we will add kfence support. No functionality changes in this patch. Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/0cb8ddcccdcf61ea06ab4d92aacd770c16cc0f2c.1729271995.git.ritesh.list@gmail.com
2024-10-23book3s64/hash: Add hash_debug_pagealloc_alloc_slots() functionRitesh Harjani (IBM)
This adds hash_debug_pagealloc_alloc_slots() function instead of open coding that in htab_initialize(). This is required since we will be separating the kfence functionality to not depend upon debug_pagealloc. Now that everything required for debug_pagealloc is under a #ifdef config. Bring in linear_map_hash_slots and linear_map_hash_count variables under the same config too. Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/d1d5aabe1e4c693a983e59ccf3de08e3c28c5161.1729271995.git.ritesh.list@gmail.com
2024-10-23book3s64/hash: Add hash_debug_pagealloc_add_slot() functionRitesh Harjani (IBM)
This adds hash_debug_pagealloc_add_slot() function instead of open coding that in htab_bolt_mapping(). This is required since we will be separating kfence functionality to not depend upon debug_pagealloc. No functionality change in this patch. Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/026f0aaa1dddd89154dc8d20ceccfca4f63ccf79.1729271995.git.ritesh.list@gmail.com
2024-10-23book3s64/hash: Refactor kernel linear map related callsRitesh Harjani (IBM)
This just brings all linear map related handling at one place instead of having those functions scattered in hash_utils file. Makes it easy for review. No functionality changes in this patch. Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/56c610310aa50b5417976a39c5f15b78bc76c764.1729271995.git.ritesh.list@gmail.com
2024-10-23book3s64/hash: Remove kfence support temporarilyRitesh Harjani (IBM)
Kfence on book3s Hash on pseries is anyways broken. It fails to boot due to RMA size limitation. That is because, kfence with Hash uses debug_pagealloc infrastructure. debug_pagealloc allocates linear map for entire dram size instead of just kfence relevant objects. This means for 16TB of DRAM it will require (16TB >> PAGE_SHIFT) which is 256MB which is half of RMA region on P8. crash kernel reserves 256MB and we also need 2048 * 16KB * 3 for emergency stack and some more for paca allocations. That means there is not enough memory for reserving the full linear map in the RMA region, if the DRAM size is too big (>=16TB) (The issue is seen above 8TB with crash kernel 256 MB reservation). Now Kfence does not require linear memory map for entire DRAM. It only needs for kfence objects. So this patch temporarily removes the kfence functionality since debug_pagealloc code needs some refactoring. We will bring in kfence on Hash support in later patches. Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/1761bc39674473c8878dedca15e0d9a0d3a1b528.1729271995.git.ritesh.list@gmail.com
2024-10-23powerpc/mm/fault: Fix kfence page fault reportingRitesh Harjani (IBM)
copy_from_kernel_nofault() can be called when doing read of /proc/kcore. /proc/kcore can have some unmapped kfence objects which when read via copy_from_kernel_nofault() can cause page faults. Since *_nofault() functions define their own fixup table for handling fault, use that instead of asking kfence to handle such faults. Hence we search the exception tables for the nip which generated the fault. If there is an entry then we let the fixup table handler handle the page fault by returning an error from within ___do_page_fault(). This can be easily triggered if someone tries to do dd from /proc/kcore. eg. dd if=/proc/kcore of=/dev/null bs=1M Some example false negatives: =============================== BUG: KFENCE: invalid read in copy_from_kernel_nofault+0x9c/0x1a0 Invalid read at 0xc0000000fdff0000: copy_from_kernel_nofault+0x9c/0x1a0 0xc00000000665f950 read_kcore_iter+0x57c/0xa04 proc_reg_read_iter+0xe4/0x16c vfs_read+0x320/0x3ec ksys_read+0x90/0x154 system_call_exception+0x120/0x310 system_call_vectored_common+0x15c/0x2ec BUG: KFENCE: use-after-free read in copy_from_kernel_nofault+0x9c/0x1a0 Use-after-free read at 0xc0000000fe050000 (in kfence-#2): copy_from_kernel_nofault+0x9c/0x1a0 0xc00000000665f950 read_kcore_iter+0x57c/0xa04 proc_reg_read_iter+0xe4/0x16c vfs_read+0x320/0x3ec ksys_read+0x90/0x154 system_call_exception+0x120/0x310 system_call_vectored_common+0x15c/0x2ec Fixes: 90cbac0e995d ("powerpc: Enable KFENCE for PPC32") Suggested-by: Christophe Leroy <christophe.leroy@csgroup.eu> Reported-by: Disha Goel <disgoel@linux.ibm.com> Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/a411788081d50e3b136c6270471e35aba3dfafa3.1729271995.git.ritesh.list@gmail.com
2024-10-21powerpc/fadump: Move fadump_cma_init to setup_arch() after initmem_init()Ritesh Harjani (IBM)
During early init CMA_MIN_ALIGNMENT_BYTES can be PAGE_SIZE, since pageblock_order is still zero and it gets initialized later during initmem_init() e.g. setup_arch() -> initmem_init() -> sparse_init() -> set_pageblock_order() One such use case where this causes issue is - early_setup() -> early_init_devtree() -> fadump_reserve_mem() -> fadump_cma_init() This causes CMA memory alignment check to be bypassed in cma_init_reserved_mem(). Then later cma_activate_area() can hit a VM_BUG_ON_PAGE(pfn & ((1 << order) - 1)) if the reserved memory area was not pageblock_order aligned. Fix it by moving the fadump_cma_init() after initmem_init(), where other such cma reservations also gets called. <stack trace> ============== page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10010 flags: 0x13ffff800000000(node=1|zone=0|lastcpupid=0x7ffff) CMA raw: 013ffff800000000 5deadbeef0000100 5deadbeef0000122 0000000000000000 raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: VM_BUG_ON_PAGE(pfn & ((1 << order) - 1)) ------------[ cut here ]------------ kernel BUG at mm/page_alloc.c:778! Call Trace: __free_one_page+0x57c/0x7b0 (unreliable) free_pcppages_bulk+0x1a8/0x2c8 free_unref_page_commit+0x3d4/0x4e4 free_unref_page+0x458/0x6d0 init_cma_reserved_pageblock+0x114/0x198 cma_init_reserved_areas+0x270/0x3e0 do_one_initcall+0x80/0x2f8 kernel_init_freeable+0x33c/0x530 kernel_init+0x34/0x26c ret_from_kernel_user_thread+0x14/0x1c Fixes: 11ac3e87ce09 ("mm: cma: use pageblock_order as the single alignment") Suggested-by: David Hildenbrand <david@redhat.com> Reported-by: Sachin P Bappalige <sachinpb@linux.ibm.com> Acked-by: Hari Bathini <hbathini@linux.ibm.com> Reviewed-by: Madhavan Srinivasan <maddy@linux.ibm.com> Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/3ae208e48c0d9cefe53d2dc4f593388067405b7d.1729146153.git.ritesh.list@gmail.com
2024-10-21powerpc/fadump: Reserve page-aligned boot_memory_size during fadump_reserve_memRitesh Harjani (IBM)
This patch refactors all CMA related initialization and alignment code to within fadump_cma_init() which gets called in the end. This also means that we keep [reserve_dump_area_start, boot_memory_size] page aligned during fadump_reserve_mem(). Then later in fadump_cma_init() we extract the aligned chunk and provide it to CMA. This inherently also fixes an issue in the current code where the reserve_dump_area_start is not aligned when the physical memory can have holes and the suitable chunk starts at an unaligned boundary. After this we should be able to call fadump_cma_init() independently later in setup_arch() where pageblock_order is non-zero. Suggested-by: Sourabh Jain <sourabhjain@linux.ibm.com> Acked-by: Hari Bathini <hbathini@linux.ibm.com> Reviewed-by: Madhavan Srinivasan <maddy@linux.ibm.com> Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/805d6b900968fb9402ad8f4e4775597db42085c4.1729146153.git.ritesh.list@gmail.com
2024-10-21powerpc/fadump: Refactor and prepare fadump_cma_init for late initRitesh Harjani (IBM)
We anyway don't use any return values from fadump_cma_init(). Since fadump_reserve_mem() from where fadump_cma_init() gets called today, already has the required checks. This patch makes this function return type as void. Let's also handle extra cases like return if fadump_supported is false or dump_active, so that in later patches we can call fadump_cma_init() separately from setup_arch(). Acked-by: Hari Bathini <hbathini@linux.ibm.com> Reviewed-by: Madhavan Srinivasan <maddy@linux.ibm.com> Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/a2afc3d6481a87a305e89cfc4a3f3d2a0b8ceab3.1729146153.git.ritesh.list@gmail.com
2024-10-16Merge branch 'topic/vdso' into nextMichael Ellerman
Merge VDSO changes we're keeping in a topic branch, in case they conflict with other VDSO changes in flight.
2024-10-16powerpc/vdso: Flag VDSO64 entry points as functionsChristophe Leroy
On powerpc64 as shown below by readelf, vDSO functions symbols have type NOTYPE. $ powerpc64-linux-gnu-readelf -a arch/powerpc/kernel/vdso/vdso64.so.dbg ELF Header: Magic: 7f 45 4c 46 02 02 01 00 00 00 00 00 00 00 00 00 Class: ELF64 Data: 2's complement, big endian Version: 1 (current) OS/ABI: UNIX - System V ABI Version: 0 Type: DYN (Shared object file) Machine: PowerPC64 Version: 0x1 ... Symbol table '.dynsym' contains 12 entries: Num: Value Size Type Bind Vis Ndx Name ... 1: 0000000000000524 84 NOTYPE GLOBAL DEFAULT 8 __[...]@@LINUX_2.6.15 ... 4: 0000000000000000 0 OBJECT GLOBAL DEFAULT ABS LINUX_2.6.15 5: 00000000000006c0 48 NOTYPE GLOBAL DEFAULT 8 __[...]@@LINUX_2.6.15 Symbol table '.symtab' contains 56 entries: Num: Value Size Type Bind Vis Ndx Name ... 45: 0000000000000000 0 OBJECT GLOBAL DEFAULT ABS LINUX_2.6.15 46: 00000000000006c0 48 NOTYPE GLOBAL DEFAULT 8 __kernel_getcpu 47: 0000000000000524 84 NOTYPE GLOBAL DEFAULT 8 __kernel_clock_getres To overcome that, commit ba83b3239e65 ("selftests: vDSO: fix vDSO symbols lookup for powerpc64") was applied to have selftests also look for NOTYPE symbols, but the correct fix should be to flag VDSO entry points as functions. The original commit that brought VDSO support into powerpc/64 has the following explanation: Note that the symbols exposed by the vDSO aren't "normal" function symbols, apps can't be expected to link against them directly, the vDSO's are both seen as if they were linked at 0 and the symbols just contain offsets to the various functions. This is done on purpose to avoid a relocation step (ppc64 functions normally have descriptors with abs addresses in them). When glibc uses those functions, it's expected to use it's own trampolines that know how to reach them. The descriptors it's talking about are the OPD function descriptors used on ABI v1 (big endian). But it would be more correct for a text symbol to have type function, even if there's no function descriptor for it. glibc has a special case already for handling the VDSO symbols which creates a fake opd pointing at the kernel symbol. So changing the VDSO symbol type to function shouldn't affect that. For ABI v2, there is no function descriptors and VDSO functions can safely have function type. So lets flag VDSO entry points as functions and revert the selftest change. Link: https://github.com/mpe/linux-fullhistory/commit/5f2dd691b62da9d9cc54b938f8b29c22c93cb805 Fixes: ba83b3239e65 ("selftests: vDSO: fix vDSO symbols lookup for powerpc64") Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Reviewed-By: Segher Boessenkool <segher@kernel.crashing.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/b6ad2f1ee9887af3ca5ecade2a56f4acda517a85.1728512263.git.christophe.leroy@csgroup.eu
2024-10-16powerpc/vdso: Implement __arch_get_vdso_rng_data()Christophe Leroy
VDSO time functions do not call any other function, so they don't need to save/restore LR. However, retrieving the address of VDSO data page requires using LR hence saving then restoring it, which can be heavy on some CPUs. On the other hand, VDSO functions on powerpc are not standard functions and require a wrapper function to call C VDSO functions. And that wrapper has to save and restore LR in order to call the C VDSO function, so retrieving VDSO data page address in that wrapper doesn't require additional save/restore of LR. For random VDSO functions it is a bit different. Because the function calls __arch_chacha20_blocks_nostack(), it saves and restores LR. Retrieving VDSO data page address can then be done there without additional save/restore of LR. So lets implement __arch_get_vdso_rng_data() and simplify the wrapper. It starts paving the way for the day powerpc will implement a more standard ABI for VDSO functions. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://patch.msgid.link/a1a9bd0df508f1b5c04684b7366940577dfc6262.1727858295.git.christophe.leroy@csgroup.eu
generated by cgit (git 2.34.1) at 2025-09-11 06:34:08 +0000