- 20 Jun, 2023 1 commit
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Aneesh Kumar K.V authored
No functional change in this patch. Signed-off-by:
Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Tested-by:
Sachin Sant <sachinp@linux.ibm.com <mailto:sachinp@linux.ibm.com>> Signed-off-by:
Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/20230616110826.344417-2-aneesh.kumar@linux.ibm.com
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- 19 Jun, 2023 14 commits
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Aditya Gupta authored
ppc_save_regs() skips one stack frame while saving the CPU register states. Instead of saving current R1, it pulls the previous stack frame pointer. When vmcores caused by direct panic call (such as `echo c > /proc/sysrq-trigger`), are debugged with gdb, gdb fails to show the backtrace correctly. On further analysis, it was found that it was because of mismatch between r1 and NIP. GDB uses NIP to get current function symbol and uses corresponding debug info of that function to unwind previous frames, but due to the mismatching r1 and NIP, the unwinding does not work, and it fails to unwind to the 2nd frame and hence does not show the backtrace. GDB backtrace with vmcore of kernel without this patch: --------- (gdb) bt #0 0xc0000000002a53e8 in crash_setup_regs (oldregs=<optimized out>, newregs=0xc000000004f8f8d8) at ./arch/powerpc/include/asm/kexec.h:69 #1 __crash_kexec (regs=<optimized out>) at kernel/kexec_core.c:974 #2 0x0000000000000063 in ?? () #3 0xc000000003579320 in ?? () --------- Further analysis revealed that the mismatch occurred because "ppc_save_regs" was saving the previous stack's SP instead of the current r1. This patch fixes this by storing current r1 in the saved pt_regs. GDB backtrace with vmcore of patched kernel: -------- (gdb) bt #0 0xc0000000002a53e8 in crash_setup_regs (oldregs=0x0, newregs=0xc00000000670b8d8) at ./arch/powerpc/include/asm/kexec.h:69 #1 __crash_kexec (regs=regs@entry=0x0) at kernel/kexec_core.c:974 #2 0xc000000000168918 in panic (fmt=fmt@entry=0xc000000001654a60 "sysrq triggered crash\n") at kernel/panic.c:358 #3 0xc000000000b735f8 in sysrq_handle_crash (key=<optimized out>) at drivers/tty/sysrq.c:155 #4 0xc000000000b742cc in __handle_sysrq (key=key@entry=99, check_mask=check_mask@entry=false) at drivers/tty/sysrq.c:602 #5 0xc000000000b7506c in write_sysrq_trigger (file=<optimized out>, buf=<optimized out>, count=2, ppos=<optimized out>) at drivers/tty/sysrq.c:1163 #6 0xc00000000069a7bc in pde_write (ppos=<optimized out>, count=<optimized out>, buf=<optimized out>, file=<optimized out>, pde=0xc00000000362cb40) at fs/proc/inode.c:340 #7 proc_reg_write (file=<optimized out>, buf=<optimized out>, count=<optimized out>, ppos=<optimized out>) at fs/proc/inode.c:352 #8 0xc0000000005b3bbc in vfs_write (file=file@entry=0xc000000006aa6b00, buf=buf@entry=0x61f498b4f60 <error: Cannot access memory at address 0x61f498b4f60>, count=count@entry=2, pos=pos@entry=0xc00000000670bda0) at fs/read_write.c:582 #9 0xc0000000005b4264 in ksys_write (fd=<optimized out>, buf=0x61f498b4f60 <error: Cannot access memory at address 0x61f498b4f60>, count=2) at fs/read_write.c:637 #10 0xc00000000002ea2c in system_call_exception (regs=0xc00000000670be80, r0=<optimized out>) at arch/powerpc/kernel/syscall.c:171 #11 0xc00000000000c270 in system_call_vectored_common () at arch/powerpc/kernel/interrupt_64.S:192 -------- Nick adds: So this now saves regs as though it was an interrupt taken in the caller, at the instruction after the call to ppc_save_regs, whereas previously the NIP was there, but R1 came from the caller's caller and that mismatch is what causes gdb's dwarf unwinder to go haywire. Signed-off-by:Aditya Gupta <adityag@linux.ibm.com> Fixes: d16a58f8 ("powerpc: Improve ppc_save_regs()") Reivewed-by:
Nicholas Piggin <npiggin@gmail.com> Signed-off-by:
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Naveen N Rao authored
Ftrace on ppc32 expects a three instruction sequence at the beginning of each function when specifying -pg: mflr r0 stw r0,4(r1) bl _mcount This is the case with all supported versions of gcc. Clang however emits a branch to _mcount after the function prologue, similar to the pre -mprofile-kernel ABI on ppc64. This is not supported. Disable ftrace on ppc32 if using clang for now. This can be re-enabled later if clang picks up support for -fpatchable-function-entry on ppc32. Signed-off-by:
Naveen N Rao <naveen@kernel.org> Acked-by:
Nick Desaulniers <ndesaulniers@google.com> Link: https://github.com/llvm/llvm-project/issues/63220Signed-off-by:
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Colin Ian King authored
Currently pointer iov is being dereferenced before the null check of iov which can lead to null pointer dereference errors. Fix this by moving the iov null check before the dereferencing. Detected using cppcheck static analysis: linux/arch/powerpc/platforms/powernv/pci-sriov.c:597:12: warning: Either the condition '!iov' is redundant or there is possible null pointer dereference: iov. [nullPointerRedundantCheck] num_vfs = iov->num_vfs; ^ Fixes: 052da31d ("powerpc/powernv/sriov: De-indent setup and teardown") Signed-off-by:Colin Ian King <colin.i.king@gmail.com> Signed-off-by:
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Benjamin Gray authored
Add a utility 'lsdexcr' to print the current DEXCR status. Useful for quickly checking the status such as when debugging test failures or verifying the new default DEXCR does what you want (for userspace at least). Example output: # ./lsdexcr uDEXCR: 04000000 (NPHIE) HDEXCR: 00000000 Effective: 04000000 (NPHIE) SBHE (0): clear (Speculative branch hint enable) IBRTPD (3): clear (Indirect branch recurrent target ...) SRAPD (4): clear (Subroutine return address ...) NPHIE * (5): set (Non-privileged hash instruction enable) PHIE (6): clear (Privileged hash instruction enable) DEXCR[NPHIE] enabled: hashst/hashchk working Signed-off-by:Benjamin Gray <bgray@linux.ibm.com> Signed-off-by:
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Benjamin Gray authored
Test the kernel DEXCR[NPHIE] interface and hashchk exception handling. Introduces with it a DEXCR utils library for common DEXCR operations. Volatile is used to prevent the compiler optimising away the signal tests. Signed-off-by:
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Benjamin Gray authored
Adds _MSG assertion variants to provide more context behind why a failure occurred. Also include unistd.h for _exit() and stdio.h for fprintf(), and move ARRAY_SIZE macro to utils.h. The _MSG variants and ARRAY_SIZE will be used by the following DEXCR selftests. Signed-off-by:
Russell Currey <ruscur@russell.cc> Signed-off-by:
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Benjamin Gray authored
Describe the DEXCR and document how to configure it. Signed-off-by:
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Benjamin Gray authored
The HASHKEYR register contains a secret per-process key to enable unique hashes per process. In general it should not be exposed to userspace at all and a regular process has no need to know its key. However, checkpoint restore in userspace (CRIU) functionality requires that a process be able to set the HASHKEYR of another process, otherwise existing hashes on the stack would be invalidated by a new random key. Exposing HASHKEYR in this way also makes it appear in core dumps, which is a security concern. Multiple threads may share a key, for example just after a fork() call, where the kernel cannot know if the child is going to return back along the parent's stack. If such a thread is coerced into making a core dump, then the HASHKEYR value will be readable and able to be used against all other threads sharing that key, effectively undoing any protection offered by hashst/hashchk. Therefore we expose HASHKEYR to ptrace when CONFIG_CHECKPOINT_RESTORE is enabled, providing a choice of increased security or migratable ROP protected processes. This is similar to how ARM exposes its PAC keys. Signed-off-by:
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Benjamin Gray authored
The DEXCR register is of interest when ptracing processes. Currently it is static, but eventually will be dynamically controllable by a process. If a process can control its own, then it is useful for it to be ptrace-able to (e.g., for checkpoint-restore functionality). It is also relevant to core dumps (the NPHIE aspect in particular), which use the ptrace mechanism (or is it the other way around?) to decide what to dump. The HDEXCR is useful here too, as the NPHIE aspect may be set in the HDEXCR without being set in the DEXCR. Although the HDEXCR is per-cpu and we don't track it in the task struct (it's useless in normal operation), it would be difficult to imagine why a hypervisor would set it to different values within a guest. A hypervisor cannot safely set NPHIE differently at least, as that would break programs. Expose a read-only view of the userspace DEXCR and HDEXCR to ptrace. The HDEXCR is always readonly, and is useful for diagnosing the core dumps (as the HDEXCR may set NPHIE without the DEXCR setting it). Signed-off-by:
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Benjamin Gray authored
The ISA 3.1B hashst and hashchk instructions use a per-cpu SPR HASHKEYR to hold a key used in the hash calculation. This key should be different for each process to make it harder for a malicious process to recreate valid hash values for a victim process. Add support for storing a per-thread hash key, and setting/clearing HASHKEYR appropriately. Signed-off-by:
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Benjamin Gray authored
Recognise and pass the appropriate signal to the user program when a hashchk instruction triggers. This is independent of allowing configuration of DEXCR[NPHIE], as a hypervisor can enforce this aspect regardless of the kernel. The signal mirrors how ARM reports their similar check failure. For example, their FPAC handler in arch/arm64/kernel/traps.c do_el0_fpac() does this. When we fail to read the instruction that caused the fault we send a segfault, similar to how emulate_math() does it. Signed-off-by:
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Benjamin Gray authored
ISA 3.1B introduces the Dynamic Execution Control Register (DEXCR). It is a per-cpu register that allows control over various CPU behaviours including branch hint usage, indirect branch speculation, and hashst/hashchk support. Add some definitions and basic support for the DEXCR in the kernel. Right now it just * Initialises the DEXCR and HASHKEYR to a fixed value when a CPU onlines. * Clears them in reset_sprs(). * Detects when the NPHIE aspect is supported (the others don't get looked at in this series, so there's no need to waste a CPU_FTR on them). We initialise the HASHKEYR to ensure that all cores have the same key, so an HV enforced NPHIE + swapping cores doesn't randomly crash a process using hash instructions. The stores to HASHKEYR are unconditional because the ISA makes no mention of the SPR being missing if support for doing the hashes isn't present. So all that would happen is the HASHKEYR value gets ignored. This helps slightly if NPHIE detection fails; e.g., we currently only detect it on pseries. Signed-off-by: -
Benjamin Gray authored
ptrace-decl.h uses user_regset_get2_fn (among other things) from regset.h. While all current users of ptrace-decl.h include regset.h before it anyway, it adds an implicit ordering dependency and breaks source tooling that tries to inspect ptrace-decl.h by itself. Signed-off-by:
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Benjamin Gray authored
The functions here use struct task_struct fields, so need to import the full definition from <linux/sched.h>. The <asm/current.h> header that defines current only forward declares struct task_struct. Failing to include this <linux/sched.h> header leads to a compilation error when a translation unit does not also include <linux/sched.h> indirectly. Signed-off-by:
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- 15 Jun, 2023 4 commits
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Nicholas Piggin authored
Add --orphan-handlin for vdsos, and adjust vdso linker scripts to deal with orphan sections. Signed-off-by:
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Nicholas Piggin authored
The refcount on mm is dropped before the coprocessor is detached. Reported-by:
Sachin Sant <sachinp@linux.ibm.com> Fixes: 7bc6f71b ("powerpc/vas: Define and use common vas_window struct") Fixes: b22f2d88 ("powerpc/pseries/vas: Integrate API with open/close windows") Signed-off-by:
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Nicholas Piggin authored
This file contains only the enter_prom implementation now. Trim includes and update header comment while we're here. Signed-off-by:
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Nicholas Piggin authored
The _switch stack frame setup are substantially the same, so are the comments. The difference in how the stack and current are switched, and other hardware and software housekeeping is done is moved into macros. Generated code should be unchanged. Signed-off-by:
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- 14 Jun, 2023 16 commits
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Nicholas Piggin authored
Change the order of some operations and change some register numbers in preparation to merge 32-bit and 64-bit switch. Signed-off-by:
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Nicholas Piggin authored
64-bit has removed the sync from _switch since commit 9145effd ("powerpc/64: Drop explicit hwsync in context switch"). The same logic there should apply to 32-bit. Remove the sync and replace with a placeholder comment (32 and 64 will be merged with a later change). Signed-off-by:
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Nicholas Piggin authored
More some 64-bit specifics out from the function epilogue and rearrange this to be a bit neater, use 32-bit mem ops for CR save/restore, and change some register numbers. This is preparation to consolidate 32-bit and 64-bit switch code. Signed-off-by:
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Nicholas Piggin authored
The large hunk of SLB pinning in _switch asm code makes it more difficult to see everything else that's going on. It is a less important path now, so icache and fetch footprint overhead can be avoided. Move context switch stack SLB pinning out of line. Signed-off-by:
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Nicholas Piggin authored
LLVM assembler does not recognise 3-operand cmpi, use cmpwi. Signed-off-by:
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Nicholas Piggin authored
ELFv2 was introduced together with little-endian. ELFv1 with LE has never been a thing. The GNU toolchain can create such a beast, but anyone doing that is a maniac who needs to be stopped so I consider this patch a feature. Signed-off-by:
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Nicholas Piggin authored
-mprofile-kernel is an optimised calling convention for mcount that Linux has only implemented with the ELFv2 ABI, so it was disabled for big endian kernels. However it does work with ELFv2 big endian, so let's allow that if the compiler supports it. Acked-by:
Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Suggested-by:
Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by:
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Nicholas Piggin authored
All supported toolchains now support ELFv2 on big-endian, so flip the default on this and hide the option behind EXPERT for the purpose of bug hunting. Signed-off-by:
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Nicholas Piggin authored
The LLVM linker does not support ELFv1 at all, so BE kernels must be built with ELFv2. The LLD version check was added to be conservative, LLD simply fails to link ELFv1 entirely, effectively requiring LLD >= 15 and ELFv2 for BE builds. Instead remove that restriction until proven otherwise (LLD 14.0 links a booting ELFv2 BE vmlinux for me). The minimum GNU binutils has increased such that ELFv2 is always supported, so remove that check while we're here. Reviewed-by:
Nathan Chancellor <nathan@kernel.org> Tested-by:
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Nicholas Piggin authored
x86 removed -pipe in commit 437e88ab ("x86/build: Remove -pipe from KBUILD_CFLAGS") and the newer arm64 and riscv seem to have never used it, so that seems to be the way the world's going. Compile performance building defconfig on a POWER10 PowerNV system was in the noise after 10 builds each. No point in adding options unless they help something, so remove it. Signed-off-by:
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Nicholas Piggin authored
Tidy pass over boot Makefile. Move variables together where possible. Signed-off-by:
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Nicholas Piggin authored
BOOTCFLAGS no longer contains anything that BOOTASFLAGS needs (except -pipe). Separate them to avoid fragility with cross-contamination of flags which has caused several build problems. Suggested-by:
Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/lkml/CAHk-=whyWUdJDeOBN1hRWYSkQkvzYiQ5RbSW5rJjExgnbSNX9Q@mail.gmail.com/Signed-off-by:
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Nicholas Piggin authored
Add BOOTCPPFLAGS variable for the CPP options required by C and AS. Signed-off-by:
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Nicholas Piggin authored
Add BOOTTARGETFLAGS variable with target / ABI options common to CFLAGS and AFLAGS. Signed-off-by:
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Uwe Kleine-König authored
After commit b8a1a4cd ("i2c: Provide a temporary .probe_new() call-back type"), all drivers being converted to .probe_new() and then 03c835f4 ("i2c: Switch .probe() to not take an id parameter") convert back to (the new) .probe() to be able to eventually drop .probe_new() from struct i2c_driver. Signed-off-by:
Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by:
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Uwe Kleine-König authored
After commit b8a1a4cd ("i2c: Provide a temporary .probe_new() call-back type"), all drivers being converted to .probe_new() and then 03c835f4 ("i2c: Switch .probe() to not take an id parameter") convert back to (the new) .probe() to be able to eventually drop .probe_new() from struct i2c_driver. Signed-off-by:
Jean Delvare <jdelvare@suse.de> Reviewed-by:
Dmitry Torokhov <dmitry.torokhov@gmail.com> Signed-off-by:
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- 09 Jun, 2023 5 commits
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Christophe Leroy authored
Looking at generated code for handle_signal32() shows calls to a function called __unsafe_save_user_regs.constprop.0 while user access is open. And that __unsafe_save_user_regs.constprop.0 function has two nops at the begining, allowing it to be traced, which is unexpected during user access open window. The solution could be to mark __unsafe_save_user_regs() no trace, but to be on the safe side the most efficient is to flag it __always_inline as already done for function __unsafe_restore_general_regs(). The function is relatively small and only called twice, so the size increase will remain in the noise. Do the same with save_tm_user_regs_unsafe() as it may suffer the same issue. Fixes: ef75e731 ("powerpc/signal32: Transform save_user_regs() and save_tm_user_regs() in 'unsafe' version") Signed-off-by:
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Christophe Leroy authored
A disassembly of interrupt_exit_kernel_prepare() shows a useless read of MSR register. This is shown by r9 being re-used immediately without doing anything with the value read. c000e0e0: 60 00 00 00 nop c000e0e4: 7d 3a c2 a6 mfmd_ap r9 c000e0e8: 7d 20 00 a6 mfmsr r9 c000e0ec: 7c 51 13 a6 mtspr 81,r2 c000e0f0: 81 3f 00 84 lwz r9,132(r31) c000e0f4: 71 29 80 00 andi. r9,r9,32768 This is due to the use of local_irq_save(). The flags read by local_irq_save() are never used, use local_irq_disable() instead. Fixes: 13799748 ("powerpc/64: use interrupt restart table to speed up return from interrupt") Signed-off-by:
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Christophe Leroy authored
The following boottime error is encountered with SMP kernel: kcsan: improperly instrumented type=(0): arch_spin_unlock(&arch_spinlock) kcsan: improperly instrumented type=(0): spin_unlock(&test_spinlock) kcsan: improperly instrumented type=(KCSAN_ACCESS_WRITE): arch_spin_unlock(&arch_spinlock) kcsan: improperly instrumented type=(KCSAN_ACCESS_WRITE): spin_unlock(&test_spinlock) kcsan: improperly instrumented type=(KCSAN_ACCESS_WRITE | KCSAN_ACCESS_COMPOUND): arch_spin_unlock(&arch_spinlock) kcsan: improperly instrumented type=(KCSAN_ACCESS_WRITE | KCSAN_ACCESS_COMPOUND): spin_unlock(&test_spinlock) kcsan: selftest: test_barrier failed kcsan: selftest: 2/3 tests passed Kernel panic - not syncing: selftests failed Properly instrument arch_spin_unlock() with kcsan_mb(). Signed-off-by:
Marco Elver <elver@google.com> Signed-off-by:
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Christophe Leroy authored
The stubs were provided by commit 725aea87 ("xtensa: enable KCSAN") to make linker happy allthought they are not meant to be used at all. KCSAN core has been fixed to not require them anymore on 32 bits architectures. Then they can be removed. Signed-off-by:
Max Filippov <jcmvbkbc@gmail.com> Acked-by:
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Rohan McLure authored
Enable HAVE_ARCH_KCSAN on all powerpc platforms, permitting use of the kernel concurrency sanitiser through the CONFIG_KCSAN_* kconfig options. Boots and passes selftests on 32-bit and 64-bit platforms. See documentation in Documentation/dev-tools/kcsan.rst for more information. Signed-off-by:
Rohan McLure <rmclure@linux.ibm.com> Signed-off-by:
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