kernel/linux.git/arch/powerpc/include/asm/switch_to.h, branch linux-7.0.y

powerpc/83xx: Fix build failure with FPU=n

2024-03-07T12:06:19+00:00

Building eg. 83xx/mpc832x_rdb_defconfig with FPU=n, fails with: arch/powerpc/platforms/83xx/suspend.c: In function 'mpc83xx_suspend_enter': arch/powerpc/platforms/83xx/suspend.c:209:17: error: implicit declaration of function 'enable_kernel_fp' 209 | enable_kernel_fp(); Fix it by providing an enable_kernel_fp() stub for FPU=n builds, which allows using IS_ENABLED(CONFIG_PPC_FPU) around the call to enable_kernel_fp(). Signed-off-by: Michael Ellerman Link: https://msgid.link/20240306125853.3714578-2-mpe@ellerman.id.au

powerpc: Fix missing declaration of [en/dis]able_kernel_altivec()

2022-05-04T09:37:46+00:00

When CONFIG_PPC64 is set and CONFIG_ALTIVEC is not the following build failures occur: drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/dc_fpu.c: In function 'dc_fpu_begin': >> drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/dc_fpu.c:61:17: error: implicit declaration of function 'enable_kernel_altivec'; did you mean 'enable_kernel_vsx'? [-Werror=implicit-function-declaration] 61 | enable_kernel_altivec(); | ^~~~~~~~~~~~~~~~~~~~~ | enable_kernel_vsx drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/dc_fpu.c: In function 'dc_fpu_end': >> drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/dc_fpu.c:89:17: error: implicit declaration of function 'disable_kernel_altivec'; did you mean 'disable_kernel_vsx'? [-Werror=implicit-function-declaration] 89 | disable_kernel_altivec(); | ^~~~~~~~~~~~~~~~~~~~~~ | disable_kernel_vsx cc1: some warnings being treated as errors This commit adds stub instances of both enable_kernel_altivec() and disable_kernel_altivec() the same way as done in commit bd73758803c2 regarding enable_kernel_vsx() and disable_kernel_vsx(). Reported-by: kernel test robot Signed-off-by: Magali Lemes Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220221230741.293064-1-magalilemes00@gmail.com

KVM: PPC: Book3S HV P9: Use Linux SPR save/restore to manage some host SPRs

2021-11-24T10:09:01+00:00

Linux implements SPR save/restore including storage space for registers in the task struct for process context switching. Make use of this similarly to the way we make use of the context switching fp/vec save restore. This improves code reuse, allows some stack space to be saved, and helps with avoiding VRSAVE updates if they are not required. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20211123095231.1036501-39-npiggin@gmail.com

KVM: PPC: Book3S HV P9: Reduce mtmsrd instructions required to save host SPRs

2021-11-24T10:08:58+00:00

This reduces the number of mtmsrd required to enable facility bits when saving/restoring registers, by having the KVM code set all bits up front rather than using individual facility functions that set their particular MSR bits. Signed-off-by: Nicholas Piggin Reviewed-by: Fabiano Rosas Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20211123095231.1036501-20-npiggin@gmail.com

powerpc: Fix missing declaration of [en/dis]able_kernel_vsx()

2021-03-10T00:15:00+00:00

Add stub instances of enable_kernel_vsx() and disable_kernel_vsx() when CONFIG_VSX is not set, to avoid following build failure. CC [M] drivers/gpu/drm/amd/amdgpu/../display/dc/calcs/dcn_calcs.o In file included from ./drivers/gpu/drm/amd/amdgpu/../display/dc/dm_services_types.h:29, from ./drivers/gpu/drm/amd/amdgpu/../display/dc/dm_services.h:37, from drivers/gpu/drm/amd/amdgpu/../display/dc/calcs/dcn_calcs.c:27: drivers/gpu/drm/amd/amdgpu/../display/dc/calcs/dcn_calcs.c: In function 'dcn_bw_apply_registry_override': ./drivers/gpu/drm/amd/amdgpu/../display/dc/os_types.h:64:3: error: implicit declaration of function 'enable_kernel_vsx'; did you mean 'enable_kernel_fp'? [-Werror=implicit-function-declaration] 64 | enable_kernel_vsx(); \ | ^~~~~~~~~~~~~~~~~ drivers/gpu/drm/amd/amdgpu/../display/dc/calcs/dcn_calcs.c:640:2: note: in expansion of macro 'DC_FP_START' 640 | DC_FP_START(); | ^~~~~~~~~~~ ./drivers/gpu/drm/amd/amdgpu/../display/dc/os_types.h:75:3: error: implicit declaration of function 'disable_kernel_vsx'; did you mean 'disable_kernel_fp'? [-Werror=implicit-function-declaration] 75 | disable_kernel_vsx(); \ | ^~~~~~~~~~~~~~~~~~ drivers/gpu/drm/amd/amdgpu/../display/dc/calcs/dcn_calcs.c:676:2: note: in expansion of macro 'DC_FP_END' 676 | DC_FP_END(); | ^~~~~~~~~ cc1: some warnings being treated as errors make[5]: *** [drivers/gpu/drm/amd/amdgpu/../display/dc/calcs/dcn_calcs.o] Error 1 This works because the caller is checking if VSX is available using cpu_has_feature(): #define DC_FP_START() { \ if (cpu_has_feature(CPU_FTR_VSX_COMP)) { \ preempt_disable(); \ enable_kernel_vsx(); \ } else if (cpu_has_feature(CPU_FTR_ALTIVEC_COMP)) { \ preempt_disable(); \ enable_kernel_altivec(); \ } else if (!cpu_has_feature(CPU_FTR_FPU_UNAVAILABLE)) { \ preempt_disable(); \ enable_kernel_fp(); \ } \ When CONFIG_VSX is not selected, cpu_has_feature(CPU_FTR_VSX_COMP) constant folds to 'false' so the call to enable_kernel_vsx() is discarded and the build succeeds. Fixes: 16a9dea110a6 ("amdgpu: Enable initial DCN support on POWER") Cc: stable@vger.kernel.org # v5.6+ Reported-by: Geert Uytterhoeven Reported-by: kernel test robot Signed-off-by: Christophe Leroy [mpe: Incorporate some discussion comments into the change log] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/8d7d285a027e9d21f5ff7f850fa71a2655b0c4af.1615279170.git.christophe.leroy@csgroup.eu

powerpc: Use mm_context vas_windows counter to issue CP_ABORT

2020-04-20T06:53:01+00:00

set_thread_uses_vas() sets used_vas flag for a process that opened VAS window and issue CP_ABORT during context switch for only that process. In multi-thread application, windows can be shared. For example Thread A can open a window and Thread B can run COPY/PASTE instructions to send NX request which may cause corruption or snooping or a covert channel Also once this flag is set, continue to run CP_ABORT even the VAS window is closed. So define vas-windows counter in process mm_context, increment this counter for each window open and decrement it for window close. If vas-windows is set, issue CP_ABORT during context switch. It means clear the foreign real address mapping only if the process / thread uses COPY/PASTE. Then disable it for that process if windows are not open. Moved set_thread_uses_vas() code to vas_tx_win_open() as this functionality is needed only for userspace open windows. We are adding VAS userspace support along with this fix. So no need to include this fix in stable releases. Fixes: 9d2a4d71332c ("powerpc: Define set_thread_uses_vas()") Signed-off-by: Haren Myneni Reported-by: Nicholas Piggin Suggested-by: Milton Miller Suggested-by: Nicholas Piggin Reviewed-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/1587017291.2275.1077.camel@hbabu-laptop

powerpc/64s: Implement interrupt exit logic in C

2020-04-01T02:42:14+00:00

Implement the bulk of interrupt return logic in C. The asm return code must handle a few cases: restoring full GPRs, and emulating stack store. The stack store emulation is significantly simplfied, rather than creating a new return frame and switching to that before performing the store, it uses the PACA to keep a scratch register around to perform the store. The asm return code is moved into 64e for now. The new logic has made allowance for 64e, but I don't have a full environment that works well to test it, and even booting in emulated qemu is not great for stress testing. 64e shouldn't be too far off working with this, given a bit more testing and auditing of the logic. This is slightly faster on a POWER9 (page fault speed increases about 1.1%), probably due to reduced mtmsrd. mpe: Includes fixes from Nick for _TIF_EMULATE_STACK_STORE handling (including the fast_interrupt_return path), to remove trace_hardirqs_on(), and fixes the interrupt-return part of the MSR_VSX restore bug caught by tm-unavailable selftest. mpe: Incorporate fix from Nick: The return-to-kernel path has to replay any soft-pending interrupts if it is returning to a context that had interrupts soft-enabled. It has to do this carefully and avoid plain enabling interrupts if this is an irq context, which can cause multiple nesting of interrupts on the stack, and other unexpected issues. The code which avoided this case got the soft-mask state wrong, and marked interrupts as enabled before going around again to retry. This seems to be mostly harmless except when PREEMPT=y, this calls preempt_schedule_irq with irqs apparently enabled and runs into a BUG in kernel/sched/core.c Signed-off-by: Nicholas Piggin Signed-off-by: Michal Suchanek Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200225173541.1549955-29-npiggin@gmail.com

powerpc/64/sycall: Implement syscall entry/exit logic in C

2020-04-01T02:42:13+00:00

System call entry and particularly exit code is beyond the limit of what is reasonable to implement in asm. This conversion moves all conditional branches out of the asm code, except for the case that all GPRs should be restored at exit. Null syscall test is about 5% faster after this patch, because the exit work is handled under local_irq_disable, and the hard mask and pending interrupt replay is handled after that, which avoids games with MSR. mpe: Includes subsequent fixes from Nick: This fixes 4 issues caught by TM selftests. First was a tm-syscall bug that hit due to tabort_syscall being called after interrupts were reconciled (in a subsequent patch), which led to interrupts being enabled before tabort_syscall was called. Rather than going through an un-reconciling interrupts for the return, I just go back to putting the test early in asm, the C-ification of that wasn't a big win anyway. Second is the syscall return _TIF_USER_WORK_MASK check would go into an infinite loop if _TIF_RESTORE_TM became set. The asm code uses _TIF_USER_WORK_MASK to brach to slowpath which includes restore_tm_state. Third is system call return was not calling restore_tm_state, I missed this completely (alhtough it's in the return from interrupt C conversion because when the asm syscall code encountered problems it would branch to the interrupt return code. Fourth is MSR_VEC missing from restore_math, which was caught by tm-unavailable selftest taking an unexpected facility unavailable interrupt when testing VSX unavailble exception with MSR.FP=1 MSR.VEC=1. Fourth case also has a fixup in a subsequent patch. Signed-off-by: Nicholas Piggin Signed-off-by: Michal Suchanek Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200225173541.1549955-26-npiggin@gmail.com

powerpc: use task_pid_nr() for TID allocation

2018-06-03T10:40:31+00:00

The current implementation of TID allocation, using a global IDR, may result in an errant process starving the system of available TIDs. Instead, use task_pid_nr(), as mentioned by the original author. The scenario described which prevented it's use is not applicable, as set_thread_tidr can only be called after the task struct has been populated. In the unlikely event that 2 threads share the TID and are waiting, all potential outcomes have been determined safe. Signed-off-by: Alastair D'Silva Reviewed-by: Frederic Barrat Reviewed-by: Andrew Donnellan Signed-off-by: Michael Ellerman

powerpc/kernel: Make function __giveup_fpu() static

2018-03-13T04:50:35+00:00

__giveup_fpu() is never called outside process.c, so it can be static. That also means we don't need an empty definition in switch_to.h Signed-off-by: Mathieu Malaterre [mpe: Also drop the empty version, rewrite change log] Signed-off-by: Michael Ellerman