linux.git/arch/powerpc/kernel/exceptions-64s.S, branch v6.16 Linux kernel source tree powerpc/cell: Remove support for IBM Cell Blades 2025-02-26T15:45:07+00:00 Michael Ellerman mpe@ellerman.id.au 2024-12-18T10:54:49+00:00 05bf59fbeef3438c916a6bd3f16fc2839e9f2160 IBM Cell Blades used the Cell processor and the "blade" server form factor. They were sold as models QS20, QS21 & QS22 from roughly 2006 to 2012 [1]. They were used in a few supercomputers (eg. Roadrunner) that have since been dismantled, and were not that widely used otherwise. Until recently I still had a working QS22, which meant I was able to keep the platform support working, but unfortunately that machine has now died. I'm not aware of any users. If there is a user that wants to keep the upstream support working, we can look at bringing some of the code back as appropriate. See previous discussion at [2]. Remove the top-level config symbol PPC_IBM_CELL_BLADE, and then the dependent symbols PPC_CELL_NATIVE, PPC_CELL_COMMON, CBE_RAS, PPC_IBM_CELL_RESETBUTTON, PPC_IBM_CELL_POWERBUTTON, CBE_THERM, and AXON_MSI. Then remove the associated C files and headers, and trim unused header content (some is shared with PS3). Note that PPC_CELL_COMMON sounds like it would build code shared with PS3, but it does not. It's a relic from when code was shared between the Blade support and QPACE support. Most of the primary authors already have CREDITS entries, with the exception of Christian, so add one for him. [1]: https://www.theregister.com/2011/06/28/ibm_kills_qs22_blade [2]: https://lore.kernel.org/linuxppc-dev/60581044-df82-40ad-b94c-56468007a93e@app.fastmail.com Acked-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Jeremy Kerr <jk@ozlabs.org> Acked-by: Segher Boessenkool <segher@kernel.crashing.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com> Link: https://patch.msgid.link/20241218105523.416573-1-mpe@ellerman.id.au 
IBM Cell Blades used the Cell processor and the "blade" server form
factor. They were sold as models QS20, QS21 & QS22 from roughly 2006 to
2012 [1]. They were used in a few supercomputers (eg. Roadrunner) that
have since been dismantled, and were not that widely used otherwise.

Until recently I still had a working QS22, which meant I was able to
keep the platform support working, but unfortunately that machine has
now died.

I'm not aware of any users. If there is a user that wants to keep the
upstream support working, we can look at bringing some of the code back
as appropriate.

See previous discussion at [2].

Remove the top-level config symbol PPC_IBM_CELL_BLADE, and then
the dependent symbols PPC_CELL_NATIVE, PPC_CELL_COMMON, CBE_RAS,
PPC_IBM_CELL_RESETBUTTON, PPC_IBM_CELL_POWERBUTTON, CBE_THERM, and
AXON_MSI. Then remove the associated C files and headers, and trim
unused header content (some is shared with PS3).

Note that PPC_CELL_COMMON sounds like it would build code shared with
PS3, but it does not. It's a relic from when code was shared between the
Blade support and QPACE support.

Most of the primary authors already have CREDITS entries, with the
exception of Christian, so add one for him.

[1]: https://www.theregister.com/2011/06/28/ibm_kills_qs22_blade
[2]: https://lore.kernel.org/linuxppc-dev/60581044-df82-40ad-b94c-56468007a93e@app.fastmail.com

Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Jeremy Kerr <jk@ozlabs.org>
Acked-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20241218105523.416573-1-mpe@ellerman.id.au
powerpc/64s: Remove the "fast endian switch" syscall 2024-09-05T12:30:05+00:00 Michael Ellerman mpe@ellerman.id.au 2024-08-23T07:08:30+00:00 29dbb984496daa490f3c1181b734b538a6f7b534 The non-standard "fast endian switch" syscall was added in 2008[1], but was never widely used. It was disabled by default in 2017[2], and there's no evidence it's ever been used since. Remove it entirely. A normal endian switch syscall was added in 2015[3]. [1]: 745a14cc264b ("[POWERPC] Add fast little-endian switch system call") [2]: 529d235a0e19 ("powerpc: Add a proper syscall for switching endianness") [3]: 727f13616c45 ("powerpc: Disable the fast-endian switch syscall by default") Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/20240823070830.1269033-1-mpe@ellerman.id.au 
The non-standard "fast endian switch" syscall was added in 2008[1],
but was never widely used. It was disabled by default in 2017[2], and
there's no evidence it's ever been used since.

Remove it entirely.

A normal endian switch syscall was added in 2015[3].

[1]: 745a14cc264b ("[POWERPC] Add fast little-endian switch system call")
[2]: 529d235a0e19 ("powerpc: Add a proper syscall for switching endianness")
[3]: 727f13616c45 ("powerpc: Disable the fast-endian switch syscall by default")

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240823070830.1269033-1-mpe@ellerman.id.au
docs: move powerpc under arch 2023-10-10T19:35:55+00:00 Costa Shulyupin costa.shul@redhat.com 2023-08-26T16:56:08+00:00 17e02586ed18501c11115b8dea9055a5973f45a4 and fix all in-tree references. Architecture-specific documentation is being moved into Documentation/arch/ as a way of cleaning up the top-level documentation directory and making the docs hierarchy more closely match the source hierarchy. Signed-off-by: Costa Shulyupin <costa.shul@redhat.com> Acked-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Jonathan Corbet <corbet@lwn.net> Link: https://lore.kernel.org/r/20230826165737.2101199-1-costa.shul@redhat.com 
and fix all in-tree references.

Architecture-specific documentation is being moved into Documentation/arch/
as a way of cleaning up the top-level documentation directory and making
the docs hierarchy more closely match the source hierarchy.

Signed-off-by: Costa Shulyupin <costa.shul@redhat.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20230826165737.2101199-1-costa.shul@redhat.com
powerpc: add CFUNC assembly label annotation 2023-04-20T02:54:24+00:00 Nicholas Piggin npiggin@gmail.com 2023-04-08T02:17:50+00:00 4e991e3c16a350d1eeffc100ce3fb25292596d03 This macro is to be used in assembly where C functions are called. pcrel addressing mode requires branches to functions with a localentry value of 1 to have either a trailing nop or @notoc. This macro permits the latter without changing callers. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> [mpe: Add dummy definitions to fix selftests build] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/20230408021752.862660-5-npiggin@gmail.com 
This macro is to be used in assembly where C functions are called.
pcrel addressing mode requires branches to functions with a
localentry value of 1 to have either a trailing nop or @notoc.
This macro permits the latter without changing callers.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Add dummy definitions to fix selftests build]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230408021752.862660-5-npiggin@gmail.com
Merge branch 'topic/objtool' into next 2022-12-08T12:57:47+00:00 Michael Ellerman mpe@ellerman.id.au 2022-12-08T12:57:47+00:00 f24f21c4122e837fa031cc512a7f20eb8c554c5e Merge the powerpc objtool support, which we were keeping in a topic branch in case of any merge conflicts. 
Merge the powerpc objtool support, which we were keeping in a topic
branch in case of any merge conflicts.
powerpc/64s: Zeroise gprs on interrupt routine entry on Book3S 2022-12-02T09:46:05+00:00 Rohan McLure rmclure@linux.ibm.com 2022-12-01T07:10:17+00:00 1df45d78b8a89da6544fab5267e8f5da15073d28 Zeroise user state in gprs (assign to zero) to reduce the influence of user registers on speculation within kernel syscall handlers. Clears occur at the very beginning of the sc and scv 0 interrupt handlers, with restores occurring following the execution of the syscall handler. Zeroise GPRS r0, r2-r11, r14-r31, on entry into the kernel for all other interrupt sources. The remaining gprs are overwritten by entry macros to interrupt handlers, irrespective of whether or not a given handler consumes these register values. If an interrupt does not select the IMSR_R12 IOption, zeroise r12. Prior to this commit, r14-r31 are restored on a per-interrupt basis at exit, but now they are always restored on 64bit Book3S. Remove explicit REST_NVGPRS invocations on 64-bit Book3S. 32-bit systems do not clear user registers on interrupt, and continue to depend on the return value of interrupt_exit_user_prepare to determine whether or not to restore non-volatiles. The mmap_bench benchmark in selftests should rapidly invoke pagefaults. See ~0.8% performance regression with this mitigation, but this indicates the worst-case performance due to heavier-weight interrupt handlers. This mitigation is able to be enabled/disabled through CONFIG_INTERRUPT_SANITIZE_REGISTERS. Reviewed-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Rohan McLure <rmclure@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20221201071019.1953023-5-rmclure@linux.ibm.com 
Zeroise user state in gprs (assign to zero) to reduce the influence of user
registers on speculation within kernel syscall handlers. Clears occur
at the very beginning of the sc and scv 0 interrupt handlers, with
restores occurring following the execution of the syscall handler.

Zeroise GPRS r0, r2-r11, r14-r31, on entry into the kernel for all
other interrupt sources. The remaining gprs are overwritten by
entry macros to interrupt handlers, irrespective of whether or not a
given handler consumes these register values. If an interrupt does not
select the IMSR_R12 IOption, zeroise r12.

Prior to this commit, r14-r31 are restored on a per-interrupt basis at
exit, but now they are always restored on 64bit Book3S. Remove explicit
REST_NVGPRS invocations on 64-bit Book3S. 32-bit systems do not clear
user registers on interrupt, and continue to depend on the return value
of interrupt_exit_user_prepare to determine whether or not to restore
non-volatiles.

The mmap_bench benchmark in selftests should rapidly invoke pagefaults.
See ~0.8% performance regression with this mitigation, but this
indicates the worst-case performance due to heavier-weight interrupt
handlers. This mitigation is able to be enabled/disabled through
CONFIG_INTERRUPT_SANITIZE_REGISTERS.

Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221201071019.1953023-5-rmclure@linux.ibm.com
powerpc/64s: IOption for MSR stored in r12 2022-12-02T09:46:01+00:00 Rohan McLure rmclure@linux.ibm.com 2022-12-01T07:10:16+00:00 2487fd2e6d61b5293eed8ecd25add3cc78593d38 Interrupt handlers in asm/exceptions-64s.S contain a great deal of common code produced by the GEN_COMMON macros. Currently, at the exit point of the macro, r12 will contain the contents of the MSR. A future patch will cause these macros to zeroise architected registers to avoid potential speculation influence of user data. Provide an IOption that signals that r12 must be retained, as the interrupt handler assumes it to hold the contents of the MSR. Reviewed-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Rohan McLure <rmclure@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20221201071019.1953023-4-rmclure@linux.ibm.com 
Interrupt handlers in asm/exceptions-64s.S contain a great deal of common
code produced by the GEN_COMMON macros. Currently, at the exit point of
the macro, r12 will contain the contents of the MSR. A future patch will
cause these macros to zeroise architected registers to avoid potential
speculation influence of user data.

Provide an IOption that signals that r12 must be retained, as the
interrupt handler assumes it to hold the contents of the MSR.

Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221201071019.1953023-4-rmclure@linux.ibm.com
powerpc: add a definition for the marker offset within the interrupt frame 2022-12-02T06:54:08+00:00 Nicholas Piggin npiggin@gmail.com 2022-11-27T12:49:33+00:00 d2e8ff9f1492f44c5a6d93f759eea27574d753de Define a constant rather than open-code the offset for the "regs" marker. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20221127124942.1665522-9-npiggin@gmail.com 
Define a constant rather than open-code the offset for the
"regs" marker.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221127124942.1665522-9-npiggin@gmail.com
powerpc: add definition for pt_regs offset within an interrupt frame 2022-12-02T06:54:08+00:00 Nicholas Piggin npiggin@gmail.com 2022-11-27T12:49:32+00:00 c03be0a3f3cc656eab5c427b78959b8f1b169a11 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 
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
powerpc: Fix objtool unannotated intra-function call warnings 2022-11-15T09:11:47+00:00 Sathvika Vasireddy sv@linux.ibm.com 2022-11-14T17:57:41+00:00 29a011fc79e625b2b02f25262657f7c4c59ae9f7 Objtool throws unannotated intra-function call warnings in the following assembly files: arch/powerpc/kernel/vector.o: warning: objtool: .text+0x53c: unannotated intra-function call arch/powerpc/kvm/book3s_hv_rmhandlers.o: warning: objtool: .text+0x60: unannotated intra-function call arch/powerpc/kvm/book3s_hv_rmhandlers.o: warning: objtool: .text+0x124: unannotated intra-function call arch/powerpc/kvm/book3s_hv_rmhandlers.o: warning: objtool: .text+0x5d4: unannotated intra-function call arch/powerpc/kvm/book3s_hv_rmhandlers.o: warning: objtool: .text+0x5dc: unannotated intra-function call arch/powerpc/kvm/book3s_hv_rmhandlers.o: warning: objtool: .text+0xcb8: unannotated intra-function call arch/powerpc/kvm/book3s_hv_rmhandlers.o: warning: objtool: .text+0xd0c: unannotated intra-function call arch/powerpc/kvm/book3s_hv_rmhandlers.o: warning: objtool: .text+0x1030: unannotated intra-function call arch/powerpc/kernel/head_64.o: warning: objtool: .text+0x358: unannotated intra-function call arch/powerpc/kernel/head_64.o: warning: objtool: .text+0x728: unannotated intra-function call arch/powerpc/kernel/head_64.o: warning: objtool: .text+0x4d94: unannotated intra-function call arch/powerpc/kernel/head_64.o: warning: objtool: .text+0x4ec4: unannotated intra-function call arch/powerpc/kvm/book3s_hv_interrupts.o: warning: objtool: .text+0x6c: unannotated intra-function call arch/powerpc/kernel/misc_64.o: warning: objtool: .text+0x64: unannotated intra-function call Objtool does not add STT_NOTYPE symbols with size 0 to the rbtree, which is why find_call_destination() function is not able to find the destination symbol for 'bl' instruction. For such symbols, objtool is throwing unannotated intra-function call warnings in assembly files. Fix these warnings by annotating those symbols with SYM_FUNC_START_LOCAL and SYM_FUNC_END macros, inorder to set symbol type to STT_FUNC and symbol size accordingly. Tested-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org> Signed-off-by: Sathvika Vasireddy <sv@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20221114175754.1131267-4-sv@linux.ibm.com 
Objtool throws unannotated intra-function call warnings in the following
assembly files:

arch/powerpc/kernel/vector.o: warning: objtool: .text+0x53c: unannotated intra-function call

arch/powerpc/kvm/book3s_hv_rmhandlers.o: warning: objtool: .text+0x60: unannotated intra-function call
arch/powerpc/kvm/book3s_hv_rmhandlers.o: warning: objtool: .text+0x124: unannotated intra-function call
arch/powerpc/kvm/book3s_hv_rmhandlers.o: warning: objtool: .text+0x5d4: unannotated intra-function call
arch/powerpc/kvm/book3s_hv_rmhandlers.o: warning: objtool: .text+0x5dc: unannotated intra-function call
arch/powerpc/kvm/book3s_hv_rmhandlers.o: warning: objtool: .text+0xcb8: unannotated intra-function call
arch/powerpc/kvm/book3s_hv_rmhandlers.o: warning: objtool: .text+0xd0c: unannotated intra-function call
arch/powerpc/kvm/book3s_hv_rmhandlers.o: warning: objtool: .text+0x1030: unannotated intra-function call

arch/powerpc/kernel/head_64.o: warning: objtool: .text+0x358: unannotated intra-function call
arch/powerpc/kernel/head_64.o: warning: objtool: .text+0x728: unannotated intra-function call
arch/powerpc/kernel/head_64.o: warning: objtool: .text+0x4d94: unannotated intra-function call
arch/powerpc/kernel/head_64.o: warning: objtool: .text+0x4ec4: unannotated intra-function call

arch/powerpc/kvm/book3s_hv_interrupts.o: warning: objtool: .text+0x6c: unannotated intra-function call
arch/powerpc/kernel/misc_64.o: warning: objtool: .text+0x64: unannotated intra-function call

Objtool does not add STT_NOTYPE symbols with size 0 to the rbtree, which
is why find_call_destination() function is not able to find the
destination symbol for 'bl' instruction. For such symbols, objtool is
throwing unannotated intra-function call warnings in assembly files. Fix
these warnings by annotating those symbols with SYM_FUNC_START_LOCAL and
SYM_FUNC_END macros, inorder to set symbol type to STT_FUNC and symbol
size accordingly.

Tested-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Sathvika Vasireddy <sv@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221114175754.1131267-4-sv@linux.ibm.com