linux.git - Linus' kernel tree

Age	Commit message (Collapse)	Author
2025-02-26	powerpc/static_call: Implement inline static calls	Christophe Leroy
	Implement inline static calls: - Put a 'bl' to the destination function ('b' if tail call) - Put a 'nop' when the destination function is NULL ('blr' if tail call) - Put a 'li r3,0' when the destination is the RET0 function and not a tail call. If the destination is too far (over the 32Mb limit), go via the trampoline. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com> Link: https://patch.msgid.link/3dbd0b2ba577c942729235d0211d04a406653d81.1733245362.git.christophe.leroy@csgroup.eu
2025-02-26	powerpc: Prepare arch_static_call_transform() for supporting inline static calls	Christophe Leroy
	Reorganise arch_static_call_transform() in order to ease the support of inline static calls in following patch: - remove 'target' to nhide whether it is a 'return 0' or not. - Don't bail out if 'tramp' is NULL, just do nothing until next patch. Note that 'target' was 'tramp + PPC_SCT_RET0', is_short was perforce true. So in the 'if (func && !is_short)' leg, target was perforce equal to 'func'. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com> Link: https://patch.msgid.link/7a8b9245e773307c315c2548a4c6cad570ac2648.1733245362.git.christophe.leroy@csgroup.eu
2024-11-07	asm-generic: introduce text-patching.h	Mike Rapoport (Microsoft)
	Several architectures support text patching, but they name the header files that declare patching functions differently. Make all such headers consistently named text-patching.h and add an empty header in asm-generic for architectures that do not support text patching. Link: https://lkml.kernel.org/r/20241023162711.2579610-4-rppt@kernel.org Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> # m68k Acked-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org> Tested-by: kdevops <kdevops@lists.linux.dev> Cc: Andreas Larsson <andreas@gaisler.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Ard Biesheuvel <ardb@kernel.org> Cc: Borislav Petkov (AMD) <bp@alien8.de> Cc: Brian Cain <bcain@quicinc.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Dinh Nguyen <dinguyen@kernel.org> Cc: Guo Ren <guoren@kernel.org> Cc: Helge Deller <deller@gmx.de> Cc: Huacai Chen <chenhuacai@kernel.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Johannes Berg <johannes@sipsolutions.net> Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de> Cc: Kent Overstreet <kent.overstreet@linux.dev> Cc: Liam R. Howlett <Liam.Howlett@Oracle.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masami Hiramatsu (Google) <mhiramat@kernel.org> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Simek <monstr@monstr.eu> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Richard Weinberger <richard@nod.at> Cc: Russell King <linux@armlinux.org.uk> Cc: Song Liu <song@kernel.org> Cc: Stafford Horne <shorne@gmail.com> Cc: Steven Rostedt (Google) <rostedt@goodmis.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Uladzislau Rezki (Sony) <urezki@gmail.com> Cc: Vineet Gupta <vgupta@kernel.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-08-21	powerpc/32: Convert patch_instruction() to patch_uint()	Benjamin Gray
	These changes are for patch_instruction() uses on data. Unlike ppc64 these should not be incorrect as-is, but using the patch_uint() alias better reflects what kind of data being patched and allows for benchmarking the effect of different patch_* implementations (e.g., skipping instruction flushing when patching data). Signed-off-by: Benjamin Gray <bgray@linux.ibm.com> Tested-by: Hari Bathini <hbathini@linux.ibm.com> Acked-by: Naveen N Rao <naveen@kernel.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/20240515024445.236364-5-bgray@linux.ibm.com
2021-10-22	powerpc/32: Add support for out-of-line static calls	Christophe Leroy
	Add support for out-of-line static calls on PPC32. This change improve performance of calls to global function pointers by using direct calls instead of indirect calls. The trampoline is initialy populated with a 'blr' or branch to target, followed by an unreachable long jump sequence. In order to cater with parallele execution, the trampoline needs to be updated in a way that ensures it remains consistent at all time. This means we can't use the traditional lis/addi to load r12 with the target address, otherwise there would be a window during which the first instruction contains the upper part of the new target address while the second instruction still contains the lower part of the old target address. To avoid that the target address is stored just after the 'bctr' and loaded from there with a single instruction. Then, depending on the target distance, arch_static_call_transform() will either replace the first instruction by a direct 'bl <target>' or 'nop' in order to have the trampoline fall through the long jump sequence. For the special case of __static_call_return0(), to avoid the risk of a far branch, a version of it is inlined at the end of the trampoline. Performancewise the long jump sequence is probably not better than the indirect calls set by GCC when we don't use static calls, but such calls are unlikely to be required on powerpc32: With most configurations the kernel size is far below 32 Mbytes so only modules may happen to be too far. And even modules are likely to be close enough as they are allocated below the kernel core and as close as possible of the kernel text. static_call selftest is running successfully with this change. With this patch, __do_irq() has the following sequence to trace irq entries: c0004a00 <__SCT__tp_func_irq_entry>: c0004a00: 48 00 00 e0 b c0004ae0 <__traceiter_irq_entry> c0004a04: 3d 80 c0 00 lis r12,-16384 c0004a08: 81 8c 4a 1c lwz r12,18972(r12) c0004a0c: 7d 89 03 a6 mtctr r12 c0004a10: 4e 80 04 20 bctr c0004a14: 38 60 00 00 li r3,0 c0004a18: 4e 80 00 20 blr c0004a1c: 00 00 00 00 .long 0x0 ... c0005654 <__do_irq>: ... c0005664: 7c 7f 1b 78 mr r31,r3 ... c00056a0: 81 22 00 00 lwz r9,0(r2) c00056a4: 39 29 00 01 addi r9,r9,1 c00056a8: 91 22 00 00 stw r9,0(r2) c00056ac: 3d 20 c0 af lis r9,-16209 c00056b0: 81 29 74 cc lwz r9,29900(r9) c00056b4: 2c 09 00 00 cmpwi r9,0 c00056b8: 41 82 00 10 beq c00056c8 <__do_irq+0x74> c00056bc: 80 69 00 04 lwz r3,4(r9) c00056c0: 7f e4 fb 78 mr r4,r31 c00056c4: 4b ff f3 3d bl c0004a00 <__SCT__tp_func_irq_entry> Before this patch, __do_irq() was doing the following to trace irq entries: c0005700 <__do_irq>: ... c0005710: 7c 7e 1b 78 mr r30,r3 ... c000574c: 93 e1 00 0c stw r31,12(r1) c0005750: 81 22 00 00 lwz r9,0(r2) c0005754: 39 29 00 01 addi r9,r9,1 c0005758: 91 22 00 00 stw r9,0(r2) c000575c: 3d 20 c0 af lis r9,-16209 c0005760: 83 e9 f4 cc lwz r31,-2868(r9) c0005764: 2c 1f 00 00 cmpwi r31,0 c0005768: 41 82 00 24 beq c000578c <__do_irq+0x8c> c000576c: 81 3f 00 00 lwz r9,0(r31) c0005770: 80 7f 00 04 lwz r3,4(r31) c0005774: 7d 29 03 a6 mtctr r9 c0005778: 7f c4 f3 78 mr r4,r30 c000577c: 4e 80 04 21 bctrl c0005780: 85 3f 00 0c lwzu r9,12(r31) c0005784: 2c 09 00 00 cmpwi r9,0 c0005788: 40 82 ff e4 bne c000576c <__do_irq+0x6c> Behind the fact of now using a direct 'bl' instead of a 'load/mtctr/bctr' sequence, we can also see that we get one less register on the stack. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/6ec2a7865ed6a5ec54ab46d026785bafe1d837ea.1630484892.git.christophe.leroy@csgroup.eu