kernel.git/arch/powerpc/kernel/head_64.S, branch linux-6.5.y

powerpc/64e: Fix secondary thread bringup for ELFv2 kernels

2023-08-01T11:01:27Z

When booting on e6500 with an ELF v2 ABI kernel, the secondary threads do not start correctly: [ 0.051118] smp: Bringing up secondary CPUs ... [ 5.072700] Processor 1 is stuck. This occurs because the startup code is written to use function descriptors when loading the entry point for the secondary threads. When building with ELF v2 ABI there are no function descriptors, and the code loads junk values for the entry point address. Fix it by using ppc_function_entry() in C, and DOTSYM() in asm, both of which work correctly for ELF v2 ABI as well as ELF v1 ABI kernels. Fixes: 8c5fa3b5c4df ("powerpc/64: Make ELFv2 the default for big-endian builds") Signed-off-by: Michael Ellerman Link: https://msgid.link/20230801102650.48705-1-mpe@ellerman.id.au

powerpc/64: vmlinux support building with PCREL addresing

2023-04-20T02:59:21Z

PC-Relative or PCREL addressing is an extension to the ELF ABI which uses Power ISA v3.1 PC-relative instructions to calculate addresses, rather than the traditional TOC scheme. Add an option to build vmlinux using pcrel addressing. Modules continue to use TOC addressing. - TOC address helpers and r2 are poisoned with -1 when running vmlinux. r2 could be used for something useful once things are ironed out. - Assembly must call C functions with @notoc annotation, or the linker complains aobut a missing nop after the call. This is done with the CFUNC macro introduced earlier. - Boot: with the exception of prom_init, the execution branches to the kernel virtual address early in boot, before any addresses are generated, which ensures 34-bit pcrel addressing does not miss the high PAGE_OFFSET bits. TOC relative addressing has a similar requirement. prom_init does not go to the virtual address and its addresses should not carry over to the post-prom kernel. - Ftrace trampolines are converted from TOC addressing to pcrel addressing, including module ftrace trampolines that currently use the kernel TOC to find ftrace target functions. - BPF function prologue and function calling generation are converted from TOC to pcrel. - copypage_64.S has an interesting problem, prefixed instructions have alignment restrictions so the linker can add padding, which makes the assembler treat the difference between two local labels as non-constant even if alignment is arranged so padding is not required. This may need toolchain help to solve nicely, for now move the prefix instruction out of the alternate patch section to work around it. This reduces kernel text size by about 6%. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://msgid.link/20230408021752.862660-6-npiggin@gmail.com

powerpc: add CFUNC assembly label annotation

2023-04-20T02:54:24Z

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 [mpe: Add dummy definitions to fix selftests build] Signed-off-by: Michael Ellerman Link: https://msgid.link/20230408021752.862660-5-npiggin@gmail.com

powerpc/64s: Run at the kernel virtual address earlier in boot

2023-04-20T02:23:14Z

This mostly consolidates the Book3E and Book3S behaviour in boot WRT executing from the physical or virtual address. Book3E sets up kernel virtual linear map in start_initialization_book3e and runs from the virtual linear alias after that. This change makes Book3S begin to execute from the virtual alias at the same point. Book3S can not use its MMU for that at this point, but when the MMU is disabled, the virtual linear address correctly aliases to physical memory because the top bits of the address are ignored with MMU disabled. Secondaries execute from the virtual address similarly early. This reduces the differences between subarchs, but the main motivation was to enable the PC-relative addressing ABI for Book3S, where pointer calculations must execute from the virtual address or the top bits of the pointer will be lost. This is similar to the requirement the TOC relative addressing already has that the TOC pointer use its virtual address. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://msgid.link/20230408021752.862660-3-npiggin@gmail.com

powerpc/64: Move initial base and TOC pointer calculation

2023-04-20T02:23:14Z

A later change moves the non-prom case to run at the virtual address earlier, which calls for virtual TOC and kernel base. Split these two calculations for prom and non-prom to make that change simpler. Signed-off-by: Nicholas Piggin [mpe: Retain relative_toc call for start_initialization_book3e] Signed-off-by: Michael Ellerman Link: https://msgid.link/20230408021752.862660-2-npiggin@gmail.com

powerpc/64: Fix unannotated intra-function call warning

2023-02-17T11:11:55Z

objtool throws the following warning: arch/powerpc/kernel/head_64.o: warning: objtool: .text+0x6128: unannotated intra-function call Fix the warning by annotating start_initialization_book3s symbol with the SYM_FUNC_START_LOCAL and SYM_FUNC_END macros. Reported-by: Stephen Rothwell Signed-off-by: Sathvika Vasireddy Fixes: 58f24eea5278 ("powerpc/64s: Refactor initialisation after prom") Suggested-by: Josh Poimboeuf Tested-by: Stephen Rothwell Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20230217043226.1020041-1-sv@linux.ibm.com

powerpc/64e: Simplify address calculation in secondary hold loop

2023-02-10T11:17:36Z

As the earlier comment explains, __secondary_hold_spinloop does not have to be accessed at its virtual address, slightly simplifying code. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20230203113858.1152093-4-npiggin@gmail.com

powerpc/64s: Refactor initialisation after prom

2023-02-10T11:17:36Z

Move some basic Book3S initialisation after prom to a function similar to what Book3E looks like. Book3E returns from this function at the virtual address mapping, and Book3S will do the same in a later change, so making them look similar helps with that. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20230203113858.1152093-3-npiggin@gmail.com

Merge branch 'topic/objtool' into next

2022-12-08T12:57:47Z

Merge the powerpc objtool support, which we were keeping in a topic branch in case of any merge conflicts.

powerpc: allow minimum sized kernel stack frames

2022-12-02T06:54:09Z

This affects only 64-bit ELFv2 kernels, and reduces the minimum asm-created stack frame size from 112 to 32 byte on those kernels. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20221127124942.1665522-16-npiggin@gmail.com