kernel.git/arch/powerpc/kernel/exceptions-64s.S, branch linux-6.1.y

powerpc/64s/interrupt: Perf NMI should not take normal exit path

2022-10-18T11:46:19Z

NMI interrupts should exit with EXCEPTION_RESTORE_REGS not with interrupt_return_srr, which is what the perf NMI handler currently does. This breaks if a PMI hits after interrupt_exit_user_prepare_main() has switched the context tracking to user mode, then the CT_WARN_ON() in interrupt_exit_kernel_prepare() fires because it returns to kernel with context set to user. This could possibly be solved by soft-disabling PMIs in the exit path, but that reduces our ability to profile that code. The warning could be removed, but it's potentially useful. All other NMIs and soft-NMIs return using EXCEPTION_RESTORE_REGS, so this makes perf interrupts consistent with that and seems like the best fix. Signed-off-by: Nicholas Piggin [mpe: Squash in fixups from Nick] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20221006140413.126443-3-npiggin@gmail.com

powerpc/64s/interrupt: Fix stack frame regs marker

2022-10-05T00:09:22Z

The value of the stack frame regs marker that gets saved on the stack in interrupt entry code does not match the regs marker value, which breaks stack frame marker matching. This stray instruction looks to have been introduced in a mismerge. Fixes: bf75a3258a403 ("powerpc/64s/interrupt: move early boot ILE fixup into a macro") Signed-off-by: Nicholas Piggin [mpe: Mismerge by yours truly -_-] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20221004132952.984341-1-npiggin@gmail.com

powerpc/64s/interrupt: Change must-hard-mask interrupt check from BUG to WARN

2022-10-04T12:16:20Z

This new assertion added is generally harmless and gets fixed up naturally, but it does indicate a problem with MSR manipulation somewhere. Fixes: c39fb71a54f0 ("powerpc/64s/interrupt: masked handler debug check for previous hard disable") Reported-by: Sachin Sant Signed-off-by: Nicholas Piggin Tested-by: Sachin Sant Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20221004051157.308999-1-npiggin@gmail.com

powerpc/64s: Remove lost/old comment

2022-09-30T08:35:51Z

The bulk of this was moved/reworded in: 57f266497d81 ("powerpc: Use gas sections for arranging exception vectors") And now appears around line 700 in arch/powerpc/kernel/exceptions-64s.S. Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220928130941.1732818-1-mpe@ellerman.id.au

powerpc/64s: Remove old STAB comment

2022-09-30T08:35:51Z

This used to be about the 0x4300 handler, but that was moved in commit da2bc4644c75 ("powerpc/64s: Add new exception vector macros"). Note that "STAB" here refers to "Segment Table" not the debug format. Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220928130912.1732466-1-mpe@ellerman.id.au

powerpc/64s/interrupt: halt early boot interrupts if paca is not set up

2022-09-28T09:22:13Z

Ensure r13 is zero from very early in boot until it gets set to the boot paca pointer. This allows early program and mce handlers to halt if there is no valid paca, rather than potentially run off into the weeds. This preserves register and memory contents for low level debugging tools. Nothing could be printed to console at this point in any case because even udbg is only set up after the boot paca is set, so this shouldn't be missed. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220926055620.2676869-6-npiggin@gmail.com

powerpc/64s: early boot machine check handler

2022-09-28T09:22:13Z

Use the early boot interrupt fixup in the machine check handler to allow the machine check handler to run before interrupt endian is set up. Branch to an early boot handler that just does a basic crash, which allows it to run before ppc_md is set up. MSR[ME] is enabled on the boot CPU earlier, and the machine check stack is temporarily set to the middle of the init task stack. This allows machine checks (e.g., due to invalid data access in real mode) to print something useful earlier in boot (as soon as udbg is set up, if CONFIG_PPC_EARLY_DEBUG=y). Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220926055620.2676869-3-npiggin@gmail.com

powerpc/64s/interrupt: move early boot ILE fixup into a macro

2022-09-28T09:22:12Z

In preparation for using this sequence in machine check interrupt, move it into a macro, with a small change to make it position independent. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220926055620.2676869-2-npiggin@gmail.com

powerpc/64: provide a helper macro to load r2 with the kernel TOC

2022-09-28T09:22:12Z

A later change stops the kernel using r2 and loads it with a poison value. Provide a PACATOC loading abstraction which can hide this detail. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220926034057.2360083-5-npiggin@gmail.com

powerpc/64: use 32-bit immediate for STACK_FRAME_REGS_MARKER

2022-09-28T09:22:12Z

Using a 32-bit constant for this marker allows it to be loaded with two ALU instructions, like 32-bit. This avoids a TOC entry and a TOC load that depends on the r2 value that has just been loaded from the PACA. This changes the value for 32-bit as well, so both have the same value in the low 4 bytes and 64-bit has 0 in the top bytes. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220926034057.2360083-2-npiggin@gmail.com