powerpc/64s: add a table of implicit soft-masked addresses

2021-06-30T12:21:20Z

Commit 9d1988ca87dd ("powerpc/64: treat low kernel text as irqs soft-masked") ends up catching too much code, including ret_from_fork, and parts of interrupt and syscall return that do not expect to be interrupts to be soft-masked. If an interrupt gets marked pending, and then the code proceeds out of the implicit soft-masked region it will fail to deal with the pending interrupt. Fix this by adding a new table of addresses which explicitly marks the regions of code that are soft masked. This table is only checked for interrupts that below __end_soft_masked, so most kernel interrupts will not have the overhead of the table search. Fixes: 9d1988ca87dd ("powerpc/64: treat low kernel text as irqs soft-masked") Reported-by: Sachin Sant Signed-off-by: Nicholas Piggin Tested-by: Sachin Sant Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210630074621.2109197-5-npiggin@gmail.com

powerpc/64: allow alternate return locations for soft-masked interrupts

2021-06-24T14:06:56Z

The exception table fixup adjusts a failed page fault's interrupt return location if it was taken at an address specified in the exception table, to a corresponding fixup handler address. Introduce a variation of that idea which adds a fixup table for NMIs and soft-masked asynchronous interrupts. This will be used to protect certain critical sections that are sensitive to being clobbered by interrupts coming in (due to using the same SPRs and/or irq soft-mask state). Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210617155116.2167984-10-npiggin@gmail.com

kernel/arch/powerpc/lib/restart_table.c, branch linux-6.2.y

powerpc/64s: add a table of implicit soft-masked addresses

powerpc/64: allow alternate return locations for soft-masked interrupts