Commit 787c70f2 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
Browse files

powerpc/64s: Fix scv implicit soft-mask table for relocated kernels 



The implict soft-mask table addresses get relocated if they use a
relative symbol like a label. This is right for code that runs relocated
but not for unrelocated. The scv interrupt vectors run unrelocated, so
absolute addresses are required for their soft-mask table entry.

This fixes crashing with relocated kernels, usually an asynchronous
interrupt hitting in the scv handler, then hitting the trap that checks
whether r1 is in userspace.

Fixes: 325678fd ("powerpc/64s: add a table of implicit soft-masked addresses")
Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210820103431.1701240-1-npiggin@gmail.com
parent 310d2e83

arch/powerpc/kernel/exceptions-64s.S

+4 −3
Original line number Diff line number Diff line
@@ -812,7 +812,6 @@ __start_interrupts: 
 * syscall register convention is in Documentation/powerpc/syscall64-abi.rst

 */

EXC_VIRT_BEGIN(system_call_vectored, 0x3000, 0x1000)

1:

	/* SCV 0 */

	mr	r9,r13

	GET_PACA(r13)
@@ -842,10 +841,12 @@ EXC_VIRT_BEGIN(system_call_vectored, 0x3000, 0x1000) 
	b	system_call_vectored_sigill

#endif

	.endr

2:

EXC_VIRT_END(system_call_vectored, 0x3000, 0x1000)



SOFT_MASK_TABLE(1b, 2b) // Treat scv vectors as soft-masked, see comment above.

// Treat scv vectors as soft-masked, see comment above.

// Use absolute values rather than labels here, so they don't get relocated,

// because this code runs unrelocated.

SOFT_MASK_TABLE(0xc000000000003000, 0xc000000000004000)



#ifdef CONFIG_RELOCATABLE

TRAMP_VIRT_BEGIN(system_call_vectored_tramp)