| Message ID | 20211221135101.2085547-1-mpe@ellerman.id.au (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [1/3] powerpc/64s: Mask NIP before checking against SRR0 | expand |
> On 21-Dec-2021, at 7:20 PM, Michael Ellerman <mpe@ellerman.id.au> wrote: > > When CONFIG_PPC_RFI_SRR_DEBUG=y we check that NIP and SRR0 match when > returning from interrupts. This can trigger falsely if NIP has either of > its two low bits set via sigreturn or ptrace, while SRR0 has its low two > bits masked in hardware. > > As a quick fix make sure to mask the low bits before doing the check. > > Fixes: 59dc5bfca0cb ("powerpc/64s: avoid reloading (H)SRR registers if they are still valid") > Reported-by: Sachin Sant <sachinp@linux.vnet.ibm.com> > Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> > --- Tested this 3 patch series successfully (with and without PPC_RFI_SRR_DEBUG) on Power9/Power10 LPAR as well as Power9 PowerNV. Tested-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
On Wed, 22 Dec 2021 00:50:59 +1100, Michael Ellerman wrote: > When CONFIG_PPC_RFI_SRR_DEBUG=y we check that NIP and SRR0 match when > returning from interrupts. This can trigger falsely if NIP has either of > its two low bits set via sigreturn or ptrace, while SRR0 has its low two > bits masked in hardware. > > As a quick fix make sure to mask the low bits before doing the check. > > [...] Applied to powerpc/next. [1/3] powerpc/64s: Mask NIP before checking against SRR0 https://git.kernel.org/powerpc/c/314f6c23dd8d417281eb9e8a516dd98036f2e7b3 [2/3] powerpc/64s: Use EMIT_WARN_ENTRY for SRR debug warnings https://git.kernel.org/powerpc/c/fd1eaaaaa6864b5fb8f99880fcefb49760b8fe4e [3/3] selftests/powerpc: Add a test of sigreturning to an unaligned address https://git.kernel.org/powerpc/c/beeac538c366cd2828092adecd1edab28326c55b cheers
diff --git a/arch/powerpc/kernel/interrupt_64.S b/arch/powerpc/kernel/interrupt_64.S index 2ad223597ca2..4fd65d39d5d3 100644 --- a/arch/powerpc/kernel/interrupt_64.S +++ b/arch/powerpc/kernel/interrupt_64.S @@ -30,6 +30,7 @@ .ifc \srr,srr mfspr r11,SPRN_SRR0 ld r12,_NIP(r1) + clrrdi r12,r12,2 100: tdne r11,r12 EMIT_BUG_ENTRY 100b,__FILE__,__LINE__,(BUGFLAG_WARNING | BUGFLAG_ONCE) mfspr r11,SPRN_SRR1 @@ -39,6 +40,7 @@ .else mfspr r11,SPRN_HSRR0 ld r12,_NIP(r1) + clrrdi r12,r12,2 100: tdne r11,r12 EMIT_BUG_ENTRY 100b,__FILE__,__LINE__,(BUGFLAG_WARNING | BUGFLAG_ONCE) mfspr r11,SPRN_HSRR1
When CONFIG_PPC_RFI_SRR_DEBUG=y we check that NIP and SRR0 match when returning from interrupts. This can trigger falsely if NIP has either of its two low bits set via sigreturn or ptrace, while SRR0 has its low two bits masked in hardware. As a quick fix make sure to mask the low bits before doing the check. Fixes: 59dc5bfca0cb ("powerpc/64s: avoid reloading (H)SRR registers if they are still valid") Reported-by: Sachin Sant <sachinp@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> --- arch/powerpc/kernel/interrupt_64.S | 2 ++ 1 file changed, 2 insertions(+)