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authorNicholas Piggin <npiggin@gmail.com>2021-06-17 17:51:11 +0200
committerMichael Ellerman <mpe@ellerman.id.au>2021-06-24 16:06:56 +0200
commit13799748b957bc5659f97c036224b0f4b42172e2 (patch)
tree9d2cdb3ef6a336041e17e20c3d9aa55dd128ada8 /arch/powerpc/include/asm/paca.h
parentpowerpc/64: treat low kernel text as irqs soft-masked (diff)
downloadlinux-13799748b957bc5659f97c036224b0f4b42172e2.tar.xz
linux-13799748b957bc5659f97c036224b0f4b42172e2.zip
powerpc/64: use interrupt restart table to speed up return from interrupt
Use the restart table facility to return from interrupt or system calls without disabling MSR[EE] or MSR[RI]. Interrupt return asm is put into the low soft-masked region, to prevent interrupts being processed here, although they are still taken as masked interrupts which causes SRRs to be clobbered, and a pending soft-masked interrupt to require replaying. The return code uses restart table regions to redirct to a fixup handler rather than continue with the exit, if such an interrupt happens. In this case the interrupt return is redirected to a fixup handler which reloads r1 for the interrupt stack and reloads registers and sets state up to replay the soft-masked interrupt and try the exit again. Some types of security exit fallback flushes and barriers are currently unable to cope with reentrant interrupts, e.g., because they store some state in the scratch SPR which would be clobbered even by masked interrupts. For now the interrupts-enabled exits are disabled when these flushes are used. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> [mpe: Guard unused exit_must_hard_disable() as reported by lkp] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20210617155116.2167984-13-npiggin@gmail.com
Diffstat (limited to 'arch/powerpc/include/asm/paca.h')
-rw-r--r--arch/powerpc/include/asm/paca.h3
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h
index f5f0f3408047..dc05a862e72a 100644
--- a/arch/powerpc/include/asm/paca.h
+++ b/arch/powerpc/include/asm/paca.h
@@ -165,6 +165,9 @@ struct paca_struct {
u64 kstack; /* Saved Kernel stack addr */
u64 saved_r1; /* r1 save for RTAS calls or PM or EE=0 */
u64 saved_msr; /* MSR saved here by enter_rtas */
+#ifdef CONFIG_PPC64
+ u64 exit_save_r1; /* Syscall/interrupt R1 save */
+#endif
#ifdef CONFIG_PPC_BOOK3E
u16 trap_save; /* Used when bad stack is encountered */
#endif