diff options
| -rw-r--r-- | arch/powerpc/include/asm/ppc-opcode.h | 8 | ||||
| -rw-r--r-- | arch/powerpc/kernel/entry_64.S | 9 | ||||
| -rw-r--r-- | arch/powerpc/kernel/process.c | 27 |
3 files changed, 30 insertions, 14 deletions
diff --git a/arch/powerpc/include/asm/ppc-opcode.h b/arch/powerpc/include/asm/ppc-opcode.h index 3a8d278e7421..3b6bbf5a8683 100644 --- a/arch/powerpc/include/asm/ppc-opcode.h +++ b/arch/powerpc/include/asm/ppc-opcode.h @@ -189,8 +189,7 @@ /* sorted alphabetically */ #define PPC_INST_BHRBE 0x7c00025c #define PPC_INST_CLRBHRB 0x7c00035c -#define PPC_INST_COPY 0x7c00060c -#define PPC_INST_COPY_FIRST 0x7c20060c +#define PPC_INST_COPY 0x7c20060c #define PPC_INST_CP_ABORT 0x7c00068c #define PPC_INST_DCBA 0x7c0005ec #define PPC_INST_DCBA_MASK 0xfc0007fe @@ -223,8 +222,7 @@ #define PPC_INST_MSGSNDP 0x7c00011c #define PPC_INST_MTTMR 0x7c0003dc #define PPC_INST_NOP 0x60000000 -#define PPC_INST_PASTE 0x7c00070c -#define PPC_INST_PASTE_LAST 0x7c20070d +#define PPC_INST_PASTE 0x7c20070d #define PPC_INST_POPCNTB 0x7c0000f4 #define PPC_INST_POPCNTB_MASK 0xfc0007fe #define PPC_INST_POPCNTD 0x7c0003f4 @@ -392,6 +390,8 @@ /* Deal with instructions that older assemblers aren't aware of */ #define PPC_CP_ABORT stringify_in_c(.long PPC_INST_CP_ABORT) +#define PPC_COPY(a, b) stringify_in_c(.long PPC_INST_COPY | \ + ___PPC_RA(a) | ___PPC_RB(b)) #define PPC_DCBAL(a, b) stringify_in_c(.long PPC_INST_DCBAL | \ __PPC_RA(a) | __PPC_RB(b)) #define PPC_DCBZL(a, b) stringify_in_c(.long PPC_INST_DCBZL | \ diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index fb143859cc68..da9486e2fd89 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -536,15 +536,6 @@ _GLOBAL(_switch) * which contains larx/stcx, which will clear any reservation * of the task being switched. */ - -BEGIN_FTR_SECTION -/* - * A cp_abort (copy paste abort) here ensures that when context switching, a - * copy from one process can't leak into the paste of another. - */ - PPC_CP_ABORT -END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300) - #ifdef CONFIG_PPC_BOOK3S /* Cancel all explict user streams as they will have no use after context * switch and will stop the HW from creating streams itself diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c index 45faa9a32a01..6273b5d5baec 100644 --- a/arch/powerpc/kernel/process.c +++ b/arch/powerpc/kernel/process.c @@ -1137,6 +1137,11 @@ static inline void restore_sprs(struct thread_struct *old_thread, #endif } +#ifdef CONFIG_PPC_BOOK3S_64 +#define CP_SIZE 128 +static const u8 dummy_copy_buffer[CP_SIZE] __attribute__((aligned(CP_SIZE))); +#endif + struct task_struct *__switch_to(struct task_struct *prev, struct task_struct *new) { @@ -1226,8 +1231,28 @@ struct task_struct *__switch_to(struct task_struct *prev, batch->active = 1; } - if (current_thread_info()->task->thread.regs) + if (current_thread_info()->task->thread.regs) { restore_math(current_thread_info()->task->thread.regs); + + /* + * The copy-paste buffer can only store into foreign real + * addresses, so unprivileged processes can not see the + * data or use it in any way unless they have foreign real + * mappings. We don't have a VAS driver that allocates those + * yet, so no cpabort is required. + */ + if (cpu_has_feature(CPU_FTR_POWER9_DD1)) { + /* + * DD1 allows paste into normal system memory, so we + * do an unpaired copy here to clear the buffer and + * prevent a covert channel being set up. + * + * cpabort is not used because it is quite expensive. + */ + asm volatile(PPC_COPY(%0, %1) + : : "r"(dummy_copy_buffer), "r"(0)); + } + } #endif /* CONFIG_PPC_STD_MMU_64 */ return last; |