From f23699c93becd746295aaa506537882a46a62219 Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Fri, 18 Jun 2021 01:51:08 +1000 Subject: powerpc/64: allow alternate return locations for soft-masked interrupts 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 --- arch/powerpc/include/asm/interrupt.h | 13 ++++++++++++ arch/powerpc/include/asm/ppc_asm.h | 8 +++++++ arch/powerpc/kernel/exceptions-64e.S | 37 ++++++++++++++++++++++++++++++-- arch/powerpc/kernel/exceptions-64s.S | 41 ++++++++++++++++++++++++++++++++++++ arch/powerpc/kernel/vmlinux.lds.S | 10 +++++++++ arch/powerpc/lib/Makefile | 2 +- arch/powerpc/lib/restart_table.c | 30 ++++++++++++++++++++++++++ 7 files changed, 138 insertions(+), 3 deletions(-) create mode 100644 arch/powerpc/lib/restart_table.c (limited to 'arch/powerpc') diff --git a/arch/powerpc/include/asm/interrupt.h b/arch/powerpc/include/asm/interrupt.h index de36fb5d9c51..a4bf6c0013bb 100644 --- a/arch/powerpc/include/asm/interrupt.h +++ b/arch/powerpc/include/asm/interrupt.h @@ -73,6 +73,11 @@ #include #include +#ifdef CONFIG_PPC64 +extern char __end_soft_masked[]; +unsigned long search_kernel_restart_table(unsigned long addr); +#endif + #ifdef CONFIG_PPC_BOOK3S_64 static inline void srr_regs_clobbered(void) { @@ -269,6 +274,14 @@ static inline void interrupt_nmi_exit_prepare(struct pt_regs *regs, struct inter * new work to do (must use irq_work for that). */ +#ifdef CONFIG_PPC64 + if (arch_irq_disabled_regs(regs)) { + unsigned long rst = search_kernel_restart_table(regs->nip); + if (rst) + regs_set_return_ip(regs, rst); + } +#endif + #ifdef CONFIG_PPC64 if (nmi_disables_ftrace(regs)) this_cpu_set_ftrace_enabled(state->ftrace_enabled); diff --git a/arch/powerpc/include/asm/ppc_asm.h b/arch/powerpc/include/asm/ppc_asm.h index d6739d700f0a..c9c2c36c1f8f 100644 --- a/arch/powerpc/include/asm/ppc_asm.h +++ b/arch/powerpc/include/asm/ppc_asm.h @@ -762,6 +762,14 @@ END_FTR_SECTION_NESTED(CPU_FTR_CELL_TB_BUG, CPU_FTR_CELL_TB_BUG, 96) stringify_in_c(.long (_target) - . ;) \ stringify_in_c(.previous) +#define RESTART_TABLE(_start, _end, _target) \ + stringify_in_c(.section __restart_table,"a";)\ + stringify_in_c(.balign 8;) \ + stringify_in_c(.llong (_start);) \ + stringify_in_c(.llong (_end);) \ + stringify_in_c(.llong (_target);) \ + stringify_in_c(.previous) + #ifdef CONFIG_PPC_FSL_BOOK3E #define BTB_FLUSH(reg) \ lis reg,BUCSR_INIT@h; \ diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S index b35c97c7082f..1b79f8a75298 100644 --- a/arch/powerpc/kernel/exceptions-64e.S +++ b/arch/powerpc/kernel/exceptions-64e.S @@ -901,6 +901,28 @@ kernel_dbg_exc: bl unknown_exception b interrupt_return +.macro SEARCH_RESTART_TABLE + LOAD_REG_IMMEDIATE_SYM(r14, r11, __start___restart_table) + LOAD_REG_IMMEDIATE_SYM(r15, r11, __stop___restart_table) +300: + cmpd r14,r15 + beq 302f + ld r11,0(r14) + cmpld r10,r11 + blt 301f + ld r11,8(r14) + cmpld r10,r11 + bge 301f + ld r11,16(r14) + b 303f +301: + addi r14,r14,24 + b 300b +302: + li r11,0 +303: +.endm + /* * An interrupt came in while soft-disabled; We mark paca->irq_happened * accordingly and if the interrupt is level sensitive, we hard disable @@ -909,6 +931,9 @@ kernel_dbg_exc: */ .macro masked_interrupt_book3e paca_irq full_mask + std r14,PACA_EXGEN+EX_R14(r13) + std r15,PACA_EXGEN+EX_R15(r13) + lbz r10,PACAIRQHAPPENED(r13) .if \full_mask == 1 ori r10,r10,\paca_irq | PACA_IRQ_HARD_DIS @@ -918,15 +943,23 @@ kernel_dbg_exc: stb r10,PACAIRQHAPPENED(r13) .if \full_mask == 1 - rldicl r10,r11,48,1 /* clear MSR_EE */ - rotldi r11,r10,16 + xori r11,r11,MSR_EE /* clear MSR_EE */ mtspr SPRN_SRR1,r11 .endif + mfspr r10,SPRN_SRR0 + SEARCH_RESTART_TABLE + cmpdi r11,0 + beq 1f + mtspr SPRN_SRR0,r11 /* return to restart address */ +1: + lwz r11,PACA_EXGEN+EX_CR(r13) mtcr r11 ld r10,PACA_EXGEN+EX_R10(r13) ld r11,PACA_EXGEN+EX_R11(r13) + ld r14,PACA_EXGEN+EX_R14(r13) + ld r15,PACA_EXGEN+EX_R15(r13) mfspr r13,SPRN_SPRG_GEN_SCRATCH rfi b . diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index ee4283d014a4..b8ed1ce8c347 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -591,6 +591,36 @@ END_FTR_SECTION_IFSET(CPU_FTR_CFAR) __GEN_COMMON_BODY \name .endm +.macro SEARCH_RESTART_TABLE +#ifdef CONFIG_RELOCATABLE + mr r12,r2 + ld r2,PACATOC(r13) + LOAD_REG_ADDR(r9, __start___restart_table) + LOAD_REG_ADDR(r10, __stop___restart_table) + mr r2,r12 +#else + LOAD_REG_IMMEDIATE_SYM(r9, r12, __start___restart_table) + LOAD_REG_IMMEDIATE_SYM(r10, r12, __stop___restart_table) +#endif +300: + cmpd r9,r10 + beq 302f + ld r12,0(r9) + cmpld r11,r12 + blt 301f + ld r12,8(r9) + cmpld r11,r12 + bge 301f + ld r12,16(r9) + b 303f +301: + addi r9,r9,24 + b 300b +302: + li r12,0 +303: +.endm + /* * Restore all registers including H/SRR0/1 saved in a stack frame of a * standard exception. @@ -2646,6 +2676,7 @@ EXC_COMMON_BEGIN(soft_nmi_common) mtmsrd r9,1 kuap_kernel_restore r9, r10 + EXCEPTION_RESTORE_REGS hsrr=0 RFI_TO_KERNEL @@ -2703,6 +2734,16 @@ masked_interrupt: stb r9,PACASRR_VALID(r13) .endif + SEARCH_RESTART_TABLE + cmpdi r12,0 + beq 3f + .if \hsrr + mtspr SPRN_HSRR0,r12 + .else + mtspr SPRN_SRR0,r12 + .endif +3: + ld r9,PACA_EXGEN+EX_CTR(r13) mtctr r9 lwz r9,PACA_EXGEN+EX_CCR(r13) diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S index 72fa3c00229a..16c5e13e00c4 100644 --- a/arch/powerpc/kernel/vmlinux.lds.S +++ b/arch/powerpc/kernel/vmlinux.lds.S @@ -9,6 +9,14 @@ #define EMITS_PT_NOTE #define RO_EXCEPTION_TABLE_ALIGN 0 +#define RESTART_TABLE(align) \ + . = ALIGN(align); \ + __restart_table : AT(ADDR(__restart_table) - LOAD_OFFSET) { \ + __start___restart_table = .; \ + KEEP(*(__restart_table)) \ + __stop___restart_table = .; \ + } + #include #include #include @@ -124,6 +132,8 @@ SECTIONS RO_DATA(PAGE_SIZE) #ifdef CONFIG_PPC64 + RESTART_TABLE(8) + . = ALIGN(8); __stf_entry_barrier_fixup : AT(ADDR(__stf_entry_barrier_fixup) - LOAD_OFFSET) { __start___stf_entry_barrier_fixup = .; diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile index cc1a8a0f311e..4c92c80454f3 100644 --- a/arch/powerpc/lib/Makefile +++ b/arch/powerpc/lib/Makefile @@ -42,7 +42,7 @@ obj-$(CONFIG_PPC_BOOK3S_64) += copyuser_power7.o copypage_power7.o \ memcpy_power7.o obj64-y += copypage_64.o copyuser_64.o mem_64.o hweight_64.o \ - memcpy_64.o copy_mc_64.o + memcpy_64.o copy_mc_64.o restart_table.o ifndef CONFIG_PPC_QUEUED_SPINLOCKS obj64-$(CONFIG_SMP) += locks.o diff --git a/arch/powerpc/lib/restart_table.c b/arch/powerpc/lib/restart_table.c new file mode 100644 index 000000000000..7cd20757cc33 --- /dev/null +++ b/arch/powerpc/lib/restart_table.c @@ -0,0 +1,30 @@ +#include +#include + +struct restart_table_entry { + unsigned long start; + unsigned long end; + unsigned long fixup; +}; + +extern struct restart_table_entry __start___restart_table[]; +extern struct restart_table_entry __stop___restart_table[]; + +/* Given an address, look for it in the kernel exception table */ +unsigned long search_kernel_restart_table(unsigned long addr) +{ + struct restart_table_entry *rte = __start___restart_table; + + while (rte < __stop___restart_table) { + unsigned long start = rte->start; + unsigned long end = rte->end; + unsigned long fixup = rte->fixup; + + if (addr >= start && addr < end) + return fixup; + + rte++; + } + return 0; +} +NOKPROBE_SYMBOL(search_kernel_restart_table); -- cgit v1.2.3-59-g8ed1b