diff options
Diffstat (limited to 'arch/powerpc/kernel/rtas_entry.S')
| -rw-r--r-- | arch/powerpc/kernel/rtas_entry.S | 172 |
1 files changed, 172 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/rtas_entry.S b/arch/powerpc/kernel/rtas_entry.S new file mode 100644 index 000000000000..9a434d42e660 --- /dev/null +++ b/arch/powerpc/kernel/rtas_entry.S @@ -0,0 +1,172 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ + +#include <asm/asm-offsets.h> +#include <asm/bug.h> +#include <asm/page.h> +#include <asm/ppc_asm.h> + +/* + * RTAS is called with MSR IR, DR, EE disabled, and LR in the return address. + * + * Note: r3 is an input parameter to rtas, so don't trash it... + */ + +#ifdef CONFIG_PPC32 +_GLOBAL(enter_rtas) + stwu r1,-INT_FRAME_SIZE(r1) + mflr r0 + stw r0,INT_FRAME_SIZE+4(r1) + LOAD_REG_ADDR(r4, rtas) + lis r6,1f@ha /* physical return address for rtas */ + addi r6,r6,1f@l + tophys(r6,r6) + lwz r8,RTASENTRY(r4) + lwz r4,RTASBASE(r4) + mfmsr r9 + stw r9,8(r1) + li r9,MSR_KERNEL & ~(MSR_IR|MSR_DR) + mtlr r6 + stw r1, THREAD + RTAS_SP(r2) + mtspr SPRN_SRR0,r8 + mtspr SPRN_SRR1,r9 + rfi +1: + lis r8, 1f@h + ori r8, r8, 1f@l + LOAD_REG_IMMEDIATE(r9,MSR_KERNEL) + mtspr SPRN_SRR0,r8 + mtspr SPRN_SRR1,r9 + rfi /* Reactivate MMU translation */ +1: + lwz r8,INT_FRAME_SIZE+4(r1) /* get return address */ + lwz r9,8(r1) /* original msr value */ + addi r1,r1,INT_FRAME_SIZE + li r0,0 + stw r0, THREAD + RTAS_SP(r2) + mtlr r8 + mtmsr r9 + blr /* return to caller */ +_ASM_NOKPROBE_SYMBOL(enter_rtas) + +#else /* CONFIG_PPC32 */ +#include <asm/exception-64s.h> + +/* + * 32-bit rtas on 64-bit machines has the additional problem that RTAS may + * not preserve the upper parts of registers it uses. + */ +_GLOBAL(enter_rtas) + mflr r0 + std r0,16(r1) + stdu r1,-SWITCH_FRAME_SIZE(r1) /* Save SP and create stack space. */ + + /* Because RTAS is running in 32b mode, it clobbers the high order half + * of all registers that it saves. We therefore save those registers + * RTAS might touch to the stack. (r0, r3-r12 are caller saved) + */ + SAVE_GPR(2, r1) /* Save the TOC */ + SAVE_NVGPRS(r1) /* Save the non-volatiles */ + + mfcr r4 + std r4,_CCR(r1) + mfctr r5 + std r5,_CTR(r1) + mfspr r6,SPRN_XER + std r6,_XER(r1) + mfdar r7 + std r7,_DAR(r1) + mfdsisr r8 + std r8,_DSISR(r1) + + /* Temporary workaround to clear CR until RTAS can be modified to + * ignore all bits. + */ + li r0,0 + mtcr r0 + + mfmsr r6 + + /* Unfortunately, the stack pointer and the MSR are also clobbered, + * so they are saved in the PACA which allows us to restore + * our original state after RTAS returns. + */ + std r1,PACAR1(r13) + std r6,PACASAVEDMSR(r13) + + /* Setup our real return addr */ + LOAD_REG_ADDR(r4,rtas_return_loc) + clrldi r4,r4,2 /* convert to realmode address */ + mtlr r4 + +__enter_rtas: + LOAD_REG_ADDR(r4, rtas) + ld r5,RTASENTRY(r4) /* get the rtas->entry value */ + ld r4,RTASBASE(r4) /* get the rtas->base value */ + + /* + * RTAS runs in 32-bit big endian real mode, but leave MSR[RI] on as we + * may hit NMI (SRESET or MCE) while in RTAS. RTAS should disable RI in + * its critical regions (as specified in PAPR+ section 7.2.1). MSR[S] + * is not impacted by RFI_TO_KERNEL (only urfid can unset it). So if + * MSR[S] is set, it will remain when entering RTAS. + */ + LOAD_REG_IMMEDIATE(r6, MSR_ME | MSR_RI) + + li r0,0 + mtmsrd r0,1 /* disable RI before using SRR0/1 */ + + mtspr SPRN_SRR0,r5 + mtspr SPRN_SRR1,r6 + RFI_TO_KERNEL + b . /* prevent speculative execution */ +rtas_return_loc: + FIXUP_ENDIAN + + /* Set SF before anything. */ + LOAD_REG_IMMEDIATE(r6, MSR_KERNEL & ~(MSR_IR|MSR_DR)) + mtmsrd r6 + + /* relocation is off at this point */ + GET_PACA(r13) + + bcl 20,31,$+4 +0: mflr r3 + ld r3,(1f-0b)(r3) /* get &rtas_restore_regs */ + + ld r1,PACAR1(r13) /* Restore our SP */ + ld r4,PACASAVEDMSR(r13) /* Restore our MSR */ + + mtspr SPRN_SRR0,r3 + mtspr SPRN_SRR1,r4 + RFI_TO_KERNEL + b . /* prevent speculative execution */ +_ASM_NOKPROBE_SYMBOL(enter_rtas) +_ASM_NOKPROBE_SYMBOL(__enter_rtas) +_ASM_NOKPROBE_SYMBOL(rtas_return_loc) + + .align 3 +1: .8byte rtas_restore_regs + +rtas_restore_regs: + /* relocation is on at this point */ + REST_GPR(2, r1) /* Restore the TOC */ + REST_NVGPRS(r1) /* Restore the non-volatiles */ + + ld r4,_CCR(r1) + mtcr r4 + ld r5,_CTR(r1) + mtctr r5 + ld r6,_XER(r1) + mtspr SPRN_XER,r6 + ld r7,_DAR(r1) + mtdar r7 + ld r8,_DSISR(r1) + mtdsisr r8 + + addi r1,r1,SWITCH_FRAME_SIZE /* Unstack our frame */ + ld r0,16(r1) /* get return address */ + + mtlr r0 + blr /* return to caller */ + +#endif /* CONFIG_PPC32 */ |