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-rw-r--r--arch/powerpc/kernel/rtas_entry.S176
1 files changed, 176 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/rtas_entry.S b/arch/powerpc/kernel/rtas_entry.S
new file mode 100644
index 000000000..6ce95ddad
--- /dev/null
+++ b/arch/powerpc/kernel/rtas_entry.S
@@ -0,0 +1,176 @@
+/* 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.
+ * If we're in HV mode, RTAS must also run in HV mode, so extract MSR_HV
+ * from the saved MSR value and insert into the value RTAS will use.
+ */
+ extrdi r0, r6, 1, 63 - MSR_HV_LG
+ LOAD_REG_IMMEDIATE(r6, MSR_ME | MSR_RI)
+ insrdi r6, r0, 1, 63 - MSR_HV_LG
+
+ 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 */