From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Anton Blanchard To: Benjamin Herrenschmidt , Paul Mackerras Subject: [PATCH 11/39] powerpc: endian safe trampoline Date: Mon, 23 Sep 2013 12:04:45 +1000 Message-Id: <1379901913-5945-12-git-send-email-anton@samba.org> In-Reply-To: <1379901913-5945-1-git-send-email-anton@samba.org> References: <1379901913-5945-1-git-send-email-anton@samba.org> Cc: linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Benjamin Herrenschmidt Create a trampoline that works in either endian and flips to the expected endian. Use it for primary and secondary thread entry as well as RTAS and OF call return. Signed-off-by: Benjamin Herrenschmidt Signed-off-by: Anton Blanchard --- arch/powerpc/include/asm/ppc_asm.h | 31 ++++++++++++++++++++++++++++++- arch/powerpc/kernel/entry_64.S | 36 ++++++++++++++++++++---------------- arch/powerpc/kernel/head_64.S | 3 +++ 3 files changed, 53 insertions(+), 17 deletions(-) diff --git a/arch/powerpc/include/asm/ppc_asm.h b/arch/powerpc/include/asm/ppc_asm.h index 0c51fb4..ce05bba 100644 --- a/arch/powerpc/include/asm/ppc_asm.h +++ b/arch/powerpc/include/asm/ppc_asm.h @@ -845,6 +845,35 @@ END_FTR_SECTION_NESTED(CPU_FTR_HAS_PPR,CPU_FTR_HAS_PPR,946) #define N_SLINE 68 #define N_SO 100 -#endif /* __ASSEMBLY__ */ +/* + * Create an endian fixup trampoline + * + * This starts with a "tdi 0,0,0x48" instruction which is + * essentially a "trap never", and thus akin to a nop. + * + * The opcode for this instruction read with the wrong endian + * however results in a b . + 8 + * + * So essentially we use that trick to execute the following + * trampoline in "reverse endian" if we are running with the + * MSR_LE bit set the "wrong" way for whatever endianness the + * kernel is built for. + */ +#ifdef CONFIG_PPC_BOOK3E +#define FIXUP_ENDIAN +#else +#define FIXUP_ENDIAN \ + tdi 0,0,0x48; /* Reverse endian of b . + 8 */ \ + b $+36; /* Skip trampoline if endian is good */ \ + .long 0x05009f42; /* bcl 20,31,$+4 */ \ + .long 0xa602487d; /* mflr r10 */ \ + .long 0x1c004a39; /* addi r10,r10,28 */ \ + .long 0xa600607d; /* mfmsr r11 */ \ + .long 0x01006b69; /* xori r11,r11,1 */ \ + .long 0xa6035a7d; /* mtsrr0 r10 */ \ + .long 0xa6037b7d; /* mtsrr1 r11 */ \ + .long 0x2400004c /* rfid */ +#endif /* !CONFIG_PPC_BOOK3E */ +#endif /* __ASSEMBLY__ */ #endif /* _ASM_POWERPC_PPC_ASM_H */ diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index c04cdf7..889ea2b 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -1017,7 +1017,7 @@ _GLOBAL(enter_rtas) li r9,1 rldicr r9,r9,MSR_SF_LG,(63-MSR_SF_LG) - ori r9,r9,MSR_IR|MSR_DR|MSR_FE0|MSR_FE1|MSR_FP|MSR_RI + ori r9,r9,MSR_IR|MSR_DR|MSR_FE0|MSR_FE1|MSR_FP|MSR_RI|MSR_LE andc r6,r0,r9 sync /* disable interrupts so SRR0/1 */ mtmsrd r0 /* don't get trashed */ @@ -1032,6 +1032,8 @@ _GLOBAL(enter_rtas) b . /* prevent speculative execution */ _STATIC(rtas_return_loc) + FIXUP_ENDIAN + /* relocation is off at this point */ GET_PACA(r4) clrldi r4,r4,2 /* convert to realmode address */ @@ -1103,28 +1105,30 @@ _GLOBAL(enter_prom) std r10,_CCR(r1) std r11,_MSR(r1) - /* Get the PROM entrypoint */ - mtlr r4 + /* Put PROM address in SRR0 */ + mtsrr0 r4 + + /* Setup our trampoline return addr in LR */ + bcl 20,31,$+4 +0: mflr r4 + addi r4,r4,(1f - 0b) + mtlr r4 - /* Switch MSR to 32 bits mode + /* Prepare a 32-bit mode big endian MSR */ #ifdef CONFIG_PPC_BOOK3E rlwinm r11,r11,0,1,31 - mtmsr r11 + mtsrr1 r11 + rfi #else /* CONFIG_PPC_BOOK3E */ - mfmsr r11 - li r12,1 - rldicr r12,r12,MSR_SF_LG,(63-MSR_SF_LG) - andc r11,r11,r12 - li r12,1 - rldicr r12,r12,MSR_ISF_LG,(63-MSR_ISF_LG) - andc r11,r11,r12 - mtmsrd r11 + LOAD_REG_IMMEDIATE(r12, MSR_SF | MSR_ISF | MSR_LE) + andc r11,r11,r12 + mtsrr1 r11 + rfid #endif /* CONFIG_PPC_BOOK3E */ - isync - /* Enter PROM here... */ - blrl +1: /* Return from OF */ + FIXUP_ENDIAN /* Just make sure that r1 top 32 bits didn't get * corrupt by OF diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S index 3d11d80..2ae41ab 100644 --- a/arch/powerpc/kernel/head_64.S +++ b/arch/powerpc/kernel/head_64.S @@ -68,6 +68,7 @@ _stext: _GLOBAL(__start) /* NOP this out unconditionally */ BEGIN_FTR_SECTION + FIXUP_ENDIAN b .__start_initialization_multiplatform END_FTR_SECTION(0, 1) @@ -115,6 +116,7 @@ __run_at_load: */ .globl __secondary_hold __secondary_hold: + FIXUP_ENDIAN #ifndef CONFIG_PPC_BOOK3E mfmsr r24 ori r24,r24,MSR_RI @@ -205,6 +207,7 @@ _GLOBAL(generic_secondary_thread_init) * as SCOM before entry). */ _GLOBAL(generic_secondary_smp_init) + FIXUP_ENDIAN mr r24,r3 mr r25,r4 -- 1.8.1.2