From 57f266497d81e16141bd2c9009e91dad34ea5f70 Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Wed, 28 Sep 2016 11:31:48 +1000 Subject: powerpc: Use gas sections for arranging exception vectors Use assembler sections of fixed size and location to arrange the 64-bit Book3S exception vector code (64-bit Book3E also uses it in head_64.S for 0x0..0x100). This allows better flexibility in arranging exception code and hiding unimportant details behind macros. Gas sections can be a bit painful to use this way, mainly because the assembler does not know where they will be finally linked. Taking absolute addresses requires a bit of trickery for example, but it can be hidden behind macros for the most part. Generated code is mostly the same except locations, offsets, alignments. The "+ 0x2" is only required for the trap number / kvm exit number, which gets loaded as a constant into a register. Previously, code also used + 0x2 for label names, but we changed to using "H" to distinguish HV case for that. Remove the last vestiges of that. __after_prom_start is taking absolute address of a label in another fixed section. Newer toolchains seemed to compile this okay, but older ones do not. FIXED_SYMBOL_ABS_ADDR is more foolproof, it just takes an additional line to define. Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman --- arch/powerpc/kernel/head_64.S | 44 ++++++++++++++++++++++++++++--------------- 1 file changed, 29 insertions(+), 15 deletions(-) (limited to 'arch/powerpc/kernel/head_64.S') diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S index 6e21812ee672..79da0641bae2 100644 --- a/arch/powerpc/kernel/head_64.S +++ b/arch/powerpc/kernel/head_64.S @@ -28,6 +28,7 @@ #include #include #include +#include #include #include #include @@ -65,9 +66,14 @@ * 2. The kernel is entered at __start */ - .text - .globl _stext -_stext: +OPEN_FIXED_SECTION(first_256B, 0x0, 0x100) +USE_FIXED_SECTION(first_256B) + /* + * Offsets are relative from the start of fixed section, and + * first_256B starts at 0. Offsets are a bit easier to use here + * than the fixed section entry macros. + */ + . = 0x0 _GLOBAL(__start) /* NOP this out unconditionally */ BEGIN_FTR_SECTION @@ -104,6 +110,7 @@ __secondary_hold_acknowledge: . = 0x5c .globl __run_at_load __run_at_load: +DEFINE_FIXED_SYMBOL(__run_at_load) .long 0x72756e30 /* "run0" -- relocate to 0 by default */ #endif @@ -133,7 +140,7 @@ __secondary_hold: /* Tell the master cpu we're here */ /* Relocation is off & we are located at an address less */ /* than 0x100, so only need to grab low order offset. */ - std r24,__secondary_hold_acknowledge-_stext(0) + std r24,(ABS_ADDR(__secondary_hold_acknowledge))(0) sync li r26,0 @@ -141,7 +148,7 @@ __secondary_hold: tovirt(r26,r26) #endif /* All secondary cpus wait here until told to start. */ -100: ld r12,__secondary_hold_spinloop-_stext(r26) +100: ld r12,(ABS_ADDR(__secondary_hold_spinloop))(r26) cmpdi 0,r12,0 beq 100b @@ -166,12 +173,13 @@ __secondary_hold: #else BUG_OPCODE #endif +CLOSE_FIXED_SECTION(first_256B) /* This value is used to mark exception frames on the stack. */ .section ".toc","aw" exception_marker: .tc ID_72656773_68657265[TC],0x7265677368657265 - .text + .previous /* * On server, we include the exception vectors code here as it @@ -180,8 +188,12 @@ exception_marker: */ #ifdef CONFIG_PPC_BOOK3S #include "exceptions-64s.S" +#else +OPEN_TEXT_SECTION(0x100) #endif +USE_TEXT_SECTION() + #ifdef CONFIG_PPC_BOOK3E /* * The booting_thread_hwid holds the thread id we want to boot in cpu @@ -558,7 +570,7 @@ __after_prom_start: #if defined(CONFIG_PPC_BOOK3E) tovirt(r26,r26) /* on booke, we already run at PAGE_OFFSET */ #endif - lwz r7,__run_at_load-_stext(r26) + lwz r7,(FIXED_SYMBOL_ABS_ADDR(__run_at_load))(r26) #if defined(CONFIG_PPC_BOOK3E) tophys(r26,r26) #endif @@ -601,7 +613,7 @@ __after_prom_start: #if defined(CONFIG_PPC_BOOK3E) tovirt(r26,r26) /* on booke, we already run at PAGE_OFFSET */ #endif - lwz r7,__run_at_load-_stext(r26) + lwz r7,(FIXED_SYMBOL_ABS_ADDR(__run_at_load))(r26) cmplwi cr0,r7,1 bne 3f @@ -611,19 +623,21 @@ __after_prom_start: sub r5,r5,r11 #else /* just copy interrupts */ - LOAD_REG_IMMEDIATE(r5, __end_interrupts - _stext) + LOAD_REG_IMMEDIATE(r5, FIXED_SYMBOL_ABS_ADDR(__end_interrupts)) #endif b 5f 3: #endif - lis r5,(copy_to_here - _stext)@ha - addi r5,r5,(copy_to_here - _stext)@l /* # bytes of memory to copy */ + /* # bytes of memory to copy */ + lis r5,(ABS_ADDR(copy_to_here))@ha + addi r5,r5,(ABS_ADDR(copy_to_here))@l bl copy_and_flush /* copy the first n bytes */ /* this includes the code being */ /* executed here. */ - addis r8,r3,(4f - _stext)@ha /* Jump to the copy of this code */ - addi r12,r8,(4f - _stext)@l /* that we just made */ + /* Jump to the copy of this code that we just made */ + addis r8,r3,(ABS_ADDR(4f))@ha + addi r12,r8,(ABS_ADDR(4f))@l mtctr r12 bctr @@ -635,8 +649,8 @@ p_end: .llong _end - copy_to_here * Now copy the rest of the kernel up to _end, add * _end - copy_to_here to the copy limit and run again. */ - addis r8,r26,(p_end - _stext)@ha - ld r8,(p_end - _stext)@l(r8) + addis r8,r26,(ABS_ADDR(p_end))@ha + ld r8,(ABS_ADDR(p_end))@l(r8) add r5,r5,r8 5: bl copy_and_flush /* copy the rest */ -- cgit v1.2.3-59-g8ed1b