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powerpc: Use gas sections for arranging exception vectors

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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 <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Nicholas Piggin
2016-09-28 11:31:48 +10:00
committed by Michael Ellerman
parent 573819e343
commit 57f266497d
5 changed files with 405 additions and 68 deletions
Download Patch File Download Diff File Expand all files Collapse all files

111
arch/powerpc/kernel/exceptions-64s.S
View File

@@ -19,16 +19,68 @@
#include <asm/head-64.h>
/*
* There are a few constraints to be concerned with.
* - Real mode exceptions code/data must be located at their physical location.
* - Virtual mode exceptions must be mapped at their 0xc000... location.
* - Fixed location code must not call directly beyond the __end_interrupts
* area when built with CONFIG_RELOCATABLE. LOAD_HANDLER / bctr sequence
* must be used.
* - LOAD_HANDLER targets must be within first 64K of physical 0 /
* virtual 0xc00...
* - Conditional branch targets must be within +/-32K of caller.
*
* "Virtual exceptions" run with relocation on (MSR_IR=1, MSR_DR=1), and
* therefore don't have to run in physically located code or rfid to
* virtual mode kernel code. However on relocatable kernels they do have
* to branch to KERNELBASE offset because the rest of the kernel (outside
* the exception vectors) may be located elsewhere.
*
* Virtual exceptions correspond with physical, except their entry points
* are offset by 0xc000000000000000 and also tend to get an added 0x4000
* offset applied. Virtual exceptions are enabled with the Alternate
* Interrupt Location (AIL) bit set in the LPCR. However this does not
* guarantee they will be delivered virtually. Some conditions (see the ISA)
* cause exceptions to be delivered in real mode.
*
* It's impossible to receive interrupts below 0x300 via AIL.
*
* KVM: None of the virtual exceptions are from the guest. Anything that
* escalated to HV=1 from HV=0 is delivered via real mode handlers.
*
*
* We layout physical memory as follows:
* 0x0000 - 0x00ff : Secondary processor spin code
* 0x0100 - 0x17ff : pSeries Interrupt prologs
* 0x1800 - 0x4000 : interrupt support common interrupt prologs
* 0x4000 - 0x5fff : pSeries interrupts with IR=1,DR=1
* 0x6000 - 0x6fff : more interrupt support including for IR=1,DR=1
* 0x0100 - 0x18ff : Real mode pSeries interrupt vectors
* 0x1900 - 0x3fff : Real mode trampolines
* 0x4000 - 0x58ff : Relon (IR=1,DR=1) mode pSeries interrupt vectors
* 0x5900 - 0x6fff : Relon mode trampolines
* 0x7000 - 0x7fff : FWNMI data area
* 0x8000 - 0x8fff : Initial (CPU0) segment table
* 0x9000 - : Early init and support code
* 0x8000 - .... : Common interrupt handlers, remaining early
* setup code, rest of kernel.
*/
OPEN_FIXED_SECTION(real_vectors, 0x0100, 0x1900)
OPEN_FIXED_SECTION(real_trampolines, 0x1900, 0x4000)
OPEN_FIXED_SECTION(virt_vectors, 0x4000, 0x5900)
OPEN_FIXED_SECTION(virt_trampolines, 0x5900, 0x7000)
#if defined(CONFIG_PPC_PSERIES) || defined(CONFIG_PPC_POWERNV)
/*
* Data area reserved for FWNMI option.
* This address (0x7000) is fixed by the RPA.
* pseries and powernv need to keep the whole page from
* 0x7000 to 0x8000 free for use by the firmware
*/
ZERO_FIXED_SECTION(fwnmi_page, 0x7000, 0x8000)
OPEN_TEXT_SECTION(0x8000)
#else
OPEN_TEXT_SECTION(0x7000)
#endif
USE_FIXED_SECTION(real_vectors)
#define LOAD_SYSCALL_HANDLER(reg) \
ld reg,PACAKBASE(r13); \
ori reg,reg,(ABS_ADDR(system_call_common))@l;
/* Syscall routine is used twice, in reloc-off and reloc-on paths */
#define SYSCALL_PSERIES_1 \
BEGIN_FTR_SECTION \
@@ -42,7 +94,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_REAL_LE) \
#define SYSCALL_PSERIES_2_RFID \
mfspr r12,SPRN_SRR1 ; \
LOAD_HANDLER(r10, system_call_common) ; \
LOAD_SYSCALL_HANDLER(r10) ; \
mtspr SPRN_SRR0,r10 ; \
ld r10,PACAKMSR(r13) ; \
mtspr SPRN_SRR1,r10 ; \
@@ -63,7 +115,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_REAL_LE) \
* is volatile across system calls.
*/
#define SYSCALL_PSERIES_2_DIRECT \
LOAD_HANDLER(r12, system_call_common) ; \
LOAD_SYSCALL_HANDLER(r12) ; \
mtctr r12 ; \
mfspr r12,SPRN_SRR1 ; \
li r10,MSR_RI ; \
@@ -86,7 +138,6 @@ END_FTR_SECTION_IFSET(CPU_FTR_REAL_LE) \
* Therefore any relative branches in this section must only
* branch to labels in this section.
*/
. = 0x100
.globl __start_interrupts
__start_interrupts:
@@ -200,9 +251,6 @@ EXC_REAL_BEGIN(instruction_access_slb, 0x480, 0x500)
#endif
EXC_REAL_END(instruction_access_slb, 0x480, 0x500)
/* We open code these as we can't have a ". = x" (even with
* x = "." within a feature section
*/
EXC_REAL_BEGIN(hardware_interrupt, 0x500, 0x600)
.globl hardware_interrupt_hv;
hardware_interrupt_hv:
@@ -306,7 +354,6 @@ __EXC_REAL_OOL_HV(h_facility_unavailable, 0xf80, 0xfa0)
EXC_REAL_NONE(0xfa0, 0x1200)
#ifdef CONFIG_CBE_RAS
EXC_REAL_HV(cbe_system_error, 0x1200, 0x1300)
@@ -359,7 +406,6 @@ TRAMP_KVM_HV_SKIP(PACA_EXGEN, 0x1800)
#else /* CONFIG_CBE_RAS */
EXC_REAL_NONE(0x1800, 0x1900)
. = 0x1800
#endif
@@ -606,7 +652,13 @@ masked_##_H##interrupt: \
GET_SCRATCH0(r13); \
##_H##rfid; \
b .
/*
* Real mode exceptions actually use this too, but alternate
* instruction code patches (which end up in the common .text area)
* cannot reach these if they are put there.
*/
USE_FIXED_SECTION(virt_trampolines)
MASKED_INTERRUPT()
MASKED_INTERRUPT(H)
@@ -620,6 +672,7 @@ masked_##_H##interrupt: \
* in the generated frame has EE set to 1 or the exception
* handler will not properly re-enable them.
*/
USE_TEXT_SECTION()
_GLOBAL(__replay_interrupt)
/* We are going to jump to the exception common code which
* will retrieve various register values from the PACA which
@@ -862,7 +915,7 @@ EXC_VIRT(altivec_assist, 0x5700, 0x5800, 0x1700)
EXC_VIRT_NONE(0x5800, 0x5900)
TRAMP_REAL_BEGIN(ppc64_runlatch_on_trampoline)
EXC_COMMON_BEGIN(ppc64_runlatch_on_trampoline)
b __ppc64_runlatch_on
/*
@@ -1070,6 +1123,7 @@ __TRAMP_REAL_VIRT_OOL(vsx_unavailable, 0xf40)
__TRAMP_REAL_VIRT_OOL(facility_unavailable, 0xf60)
__TRAMP_REAL_VIRT_OOL_HV(h_facility_unavailable, 0xf80)
USE_FIXED_SECTION(virt_trampolines)
/*
* The __end_interrupts marker must be past the out-of-line (OOL)
* handlers, so that they are copied to real address 0x100 when running
@@ -1080,21 +1134,7 @@ __TRAMP_REAL_VIRT_OOL_HV(h_facility_unavailable, 0xf80)
.align 7
.globl __end_interrupts
__end_interrupts:
#if defined(CONFIG_PPC_PSERIES) || defined(CONFIG_PPC_POWERNV)
/*
* Data area reserved for FWNMI option.
* This address (0x7000) is fixed by the RPA.
*/
.= 0x7000
.globl fwnmi_data_area
fwnmi_data_area:
/* pseries and powernv need to keep the whole page from
* 0x7000 to 0x8000 free for use by the firmware
*/
. = 0x8000
#endif /* defined(CONFIG_PPC_PSERIES) || defined(CONFIG_PPC_POWERNV) */
DEFINE_FIXED_SYMBOL(__end_interrupts)
EXC_COMMON(facility_unavailable_common, 0xf60, facility_unavailable_exception)
EXC_COMMON(h_facility_unavailable_common, 0xf80, facility_unavailable_exception)
@@ -1106,7 +1146,7 @@ EXC_COMMON(cbe_thermal_common, 0x1800, cbe_thermal_exception)
#endif /* CONFIG_CBE_RAS */
EXC_COMMON_BEGIN(hmi_exception_early)
TRAMP_REAL_BEGIN(hmi_exception_early)
EXCEPTION_PROLOG_1(PACA_EXGEN, KVMTEST_HV, 0xe60)
mr r10,r1 /* Save r1 */
ld r1,PACAEMERGSP(r13) /* Use emergency stack */
@@ -1430,6 +1470,13 @@ TRAMP_REAL_BEGIN(power4_fixup_nap)
blr
#endif
CLOSE_FIXED_SECTION(real_vectors);
CLOSE_FIXED_SECTION(real_trampolines);
CLOSE_FIXED_SECTION(virt_vectors);
CLOSE_FIXED_SECTION(virt_trampolines);
USE_TEXT_SECTION()
/*
* Hash table stuff
*/