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powerpc/64e: provide an addressing macro for use with TOC in alternate register

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The interrupt entry code carefully saves a minimal number of registers,
so in some places the TOC is required, it is loaded into a different
register, so provide a macro that can supply an alternate TOC register.

This continues to use got addressing because TOC-relative results in
"got/toc optimization is not supported" messages by the linker. Having
r2 be one of the saved registers and using that for TOC addressing may
be the best way to avoid that and switch this to TOC addressing.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220926034057.2360083-6-npiggin@gmail.com
This commit is contained in:
Nicholas Piggin 2022-09-26 13:40:57 +10:00 • committed by Michael Ellerman
parent 8e93fb33c8
commit 3569d84bb2
3 changed files with 19 additions and 8 deletions
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11
arch/powerpc/include/asm/ppc_asm.h
View file

@ -346,6 +346,17 @@ n:
addis reg,r2,name@toc@ha; \
addi reg,reg,name@toc@l
#ifdef CONFIG_PPC_BOOK3E_64
/*
* This is used in register-constrained interrupt handlers. Not to be used
* by BOOK3S. ld complains with "got/toc optimization is not supported" if r2
* is not used for the TOC offset, so use @got(tocreg). If the interrupt
* handlers saved r2 instead, LOAD_REG_ADDR could be used.
*/
#define LOAD_REG_ADDR_ALTTOC(reg,tocreg,name) \
ld reg,name@got(tocreg)
#endif
#define LOAD_REG_ADDRBASE(reg,name) LOAD_REG_ADDR(reg,name)
#define ADDROFF(name) 0

14
arch/powerpc/kernel/exceptions-64e.S
View file

@ -688,8 +688,8 @@ END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
#ifdef CONFIG_RELOCATABLE
__LOAD_PACA_TOC(r15)
ld r14,interrupt_base_book3e@got(r15)
ld r15,__end_interrupts@got(r15)
LOAD_REG_ADDR_ALTTOC(r14, r15, interrupt_base_book3e)
LOAD_REG_ADDR_ALTTOC(r15, r15, __end_interrupts)
cmpld cr0,r10,r14
cmpld cr1,r10,r15
#else
@ -759,8 +759,8 @@ kernel_dbg_exc:
#ifdef CONFIG_RELOCATABLE
__LOAD_PACA_TOC(r15)
ld r14,interrupt_base_book3e@got(r15)
ld r15,__end_interrupts@got(r15)
LOAD_REG_ADDR_ALTTOC(r14, r15, interrupt_base_book3e)
LOAD_REG_ADDR_ALTTOC(r15, r15, __end_interrupts)
cmpld cr0,r10,r14
cmpld cr1,r10,r15
#else
@ -884,8 +884,8 @@ kernel_dbg_exc:
.macro SEARCH_RESTART_TABLE
#ifdef CONFIG_RELOCATABLE
__LOAD_PACA_TOC(r11)
ld r14,__start___restart_table@got(r11)
ld r15,__stop___restart_table@got(r11)
LOAD_REG_ADDR_ALTTOC(r14, r11, __start___restart_table)
LOAD_REG_ADDR_ALTTOC(r15, r11, __stop___restart_table)
#else
LOAD_REG_IMMEDIATE_SYM(r14, r11, __start___restart_table)
LOAD_REG_IMMEDIATE_SYM(r15, r11, __stop___restart_table)
@ -1303,7 +1303,7 @@ a2_tlbinit_after_linear_map:
/* Now we branch the new virtual address mapped by this entry */
#ifdef CONFIG_RELOCATABLE
__LOAD_PACA_TOC(r5)
ld r3,1f@got(r5)
LOAD_REG_ADDR_ALTTOC(r3, r5, 1f)
#else
LOAD_REG_IMMEDIATE_SYM(r3, r5, 1f)
#endif

2
arch/powerpc/mm/nohash/tlb_low_64e.S
View file

@ -1119,7 +1119,7 @@ tlb_load_linear:
* final implementation, especially when dealing with hypervisors
*/
__LOAD_PACA_TOC(r11)
ld r11,linear_map_top@got(r11)
LOAD_REG_ADDR_ALTTOC(r11, r11, linear_map_top)
ld r10,0(r11)
tovirt(10,10)
cmpld cr0,r16,r10