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powerpc: Fix 0 vs. r0 confusion in X/D-form instructions

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Instructions such as dcbi are in the X-form; they have RA and RB fields
and the effective address (EA) is computed as (RA|0)+(RB). In words,
this means that if RA is zero, the left-hand side of the addition is
zero, otherwise the corresponding GPR is used. r0 can never be used on
the left-hand side of a X-form instruction.

For D-form instructions such as addis, the Power ISA illustrates this in
the instruction pseudo-code:

	if RA = 0 then RT <-        EXTS(SI || 0x0000)
	else           RT <- (RA) + EXIS(SI || 0x0000)

In all of these cases, RA=0 indicates the value zero, not register r0.

I verified with gazerbeam_defconfig (MPC83xx) and qemu-ppce500_defconfig
(MPC85xx) that this patch results in the same machine code.

Signed-off-by: J. Neuschäfer <j.ne@posteo.net>
This commit is contained in:
J. Neuschäfer 2024-12-12 18:05:46 +01:00 • committed by Tom Rini
parent e5aef1bbf1
commit fd1c2938c0
3 changed files with 51 additions and 51 deletions
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72
arch/powerpc/cpu/mpc83xx/start.S
View file

@ -550,133 +550,133 @@ init_e300_core: /* time t 10 */
/* setup_bats - set them up to some initial state */ /* setup_bats - set them up to some initial state */
.globl setup_bats .globl setup_bats
setup_bats: setup_bats:
addis r0, r0, 0x0000 addis r0, 0, 0x0000
/* IBAT 0 */ /* IBAT 0 */
addis r4, r0, CFG_SYS_IBAT0L@h addis r4, 0, CFG_SYS_IBAT0L@h
ori r4, r4, CFG_SYS_IBAT0L@l ori r4, r4, CFG_SYS_IBAT0L@l
addis r3, r0, CFG_SYS_IBAT0U@h addis r3, 0, CFG_SYS_IBAT0U@h
ori r3, r3, CFG_SYS_IBAT0U@l ori r3, r3, CFG_SYS_IBAT0U@l
mtspr IBAT0L, r4 mtspr IBAT0L, r4
mtspr IBAT0U, r3 mtspr IBAT0U, r3
/* DBAT 0 */ /* DBAT 0 */
addis r4, r0, CFG_SYS_DBAT0L@h addis r4, 0, CFG_SYS_DBAT0L@h
ori r4, r4, CFG_SYS_DBAT0L@l ori r4, r4, CFG_SYS_DBAT0L@l
addis r3, r0, CFG_SYS_DBAT0U@h addis r3, 0, CFG_SYS_DBAT0U@h
ori r3, r3, CFG_SYS_DBAT0U@l ori r3, r3, CFG_SYS_DBAT0U@l
mtspr DBAT0L, r4 mtspr DBAT0L, r4
mtspr DBAT0U, r3 mtspr DBAT0U, r3
/* IBAT 1 */ /* IBAT 1 */
addis r4, r0, CFG_SYS_IBAT1L@h addis r4, 0, CFG_SYS_IBAT1L@h
ori r4, r4, CFG_SYS_IBAT1L@l ori r4, r4, CFG_SYS_IBAT1L@l
addis r3, r0, CFG_SYS_IBAT1U@h addis r3, 0, CFG_SYS_IBAT1U@h
ori r3, r3, CFG_SYS_IBAT1U@l ori r3, r3, CFG_SYS_IBAT1U@l
mtspr IBAT1L, r4 mtspr IBAT1L, r4
mtspr IBAT1U, r3 mtspr IBAT1U, r3
/* DBAT 1 */ /* DBAT 1 */
addis r4, r0, CFG_SYS_DBAT1L@h addis r4, 0, CFG_SYS_DBAT1L@h
ori r4, r4, CFG_SYS_DBAT1L@l ori r4, r4, CFG_SYS_DBAT1L@l
addis r3, r0, CFG_SYS_DBAT1U@h addis r3, 0, CFG_SYS_DBAT1U@h
ori r3, r3, CFG_SYS_DBAT1U@l ori r3, r3, CFG_SYS_DBAT1U@l
mtspr DBAT1L, r4 mtspr DBAT1L, r4
mtspr DBAT1U, r3 mtspr DBAT1U, r3
/* IBAT 2 */ /* IBAT 2 */
addis r4, r0, CFG_SYS_IBAT2L@h addis r4, 0, CFG_SYS_IBAT2L@h
ori r4, r4, CFG_SYS_IBAT2L@l ori r4, r4, CFG_SYS_IBAT2L@l
addis r3, r0, CFG_SYS_IBAT2U@h addis r3, 0, CFG_SYS_IBAT2U@h
ori r3, r3, CFG_SYS_IBAT2U@l ori r3, r3, CFG_SYS_IBAT2U@l
mtspr IBAT2L, r4 mtspr IBAT2L, r4
mtspr IBAT2U, r3 mtspr IBAT2U, r3
/* DBAT 2 */ /* DBAT 2 */
addis r4, r0, CFG_SYS_DBAT2L@h addis r4, 0, CFG_SYS_DBAT2L@h
ori r4, r4, CFG_SYS_DBAT2L@l ori r4, r4, CFG_SYS_DBAT2L@l
addis r3, r0, CFG_SYS_DBAT2U@h addis r3, 0, CFG_SYS_DBAT2U@h
ori r3, r3, CFG_SYS_DBAT2U@l ori r3, r3, CFG_SYS_DBAT2U@l
mtspr DBAT2L, r4 mtspr DBAT2L, r4
mtspr DBAT2U, r3 mtspr DBAT2U, r3
/* IBAT 3 */ /* IBAT 3 */
addis r4, r0, CFG_SYS_IBAT3L@h addis r4, 0, CFG_SYS_IBAT3L@h
ori r4, r4, CFG_SYS_IBAT3L@l ori r4, r4, CFG_SYS_IBAT3L@l
addis r3, r0, CFG_SYS_IBAT3U@h addis r3, 0, CFG_SYS_IBAT3U@h
ori r3, r3, CFG_SYS_IBAT3U@l ori r3, r3, CFG_SYS_IBAT3U@l
mtspr IBAT3L, r4 mtspr IBAT3L, r4
mtspr IBAT3U, r3 mtspr IBAT3U, r3
/* DBAT 3 */ /* DBAT 3 */
addis r4, r0, CFG_SYS_DBAT3L@h addis r4, 0, CFG_SYS_DBAT3L@h
ori r4, r4, CFG_SYS_DBAT3L@l ori r4, r4, CFG_SYS_DBAT3L@l
addis r3, r0, CFG_SYS_DBAT3U@h addis r3, 0, CFG_SYS_DBAT3U@h
ori r3, r3, CFG_SYS_DBAT3U@l ori r3, r3, CFG_SYS_DBAT3U@l
mtspr DBAT3L, r4 mtspr DBAT3L, r4
mtspr DBAT3U, r3 mtspr DBAT3U, r3
#ifdef CONFIG_HIGH_BATS #ifdef CONFIG_HIGH_BATS
/* IBAT 4 */ /* IBAT 4 */
addis r4, r0, CFG_SYS_IBAT4L@h addis r4, 0, CFG_SYS_IBAT4L@h
ori r4, r4, CFG_SYS_IBAT4L@l ori r4, r4, CFG_SYS_IBAT4L@l
addis r3, r0, CFG_SYS_IBAT4U@h addis r3, 0, CFG_SYS_IBAT4U@h
ori r3, r3, CFG_SYS_IBAT4U@l ori r3, r3, CFG_SYS_IBAT4U@l
mtspr IBAT4L, r4 mtspr IBAT4L, r4
mtspr IBAT4U, r3 mtspr IBAT4U, r3
/* DBAT 4 */ /* DBAT 4 */
addis r4, r0, CFG_SYS_DBAT4L@h addis r4, 0, CFG_SYS_DBAT4L@h
ori r4, r4, CFG_SYS_DBAT4L@l ori r4, r4, CFG_SYS_DBAT4L@l
addis r3, r0, CFG_SYS_DBAT4U@h addis r3, 0, CFG_SYS_DBAT4U@h
ori r3, r3, CFG_SYS_DBAT4U@l ori r3, r3, CFG_SYS_DBAT4U@l
mtspr DBAT4L, r4 mtspr DBAT4L, r4
mtspr DBAT4U, r3 mtspr DBAT4U, r3
/* IBAT 5 */ /* IBAT 5 */
addis r4, r0, CFG_SYS_IBAT5L@h addis r4, 0, CFG_SYS_IBAT5L@h
ori r4, r4, CFG_SYS_IBAT5L@l ori r4, r4, CFG_SYS_IBAT5L@l
addis r3, r0, CFG_SYS_IBAT5U@h addis r3, 0, CFG_SYS_IBAT5U@h
ori r3, r3, CFG_SYS_IBAT5U@l ori r3, r3, CFG_SYS_IBAT5U@l
mtspr IBAT5L, r4 mtspr IBAT5L, r4
mtspr IBAT5U, r3 mtspr IBAT5U, r3
/* DBAT 5 */ /* DBAT 5 */
addis r4, r0, CFG_SYS_DBAT5L@h addis r4, 0, CFG_SYS_DBAT5L@h
ori r4, r4, CFG_SYS_DBAT5L@l ori r4, r4, CFG_SYS_DBAT5L@l
addis r3, r0, CFG_SYS_DBAT5U@h addis r3, 0, CFG_SYS_DBAT5U@h
ori r3, r3, CFG_SYS_DBAT5U@l ori r3, r3, CFG_SYS_DBAT5U@l
mtspr DBAT5L, r4 mtspr DBAT5L, r4
mtspr DBAT5U, r3 mtspr DBAT5U, r3
/* IBAT 6 */ /* IBAT 6 */
addis r4, r0, CFG_SYS_IBAT6L@h addis r4, 0, CFG_SYS_IBAT6L@h
ori r4, r4, CFG_SYS_IBAT6L@l ori r4, r4, CFG_SYS_IBAT6L@l
addis r3, r0, CFG_SYS_IBAT6U@h addis r3, 0, CFG_SYS_IBAT6U@h
ori r3, r3, CFG_SYS_IBAT6U@l ori r3, r3, CFG_SYS_IBAT6U@l
mtspr IBAT6L, r4 mtspr IBAT6L, r4
mtspr IBAT6U, r3 mtspr IBAT6U, r3
/* DBAT 6 */ /* DBAT 6 */
addis r4, r0, CFG_SYS_DBAT6L@h addis r4, 0, CFG_SYS_DBAT6L@h
ori r4, r4, CFG_SYS_DBAT6L@l ori r4, r4, CFG_SYS_DBAT6L@l
addis r3, r0, CFG_SYS_DBAT6U@h addis r3, 0, CFG_SYS_DBAT6U@h
ori r3, r3, CFG_SYS_DBAT6U@l ori r3, r3, CFG_SYS_DBAT6U@l
mtspr DBAT6L, r4 mtspr DBAT6L, r4
mtspr DBAT6U, r3 mtspr DBAT6U, r3
/* IBAT 7 */ /* IBAT 7 */
addis r4, r0, CFG_SYS_IBAT7L@h addis r4, 0, CFG_SYS_IBAT7L@h
ori r4, r4, CFG_SYS_IBAT7L@l ori r4, r4, CFG_SYS_IBAT7L@l
addis r3, r0, CFG_SYS_IBAT7U@h addis r3, 0, CFG_SYS_IBAT7U@h
ori r3, r3, CFG_SYS_IBAT7U@l ori r3, r3, CFG_SYS_IBAT7U@l
mtspr IBAT7L, r4 mtspr IBAT7L, r4
mtspr IBAT7U, r3 mtspr IBAT7U, r3
/* DBAT 7 */ /* DBAT 7 */
addis r4, r0, CFG_SYS_DBAT7L@h addis r4, 0, CFG_SYS_DBAT7L@h
ori r4, r4, CFG_SYS_DBAT7L@l ori r4, r4, CFG_SYS_DBAT7L@l
addis r3, r0, CFG_SYS_DBAT7U@h addis r3, 0, CFG_SYS_DBAT7U@h
ori r3, r3, CFG_SYS_DBAT7U@l ori r3, r3, CFG_SYS_DBAT7U@l
mtspr DBAT7L, r4 mtspr DBAT7L, r4
mtspr DBAT7U, r3 mtspr DBAT7U, r3
@ -1057,7 +1057,7 @@ lock_ram_in_cache:
(CFG_SYS_INIT_RAM_ADDR & 31) + 31) / 32 (CFG_SYS_INIT_RAM_ADDR & 31) + 31) / 32
mtctr r4 mtctr r4
1: 1:
dcbz r0, r3 dcbz 0, r3
addi r3, r3, 32 addi r3, r3, 32
bdnz 1b bdnz 1b
@ -1078,8 +1078,8 @@ unlock_ram_in_cache:
li r4, ((CFG_SYS_INIT_RAM_SIZE & ~31) + \ li r4, ((CFG_SYS_INIT_RAM_SIZE & ~31) + \
(CFG_SYS_INIT_RAM_ADDR & 31) + 31) / 32 (CFG_SYS_INIT_RAM_ADDR & 31) + 31) / 32
mtctr r4 mtctr r4
1: icbi r0, r3 1: icbi 0, r3
dcbi r0, r3 dcbi 0, r3
addi r3, r3, 32 addi r3, r3, 32
bdnz 1b bdnz 1b
sync /* Wait for all icbi to complete on bus */ sync /* Wait for all icbi to complete on bus */

24
arch/powerpc/cpu/mpc85xx/start.S
View file

@ -1203,12 +1203,12 @@ switch_as:
mtctr r2 mtctr r2
li r0,0 li r0,0
1: 1:
dcbz r0,r3 dcbz 0,r3
#ifdef CONFIG_E6500 /* Lock/unlock L2 cache long with L1 */ #ifdef CONFIG_E6500 /* Lock/unlock L2 cache long with L1 */
dcbtls 2, r0, r3 dcbtls 2, 0, r3
dcbtls 0, r0, r3 dcbtls 0, 0, r3
#else #else
dcbtls 0, r0, r3 dcbtls 0, 0, r3
#endif #endif
addi r3,r3,CONFIG_SYS_CACHELINE_SIZE addi r3,r3,CONFIG_SYS_CACHELINE_SIZE
bdnz 1b bdnz 1b
@ -1514,7 +1514,7 @@ out16:
/*------------------------------------------------------------------------------- */ /*------------------------------------------------------------------------------- */
.globl out16r .globl out16r
out16r: out16r:
sthbrx r4,r0,r3 sthbrx r4,0,r3
sync sync
blr blr
@ -1534,7 +1534,7 @@ out32:
/*------------------------------------------------------------------------------- */ /*------------------------------------------------------------------------------- */
.globl out32r .globl out32r
out32r: out32r:
stwbrx r4,r0,r3 stwbrx r4,0,r3
sync sync
blr blr
@ -1553,7 +1553,7 @@ in16:
/*------------------------------------------------------------------------------- */ /*------------------------------------------------------------------------------- */
.globl in16r .globl in16r
in16r: in16r:
lhbrx r3,r0,r3 lhbrx r3,0,r3
blr blr
/*------------------------------------------------------------------------------- */ /*------------------------------------------------------------------------------- */
@ -1571,7 +1571,7 @@ in32:
/*------------------------------------------------------------------------------- */ /*------------------------------------------------------------------------------- */
.globl in32r .globl in32r
in32r: in32r:
lwbrx r3,r0,r3 lwbrx r3,0,r3
blr blr
#endif /* !MINIMAL_SPL */ #endif /* !MINIMAL_SPL */
@ -1832,12 +1832,12 @@ unlock_ram_in_cache:
andi. r4,r4,0x1ff andi. r4,r4,0x1ff
slwi r4,r4,(10 - 1 - L1_CACHE_SHIFT) slwi r4,r4,(10 - 1 - L1_CACHE_SHIFT)
mtctr r4 mtctr r4
1: dcbi r0,r3 1: dcbi 0,r3
#ifdef CONFIG_E6500 /* lock/unlock L2 cache long with L1 */ #ifdef CONFIG_E6500 /* lock/unlock L2 cache long with L1 */
dcblc 2, r0, r3 dcblc 2, 0, r3
dcblc 0, r0, r3 dcblc 0, 0, r3
#else #else
dcblc r0,r3 dcblc 0,r3
#endif #endif
addi r3,r3,CONFIG_SYS_CACHELINE_SIZE addi r3,r3,CONFIG_SYS_CACHELINE_SIZE
bdnz 1b bdnz 1b

6
arch/powerpc/lib/ppccache.S
View file

@ -20,7 +20,7 @@
/*------------------------------------------------------------------------------- */ /*------------------------------------------------------------------------------- */
.globl ppcDcbf .globl ppcDcbf
ppcDcbf: ppcDcbf:
dcbf r0,r3 dcbf 0,r3
blr blr
/*------------------------------------------------------------------------------- */ /*------------------------------------------------------------------------------- */
@ -31,7 +31,7 @@ ppcDcbf:
/*------------------------------------------------------------------------------- */ /*------------------------------------------------------------------------------- */
.globl ppcDcbi .globl ppcDcbi
ppcDcbi: ppcDcbi:
dcbi r0,r3 dcbi 0,r3
blr blr
/*-------------------------------------------------------------------------- /*--------------------------------------------------------------------------
@ -43,7 +43,7 @@ ppcDcbi:
.globl ppcDcbz .globl ppcDcbz
ppcDcbz: ppcDcbz:
dcbz r0,r3 dcbz 0,r3
blr blr
/*------------------------------------------------------------------------------- */ /*------------------------------------------------------------------------------- */