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From: Nicholas Piggin <npiggin@gmail.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: Nicholas Piggin <npiggin@gmail.com>
Subject: [PATCH v2 3/5] powerpc/64: avoid using r13 in relocate
Date: Mon, 26 Sep 2022 15:56:18 +1000	[thread overview]
Message-ID: <20220926055620.2676869-4-npiggin@gmail.com> (raw)
In-Reply-To: <20220926055620.2676869-1-npiggin@gmail.com>

relocate() uses r13 in early boot before it is used for the paca. Use
a different register for this so r13 is kept unchanged until it is
set to the paca pointer.

Avoid r14 as well while we're here, there's no reason not to use the
volatile registers which is a bit less surprising, and r14 could be used
as another fixed reg one day.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/kernel/reloc_64.S | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/kernel/reloc_64.S b/arch/powerpc/kernel/reloc_64.S
index 232e4549defe..efd52f2e7033 100644
--- a/arch/powerpc/kernel/reloc_64.S
+++ b/arch/powerpc/kernel/reloc_64.S
@@ -27,8 +27,8 @@ _GLOBAL(relocate)
 	add	r9,r9,r12	/* r9 has runtime addr of .rela.dyn section */
 	ld	r10,(p_st - 0b)(r12)
 	add	r10,r10,r12	/* r10 has runtime addr of _stext */
-	ld	r13,(p_sym - 0b)(r12)
-	add	r13,r13,r12	/* r13 has runtime addr of .dynsym */
+	ld	r4,(p_sym - 0b)(r12)
+	add	r4,r4,r12	/* r4 has runtime addr of .dynsym */
 
 	/*
 	 * Scan the dynamic section for the RELA, RELASZ and RELAENT entries.
@@ -84,16 +84,16 @@ _GLOBAL(relocate)
 	ld	r0,16(r9)	/* reloc->r_addend */
 	b	.Lstore
 .Luaddr64:
-	srdi	r14,r0,32	/* ELF64_R_SYM(reloc->r_info) */
+	srdi	r5,r0,32	/* ELF64_R_SYM(reloc->r_info) */
 	clrldi	r0,r0,32
 	cmpdi	r0,R_PPC64_UADDR64
 	bne	.Lnext
 	ld	r6,0(r9)
 	ld	r0,16(r9)
-	mulli	r14,r14,24	/* 24 == sizeof(elf64_sym) */
-	add	r14,r14,r13	/* elf64_sym[ELF64_R_SYM] */
-	ld	r14,8(r14)
-	add	r0,r0,r14
+	mulli	r5,r5,24	/* 24 == sizeof(elf64_sym) */
+	add	r5,r5,r4	/* elf64_sym[ELF64_R_SYM] */
+	ld	r5,8(r5)
+	add	r0,r0,r5
 .Lstore:
 	add	r0,r0,r3
 	stdx	r0,r7,r6
-- 
2.37.2


  parent reply	other threads:[~2022-09-26  5:59 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-26  5:56 [PATCH v2 0/5] powerpc/64s: improve boot debugging Nicholas Piggin
2022-09-26  5:56 ` [PATCH v2 1/5] powerpc/64s/interrupt: move early boot ILE fixup into a macro Nicholas Piggin
2022-09-26  5:56 ` [PATCH v2 2/5] powerpc/64s: early boot machine check handler Nicholas Piggin
2022-09-26  5:56 ` Nicholas Piggin [this message]
2022-09-26  5:56 ` [PATCH v2 4/5] powerpc/64: don't set boot CPU's r13 to paca until the structure is set up Nicholas Piggin
2022-09-26  5:56 ` [PATCH v2 5/5] powerpc/64s/interrupt: halt early boot interrupts if paca is not " Nicholas Piggin
2022-10-04 13:25 ` [PATCH v2 0/5] powerpc/64s: improve boot debugging Michael Ellerman

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