[PATCH] arm64: el2_setup.h: Rename some labels to be more diff-friendly

Subsystems: arm64 port (aarch64 architecture), the rest

STALE797d LANDED

Landed in mainline as 5b39db6037e7 on 2024-08-16.

2 messages, 2 authors, 2024-08-16 · open the first message on its own page

[PATCH] arm64: el2_setup.h: Rename some labels to be more diff-friendly

From: Dave Martin <Dave.Martin@arm.com>
Date: 2024-07-29 16:26:29

A minor anti-pattern has established itself in __init_el2_fgt,
where each block of instructions is skipped by jumping to a label
named for the next (typically unrelated) block.

This makes diffs more noisy than necessary, since appending each
new block to deal with some new architecture feature now requires
altering a branch destination in the existing code.

Fix it by naming the affected labels based on the block that is
skipping itself instead, as is done elsewhere in the el2_setup code.

No functional change.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>

---

Based on: v6.11-rc1

Other than a brainless boot test, checked by comparing the disassembly
of vmlinux:init_kernel_el.  Snap!

Needless to say, kallsyms references change (as expected).

---
 arch/arm64/include/asm/el2_setup.h | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)
diff --git a/arch/arm64/include/asm/el2_setup.h b/arch/arm64/include/asm/el2_setup.h
index fd87c4b8f984..8eb113a6b452 100644
--- a/arch/arm64/include/asm/el2_setup.h
+++ b/arch/arm64/include/asm/el2_setup.h
@@ -165,42 +165,45 @@
 	mrs	x1, id_aa64dfr0_el1
 	ubfx	x1, x1, #ID_AA64DFR0_EL1_PMSVer_SHIFT, #4
 	cmp	x1, #3
-	b.lt	.Lset_debug_fgt_\@
+	b.lt	.Lskip_spe_fgt_\@
 	/* Disable PMSNEVFR_EL1 read and write traps */
 	orr	x0, x0, #(1 << 62)
 
-.Lset_debug_fgt_\@:
+.Lskip_spe_fgt_\@:
 	msr_s	SYS_HDFGRTR_EL2, x0
 	msr_s	SYS_HDFGWTR_EL2, x0
 
 	mov	x0, xzr
 	mrs	x1, id_aa64pfr1_el1
 	ubfx	x1, x1, #ID_AA64PFR1_EL1_SME_SHIFT, #4
-	cbz	x1, .Lset_pie_fgt_\@
+	cbz	x1, .Lskip_debug_fgt_\@
 
 	/* Disable nVHE traps of TPIDR2 and SMPRI */
 	orr	x0, x0, #HFGxTR_EL2_nSMPRI_EL1_MASK
 	orr	x0, x0, #HFGxTR_EL2_nTPIDR2_EL0_MASK
 
-.Lset_pie_fgt_\@:
+.Lskip_debug_fgt_\@:
 	mrs_s	x1, SYS_ID_AA64MMFR3_EL1
 	ubfx	x1, x1, #ID_AA64MMFR3_EL1_S1PIE_SHIFT, #4
-	cbz	x1, .Lset_fgt_\@
+	cbz	x1, .Lskip_pie_fgt_\@
 
 	/* Disable trapping of PIR_EL1 / PIRE0_EL1 */
 	orr	x0, x0, #HFGxTR_EL2_nPIR_EL1
 	orr	x0, x0, #HFGxTR_EL2_nPIRE0_EL1
 
-.Lset_fgt_\@:
+.Lskip_pie_fgt_\@:
 	msr_s	SYS_HFGRTR_EL2, x0
 	msr_s	SYS_HFGWTR_EL2, x0
 	msr_s	SYS_HFGITR_EL2, xzr
 
 	mrs	x1, id_aa64pfr0_el1		// AMU traps UNDEF without AMU
 	ubfx	x1, x1, #ID_AA64PFR0_EL1_AMU_SHIFT, #4
-	cbz	x1, .Lskip_fgt_\@
+	cbz	x1, .Lskip_amu_fgt_\@
 
 	msr_s	SYS_HAFGRTR_EL2, xzr
+
+.Lskip_amu_fgt_\@:
+
 .Lskip_fgt_\@:
 .endm
 
base-commit: 8400291e289ee6b2bf9779ff1c83a291501f017b
-- 
2.34.1

Re: [PATCH] arm64: el2_setup.h: Rename some labels to be more diff-friendly

From: Will Deacon <will@kernel.org>
Date: 2024-08-16 15:20:17

On Mon, 29 Jul 2024 17:25:42 +0100, Dave Martin wrote:
A minor anti-pattern has established itself in __init_el2_fgt,
where each block of instructions is skipped by jumping to a label
named for the next (typically unrelated) block.

This makes diffs more noisy than necessary, since appending each
new block to deal with some new architecture feature now requires
altering a branch destination in the existing code.

[...]
Applied to arm64 (for-next/misc), thanks!

[1/1] arm64: el2_setup.h: Rename some labels to be more diff-friendly
      https://git.kernel.org/arm64/c/5b39db6037e7

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev
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