linux-kernel - [PATCH v3] arm64: Cleanup __cpu_set_tcr

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Date: Mon,  8 Apr 2024 11:40:16 +0900
From: Seongsu Park <sgsu.park@...sung.com>
To: will@...nel.org, catalin.marinas@....com, mark.rutland@....com
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	sgsu.park@...sung.com, Leem ChaeHoon <infinite.run@...il.com>, Gyeonggeon
	Choi <gychoi@...dent.42seoul.kr>, Soomin Cho <to.soomin@...il.com>, DaeRo
	Lee <skseofh@...il.com>, kmasta <kmasta.study@...il.com>
Subject: [PATCH v3] arm64: Cleanup __cpu_set_tcr_t0sz()

In cpu_set_default_tcr_t0sz(), it is an error to shift TCR_T0SZ_OFFSET
twice form TCR_T0SZ() and __cpu_set_tcr_t0sz().
Since TCR_T0SZ_OFFSET is 0, no error occurred.
We need to clarify whether the parameter of __cpu_set_tcr_t0sz is a
shifted value or an unshifted value.

We have already shifted the value of t0sz in TCR_T0SZ by TCR_T0SZ_OFFSET.
This is necessary for consistency with TCR_T1SZ.
Therefore, the parameter of __cpu_set_tcr_t0sz is clarified as a shifted
value.

Co-developed-by: Leem ChaeHoon <infinite.run@...il.com>
Signed-off-by: Leem ChaeHoon <infinite.run@...il.com>
Co-developed-by: Gyeonggeon Choi <gychoi@...dent.42seoul.kr>
Signed-off-by: Gyeonggeon Choi <gychoi@...dent.42seoul.kr>
Co-developed-by: Soomin Cho <to.soomin@...il.com>
Signed-off-by: Soomin Cho <to.soomin@...il.com>
Co-developed-by: DaeRo Lee <skseofh@...il.com>
Signed-off-by: DaeRo Lee <skseofh@...il.com>
Co-developed-by: kmasta <kmasta.study@...il.com>
Signed-off-by: kmasta <kmasta.study@...il.com>
Signed-off-by: Seongsu Park <sgsu.park@...sung.com>
---

v2:
 - Condition is updated
v3:
 - Commit message is updated
 - cpu_set_tcr_t0sz macro is added

---
 arch/arm64/include/asm/mmu_context.h | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h
index c768d16b81a4..fb603ec7f61f 100644
--- a/arch/arm64/include/asm/mmu_context.h
+++ b/arch/arm64/include/asm/mmu_context.h
@@ -72,15 +72,16 @@ static inline void __cpu_set_tcr_t0sz(unsigned long t0sz)
 {
 	unsigned long tcr = read_sysreg(tcr_el1);
 
-	if ((tcr & TCR_T0SZ_MASK) >> TCR_T0SZ_OFFSET == t0sz)
+	if ((tcr & TCR_T0SZ_MASK) == t0sz)
 		return;
 
 	tcr &= ~TCR_T0SZ_MASK;
-	tcr |= t0sz << TCR_T0SZ_OFFSET;
+	tcr |= t0sz;
 	write_sysreg(tcr, tcr_el1);
 	isb();
 }
 
+#define cpu_set_tcr_t0sz(t0sz)		__cpu_set_tcr_t0sz(TCR_T0SZ(t0sz))
 #define cpu_set_default_tcr_t0sz()	__cpu_set_tcr_t0sz(TCR_T0SZ(vabits_actual))
 #define cpu_set_idmap_tcr_t0sz()	__cpu_set_tcr_t0sz(idmap_t0sz)
 
@@ -134,7 +135,7 @@ static inline void cpu_install_ttbr0(phys_addr_t ttbr0, unsigned long t0sz)
 {
 	cpu_set_reserved_ttbr0();
 	local_flush_tlb_all();
-	__cpu_set_tcr_t0sz(t0sz);
+	cpu_set_tcr_t0sz(t0sz);
 
 	/* avoid cpu_switch_mm() and its SW-PAN and CNP interactions */
 	write_sysreg(ttbr0, ttbr0_el1);
-- 
2.34.1