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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        "Peter Zijlstra (Intel)" <peterz@infradead.org>
Subject: [PATCH 5.4 48/58] selftests/rseq: x86-64: use %fs segment selector for accessing rseq thread area
Date:   Tue,  5 Jul 2022 13:58:24 +0200
Message-Id: <20220705115611.666069493@linuxfoundation.org>
In-Reply-To: <20220705115610.236040773@linuxfoundation.org>
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From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

commit 4e15bb766b6c6e963a4d33629034d0ec3b7637df upstream.

Rather than use rseq_get_abi() and pass its result through a register to
the inline assembler, directly access the per-thread rseq area through a
memory reference combining the %fs segment selector, the constant offset
of the field in struct rseq, and the rseq_offset value (in a register).

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220124171253.22072-15-mathieu.desnoyers@efficios.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 tools/testing/selftests/rseq/rseq-x86.h |   58 ++++++++++++++++----------------
 1 file changed, 30 insertions(+), 28 deletions(-)

--- a/tools/testing/selftests/rseq/rseq-x86.h
+++ b/tools/testing/selftests/rseq/rseq-x86.h
@@ -28,6 +28,8 @@
 
 #ifdef __x86_64__
 
+#define RSEQ_ASM_TP_SEGMENT	%%fs
+
 #define rseq_smp_mb()	\
 	__asm__ __volatile__ ("lock; addl $0,-128(%%rsp)" ::: "memory", "cc")
 #define rseq_smp_rmb()	rseq_barrier()
@@ -123,14 +125,14 @@ int rseq_cmpeqv_storev(intptr_t *v, intp
 		RSEQ_ASM_DEFINE_EXIT_POINT(1f, %l[error2])
 #endif
 		/* Start rseq by storing table entry pointer into rseq_cs. */
-		RSEQ_ASM_STORE_RSEQ_CS(1, 3b, RSEQ_CS_OFFSET(%[rseq_abi]))
-		RSEQ_ASM_CMP_CPU_ID(cpu_id, RSEQ_CPU_ID_OFFSET(%[rseq_abi]), 4f)
+		RSEQ_ASM_STORE_RSEQ_CS(1, 3b, RSEQ_ASM_TP_SEGMENT:RSEQ_CS_OFFSET(%[rseq_offset]))
+		RSEQ_ASM_CMP_CPU_ID(cpu_id, RSEQ_ASM_TP_SEGMENT:RSEQ_CPU_ID_OFFSET(%[rseq_offset]), 4f)
 		RSEQ_INJECT_ASM(3)
 		"cmpq %[v], %[expect]\n\t"
 		"jnz %l[cmpfail]\n\t"
 		RSEQ_INJECT_ASM(4)
 #ifdef RSEQ_COMPARE_TWICE
-		RSEQ_ASM_CMP_CPU_ID(cpu_id, RSEQ_CPU_ID_OFFSET(%[rseq_abi]), %l[error1])
+		RSEQ_ASM_CMP_CPU_ID(cpu_id, RSEQ_ASM_TP_SEGMENT:RSEQ_CPU_ID_OFFSET(%[rseq_offset]), %l[error1])
 		"cmpq %[v], %[expect]\n\t"
 		"jnz %l[error2]\n\t"
 #endif
@@ -141,7 +143,7 @@ int rseq_cmpeqv_storev(intptr_t *v, intp
 		RSEQ_ASM_DEFINE_ABORT(4, "", abort)
 		: /* gcc asm goto does not allow outputs */
 		: [cpu_id]		"r" (cpu),
-		  [rseq_abi]		"r" (rseq_get_abi()),
+		  [rseq_offset]		"r" ((long)rseq_offset),
 		  [v]			"m" (*v),
 		  [expect]		"r" (expect),
 		  [newv]		"r" (newv)
@@ -189,15 +191,15 @@ int rseq_cmpnev_storeoffp_load(intptr_t
 		RSEQ_ASM_DEFINE_EXIT_POINT(1f, %l[error2])
 #endif
 		/* Start rseq by storing table entry pointer into rseq_cs. */
-		RSEQ_ASM_STORE_RSEQ_CS(1, 3b, RSEQ_CS_OFFSET(%[rseq_abi]))
-		RSEQ_ASM_CMP_CPU_ID(cpu_id, RSEQ_CPU_ID_OFFSET(%[rseq_abi]), 4f)
+		RSEQ_ASM_STORE_RSEQ_CS(1, 3b, RSEQ_ASM_TP_SEGMENT:RSEQ_CS_OFFSET(%[rseq_offset]))
+		RSEQ_ASM_CMP_CPU_ID(cpu_id, RSEQ_ASM_TP_SEGMENT:RSEQ_CPU_ID_OFFSET(%[rseq_offset]), 4f)
 		RSEQ_INJECT_ASM(3)
 		"movq %[v], %%rbx\n\t"
 		"cmpq %%rbx, %[expectnot]\n\t"
 		"je %l[cmpfail]\n\t"
 		RSEQ_INJECT_ASM(4)
 #ifdef RSEQ_COMPARE_TWICE
-		RSEQ_ASM_CMP_CPU_ID(cpu_id, RSEQ_CPU_ID_OFFSET(%[rseq_abi]), %l[error1])
+		RSEQ_ASM_CMP_CPU_ID(cpu_id, RSEQ_ASM_TP_SEGMENT:RSEQ_CPU_ID_OFFSET(%[rseq_offset]), %l[error1])
 		"movq %[v], %%rbx\n\t"
 		"cmpq %%rbx, %[expectnot]\n\t"
 		"je %l[error2]\n\t"
@@ -212,7 +214,7 @@ int rseq_cmpnev_storeoffp_load(intptr_t
 		RSEQ_ASM_DEFINE_ABORT(4, "", abort)
 		: /* gcc asm goto does not allow outputs */
 		: [cpu_id]		"r" (cpu),
-		  [rseq_abi]		"r" (rseq_get_abi()),
+		  [rseq_offset]		"r" ((long)rseq_offset),
 		  /* final store input */
 		  [v]			"m" (*v),
 		  [expectnot]		"r" (expectnot),
@@ -255,11 +257,11 @@ int rseq_addv(intptr_t *v, intptr_t coun
 		RSEQ_ASM_DEFINE_EXIT_POINT(1f, %l[error1])
 #endif
 		/* Start rseq by storing table entry pointer into rseq_cs. */
-		RSEQ_ASM_STORE_RSEQ_CS(1, 3b, RSEQ_CS_OFFSET(%[rseq_abi]))
-		RSEQ_ASM_CMP_CPU_ID(cpu_id, RSEQ_CPU_ID_OFFSET(%[rseq_abi]), 4f)
+		RSEQ_ASM_STORE_RSEQ_CS(1, 3b, RSEQ_ASM_TP_SEGMENT:RSEQ_CS_OFFSET(%[rseq_offset]))
+		RSEQ_ASM_CMP_CPU_ID(cpu_id, RSEQ_ASM_TP_SEGMENT:RSEQ_CPU_ID_OFFSET(%[rseq_offset]), 4f)
 		RSEQ_INJECT_ASM(3)
 #ifdef RSEQ_COMPARE_TWICE
-		RSEQ_ASM_CMP_CPU_ID(cpu_id, RSEQ_CPU_ID_OFFSET(%[rseq_abi]), %l[error1])
+		RSEQ_ASM_CMP_CPU_ID(cpu_id, RSEQ_ASM_TP_SEGMENT:RSEQ_CPU_ID_OFFSET(%[rseq_offset]), %l[error1])
 #endif
 		/* final store */
 		"addq %[count], %[v]\n\t"
@@ -268,7 +270,7 @@ int rseq_addv(intptr_t *v, intptr_t coun
 		RSEQ_ASM_DEFINE_ABORT(4, "", abort)
 		: /* gcc asm goto does not allow outputs */
 		: [cpu_id]		"r" (cpu),
-		  [rseq_abi]		"r" (rseq_get_abi()),
+		  [rseq_offset]		"r" ((long)rseq_offset),
 		  /* final store input */
 		  [v]			"m" (*v),
 		  [count]		"er" (count)
@@ -309,11 +311,11 @@ int rseq_offset_deref_addv(intptr_t *ptr
 		RSEQ_ASM_DEFINE_EXIT_POINT(1f, %l[error1])
 #endif
 		/* Start rseq by storing table entry pointer into rseq_cs. */
-		RSEQ_ASM_STORE_RSEQ_CS(1, 3b, RSEQ_CS_OFFSET(%[rseq_abi]))
-		RSEQ_ASM_CMP_CPU_ID(cpu_id, RSEQ_CPU_ID_OFFSET(%[rseq_abi]), 4f)
+		RSEQ_ASM_STORE_RSEQ_CS(1, 3b, RSEQ_ASM_TP_SEGMENT:RSEQ_CS_OFFSET(%[rseq_offset]))
+		RSEQ_ASM_CMP_CPU_ID(cpu_id, RSEQ_ASM_TP_SEGMENT:RSEQ_CPU_ID_OFFSET(%[rseq_offset]), 4f)
 		RSEQ_INJECT_ASM(3)
 #ifdef RSEQ_COMPARE_TWICE
-		RSEQ_ASM_CMP_CPU_ID(cpu_id, RSEQ_CPU_ID_OFFSET(%[rseq_abi]), %l[error1])
+		RSEQ_ASM_CMP_CPU_ID(cpu_id, RSEQ_ASM_TP_SEGMENT:RSEQ_CPU_ID_OFFSET(%[rseq_offset]), %l[error1])
 #endif
 		/* get p+v */
 		"movq %[ptr], %%rbx\n\t"
@@ -327,7 +329,7 @@ int rseq_offset_deref_addv(intptr_t *ptr
 		RSEQ_ASM_DEFINE_ABORT(4, "", abort)
 		: /* gcc asm goto does not allow outputs */
 		: [cpu_id]		"r" (cpu),
-		  [rseq_abi]		"r" (rseq_get_abi()),
+		  [rseq_offset]		"r" ((long)rseq_offset),
 		  /* final store input */
 		  [ptr]			"m" (*ptr),
 		  [off]			"er" (off),
@@ -364,14 +366,14 @@ int rseq_cmpeqv_trystorev_storev(intptr_
 		RSEQ_ASM_DEFINE_EXIT_POINT(1f, %l[error2])
 #endif
 		/* Start rseq by storing table entry pointer into rseq_cs. */
-		RSEQ_ASM_STORE_RSEQ_CS(1, 3b, RSEQ_CS_OFFSET(%[rseq_abi]))
-		RSEQ_ASM_CMP_CPU_ID(cpu_id, RSEQ_CPU_ID_OFFSET(%[rseq_abi]), 4f)
+		RSEQ_ASM_STORE_RSEQ_CS(1, 3b, RSEQ_ASM_TP_SEGMENT:RSEQ_CS_OFFSET(%[rseq_offset]))
+		RSEQ_ASM_CMP_CPU_ID(cpu_id, RSEQ_ASM_TP_SEGMENT:RSEQ_CPU_ID_OFFSET(%[rseq_offset]), 4f)
 		RSEQ_INJECT_ASM(3)
 		"cmpq %[v], %[expect]\n\t"
 		"jnz %l[cmpfail]\n\t"
 		RSEQ_INJECT_ASM(4)
 #ifdef RSEQ_COMPARE_TWICE
-		RSEQ_ASM_CMP_CPU_ID(cpu_id, RSEQ_CPU_ID_OFFSET(%[rseq_abi]), %l[error1])
+		RSEQ_ASM_CMP_CPU_ID(cpu_id, RSEQ_ASM_TP_SEGMENT:RSEQ_CPU_ID_OFFSET(%[rseq_offset]), %l[error1])
 		"cmpq %[v], %[expect]\n\t"
 		"jnz %l[error2]\n\t"
 #endif
@@ -385,7 +387,7 @@ int rseq_cmpeqv_trystorev_storev(intptr_
 		RSEQ_ASM_DEFINE_ABORT(4, "", abort)
 		: /* gcc asm goto does not allow outputs */
 		: [cpu_id]		"r" (cpu),
-		  [rseq_abi]		"r" (rseq_get_abi()),
+		  [rseq_offset]		"r" ((long)rseq_offset),
 		  /* try store input */
 		  [v2]			"m" (*v2),
 		  [newv2]		"r" (newv2),
@@ -444,8 +446,8 @@ int rseq_cmpeqv_cmpeqv_storev(intptr_t *
 		RSEQ_ASM_DEFINE_EXIT_POINT(1f, %l[error3])
 #endif
 		/* Start rseq by storing table entry pointer into rseq_cs. */
-		RSEQ_ASM_STORE_RSEQ_CS(1, 3b, RSEQ_CS_OFFSET(%[rseq_abi]))
-		RSEQ_ASM_CMP_CPU_ID(cpu_id, RSEQ_CPU_ID_OFFSET(%[rseq_abi]), 4f)
+		RSEQ_ASM_STORE_RSEQ_CS(1, 3b, RSEQ_ASM_TP_SEGMENT:RSEQ_CS_OFFSET(%[rseq_offset]))
+		RSEQ_ASM_CMP_CPU_ID(cpu_id, RSEQ_ASM_TP_SEGMENT:RSEQ_CPU_ID_OFFSET(%[rseq_offset]), 4f)
 		RSEQ_INJECT_ASM(3)
 		"cmpq %[v], %[expect]\n\t"
 		"jnz %l[cmpfail]\n\t"
@@ -454,7 +456,7 @@ int rseq_cmpeqv_cmpeqv_storev(intptr_t *
 		"jnz %l[cmpfail]\n\t"
 		RSEQ_INJECT_ASM(5)
 #ifdef RSEQ_COMPARE_TWICE
-		RSEQ_ASM_CMP_CPU_ID(cpu_id, RSEQ_CPU_ID_OFFSET(%[rseq_abi]), %l[error1])
+		RSEQ_ASM_CMP_CPU_ID(cpu_id, RSEQ_ASM_TP_SEGMENT:RSEQ_CPU_ID_OFFSET(%[rseq_offset]), %l[error1])
 		"cmpq %[v], %[expect]\n\t"
 		"jnz %l[error2]\n\t"
 		"cmpq %[v2], %[expect2]\n\t"
@@ -467,7 +469,7 @@ int rseq_cmpeqv_cmpeqv_storev(intptr_t *
 		RSEQ_ASM_DEFINE_ABORT(4, "", abort)
 		: /* gcc asm goto does not allow outputs */
 		: [cpu_id]		"r" (cpu),
-		  [rseq_abi]		"r" (rseq_get_abi()),
+		  [rseq_offset]		"r" ((long)rseq_offset),
 		  /* cmp2 input */
 		  [v2]			"m" (*v2),
 		  [expect2]		"r" (expect2),
@@ -524,14 +526,14 @@ int rseq_cmpeqv_trymemcpy_storev(intptr_
 		"movq %[dst], %[rseq_scratch1]\n\t"
 		"movq %[len], %[rseq_scratch2]\n\t"
 		/* Start rseq by storing table entry pointer into rseq_cs. */
-		RSEQ_ASM_STORE_RSEQ_CS(1, 3b, RSEQ_CS_OFFSET(%[rseq_abi]))
-		RSEQ_ASM_CMP_CPU_ID(cpu_id, RSEQ_CPU_ID_OFFSET(%[rseq_abi]), 4f)
+		RSEQ_ASM_STORE_RSEQ_CS(1, 3b, RSEQ_ASM_TP_SEGMENT:RSEQ_CS_OFFSET(%[rseq_offset]))
+		RSEQ_ASM_CMP_CPU_ID(cpu_id, RSEQ_ASM_TP_SEGMENT:RSEQ_CPU_ID_OFFSET(%[rseq_offset]), 4f)
 		RSEQ_INJECT_ASM(3)
 		"cmpq %[v], %[expect]\n\t"
 		"jnz 5f\n\t"
 		RSEQ_INJECT_ASM(4)
 #ifdef RSEQ_COMPARE_TWICE
-		RSEQ_ASM_CMP_CPU_ID(cpu_id, RSEQ_CPU_ID_OFFSET(%[rseq_abi]), 6f)
+		RSEQ_ASM_CMP_CPU_ID(cpu_id, RSEQ_ASM_TP_SEGMENT:RSEQ_CPU_ID_OFFSET(%[rseq_offset]), 6f)
 		"cmpq %[v], %[expect]\n\t"
 		"jnz 7f\n\t"
 #endif
@@ -579,7 +581,7 @@ int rseq_cmpeqv_trymemcpy_storev(intptr_
 #endif
 		: /* gcc asm goto does not allow outputs */
 		: [cpu_id]		"r" (cpu),
-		  [rseq_abi]		"r" (rseq_get_abi()),
+		  [rseq_offset]		"r" ((long)rseq_offset),
 		  /* final store input */
 		  [v]			"m" (*v),
 		  [expect]		"r" (expect),