[PATCH v3 04/42] arm64/sve: Make access to FFR optional
Mark Brown
broonie at kernel.org
Tue Oct 19 10:22:09 PDT 2021
SME introduces streaming SVE mode in which FFR is not present and the
instructions for accessing it UNDEF. In preparation for handling this
update the low level SVE state access functions to take a flag specifying
if FFR should be handled. When saving the register state we store a zero
for FFR to guard against uninitialized data being read. No behaviour change
should be introduced by this patch.
Signed-off-by: Mark Brown <broonie at kernel.org>
---
arch/arm64/include/asm/fpsimd.h | 6 +++---
arch/arm64/include/asm/fpsimdmacros.h | 20 ++++++++++++++------
arch/arm64/kernel/entry-fpsimd.S | 19 ++++++++++++-------
arch/arm64/kernel/fpsimd.c | 10 ++++++----
arch/arm64/kvm/hyp/fpsimd.S | 6 ++++--
5 files changed, 39 insertions(+), 22 deletions(-)
diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h
index 917ecc301d1d..7f8a44a9a5e6 100644
--- a/arch/arm64/include/asm/fpsimd.h
+++ b/arch/arm64/include/asm/fpsimd.h
@@ -65,10 +65,10 @@ static inline void *sve_pffr(struct thread_struct *thread)
return (char *)thread->sve_state + sve_ffr_offset(thread->sve_vl);
}
-extern void sve_save_state(void *state, u32 *pfpsr);
+extern void sve_save_state(void *state, u32 *pfpsr, int save_ffr);
extern void sve_load_state(void const *state, u32 const *pfpsr,
- unsigned long vq_minus_1);
-extern void sve_flush_live(unsigned long vq_minus_1);
+ int restore_ffr, unsigned long vq_minus_1);
+extern void sve_flush_live(bool flush_ffr, unsigned long vq_minus_1);
extern unsigned int sve_get_vl(void);
extern void sve_set_vq(unsigned long vq_minus_1);
diff --git a/arch/arm64/include/asm/fpsimdmacros.h b/arch/arm64/include/asm/fpsimdmacros.h
index 00a2c0b69c2b..e5ffd8b265b6 100644
--- a/arch/arm64/include/asm/fpsimdmacros.h
+++ b/arch/arm64/include/asm/fpsimdmacros.h
@@ -217,28 +217,36 @@
.macro sve_flush_z
_for n, 0, 31, _sve_flush_z \n
.endm
-.macro sve_flush_p_ffr
+.macro sve_flush_p
_for n, 0, 15, _sve_pfalse \n
+.endm
+.macro sve_flush_ffr
_sve_wrffr 0
.endm
-.macro sve_save nxbase, xpfpsr, nxtmp
+.macro sve_save nxbase, xpfpsr, save_ffr, nxtmp
_for n, 0, 31, _sve_str_v \n, \nxbase, \n - 34
_for n, 0, 15, _sve_str_p \n, \nxbase, \n - 16
+ cbz \save_ffr, 921f
_sve_rdffr 0
_sve_str_p 0, \nxbase
_sve_ldr_p 0, \nxbase, -16
-
+ b 922f
+921:
+ str xzr, [x\nxbase] // Zero out FFR
+922:
mrs x\nxtmp, fpsr
str w\nxtmp, [\xpfpsr]
mrs x\nxtmp, fpcr
str w\nxtmp, [\xpfpsr, #4]
.endm
-.macro __sve_load nxbase, xpfpsr, nxtmp
+.macro __sve_load nxbase, xpfpsr, restore_ffr, nxtmp
_for n, 0, 31, _sve_ldr_v \n, \nxbase, \n - 34
+ cbz \restore_ffr, 921f
_sve_ldr_p 0, \nxbase
_sve_wrffr 0
+921:
_for n, 0, 15, _sve_ldr_p \n, \nxbase, \n - 16
ldr w\nxtmp, [\xpfpsr]
@@ -247,7 +255,7 @@
msr fpcr, x\nxtmp
.endm
-.macro sve_load nxbase, xpfpsr, xvqminus1, nxtmp, xtmp2
+.macro sve_load nxbase, xpfpsr, restore_ffr, xvqminus1, nxtmp, xtmp2
sve_load_vq \xvqminus1, x\nxtmp, \xtmp2
- __sve_load \nxbase, \xpfpsr, \nxtmp
+ __sve_load \nxbase, \xpfpsr, \restore_ffr, \nxtmp
.endm
diff --git a/arch/arm64/kernel/entry-fpsimd.S b/arch/arm64/kernel/entry-fpsimd.S
index afbf7dc47e1d..f588c214d44b 100644
--- a/arch/arm64/kernel/entry-fpsimd.S
+++ b/arch/arm64/kernel/entry-fpsimd.S
@@ -38,9 +38,10 @@ SYM_FUNC_END(fpsimd_load_state)
*
* x0 - pointer to buffer for state
* x1 - pointer to storage for FPSR
+ * x2 - Save FFR if non-zero
*/
SYM_FUNC_START(sve_save_state)
- sve_save 0, x1, 2
+ sve_save 0, x1, x2, 3
ret
SYM_FUNC_END(sve_save_state)
@@ -49,10 +50,11 @@ SYM_FUNC_END(sve_save_state)
*
* x0 - pointer to buffer for state
* x1 - pointer to storage for FPSR
- * x2 - VQ-1
+ * x2 - Restore FFR if non-zero
+ * x3 - VQ-1
*/
SYM_FUNC_START(sve_load_state)
- sve_load 0, x1, x2, 3, x4
+ sve_load 0, x1, x2, x3, 4, x5
ret
SYM_FUNC_END(sve_load_state)
@@ -72,13 +74,16 @@ SYM_FUNC_END(sve_set_vq)
* VQ must already be configured by caller, any further updates of VQ
* will need to ensure that the register state remains valid.
*
- * x0 = VQ - 1
+ * x0 = include FFR?
+ * x1 = VQ - 1
*/
SYM_FUNC_START(sve_flush_live)
- cbz x0, 1f // A VQ-1 of 0 is 128 bits so no extra Z state
+ cbz x1, 1f // A VQ-1 of 0 is 128 bits so no extra Z state
sve_flush_z
-1: sve_flush_p_ffr
- ret
+1: sve_flush_p
+ tbz x0, #0, 2f
+ sve_flush_ffr
+2: ret
SYM_FUNC_END(sve_flush_live)
#endif /* CONFIG_ARM64_SVE */
diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 0f6df1ece618..3d5d243c3f1c 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -289,7 +289,7 @@ static void task_fpsimd_load(void)
if (IS_ENABLED(CONFIG_ARM64_SVE) && test_thread_flag(TIF_SVE))
sve_load_state(sve_pffr(¤t->thread),
- ¤t->thread.uw.fpsimd_state.fpsr,
+ ¤t->thread.uw.fpsimd_state.fpsr, true,
sve_vq_from_vl(current->thread.sve_vl) - 1);
else
fpsimd_load_state(¤t->thread.uw.fpsimd_state);
@@ -325,7 +325,7 @@ static void fpsimd_save(void)
sve_save_state((char *)last->sve_state +
sve_ffr_offset(last->sve_vl),
- &last->st->fpsr);
+ &last->st->fpsr, true);
} else {
fpsimd_save_state(last->st);
}
@@ -962,7 +962,7 @@ void do_sve_acc(unsigned int esr, struct pt_regs *regs)
unsigned long vq_minus_one =
sve_vq_from_vl(current->thread.sve_vl) - 1;
sve_set_vq(vq_minus_one);
- sve_flush_live(vq_minus_one);
+ sve_flush_live(true, vq_minus_one);
fpsimd_bind_task_to_cpu();
} else {
fpsimd_to_sve(current);
@@ -1356,7 +1356,8 @@ void __efi_fpsimd_begin(void)
__this_cpu_write(efi_sve_state_used, true);
sve_save_state(sve_state + sve_ffr_offset(sve_max_vl),
- &this_cpu_ptr(&efi_fpsimd_state)->fpsr);
+ &this_cpu_ptr(&efi_fpsimd_state)->fpsr,
+ true);
} else {
fpsimd_save_state(this_cpu_ptr(&efi_fpsimd_state));
}
@@ -1382,6 +1383,7 @@ void __efi_fpsimd_end(void)
sve_load_state(sve_state + sve_ffr_offset(sve_max_vl),
&this_cpu_ptr(&efi_fpsimd_state)->fpsr,
+ true,
sve_vq_from_vl(sve_get_vl()) - 1);
__this_cpu_write(efi_sve_state_used, false);
diff --git a/arch/arm64/kvm/hyp/fpsimd.S b/arch/arm64/kvm/hyp/fpsimd.S
index 3c635929771a..1bb3b04b84e6 100644
--- a/arch/arm64/kvm/hyp/fpsimd.S
+++ b/arch/arm64/kvm/hyp/fpsimd.S
@@ -21,11 +21,13 @@ SYM_FUNC_START(__fpsimd_restore_state)
SYM_FUNC_END(__fpsimd_restore_state)
SYM_FUNC_START(__sve_restore_state)
- __sve_load 0, x1, 2
+ mov x2, #1
+ __sve_load 0, x1, x2, 3
ret
SYM_FUNC_END(__sve_restore_state)
SYM_FUNC_START(__sve_save_state)
- sve_save 0, x1, 2
+ mov x2, #1
+ sve_save 0, x1, x2, 3
ret
SYM_FUNC_END(__sve_save_state)
--
2.30.2
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