* [PATCH v7 1/2] arm64: adjust el0_sync so that a function can be called
2014-05-30 19:34 [PATCH v7 0/2] context tracker support for arm64 Larry Bassel
@ 2014-05-30 19:34 ` Larry Bassel
2014-05-30 19:34 ` [PATCH v7 2/2] arm64: enable context tracking Larry Bassel
2014-06-02 19:51 ` [PATCH v7 0/2] context tracker support for arm64 Kevin Hilman
2 siblings, 0 replies; 4+ messages in thread
From: Larry Bassel @ 2014-05-30 19:34 UTC (permalink / raw)
To: linux-arm-kernel
To implement the context tracker properly on arm64,
a function call needs to be made after debugging and
interrupts are turned on, but before the lr is changed
to point to ret_to_user(). If the function call
is made after the lr is changed the function will not
return to the correct place.
For similar reasons, defer the setting of x0 so that
it doesn't need to be saved around the function call
(save far_el1 in x26 temporarily instead).
Signed-off-by: Larry Bassel <larry.bassel@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
---
arch/arm64/kernel/entry.S | 19 +++++++++++++------
1 file changed, 13 insertions(+), 6 deletions(-)
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index e8b23a3..b0101b9 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -354,7 +354,6 @@ el0_sync:
lsr x24, x25, #ESR_EL1_EC_SHIFT // exception class
cmp x24, #ESR_EL1_EC_SVC64 // SVC in 64-bit state
b.eq el0_svc
- adr lr, ret_to_user
cmp x24, #ESR_EL1_EC_DABT_EL0 // data abort in EL0
b.eq el0_da
cmp x24, #ESR_EL1_EC_IABT_EL0 // instruction abort in EL0
@@ -383,7 +382,6 @@ el0_sync_compat:
lsr x24, x25, #ESR_EL1_EC_SHIFT // exception class
cmp x24, #ESR_EL1_EC_SVC32 // SVC in 32-bit state
b.eq el0_svc_compat
- adr lr, ret_to_user
cmp x24, #ESR_EL1_EC_DABT_EL0 // data abort in EL0
b.eq el0_da
cmp x24, #ESR_EL1_EC_IABT_EL0 // instruction abort in EL0
@@ -426,22 +424,25 @@ el0_da:
/*
* Data abort handling
*/
- mrs x0, far_el1
- bic x0, x0, #(0xff << 56)
+ mrs x26, far_el1
// enable interrupts before calling the main handler
enable_dbg_and_irq
+ bic x0, x26, #(0xff << 56)
mov x1, x25
mov x2, sp
+ adr lr, ret_to_user
b do_mem_abort
el0_ia:
/*
* Instruction abort handling
*/
- mrs x0, far_el1
+ mrs x26, far_el1
// enable interrupts before calling the main handler
enable_dbg_and_irq
+ mov x0, x26
orr x1, x25, #1 << 24 // use reserved ISS bit for instruction aborts
mov x2, sp
+ adr lr, ret_to_user
b do_mem_abort
el0_fpsimd_acc:
/*
@@ -450,6 +451,7 @@ el0_fpsimd_acc:
enable_dbg
mov x0, x25
mov x1, sp
+ adr lr, ret_to_user
b do_fpsimd_acc
el0_fpsimd_exc:
/*
@@ -458,16 +460,19 @@ el0_fpsimd_exc:
enable_dbg
mov x0, x25
mov x1, sp
+ adr lr, ret_to_user
b do_fpsimd_exc
el0_sp_pc:
/*
* Stack or PC alignment exception handling
*/
- mrs x0, far_el1
+ mrs x26, far_el1
// enable interrupts before calling the main handler
enable_dbg_and_irq
+ mov x0, x26
mov x1, x25
mov x2, sp
+ adr lr, ret_to_user
b do_sp_pc_abort
el0_undef:
/*
@@ -476,6 +481,7 @@ el0_undef:
// enable interrupts before calling the main handler
enable_dbg_and_irq
mov x0, sp
+ adr lr, ret_to_user
b do_undefinstr
el0_dbg:
/*
@@ -493,6 +499,7 @@ el0_inv:
mov x0, sp
mov x1, #BAD_SYNC
mrs x2, esr_el1
+ adr lr, ret_to_user
b bad_mode
ENDPROC(el0_sync)
--
1.8.3.2
^ permalink raw reply related [flat|nested] 4+ messages in thread
* [PATCH v7 2/2] arm64: enable context tracking
2014-05-30 19:34 [PATCH v7 0/2] context tracker support for arm64 Larry Bassel
2014-05-30 19:34 ` [PATCH v7 1/2] arm64: adjust el0_sync so that a function can be called Larry Bassel
@ 2014-05-30 19:34 ` Larry Bassel
2014-06-02 19:51 ` [PATCH v7 0/2] context tracker support for arm64 Kevin Hilman
2 siblings, 0 replies; 4+ messages in thread
From: Larry Bassel @ 2014-05-30 19:34 UTC (permalink / raw)
To: linux-arm-kernel
Make calls to ct_user_enter when the kernel is exited
and ct_user_exit when the kernel is entered (in el0_da,
el0_ia, el0_svc, el0_irq and all of the "error" paths).
These macros expand to function calls which will only work
properly if el0_sync and related code has been rearranged
(in a previous patch of this series).
The calls to ct_user_exit are made after hw debugging has been
enabled (enable_dbg_and_irq).
The call to ct_user_enter is made at the beginning of the
kernel_exit macro.
This patch is based on earlier work by Kevin Hilman.
Save/restore optimizations were also done by Kevin.
Signed-off-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Larry Bassel <larry.bassel@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
---
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/thread_info.h | 4 ++++
arch/arm64/kernel/entry.S | 39 +++++++++++++++++++++++++++++++++++-
3 files changed, 43 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index e759af5..ef18ae5 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -55,6 +55,7 @@ config ARM64
select RTC_LIB
select SPARSE_IRQ
select SYSCTL_EXCEPTION_TRACE
+ select HAVE_CONTEXT_TRACKING
help
ARM 64-bit (AArch64) Linux support.
diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index 720e70b..8363f34 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -100,6 +100,7 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_SIGPENDING 0
#define TIF_NEED_RESCHED 1
#define TIF_NOTIFY_RESUME 2 /* callback before returning to user */
+#define TIF_NOHZ 7
#define TIF_SYSCALL_TRACE 8
#define TIF_POLLING_NRFLAG 16
#define TIF_MEMDIE 18 /* is terminating due to OOM killer */
@@ -113,9 +114,12 @@ static inline struct thread_info *current_thread_info(void)
#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
#define _TIF_32BIT (1 << TIF_32BIT)
+#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
+#define _TIF_NOHZ (1 << TIF_NOHZ)
#define _TIF_WORK_MASK (_TIF_NEED_RESCHED | _TIF_SIGPENDING | \
_TIF_NOTIFY_RESUME)
+#define _TIF_SYSCALL_WORK (_TIF_SYSCALL_TRACE | _TIF_NOHZ)
#endif /* __KERNEL__ */
#endif /* __ASM_THREAD_INFO_H */
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index b0101b9..39d4dc9 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -30,6 +30,32 @@
#include <asm/unistd32.h>
/*
+ * Context tracking subsystem. Used to instrument transitions
+ * between user and kernel mode.
+ */
+ .macro ct_user_exit, syscall = 0
+#ifdef CONFIG_CONTEXT_TRACKING
+ bl context_tracking_user_exit
+ .if \syscall == 1
+ /*
+ * Save/restore needed during syscalls. Restore syscall arguments from
+ * the values already saved on stack during kernel_entry.
+ */
+ ldp x0, x1, [sp]
+ ldp x2, x3, [sp, #S_X2]
+ ldp x4, x5, [sp, #S_X4]
+ ldp x6, x7, [sp, #S_X6]
+ .endif
+#endif
+ .endm
+
+ .macro ct_user_enter
+#ifdef CONFIG_CONTEXT_TRACKING
+ bl context_tracking_user_enter
+#endif
+ .endm
+
+/*
* Bad Abort numbers
*-----------------
*/
@@ -91,6 +117,7 @@
.macro kernel_exit, el, ret = 0
ldp x21, x22, [sp, #S_PC] // load ELR, SPSR
.if \el == 0
+ ct_user_enter
ldr x23, [sp, #S_SP] // load return stack pointer
.endif
.if \ret
@@ -318,6 +345,7 @@ el1_irq:
bl trace_hardirqs_off
#endif
+ ct_user_exit
irq_handler
#ifdef CONFIG_PREEMPT
@@ -427,6 +455,7 @@ el0_da:
mrs x26, far_el1
// enable interrupts before calling the main handler
enable_dbg_and_irq
+ ct_user_exit
bic x0, x26, #(0xff << 56)
mov x1, x25
mov x2, sp
@@ -439,6 +468,7 @@ el0_ia:
mrs x26, far_el1
// enable interrupts before calling the main handler
enable_dbg_and_irq
+ ct_user_exit
mov x0, x26
orr x1, x25, #1 << 24 // use reserved ISS bit for instruction aborts
mov x2, sp
@@ -449,6 +479,7 @@ el0_fpsimd_acc:
* Floating Point or Advanced SIMD access
*/
enable_dbg
+ ct_user_exit
mov x0, x25
mov x1, sp
adr lr, ret_to_user
@@ -458,6 +489,7 @@ el0_fpsimd_exc:
* Floating Point or Advanced SIMD exception
*/
enable_dbg
+ ct_user_exit
mov x0, x25
mov x1, sp
adr lr, ret_to_user
@@ -480,6 +512,7 @@ el0_undef:
*/
// enable interrupts before calling the main handler
enable_dbg_and_irq
+ ct_user_exit
mov x0, sp
adr lr, ret_to_user
b do_undefinstr
@@ -493,9 +526,11 @@ el0_dbg:
mov x2, sp
bl do_debug_exception
enable_dbg
+ ct_user_exit
b ret_to_user
el0_inv:
enable_dbg
+ ct_user_exit
mov x0, sp
mov x1, #BAD_SYNC
mrs x2, esr_el1
@@ -616,9 +651,11 @@ el0_svc:
el0_svc_naked: // compat entry point
stp x0, scno, [sp, #S_ORIG_X0] // save the original x0 and syscall number
enable_dbg_and_irq
+ ct_user_exit 1
ldr x16, [tsk, #TI_FLAGS] // check for syscall tracing
- tbnz x16, #TIF_SYSCALL_TRACE, __sys_trace // are we tracing syscalls?
+ and x16, x16, #_TIF_SYSCALL_WORK // are we tracing syscalls?
+ cbnz x16, __sys_trace
adr lr, ret_fast_syscall // return address
cmp scno, sc_nr // check upper syscall limit
b.hs ni_sys
--
1.8.3.2
^ permalink raw reply related [flat|nested] 4+ messages in thread