* [PATCH v5b 8/8] newlib: libc: setjmp M-profile PACBTI-enablement
@ 2023-01-10 14:02 Victor L. Do Nascimento
2023-01-10 16:50 ` Richard Earnshaw
0 siblings, 1 reply; 2+ messages in thread
From: Victor L. Do Nascimento @ 2023-01-10 14:02 UTC (permalink / raw)
To: newlib; +Cc: Richard.Earnshaw
This patch revision provides the following improvements to proposed
patch implementation:
* Load ip directly when restoring PAC code from stack for
authentication in longjmp epilogue.
* Improve code readability by defining the JUMPBUF_PAC macro to
map onto the otherwise obscure 104 constant used in str/ldr
instructions.
Add function prologue/epilogue to conditionally add BTI landing pads
and/or PAC code generation & authentication instructions depending on
compilation flags.
---
newlib/libc/machine/arm/setjmp.S | 43 ++++++++++++++++++++++++++++++++
1 file changed, 43 insertions(+)
diff --git a/newlib/libc/machine/arm/setjmp.S b/newlib/libc/machine/arm/setjmp.S
index d814afea8..5213c063b 100644
--- a/newlib/libc/machine/arm/setjmp.S
+++ b/newlib/libc/machine/arm/setjmp.S
@@ -22,6 +22,11 @@
#define SIZE(x)
#endif
+/* Jump buffer allocation sizes. */
+#define JUMPBUF_CORE_REGS_SIZE (10 * 4)
+#define JUMPBUF_FP_REGS_SIZE (8 * 8)
+#define JUMPBUF_PAC (JUMPBUF_CORE_REGS_SIZE + JUMPBUF_FP_REGS_SIZE + 0)
+
/* Arm/Thumb interworking support:
The interworking scheme expects functions to use a BX instruction
@@ -155,6 +160,8 @@ SYM (.arm_start_of.\name):
.align 2
MODE
.globl SYM (\name)
+ .fnstart
+ .cfi_startproc
TYPE (\name)
SYM (\name):
PROLOGUE \name
@@ -162,6 +169,8 @@ SYM (\name):
.macro FUNC_END name
RET
+ .cfi_endproc
+ .fnend
SIZE (\name)
.endm
@@ -171,6 +180,21 @@ SYM (\name):
FUNC_START setjmp
+#if __ARM_FEATURE_PAC_DEFAULT
+# if __ARM_FEATURE_BTI_DEFAULT
+ pacbti ip, lr, sp
+# else
+ pac ip, lr, sp
+# endif /* __ARM_FEATURE_BTI_DEFAULT */
+ mov r3, ip
+ str r3, [r0, #JUMPBUF_PAC]
+ .cfi_register 143, 12
+#else
+# if __ARM_FEATURE_BTI_DEFAULT
+ bti
+# endif /* __ARM_FEATURE_BTI_DEFAULT */
+#endif /* __ARM_FEATURE_PAC_DEFAULT */
+
/* Save all the callee-preserved registers into the jump buffer. */
#ifdef __thumb2__
mov ip, sp
@@ -184,6 +208,10 @@ SYM (\name):
/* When setting up the jump buffer return 0. */
mov r0, #0
+#if __ARM_FEATURE_PAC_DEFAULT
+ mov ip, r3
+ aut ip, lr, sp
+#endif /* __ARM_FEATURE_PAC_DEFAULT */
FUNC_END setjmp
@@ -193,6 +221,16 @@ SYM (\name):
FUNC_START longjmp
+#if __ARM_FEATURE_BTI_DEFAULT
+ bti
+#endif /* __ARM_FEATURE_BTI_DEFAULT */
+
+#if __ARM_FEATURE_PAC_DEFAULT
+ /* Keep original jmpbuf address for retrieving pac-code
+ for authentication. */
+ mov r2, r0
+#endif /* __ARM_FEATURE_PAC_DEFAULT */
+
/* If we have stack extension code it ought to be handled here. */
/* Restore the registers, retrieving the state when setjmp() was called. */
@@ -212,5 +250,10 @@ SYM (\name):
it eq
moveq r0, #1
+#if __ARM_FEATURE_PAC_DEFAULT
+ ldr ip, [r2, #JUMPBUF_PAC]
+ aut ip, lr, sp
+#endif /* __ARM_FEATURE_PAC_DEFAULT */
+
FUNC_END longjmp
#endif
--
2.36.1
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH v5b 8/8] newlib: libc: setjmp M-profile PACBTI-enablement
2023-01-10 14:02 [PATCH v5b 8/8] newlib: libc: setjmp M-profile PACBTI-enablement Victor L. Do Nascimento
@ 2023-01-10 16:50 ` Richard Earnshaw
0 siblings, 0 replies; 2+ messages in thread
From: Richard Earnshaw @ 2023-01-10 16:50 UTC (permalink / raw)
To: Victor L. Do Nascimento, newlib
On 10/01/2023 14:02, Victor L. Do Nascimento wrote:
> This patch revision provides the following improvements to proposed
> patch implementation:
> * Load ip directly when restoring PAC code from stack for
> authentication in longjmp epilogue.
> * Improve code readability by defining the JUMPBUF_PAC macro to
> map onto the otherwise obscure 104 constant used in str/ldr
> instructions.
>
> Add function prologue/epilogue to conditionally add BTI landing pads
> and/or PAC code generation & authentication instructions depending on
> compilation flags.
Thanks. I've now pushed the entire series.
R.
> ---
> newlib/libc/machine/arm/setjmp.S | 43 ++++++++++++++++++++++++++++++++
> 1 file changed, 43 insertions(+)
>
> diff --git a/newlib/libc/machine/arm/setjmp.S b/newlib/libc/machine/arm/setjmp.S
> index d814afea8..5213c063b 100644
> --- a/newlib/libc/machine/arm/setjmp.S
> +++ b/newlib/libc/machine/arm/setjmp.S
> @@ -22,6 +22,11 @@
> #define SIZE(x)
> #endif
>
> +/* Jump buffer allocation sizes. */
> +#define JUMPBUF_CORE_REGS_SIZE (10 * 4)
> +#define JUMPBUF_FP_REGS_SIZE (8 * 8)
> +#define JUMPBUF_PAC (JUMPBUF_CORE_REGS_SIZE + JUMPBUF_FP_REGS_SIZE + 0)
> +
> /* Arm/Thumb interworking support:
>
> The interworking scheme expects functions to use a BX instruction
> @@ -155,6 +160,8 @@ SYM (.arm_start_of.\name):
> .align 2
> MODE
> .globl SYM (\name)
> + .fnstart
> + .cfi_startproc
> TYPE (\name)
> SYM (\name):
> PROLOGUE \name
> @@ -162,6 +169,8 @@ SYM (\name):
>
> .macro FUNC_END name
> RET
> + .cfi_endproc
> + .fnend
> SIZE (\name)
> .endm
>
> @@ -171,6 +180,21 @@ SYM (\name):
>
> FUNC_START setjmp
>
> +#if __ARM_FEATURE_PAC_DEFAULT
> +# if __ARM_FEATURE_BTI_DEFAULT
> + pacbti ip, lr, sp
> +# else
> + pac ip, lr, sp
> +# endif /* __ARM_FEATURE_BTI_DEFAULT */
> + mov r3, ip
> + str r3, [r0, #JUMPBUF_PAC]
> + .cfi_register 143, 12
> +#else
> +# if __ARM_FEATURE_BTI_DEFAULT
> + bti
> +# endif /* __ARM_FEATURE_BTI_DEFAULT */
> +#endif /* __ARM_FEATURE_PAC_DEFAULT */
> +
> /* Save all the callee-preserved registers into the jump buffer. */
> #ifdef __thumb2__
> mov ip, sp
> @@ -184,6 +208,10 @@ SYM (\name):
>
> /* When setting up the jump buffer return 0. */
> mov r0, #0
> +#if __ARM_FEATURE_PAC_DEFAULT
> + mov ip, r3
> + aut ip, lr, sp
> +#endif /* __ARM_FEATURE_PAC_DEFAULT */
>
> FUNC_END setjmp
>
> @@ -193,6 +221,16 @@ SYM (\name):
>
> FUNC_START longjmp
>
> +#if __ARM_FEATURE_BTI_DEFAULT
> + bti
> +#endif /* __ARM_FEATURE_BTI_DEFAULT */
> +
> +#if __ARM_FEATURE_PAC_DEFAULT
> + /* Keep original jmpbuf address for retrieving pac-code
> + for authentication. */
> + mov r2, r0
> +#endif /* __ARM_FEATURE_PAC_DEFAULT */
> +
> /* If we have stack extension code it ought to be handled here. */
>
> /* Restore the registers, retrieving the state when setjmp() was called. */
> @@ -212,5 +250,10 @@ SYM (\name):
> it eq
> moveq r0, #1
>
> +#if __ARM_FEATURE_PAC_DEFAULT
> + ldr ip, [r2, #JUMPBUF_PAC]
> + aut ip, lr, sp
> +#endif /* __ARM_FEATURE_PAC_DEFAULT */
> +
> FUNC_END longjmp
> #endif
^ permalink raw reply [flat|nested] 2+ messages in thread
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