From: "Victor L. Do Nascimento" <victor.donascimento@arm.com>
To: <newlib@sourceware.org>
Cc: <Richard.Earnshaw@foss.arm.com>
Subject: [PATCH v5b 8/8] newlib: libc: setjmp M-profile PACBTI-enablement
Date: Tue, 10 Jan 2023 14:02:08 +0000 [thread overview]
Message-ID: <yw8jpmbm8p3z.fsf@arm.com> (raw)
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
next reply other threads:[~2023-01-10 14:03 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-10 14:02 Victor L. Do Nascimento [this message]
2023-01-10 16:50 ` Richard Earnshaw
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