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Date: Wed, 10 Jul 2013 22:55:18 +0300
From: Timo Teräs <timo.teras@....fi>
To: musl@...ts.openwall.com
Cc: Timo Teräs <timo.teras@....fi>
Subject: [PATCH v3] Unwind support for ARM EABI
ARM EABI does not use the .eh_frame and .eh_frame_hdr for unwinding.
Instead the ABI specifies it's own way to unwind using .ARM.exidx and
.ARM.extab.
libgcc uses __gnu_Unwind_Find_exidx (libc must implement this) when
unwinding using exidx. This function is implemented here.
---
v3 changes per discussion at #musl:
- removed Unwind_Ptr (using uintptr_t directly)
- removed the redundant "if (match)" for data->exidx_* assignment
arch/arm/src/find_exidx.c | 42 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 42 insertions(+)
create mode 100644 arch/arm/src/find_exidx.c
diff --git a/arch/arm/src/find_exidx.c b/arch/arm/src/find_exidx.c
new file mode 100644
index 0000000..77c4472
--- /dev/null
+++ b/arch/arm/src/find_exidx.c
@@ -0,0 +1,42 @@
+#define _GNU_SOURCE
+#include <link.h>
+#include <stdint.h>
+
+struct find_exidx_data {
+ uintptr_t pc, exidx_start;
+ int exidx_len;
+};
+
+static int find_exidx(struct dl_phdr_info *info, size_t size, void *ptr)
+{
+ struct find_exidx_data *data = ptr;
+ const ElfW(Phdr) *phdr = info->dlpi_phdr;
+ uintptr_t addr, exidx_start = 0;
+ int i, match = 0, exidx_len = 0;
+
+ for (i = info->dlpi_phnum; i > 0; i--, phdr++) {
+ addr = info->dlpi_addr + phdr->p_vaddr;
+ switch (phdr->p_type) {
+ case PT_LOAD:
+ match |= data->pc >= addr && data->pc < addr + phdr->p_memsz;
+ break;
+ case PT_ARM_EXIDX:
+ exidx_start = addr;
+ exidx_len = phdr->p_memsz;
+ break;
+ }
+ }
+ data->exidx_start = exidx_start;
+ data->exidx_len = exidx_len;
+ return match;
+}
+
+uintptr_t __gnu_Unwind_Find_exidx(uintptr_t pc, int *pcount)
+{
+ struct find_exidx_data data;
+ data.pc = pc;
+ if (dl_iterate_phdr(find_exidx, &data) <= 0)
+ return 0;
+ *pcount = data.exidx_len / 8;
+ return data.exidx_start;
+}
--
1.8.3.2
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