[PATCH v2] arm64: Add support for additional relocations in the kexec purgatory code

[Catalin Marinas]

When compiling the kexec-tools with gcc6, the following additional
reolcations are generated in the purgatory.ro file:

R_AARCH64_ADR_PREL_PG_HI21
R_AARCH64_ADD_ABS_LO12_NC
R_AARCH64_LDST64_ABS_LO12_NC

This patch modifies the arm64 machine_apply_elf_rel() function to handle
these relocations.

Cc: Geoff Levand <***@infradead.org>
Signed-off-by: Catalin Marinas <***@arm.com>
---

Changes for v2:
- Fixed the type string to drop the "R_AARCH64_" prefix

kexec/arch/arm64/kexec-arm64.c | 35 +++++++++++++++++++++++++++++++++++
1 file changed, 35 insertions(+)

diff --git a/kexec/arch/arm64/kexec-arm64.c b/kexec/arch/arm64/kexec-arm64.c
index 2e8839a..e067a23 100644
--- a/kexec/arch/arm64/kexec-arm64.c
+++ b/kexec/arch/arm64/kexec-arm64.c
@@ -550,6 +550,14 @@ void machine_apply_elf_rel(struct mem_ehdr *ehdr, struct mem_sym *UNUSED(sym),
# define R_AARCH64_ADR_PREL_LO21 274
#endif

+#if !defined(R_AARCH64_ADR_PREL_PG_HI21)
+# define R_AARCH64_ADR_PREL_PG_HI21 275
+#endif
+
+#if !defined(R_AARCH64_ADD_ABS_LO12_NC)
+# define R_AARCH64_ADD_ABS_LO12_NC 277
+#endif
+
#if !defined(R_AARCH64_JUMP26)
# define R_AARCH64_JUMP26 282
#endif
@@ -558,10 +566,15 @@ void machine_apply_elf_rel(struct mem_ehdr *ehdr, struct mem_sym *UNUSED(sym),
# define R_AARCH64_CALL26 283
#endif

+#if !defined(R_AARCH64_LDST64_ABS_LO12_NC)
+# define R_AARCH64_LDST64_ABS_LO12_NC 286
+#endif
+
uint64_t *loc64;
uint32_t *loc32;
uint64_t *location = (uint64_t *)ptr;
uint64_t data = *location;
+ uint64_t imm;
const char *type = NULL;

switch(r_type) {
@@ -585,6 +598,19 @@ void machine_apply_elf_rel(struct mem_ehdr *ehdr, struct mem_sym *UNUSED(sym),
*loc32 = cpu_to_le32(le32_to_cpu(*loc32)
+ (((value - address) << 3) & 0xffffe0));
break;
+ case R_AARCH64_ADR_PREL_PG_HI21:
+ type = "ADR_PREL_PG_HI21";
+ imm = ((value & ~0xfff) - (address & ~0xfff)) >> 12;
+ loc32 = ptr;
+ *loc32 = cpu_to_le32(le32_to_cpu(*loc32)
+ + ((imm & 3) << 29) + ((imm & 0x1ffffc) << (5 - 2)));
+ break;
+ case R_AARCH64_ADD_ABS_LO12_NC:
+ type = "ADD_ABS_LO12_NC";
+ loc32 = ptr;
+ *loc32 = cpu_to_le32(le32_to_cpu(*loc32)
+ + ((value & 0xfff) << 10));
+ break;
case R_AARCH64_JUMP26:
type = "JUMP26";
loc32 = ptr;
@@ -597,6 +623,15 @@ void machine_apply_elf_rel(struct mem_ehdr *ehdr, struct mem_sym *UNUSED(sym),
*loc32 = cpu_to_le32(le32_to_cpu(*loc32)
+ (((value - address) >> 2) & 0x3ffffff));
break;
+ case R_AARCH64_LDST64_ABS_LO12_NC:
+ if (value & 7)
+ die("%s: ERROR Unaligned value: %lx\n", __func__,
+ value);
+ type = "LDST64_ABS_LO12_NC";
+ loc32 = ptr;
+ *loc32 = cpu_to_le32(le32_to_cpu(*loc32)
+ + ((value & 0xff8) << (10 - 3)));
+ break;
default:
die("%s: ERROR Unknown type: %lu\n", __func__, r_type);
break;

[Geoff Levand]

Post by Catalin Marinas
When compiling the kexec-tools with gcc6, the following additional
R_AARCH64_ADR_PREL_PG_HI21
R_AARCH64_ADD_ABS_LO12_NC
R_AARCH64_LDST64_ABS_LO12_NC

Looks good. Simon, please apply.

Reviewed-by: Geoff Levand <***@infradead.org>

[Simon Horman]

Post by Geoff Levand

Post by Catalin Marinas
When compiling the kexec-tools with gcc6, the following additional
R_AARCH64_ADR_PREL_PG_HI21
R_AARCH64_ADD_ABS_LO12_NC
R_AARCH64_LDST64_ABS_LO12_NC

Looks good. Simon, please apply.

Thanks, applied.

[Pratyush Anand]

Post by Catalin Marinas
When compiling the kexec-tools with gcc6, the following additional
R_AARCH64_ADR_PREL_PG_HI21
R_AARCH64_ADD_ABS_LO12_NC
R_AARCH64_LDST64_ABS_LO12_NC
This patch modifies the arm64 machine_apply_elf_rel() function to handle
these relocations.

Noticed that, gcc version of fedora koji(6.2.1-2.fc25) inserts another
relocation and kexec-tools generates following error.

machine_apply_elf_rel: ERROR Unknown type: 261

I have a fixup here:
https://github.com/pratyushanand/kexec-tools/commit/0eb8a908f617e0f957df7fb3ef293596f47e6832

May be I will send them separately.

~Pratyush

Post by Catalin Marinas
---
- Fixed the type string to drop the "R_AARCH64_" prefix
kexec/arch/arm64/kexec-arm64.c | 35 +++++++++++++++++++++++++++++++++++
1 file changed, 35 insertions(+)
diff --git a/kexec/arch/arm64/kexec-arm64.c b/kexec/arch/arm64/kexec-arm64.c
index 2e8839a..e067a23 100644
--- a/kexec/arch/arm64/kexec-arm64.c
+++ b/kexec/arch/arm64/kexec-arm64.c
@@ -550,6 +550,14 @@ void machine_apply_elf_rel(struct mem_ehdr *ehdr, struct mem_sym *UNUSED(sym),
# define R_AARCH64_ADR_PREL_LO21 274
#endif
+#if !defined(R_AARCH64_ADR_PREL_PG_HI21)
+# define R_AARCH64_ADR_PREL_PG_HI21 275
+#endif
+
+#if !defined(R_AARCH64_ADD_ABS_LO12_NC)
+# define R_AARCH64_ADD_ABS_LO12_NC 277
+#endif
+
#if !defined(R_AARCH64_JUMP26)
# define R_AARCH64_JUMP26 282
#endif
@@ -558,10 +566,15 @@ void machine_apply_elf_rel(struct mem_ehdr *ehdr, struct mem_sym *UNUSED(sym),
# define R_AARCH64_CALL26 283
#endif
+#if !defined(R_AARCH64_LDST64_ABS_LO12_NC)
+# define R_AARCH64_LDST64_ABS_LO12_NC 286
+#endif
+
uint64_t *loc64;
uint32_t *loc32;
uint64_t *location = (uint64_t *)ptr;
uint64_t data = *location;
+ uint64_t imm;
const char *type = NULL;
switch(r_type) {
@@ -585,6 +598,19 @@ void machine_apply_elf_rel(struct mem_ehdr *ehdr, struct mem_sym *UNUSED(sym),
*loc32 = cpu_to_le32(le32_to_cpu(*loc32)
+ (((value - address) << 3) & 0xffffe0));
break;
+ type = "ADR_PREL_PG_HI21";
+ imm = ((value & ~0xfff) - (address & ~0xfff)) >> 12;
+ loc32 = ptr;
+ *loc32 = cpu_to_le32(le32_to_cpu(*loc32)
+ + ((imm & 3) << 29) + ((imm & 0x1ffffc) << (5 - 2)));
+ break;
+ type = "ADD_ABS_LO12_NC";
+ loc32 = ptr;
+ *loc32 = cpu_to_le32(le32_to_cpu(*loc32)
+ + ((value & 0xfff) << 10));
+ break;
type = "JUMP26";
loc32 = ptr;
@@ -597,6 +623,15 @@ void machine_apply_elf_rel(struct mem_ehdr *ehdr, struct mem_sym *UNUSED(sym),
*loc32 = cpu_to_le32(le32_to_cpu(*loc32)
+ (((value - address) >> 2) & 0x3ffffff));
break;
+ if (value & 7)
+ die("%s: ERROR Unaligned value: %lx\n", __func__,
+ value);
+ type = "LDST64_ABS_LO12_NC";
+ loc32 = ptr;
+ *loc32 = cpu_to_le32(le32_to_cpu(*loc32)
+ + ((value & 0xff8) << (10 - 3)));
+ break;
die("%s: ERROR Unknown type: %lu\n", __func__, r_type);
break;