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[binutils-gdb] PowerPC PLT stub matching
- From: Alan Modra <amodra at sourceware dot org>
- To: gdb-cvs at sourceware dot org
- Date: 26 Jan 2018 05:43:43 -0000
- Subject: [binutils-gdb] PowerPC PLT stub matching
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=7433498b7f1a79bf98ba272fd461f0ff9f1daa02
commit 7433498b7f1a79bf98ba272fd461f0ff9f1daa02
Author: Alan Modra <amodra@gmail.com>
Date: Wed Jan 24 15:22:17 2018 +1030
PowerPC PLT stub matching
This patch fixes a number of bugs in ppc32 plt stub matching code.
1) The 4-insn stubs for shared libs and PIEs weren't matched.
2) The executable stub miscalculated PLT entry address (by oring a
sign-extended quantity rather than adding).
3) Comments were not accurate.
In addition, the insn arrays are made const.
* ppc-linux-tdep.c (powerpc32_plt_stub): Make const.
(powerpc32_plt_stub_so_1): Rename from powerpc32_plt_stub_so.
Remove nop. Make const. Comment.
(powerpc32_plt_stub_so_2): New.
(POWERPC32_PLT_CHECK_LEN): Rename from POWERPC32_PLT_STUB_LEN.
Correct count. Update uses.
(ppc_skip_trampoline_code): Match powerpc32_plt_stub_so_2 too.
Move common code reading PLT entry word. Correct
powerpc32_plt_stub PLT address calculation.
* ppc64-tdep.c (ppc64_standard_linkage1): Make const.
(ppc64_standard_linkage2, ppc64_standard_linkage3): Likewise.
(ppc64_standard_linkage4, ppc64_standard_linkage5): Likewise.
(ppc64_standard_linkage6, ppc64_standard_linkage7): Likewise.
(ppc64_standard_linkage8): Likewise.
* rs6000-tdep.c (ppc_insns_match_pattern): Make pattern const.
Correct insns description.
* ppc-tdep.h (ppc_insns_match_pattern): Update prototype.
Reviewed-By: Yao Qi <qiyaoltc@gmail.com>
Diff:
---
gdb/ChangeLog | 20 ++++++++++++++
gdb/ppc-linux-tdep.c | 73 +++++++++++++++++++++++++++++++++-------------------
gdb/ppc-tdep.h | 2 +-
gdb/ppc64-tdep.c | 16 ++++++------
gdb/rs6000-tdep.c | 14 +++++-----
5 files changed, 83 insertions(+), 42 deletions(-)
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index d0a8dfd..6d1ff2a 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,23 @@
+2018-01-26 Alan Modra <amodra@gmail.com>
+
+ * ppc-linux-tdep.c (powerpc32_plt_stub): Make const.
+ (powerpc32_plt_stub_so_1): Rename from powerpc32_plt_stub_so.
+ Remove nop. Make const. Comment.
+ (powerpc32_plt_stub_so_2): New.
+ (POWERPC32_PLT_CHECK_LEN): Rename from POWERPC32_PLT_STUB_LEN.
+ Correct count. Update uses.
+ (ppc_skip_trampoline_code): Match powerpc32_plt_stub_so_2 too.
+ Move common code reading PLT entry word. Correct
+ powerpc32_plt_stub PLT address calculation.
+ * ppc64-tdep.c (ppc64_standard_linkage1): Make const.
+ (ppc64_standard_linkage2, ppc64_standard_linkage3): Likewise.
+ (ppc64_standard_linkage4, ppc64_standard_linkage5): Likewise.
+ (ppc64_standard_linkage6, ppc64_standard_linkage7): Likewise.
+ (ppc64_standard_linkage8): Likewise.
+ * rs6000-tdep.c (ppc_insns_match_pattern): Make pattern const.
+ Correct insns description.
+ * ppc-tdep.h (ppc_insns_match_pattern): Update prototype.
+
2018-01-24 Pedro Alves <palves@redhat.com>
GCC PR libstdc++/83906
diff --git a/gdb/ppc-linux-tdep.c b/gdb/ppc-linux-tdep.c
index bbe9e89..ed0ea13 100644
--- a/gdb/ppc-linux-tdep.c
+++ b/gdb/ppc-linux-tdep.c
@@ -256,8 +256,8 @@ ppc_linux_return_value (struct gdbarch *gdbarch, struct value *function,
readbuf, writebuf);
}
-/* PLT stub in executable. */
-static struct ppc_insn_pattern powerpc32_plt_stub[] =
+/* PLT stub in an executable. */
+static const struct ppc_insn_pattern powerpc32_plt_stub[] =
{
{ 0xffff0000, 0x3d600000, 0 }, /* lis r11, xxxx */
{ 0xffff0000, 0x816b0000, 0 }, /* lwz r11, xxxx(r11) */
@@ -266,16 +266,30 @@ static struct ppc_insn_pattern powerpc32_plt_stub[] =
{ 0, 0, 0 }
};
-/* PLT stub in shared library. */
-static struct ppc_insn_pattern powerpc32_plt_stub_so[] =
+/* PLT stubs in a shared library or PIE.
+ The first variant is used when the PLT entry is within +/-32k of
+ the GOT pointer (r30). */
+static const struct ppc_insn_pattern powerpc32_plt_stub_so_1[] =
{
{ 0xffff0000, 0x817e0000, 0 }, /* lwz r11, xxxx(r30) */
{ 0xffffffff, 0x7d6903a6, 0 }, /* mtctr r11 */
{ 0xffffffff, 0x4e800420, 0 }, /* bctr */
- { 0xffffffff, 0x60000000, 0 }, /* nop */
{ 0, 0, 0 }
};
-#define POWERPC32_PLT_STUB_LEN ARRAY_SIZE (powerpc32_plt_stub)
+
+/* The second variant is used when the PLT entry is more than +/-32k
+ from the GOT pointer (r30). */
+static const struct ppc_insn_pattern powerpc32_plt_stub_so_2[] =
+ {
+ { 0xffff0000, 0x3d7e0000, 0 }, /* addis r11, r30, xxxx */
+ { 0xffff0000, 0x816b0000, 0 }, /* lwz r11, xxxx(r11) */
+ { 0xffffffff, 0x7d6903a6, 0 }, /* mtctr r11 */
+ { 0xffffffff, 0x4e800420, 0 }, /* bctr */
+ { 0, 0, 0 }
+ };
+
+/* The max number of insns we check using ppc_insns_match_pattern. */
+#define POWERPC32_PLT_CHECK_LEN (ARRAY_SIZE (powerpc32_plt_stub) - 1)
/* Check if PC is in PLT stub. For non-secure PLT, stub is in .plt
section. For secure PLT, stub is in .text and we need to check
@@ -306,13 +320,13 @@ powerpc_linux_in_dynsym_resolve_code (CORE_ADDR pc)
When the execution direction is EXEC_REVERSE, scan backward to
check whether we are in the middle of a PLT stub. Currently,
- we only look-behind at most 4 instructions (the max length of PLT
+ we only look-behind at most 4 instructions (the max length of a PLT
stub sequence. */
static CORE_ADDR
ppc_skip_trampoline_code (struct frame_info *frame, CORE_ADDR pc)
{
- unsigned int insnbuf[POWERPC32_PLT_STUB_LEN];
+ unsigned int insnbuf[POWERPC32_PLT_CHECK_LEN];
struct gdbarch *gdbarch = get_frame_arch (frame);
struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
@@ -323,40 +337,47 @@ ppc_skip_trampoline_code (struct frame_info *frame, CORE_ADDR pc)
/* When reverse-debugging, scan backward to check whether we are
in the middle of trampoline code. */
if (execution_direction == EXEC_REVERSE)
- scan_limit = 4; /* At more 4 instructions. */
+ scan_limit = 4; /* At most 4 instructions. */
for (i = 0; i < scan_limit; i++)
{
if (ppc_insns_match_pattern (frame, pc, powerpc32_plt_stub, insnbuf))
{
- /* Insn pattern is
+ /* Calculate PLT entry address from
lis r11, xxxx
- lwz r11, xxxx(r11)
- Branch target is in r11. */
-
- target = (ppc_insn_d_field (insnbuf[0]) << 16)
- | ppc_insn_d_field (insnbuf[1]);
- target = read_memory_unsigned_integer (target, 4, byte_order);
+ lwz r11, xxxx(r11). */
+ target = ((ppc_insn_d_field (insnbuf[0]) << 16)
+ + ppc_insn_d_field (insnbuf[1]));
+ }
+ else if (i < ARRAY_SIZE (powerpc32_plt_stub_so_1) - 1
+ && ppc_insns_match_pattern (frame, pc, powerpc32_plt_stub_so_1,
+ insnbuf))
+ {
+ /* Calculate PLT entry address from
+ lwz r11, xxxx(r30). */
+ target = (ppc_insn_d_field (insnbuf[0])
+ + get_frame_register_unsigned (frame,
+ tdep->ppc_gp0_regnum + 30));
}
- else if (ppc_insns_match_pattern (frame, pc, powerpc32_plt_stub_so,
+ else if (ppc_insns_match_pattern (frame, pc, powerpc32_plt_stub_so_2,
insnbuf))
{
- /* Insn pattern is
- lwz r11, xxxx(r30)
- Branch target is in r11. */
-
- target = get_frame_register_unsigned (frame,
- tdep->ppc_gp0_regnum + 30)
- + ppc_insn_d_field (insnbuf[0]);
- target = read_memory_unsigned_integer (target, 4, byte_order);
+ /* Calculate PLT entry address from
+ addis r11, r30, xxxx
+ lwz r11, xxxx(r11). */
+ target = ((ppc_insn_d_field (insnbuf[0]) << 16)
+ + ppc_insn_d_field (insnbuf[1])
+ + get_frame_register_unsigned (frame,
+ tdep->ppc_gp0_regnum + 30));
}
else
{
- /* Scan backward one more instructions if doesn't match. */
+ /* Scan backward one more instruction if it doesn't match. */
pc -= 4;
continue;
}
+ target = read_memory_unsigned_integer (target, 4, byte_order);
return target;
}
diff --git a/gdb/ppc-tdep.h b/gdb/ppc-tdep.h
index 3004744..156f82d 100644
--- a/gdb/ppc-tdep.h
+++ b/gdb/ppc-tdep.h
@@ -330,7 +330,7 @@ struct ppc_insn_pattern
};
extern int ppc_insns_match_pattern (struct frame_info *frame, CORE_ADDR pc,
- struct ppc_insn_pattern *pattern,
+ const struct ppc_insn_pattern *pattern,
unsigned int *insns);
extern CORE_ADDR ppc_insn_d_field (unsigned int insn);
diff --git a/gdb/ppc64-tdep.c b/gdb/ppc64-tdep.c
index 7417232..5d8ccb4 100644
--- a/gdb/ppc64-tdep.c
+++ b/gdb/ppc64-tdep.c
@@ -80,7 +80,7 @@ ppc64_plt_entry_point (struct frame_info *frame, CORE_ADDR plt_off)
/* Old ELFv1 PLT call stub. */
-static struct ppc_insn_pattern ppc64_standard_linkage1[] =
+static const struct ppc_insn_pattern ppc64_standard_linkage1[] =
{
/* addis r12, r2, <any> */
{ insn_d (-1, -1, -1, 0), insn_d (15, 12, 2, 0), 0 },
@@ -119,7 +119,7 @@ static struct ppc_insn_pattern ppc64_standard_linkage1[] =
instructions following "cmpldi r2, 0", "bnectr+" and "b <glink_i>",
but there isn't any need to match them. */
-static struct ppc_insn_pattern ppc64_standard_linkage2[] =
+static const struct ppc_insn_pattern ppc64_standard_linkage2[] =
{
/* std r2, 40(r1) <optional> */
{ -1, insn_ds (62, 2, 1, 40, 0), 1 },
@@ -162,7 +162,7 @@ static struct ppc_insn_pattern ppc64_standard_linkage2[] =
/* ELFv1 PLT call stub to access PLT entries within +/- 32k of r2. */
-static struct ppc_insn_pattern ppc64_standard_linkage3[] =
+static const struct ppc_insn_pattern ppc64_standard_linkage3[] =
{
/* std r2, 40(r1) <optional> */
{ -1, insn_ds (62, 2, 1, 40, 0), 1 },
@@ -201,7 +201,7 @@ static struct ppc_insn_pattern ppc64_standard_linkage3[] =
A more modern variant of ppc64_standard_linkage2 differing in
register usage. */
-static struct ppc_insn_pattern ppc64_standard_linkage4[] =
+static const struct ppc_insn_pattern ppc64_standard_linkage4[] =
{
/* std r2, 40(r1) <optional> */
{ -1, insn_ds (62, 2, 1, 40, 0), 1 },
@@ -243,7 +243,7 @@ static struct ppc_insn_pattern ppc64_standard_linkage4[] =
A more modern variant of ppc64_standard_linkage3 differing in
register usage. */
-static struct ppc_insn_pattern ppc64_standard_linkage5[] =
+static const struct ppc_insn_pattern ppc64_standard_linkage5[] =
{
/* std r2, 40(r1) <optional> */
{ -1, insn_ds (62, 2, 1, 40, 0), 1 },
@@ -280,7 +280,7 @@ static struct ppc_insn_pattern ppc64_standard_linkage5[] =
/* ELFv2 PLT call stub to access PLT entries more than +/- 32k from r2. */
-static struct ppc_insn_pattern ppc64_standard_linkage6[] =
+static const struct ppc_insn_pattern ppc64_standard_linkage6[] =
{
/* std r2, 24(r1) <optional> */
{ -1, insn_ds (62, 2, 1, 24, 0), 1 },
@@ -302,7 +302,7 @@ static struct ppc_insn_pattern ppc64_standard_linkage6[] =
/* ELFv2 PLT call stub to access PLT entries within +/- 32k of r2. */
-static struct ppc_insn_pattern ppc64_standard_linkage7[] =
+static const struct ppc_insn_pattern ppc64_standard_linkage7[] =
{
/* std r2, 24(r1) <optional> */
{ -1, insn_ds (62, 2, 1, 24, 0), 1 },
@@ -322,7 +322,7 @@ static struct ppc_insn_pattern ppc64_standard_linkage7[] =
/* ELFv2 PLT call stub to access PLT entries more than +/- 32k from r2,
supporting fusion. */
-static struct ppc_insn_pattern ppc64_standard_linkage8[] =
+static const struct ppc_insn_pattern ppc64_standard_linkage8[] =
{
/* std r2, 24(r1) <optional> */
{ -1, insn_ds (62, 2, 1, 24, 0), 1 },
diff --git a/gdb/rs6000-tdep.c b/gdb/rs6000-tdep.c
index f81064e..3ec3817 100644
--- a/gdb/rs6000-tdep.c
+++ b/gdb/rs6000-tdep.c
@@ -6717,17 +6717,17 @@ read_insn (struct frame_info *frame, CORE_ADDR pc)
'struct ppc_insn_pattern' objects, terminated by an entry whose
mask is zero.
- When the match is successful, fill INSN[i] with what PATTERN[i]
+ When the match is successful, fill INSNS[i] with what PATTERN[i]
matched. If PATTERN[i] is optional, and the instruction wasn't
- present, set INSN[i] to 0 (which is not a valid PPC instruction).
- INSN should have as many elements as PATTERN. Note that, if
- PATTERN contains optional instructions which aren't present in
- memory, then INSN will have holes, so INSN[i] isn't necessarily the
- i'th instruction in memory. */
+ present, set INSNS[i] to 0 (which is not a valid PPC instruction).
+ INSNS should have as many elements as PATTERN, minus the terminator.
+ Note that, if PATTERN contains optional instructions which aren't
+ present in memory, then INSNS will have holes, so INSNS[i] isn't
+ necessarily the i'th instruction in memory. */
int
ppc_insns_match_pattern (struct frame_info *frame, CORE_ADDR pc,
- struct ppc_insn_pattern *pattern,
+ const struct ppc_insn_pattern *pattern,
unsigned int *insns)
{
int i;