From 7433498b7f1a79bf98ba272fd461f0ff9f1daa02 Mon Sep 17 00:00:00 2001 From: Alan Modra Date: Wed, 24 Jan 2018 15:22:17 +1030 Subject: 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 --- 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(-) (limited to 'gdb') 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 + + * 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 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, */ { 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 ", 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) */ { -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) */ { -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) */ { -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) */ { -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) */ { -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) */ { -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) */ { -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; -- cgit v1.1