Messages in this thread |  | | Date | Wed, 04 Dec 2013 19:23:02 +0200 | From | Taras Kondratiuk <> | Subject | Re: [PATCH v3 14/15] ARM: add uprobes support |
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On 11/27/2013 04:53 AM, David Long wrote: > From: "David A. Long" <dave.long@linaro.org> > > Using Rabin Vincent's ARM uprobes patches as a base, enable uprobes > support on ARM. > > Caveats: > > - Thumb is not supported > - XOL abort/trap handling is not implemented > > Signed-off-by: David A. Long <dave.long@linaro.org> > --- > arch/arm/Kconfig | 4 + > arch/arm/include/asm/ptrace.h | 6 + > arch/arm/include/asm/thread_info.h | 5 +- > arch/arm/include/asm/uprobes.h | 34 ++++++ > arch/arm/kernel/Makefile | 1 + > arch/arm/kernel/signal.c | 4 + > arch/arm/kernel/uprobes-arm.c | 223 +++++++++++++++++++++++++++++++++++++ > arch/arm/kernel/uprobes.c | 198 ++++++++++++++++++++++++++++++++ > arch/arm/kernel/uprobes.h | 27 +++++ > 9 files changed, 501 insertions(+), 1 deletion(-) > create mode 100644 arch/arm/include/asm/uprobes.h > create mode 100644 arch/arm/kernel/uprobes-arm.c > create mode 100644 arch/arm/kernel/uprobes.c > create mode 100644 arch/arm/kernel/uprobes.h >
[snip]
> diff --git a/arch/arm/kernel/uprobes-arm.c b/arch/arm/kernel/uprobes-arm.c > new file mode 100644 > index 0000000..0a83ad7 > --- /dev/null > +++ b/arch/arm/kernel/uprobes-arm.c > @@ -0,0 +1,223 @@ > +#include <linux/kernel.h> > +#include <linux/wait.h> > +#include <linux/uprobes.h> > +#include <linux/module.h> > + > +#include "probes.h" > +#include "probes-arm.h" > +#include "uprobes.h" > + > +static int uprobes_substitute_pc(unsigned long *pinsn, u32 oregs) > +{ > + probes_opcode_t insn = *pinsn;
In a current implementation pinsn points to an ixol field of arch_uprobe structure, which has native endianness and is written via __opcode_to_mem_arm() macro in arch_uprobe_analyze_insn() function. So *pinsn should be wrapped with __opcode_to_mem_arm/__mem_to_opcode_arm() macros in this function.
> + probes_opcode_t temp; > + probes_opcode_t mask; > + int freereg; > + u32 free = 0xffff; > + u32 regs; > + > + for (regs = oregs; regs; regs >>= 4, insn >>= 4) { > + if ((regs & 0xf) == REG_TYPE_NONE) > + continue; > + > + free &= ~(1 << (insn & 0xf)); > + } > + > + /* No PC, no problem */ > + if (free & (1 << 15)) > + return 15; > + > + if (!free) > + return -1; > + > + /* > + * fls instead of ffs ensures that for "ldrd r0, r1, [pc]" we would > + * pick LR instead of R1. > + */ > + freereg = free = fls(free) - 1; > + > + temp = *pinsn; > + insn = *pinsn; > + regs = oregs; > + mask = 0xf; > + > + for (; regs; regs >>= 4, mask <<= 4, free <<= 4, temp >>= 4) { > + if ((regs & 0xf) == REG_TYPE_NONE) > + continue; > + > + if ((temp & 0xf) != 15) > + continue; > + > + insn &= ~mask; > + insn |= free & mask; > + } > + > + *pinsn = insn; > + return freereg; > +} > +
[snip]
> + > +enum probes_insn > +uprobe_decode_ldmstm(probes_opcode_t insn, > + struct arch_specific_insn *asi, struct decode_header *d) > +{ > + struct arch_uprobe *auprobe = container_of(asi, struct arch_uprobe, > + asi); > + unsigned reglist = insn & 0xffff; > + int rn = (insn >> 16) & 0xf; > + int lbit = insn & (1 << 20); > + unsigned used = reglist | (1 << rn); > + > + if (rn == 15) > + return INSN_REJECTED; > + > + if (!(used & (1 << 15))) > + return INSN_GOOD; > + > + if (used & (1 << 14)) > + return INSN_REJECTED; > + > + /* Use LR instead of PC */ > + insn ^= 0xc000; > + > + auprobe->pcreg = 14; > + auprobe->ixol[0] = insn;
insn contains canonical opcode, but ixol should contain an opcode in native endianness. So it should be
auprobe->ixol[0] = __opcode_to_mem_arm(insn);
> + > + auprobe->prehandler = uprobe_set_pc; > + if (lbit) > + auprobe->posthandler = uprobe_write_pc; > + else > + auprobe->posthandler = uprobe_unset_pc; > + > + return INSN_GOOD; > +} > +
-- Taras Kondratiuk
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